WO2025062121A1

WO2025062121A1 - Aerosol provision system, heater assembly and method

Info

Publication number: WO2025062121A1
Application number: PCT/GB2024/052408
Authority: WO
Inventors: Theresa O'DONNELL; Stefan Koch; Howard ROTHWELL; David LEADLEY; Matthew Hodgson
Original assignee: Nicoventures Trading Ltd
Current assignee: Nicoventures Trading Ltd
Priority date: 2023-09-19
Filing date: 2024-09-17
Publication date: 2025-03-27
Anticipated expiration: 2026-03-19

Abstract

Described is an aerosol provision system (1), the aerosol provision system including a heater assembly (6) and an aerosol-generating material storage region. The heater assembly comprises a substrate (62), a heater layer (64) provided on at least a first surface (62a) of the substrate and configured to generate heat, a first set of one or more capillary tubes (66, 66a) extending from a second surface (62b) of the substrate through the substrate and the heater layer and having a first characteristic, and a second set of one or more capillary tubes (66, 66b) extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic. The aerosol-generating material storage region is in fluid communication with the second surface of the substrate, and includes a first and a second aerosol-generating material. The second aerosol-generating material has a higher viscosity than the first aerosol-generating material, and the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material. Also described is a consumable for use with an aerosol provision system a method of manufacturing an aerosol provision system or a consumable and aerosol provision means.

Description

AEROSOL PROVISION SYSTEM, HEATER ASSEMBLY AND METHOD

Field

The present disclosure relates to electronic aerosol provision systems such as nicotine delivery systems (e.g. electronic cigarettes and the like).

Background

Electronic aerosol provision systems such as electronic cigarettes (e-cigarettes) generally contain a reservoir of a source liquid containing a formulation, typically including nicotine, from which an aerosol is generated, e.g. through heat vaporisation. An aerosol source for an aerosol provision system may thus comprise a heater having a heating element arranged to receive source liquid from the reservoir, for example through wicking I capillary action. While a user inhales on the device, electrical power is supplied to the heating element to vaporise source liquid in the vicinity of the heating element to generate an aerosol for inhalation by the user. Such devices are usually provided with one or more air inlet holes located away from a mouthpiece end of the system. When a user sucks on a mouthpiece connected to the mouthpiece end of the system, air is drawn in through the inlet holes and past the aerosol source. There is a flow path connecting the aerosol source and an opening in the mouthpiece so that air drawn past the aerosol source continues along the flow path to the mouthpiece opening, carrying some of the aerosol from the aerosol source with it. The aerosol-carrying air exits the aerosol provision system through the mouthpiece opening for inhalation by the user.

Typically, such electronic aerosol provision systems are provided with heater assemblies suitable for heating the source liquid to form an aerosol. An example of such a heater assembly is a wick and coil heater assembly, which is formed of a coil of wire (typically nichrome NiCr 8020) wrapped or coiled around a wick (which typically comprises a bundle of collected fibres, such as cotton fibres, extending along the longitudinal axis of the coil of wire). The ends of the wick extend on either side of the coil of wire and are inserted into the reservoir of the source liquid. However, such heater assemblies are not necessarily suited for all applications or all configurations of electronic aerosol provision systems.

So-called microfluidic heater assemblies have been proposed to try to address some of the issues of the abovementioned heater assemblies.

Additionally, it is desired to offer users of aerosol provision systems the ability to provide different sensorial experiences by combining aerosols formed from different aerosol generating materials. Such solutions are typically more costly, involving the provision of multiple heaters each supplied from a separate reservoir of liquid. However, such an approach may not suitable for cartridge designs that employ microfluidic heater assemblies due, in part, to the additional manufacturing costs that can be associated with microfluidic heater assemblies.

Alternatively, however, in the process of making such microfluidic heater assemblies the performance characteristics associated with how liquid (such as e-liquid) interacts with the heater assembly may not be satisfactory and thus a designer of such microfluidic heater assemblies may be forced to compromise between certain performance characteristics. This may result in microfluidic heater assemblies with overall less desirable performance characteristics.

Various approaches are described which seek to help address some of these issues.

Summary

According to a first aspect of certain embodiments there is provided an aerosol provision system, the aerosol provision system including a heater assembly and an aerosol-generating material storage region. The heater assembly comprises a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat, a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic, and a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic. The aerosol-generating material storage region is in fluid communication with the second surface of the substrate, and includes a first and a second aerosol-generating material. The second aerosol-generating material has a higher viscosity than the first aerosol-generating material, and the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material.

In accordance with some examples of the first aspect, the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material along the first set of one or more capillary tubes.

In accordance with some examples of the first aspect, the second set of one or more capillary tubes are configured to permit the first aerosol-generating material and the second aerosol-generating material to flow along the second set of one or more capillary tubes.

In accordance with some examples of the first aspect, the first aerosol-generating material when aerosolised by heater layer produces an aerosol having different characteristics compared to the second aerosol-generating material when aerosolised by the heater layer. In accordance with some examples of the first aspect, the first set of one or more capillary tubes are provided in one or more regions of the heater assembly such that the second aerosol-generating material is impeded or prevented from being provided to the heater layer in the one or more regions of the heater assembly.

In accordance with some examples of the first aspect, the heater layer in the one or more regions of the heater assembly is configured such that, in use, the one or more regions have a different operational characteristic compared to the rest of the heater layer.

In accordance with some examples of the first aspect, the first set of one or more capillary tubes differ from the second set of one or more capillary tubes by at least one of: a size of a cross-sectional area, the shape of the cross-sectional area, and the properties of side surfaces of the one or more capillary tubes.

In accordance with some examples of the first aspect, the aerosol-generating material storage portion comprises a first aerosol-generating material storage portion storing the first aerosol-generating material and a second aerosol-generating material storage portion storing the second aerosol-generating material, wherein the first aerosol-generating material storage portion and the second aerosol-generating material storage portion are both provided in fluid communication with the second surface of the substrate of the heater assembly.

According to a second aspect of certain embodiments there is provided a consumable for use with an aerosol provision system to generate an aerosol, the consumable including a heater assembly and an aerosol-generating material storage area. The heater assembly includes a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat, a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic, and a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic. The aerosol-generating material storage region is in fluid communication with the second surface of the substrate, and includes a first and a second aerosol-generating material. The second aerosol-generating material has a higher viscosity than the first aerosol-generating material, and the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material.

According to a third aspect of certain embodiments there is provided a method of manufacturing an aerosol provision system or a consumable for use with the aerosol provision system, the aerosol provision system or the consumable including a heater assembly, the heater assembly including a substrate, and a heater layer provided on at least a first surface of the substrate and configured to generate heat, the aerosol provision system or consumable further including an aerosol-generating material storage portion including a first aerosol-generating material and a second aerosol-generating material, wherein the second aerosol-generating material has a higher viscosity than the first aerosol-generating material. The method includes providing a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic, and providing a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic. The first set of one or more capillary tubes are configured to impede the flow of the second aerosolgenerating material.

According to a fourth aspect of certain embodiments there is provided aerosol provision means, the aerosol provision means including heater means and aerosol-generating material storage means. The heater means includes a substrate, heater layer means provided on at least a first surface of the substrate and configured to generate heat, a first set of capillary means extending from a second surface of the substrate through the substrate and the heater layer means and having a first characteristic, and a second set of capillary means extending from the second surface of the substrate through the substrate and the heater layer means and having a second characteristic different from the first characteristic. The aerosol-generating material storage means is in fluid communication with the second surface of the substrate, and includes a first and a second aerosol-generating material. The second aerosol-generating material has a higher viscosity than the first aerosol-generating material, and the first set of capillary means are configured to impede the flow of the second aerosol-generating material.

According to a fifth aspect of certain embodiments there is provided a heater assembly for an aerosol provision system, the heater assembly including a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat; and one or more capillary tubes extending from a second surface of the substrate and through the substrate and the heater layer, the one or more capillary tubes configured to supply aerosolgenerating material from the second surface of the substrate to the heater layer. The heater assembly includes a surface modification configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

In accordance with some examples of the fifth aspect, the surface modification comprises at least one of: a surface coating and a surface treatment. In accordance with some examples of the fifth aspect, the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the surface of the at least one of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

In accordance with some examples of the fifth aspect, the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the surface of the at least one of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

In accordance with some examples of the fifth aspect, the surface modification is provided on at least a part of the second surface of the substrate and is configured to adjust the characteristics of the at least a part of the surface of the second surface of the substrate with respect to the flow of aerosol-generating material capable of flowing along the second surface of the substrate.

In accordance with some examples of the fifth aspect, the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the second surface of the substrate, such that aerosol-generating material is capable of flowing towards openings of the one or more capillary tubes.

In accordance with some examples of the fifth aspect, the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the second surface of the substrate, such that the flow of aerosol-generating material toward openings of the one or more capillary tubes is reduced.

In accordance with some examples of the fifth aspect, the surface modification is provided on at least a part of the second surface of the substrate surrounding the opening of at least one of the one or more capillary tubes.

In accordance with some examples of the fifth aspect, the surface modification is provided on at least a part of the side surfaces of the one or more capillary tubes and is configured to adjust the characteristics of the at least a part of the side surfaces of the one or more capillary tubes with respect to the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes.

In accordance with some examples of the fifth aspect, the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes, such that aerosol-generating material is capable of flowing through the one or more capillary tubes at a greater rate. In accordance with some examples of the fifth aspect, the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes, such that aerosol-generating material is capable of flowing through the one or more capillary tubes at a lower rate.

In accordance with some examples of the fifth aspect, the surface modification is provided on at least a part of the surface of the heater layer and is configured to adjust the characteristics of the at least a part of the surface of the heater layer with respect to the flow of aerosol-generating material capable of flowing along the surface of the heater layer.

In accordance with some examples of the fifth aspect, the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the surface of the heater layer, such that aerosol-generating material is capable of flowing from openings of the one or more capillary tubes in the heater layer.

According to a sixth aspect of certain embodiments there is provided a consumable for use with an aerosol provision device, the consumable including an aerosol-generating material storage portion, an airflow pathway and the heater assembly of the first aspect, wherein the heater assembly is configured such that the second surface of the substrate is provided in fluid communication with the aerosol-generating material storage portion and the heater layer is provided in fluid communication with the airflow pathway.

According to a seventh aspect of certain embodiments there is provided an aerosol provision device for use with a consumable, the device including an airflow pathway and the heater assembly of the fifth aspect, wherein the heater assembly is configured such that the heater layer is provided in fluid communication with the airflow pathway.

According to an eighth aspect of certain embodiments there is provided an aerosol provision system, the aerosol provision system including an aerosol-generating material storage portion, an airflow pathway and the heater assembly of the fifth aspect, wherein the heater assembly is configured such that the second surface of the substrate is provided in fluid communication with the aerosol-generating material storage portion and the heater layer is provided in fluid communication with the airflow pathway.

According to a ninth aspect of certain embodiments there is provided method of manufacturing a heater assembly for an aerosol provision system, the heater assembly including a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat; and one or more capillary tubes extending from a second surface of the substrate and through the substrate and the heater layer, the one or more capillary tubes configured to supply aerosol-generating material from the second surface of the substrate to the heater layer. The method includes providing a surface modification configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one of the surface of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

According to a tenth aspect of certain embodiments there is provided heater means for an aerosol provision means, the heater means including a substrate, heater layer means provided on at least a first surface of the substrate and configured to generate heat, and capillary means extending from a second surface of the substrate and through the substrate and the heater layer means, the capillary means configured to supply aerosol-generating material from the second surface of the substrate to the heater layer means, wherein the heater means comprises surface modification means configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer means, the second surface of the substrate, and the side surfaces of the capillary means.

It will be appreciated that features and aspects of the invention described above in relation to the first and other aspects of the invention are equally applicable to, and may be combined with, embodiments of the invention according to other aspects of the invention as appropriate, and not just in the specific combinations described above.

Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an aerosol provision system in accordance with aspects of the present disclosure;

Figure 2 is an exploded perspective view of a cartomiser suitable for use in the aerosol provision system of Figure 1 ;

Figure 3 is a perspective view of a heater assembly in accordance with aspects of the present disclosure, wherein the heater assembly comprises a substrate, an electrically resistive layer, and capillary tubes extending through the substrate and electrically resistive layer;

Figure 4 schematically represents a first implementation of the heater assembly in which the first set of capillary tubes are configured to impede the flow of the second aerosol-generating material, whereby the cross-sectional size (diameter) of the first set of capillary tubes is set to be different to the cross-sectional size (diameter) of the second set of capillary tubes;

Figure 5 schematically represents a second implementation of the heater assembly in which the first set of capillary tubes are configured to impede the flow of the second aerosol- generating material, whereby the cross-sectional shape of the first set of capillary tubes is set to be different to the cross-sectional shape of the second set of capillary tubes;

Figure 6 schematically represents a third implementation of the heater assembly in which the first set of capillary tubes are configured to impede the flow of the second aerosol-generating material, whereby the first set of capillary tubes is provided with a surface modification change the properties of the first set of capillary tubes with respect to the properties of the second set of capillary tubes;

Figure 7 is a method in accordance with aspects of the present disclosure for forming a heater assembly;

Figures 8a and 8b schematically represent a first implementation of a heater assembly comprising surface modifications on the second surface of a substrate of the heater assembly, where Figure 8a shows a top-down view of the second surface and Figure 8b shows a perspective view of the heater assembly;

Figures 9a and 9b show second and third implementations of a heater assembly comprising surface modifications on the side surfaces of capillary tubes extending through the heater assembly, where Figure 9a shows a cross-sectional view of the heater assembly according to the second implementation comprising a fourth surface modification provided at one end of the capillary tube and Figure 9b shows a cross-sectional view of the heater assembly according to the third implementation comprising a fifth surface modification provided at another end of the capillary tube;

Figures 10a and 10b schematically represent a fourth implementation of a heater assembly comprising surface modifications on the surface of a heater layer of the heater assembly, where Figure 10a shows a top-down view of the surface of the heater layer and Figure 10b shows a perspective view of the heater assembly; and

Figure 11 is a method in accordance with aspects of the present disclosure for forming a heater assembly.

Detailed Description

Aspects and features of certain examples and embodiments are discussed I described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed I described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features. According to the present disclosure, a “non-combustible” aerosol provision system is one where a constituent aerosol-generating material of the aerosol provision system (or component thereof) is not combusted or burned in order to facilitate delivery of at least one substance to a user.

In some embodiments, the non-combustible aerosol provision system is an electronic cigarette, also known as a vaping device, electronic cigarette or electronic nicotine delivery system (END), although it is noted that the presence of nicotine in the aerosol-generating material is not a requirement. Throughout the following description the term “e-cigarette” is sometimes used but this term may be used interchangeably with aerosol (vapour) provision system.

In some embodiments, the non-combustible aerosol provision system is a hybrid system to generate aerosol using a combination of aerosol-generating materials, one or a plurality of which may be heated. Each of the aerosol-generating materials may be, for example, in the form of a solid, liquid or gel and may or may not contain nicotine. In some embodiments, the hybrid system comprises a liquid or gel aerosol-generating material and a solid aerosolgenerating material. The solid aerosol-generating material may comprise, for example, tobacco or a non-tobacco product.

Aerosol-generating material is a material that is capable of generating aerosol, for example when heated, irradiated or energized in any other way. Aerosol-generating material may, for example, be in the form of a liquid or gel which may or may not contain an active substance and/or flavourants.

In some embodiments, where suitable, the aerosol-generating material may comprise an “amorphous solid”, which may alternatively be referred to as a “monolithic solid” (i.e. non- fibrous). In some embodiments, the amorphous solid may be a dried gel. The amorphous solid is a solid material that may retain some fluid, such as liquid, within it. In some embodiments, the aerosol-generating material may for example comprise from about 50wt%, 60wt% or 70wt% of amorphous solid, to about 90wt%, 95wt% or 100wt% of amorphous solid.

In some embodiments, the or each aerosol-generating material may comprise one or more active substances and/or flavours, one or more aerosol-former materials, and optionally one or more other functional materials.

In some embodiments, the substance to be delivered comprises an active substance.

The active substance as used herein may be a physiologically active material, which is a material intended to achieve or enhance a physiological response. The active substance may for example be selected from nutraceuticals, nootropics, psychoactives. The active substance may be naturally occurring or synthetically obtained. The active substance may comprise for example nicotine, caffeine, taurine, theine, vitamins such as B6 or B12 or C, melatonin, cannabinoids, or constituents, derivatives, or combinations thereof. The active substance may comprise one or more constituents, derivatives or extracts of tobacco, cannabis or another botanical.

In some embodiments, the active substance comprises nicotine. In some embodiments, the active substance comprises caffeine, melatonin or vitamin B12.

As noted herein, the active substance may comprise one or more constituents, derivatives or extracts of cannabis, such as one or more cannabinoids or terpenes.

As noted herein, the active substance may comprise or be derived from one or more botanicals or constituents, derivatives or extracts thereof. As used herein, the term "botanical" includes any material derived from plants including, but not limited to, extracts, leaves, bark, fibres, stems, roots, seeds, flowers, fruits, pollen, husk, shells or the like. Alternatively, the material may comprise an active compound naturally existing in a botanical, obtained synthetically. The material may be in the form of liquid, gas, solid, powder, dust, crushed particles, granules, pellets, shreds, strips, sheets, or the like. Example botanicals are tobacco, eucalyptus, star anise, hemp, cocoa, cannabis, fennel, lemongrass, peppermint, spearmint, rooibos, chamomile, flax, ginger, ginkgo biloba, hazel, hibiscus, laurel, licorice (liquorice), matcha, mate, orange skin, papaya, rose, sage, tea such as green tea or black tea, thyme, clove, cinnamon, coffee, aniseed (anise), basil, bay leaves, cardamom, coriander, cumin, nutmeg, oregano, paprika, rosemary, saffron, lavender, lemon peel, mint, juniper, elderflower, vanilla, Wintergreen, beefsteak plant, curcuma, turmeric, sandalwood, cilantro, bergamot, orange blossom, myrtle, cassis, valerian, pimento, mace, damien, marjoram, olive, lemon balm, lemon basil, chive, carvi, verbena, tarragon, geranium, mulberry, ginseng, theanine, theacrine, maca, ashwagandha, damiana, guarana, chlorophyll, baobab or any combination thereof. The mint may be chosen from the following mint varieties: Mentha Arventis, Mentha c.v..Mentha niliaca, Mentha piperita, Mentha piperita citrata c.v., Mentha piperita c.v, Mentha spicata crispa, Mentha cardifolia, Memtha longifolia, Mentha suaveolens variegata, Mentha pulegium, Mentha spicata c.v. and Mentha suaveolens.

In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is tobacco. In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is selected from eucalyptus, star anise, cocoa and hemp.

In some embodiments, the active substance comprises or derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is selected from rooibos and fennel.

In some embodiments, the substance to be delivered comprises a flavour.

As used herein, the terms "flavour" and "flavourant" refer to materials which, where local regulations permit, may be used to create a desired taste, aroma or other somatosensorial sensation in a product for adult consumers. They may include naturally occurring flavour materials, botanicals, extracts of botanicals, synthetically obtained materials, or combinations thereof (e.g., tobacco, cannabis, licorice (liquorice), hydrangea, eugenol, Japanese white bark magnolia leaf, chamomile, fenugreek, clove, maple, matcha, menthol, Japanese mint, aniseed (anise), cinnamon, turmeric, Indian spices, Asian spices, herb, Wintergreen, cherry, berry, red berry, cranberry, peach, apple, orange, mango, clementine, lemon, lime, tropical fruit, papaya, rhubarb, grape, durian, dragon fruit, cucumber, blueberry, mulberry, citrus fruits, Drambuie, bourbon, scotch, whiskey, gin, tequila, rum, spearmint, peppermint, lavender, aloe vera, cardamom, celery, cascarilla, nutmeg, sandalwood, bergamot, geranium, khat, naswar, betel, shisha, pine, honey essence, rose oil, vanilla, lemon oil, orange oil, orange blossom, cherry blossom, cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, wasabi, piment, ginger, coriander, coffee, hemp, a mint oil from any species of the genus Mentha, eucalyptus, star anise, cocoa, lemongrass, rooibos, flax, ginkgo biloba, hazel, hibiscus, laurel, mate, orange skin, rose, tea such as green tea or black tea, thyme, juniper, elderflower, basil, bay leaves, cumin, oregano, paprika, rosemary, saffron, lemon peel, mint, beefsteak plant, curcuma, cilantro, myrtle, cassis, valerian, pimento, mace, damien, marjoram, olive, lemon balm, lemon basil, chive, carvi, verbena, tarragon, limonene, thymol, camphene), flavour enhancers, bitterness receptor site blockers, sensorial receptor site activators or stimulators, sugars and/or sugar substitutes (e.g., sucralose, acesulfame potassium, aspartame, saccharine, cyclamates, lactose, sucrose, glucose, fructose, sorbitol, or mannitol), and other additives such as charcoal, chlorophyll, minerals, botanicals, or breath freshening agents. They may be imitation, synthetic or natural ingredients or blends thereof. They may be in any suitable form, for example, liquid such as an oil, solid such as a powder, or gas.

In some embodiments, the flavour comprises menthol, spearmint and/or peppermint. In some embodiments, the flavour comprises flavour components of cucumber, blueberry, citrus fruits and/or redberry. In some embodiments, the flavour comprises eugenol. In some embodiments, the flavour comprises flavour components extracted from tobacco. In some embodiments, the flavour comprises flavour components extracted from cannabis.

In some embodiments, the flavour may comprise a sensate, which is intended to achieve a somatosensorial sensation which are usually chemically induced and perceived by the stimulation of the fifth cranial nerve (trigeminal nerve), in addition to or in place of aroma or taste nerves, and these may include agents providing heating, cooling, tingling, numbing effect. A suitable heat effect agent may be, but is not limited to, vanillyl ethyl ether and a suitable cooling agent may be, but not limited to eucolyptol, WS-3.

The aerosol-former material may comprise one or more constituents capable of forming an aerosol. In some embodiments, the aerosol-former material may comprise one or more of glycerine, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-butylene glycol, erythritol, meso-Erythritol, ethyl vanillate, ethyl laurate, a diethyl suberate, triethyl citrate, triacetin, a diacetin mixture, benzyl benzoate, benzyl phenyl acetate, tributyrin, lauryl acetate, lauric acid, myristic acid, and propylene carbonate.

The one or more other functional materials may comprise one or more of pH regulators, colouring agents, preservatives, binders, fillers, stabilizers, and/or antioxidants.

An aerosol-modifying agent is a substance, typically located downstream of the aerosol generation area, that is configured to modify the aerosol generated, for example by changing the taste, flavour, acidity or another characteristic of the aerosol. The aerosol-modifying agent may be provided in an aerosol-modifying agent release component, that is operable to selectively release the aerosol-modifying agent.

The aerosol-modifying agent may, for example, be an additive or a sorbent. The aerosolmodifying agent may, for example, comprise one or more of a flavourant, a colourant, water, and a carbon adsorbent. The aerosol-modifying agent may, for example, be a solid, a liquid, or a gel. The aerosol-modifying agent may be in powder, thread or granule form. The aerosol-modifying agent may be free from filtration material.

Typically, the non-combustible aerosol provision system may comprise a non-combustible aerosol provision device and a consumable for use with the non-combustible aerosol provision device. In some embodiments, the disclosure relates to consumables comprising aerosol-generating material and configured to be used with non-combustible aerosol provision devices. These consumables are sometimes referred to as articles throughout the disclosure. In some embodiments, the non-combustible aerosol provision system, such as a noncombustible aerosol provision device thereof, may comprise a power source and a controller. The power source may, for example, be an electric power source.

In some embodiments, the non-combustible aerosol provision system may comprise an area for receiving the consumable, an aerosol generator, an aerosol generation area, a housing, a mouthpiece, a filter and/or an aerosol-modifying agent.

A consumable is an article comprising or consisting of aerosol-generating material, part or all of which is intended to be consumed during use by a user. A consumable may comprise one or more other components, such as an aerosol-generating material storage area, an aerosolgenerating material transfer component, an aerosol generation area, a housing, a wrapper, a mouthpiece, a filter and/or an aerosol-modifying agent. A consumable may also comprise an aerosol generator, such as a heater, that emits heat to cause the aerosol-generating material to generate aerosol in use. The heater may, for example, comprise combustible material, a material heatable by electrical conduction, or a susceptor.

An aerosol generator is an apparatus configured to cause aerosol to be generated from the aerosol-generating material. In some embodiments, the aerosol generator is a heater configured to subject the aerosol-generating material to heat energy, so as to release one or more volatiles from the aerosol-generating material to form an aerosol.

In accordance with an aspect of the present disclosure, an aerosol provision system is provided that includes an aerosol generating-material storage area having a first aerosolgenerating material and a second aerosol-generating material, the second aerosolgenerating material having a higher viscosity than the first aerosol-generating material. A heater assembly comprises a first set of capillary tubes and a second set of capillary tubes provided to transport liquid aerosol-generating material from one side of the heater assembly to an electrically resistive layer acting as an aerosol generator. The first set of capillary tubes is arranged to impede the flow of the second aerosol-generating material. In this way, the heater assembly can be arranged to control the flow of the second aerosol-generating material to the electrically resistive layer. This can result in a passive control of the proportions of the aerosol formed from the first aerosol-generating material and the second aerosol-generating material, or can influence the characteristics, such as particle size, of the aerosol generated from each of the first and second aerosol-generating materials. This can subsequently influence or alter the user experience when using such an aerosol provision system. Additionally, it should be noted that a single heater assembly can be supplied with two different aerosol-generating materials and can subsequently be configured (by setting the respective capillary tubes) to alter the properties of the aerosol generated. This is potentially a simpler mechanism to vary the proportions I characteristics of an aerosol generated form two aerosol-generating materials, as opposed to using a series of heaters each fed with different aerosol-generating material and controlled independently.

Figure 1 schematically shows an aerosol provision system 1 in accordance with aspects of the present disclosure. The aerosol provision system 1 comprises an aerosol provision device 2 and a consumable 3, herein shown and referred to as a cartomiser 3. The aerosol provision device 2 and the cartomiser 3 together form the aerosol provision system 1.

The cartomiser 3 is configured to engage and disengage with the aerosol provision device 2. That is, the cartomiser 3 is releasably connected I connectable to the aerosol provision device 2. More specifically, the cartomiser 3 is configured to engage I disengage with the aerosol provision device 2 along the longitudinal axis L1. The cartomiser 3 and aerosol provision device 2 are provided with suitable interfaces to allow the cartomiser 3 and aerosol provision device 2 to engage I disengage from one another, e.g., a push fit interface, a screwthread interface, etc.

The cartomiser 3 comprises a reservoir which stores an aerosol-generating material. Accordingly, the reservoir may also be referred to as an aerosol-generating material storage area or portion. In the following, the aerosol-generating material is a liquid aerosolgenerating material. The liquid aerosol-generating material (herein sometimes referred to simply as liquid, source liquid or e-liquid) may be an e-liquid which may or may not contain nicotine. However, it should be appreciated that other liquids and I or aerosol-generating materials capable of flowing (e.g., such as a gel) may be used in accordance with the principles of the present disclosure. The cartomiser 3 is able to be removed from the aerosol provision device 2 when, for example, the cartomiser 3 is depleted and is to be refilled with liquid or replaced with another (full) cartomiser 3.

The aerosol provision device 2 comprises a power source (such as a rechargeable battery) and control electronics (sometimes referred to as a controller). As will be described below, the cartomiser 3 comprises an electrically powered heater assembly. When the cartomiser 3 is coupled to the aerosol provision device 2, the control electronics of the aerosol provision device 2 are configured to supply electrical power to the heater assembly of the cartomiser 3 to cause the heater assembly to generate an aerosol from the liquid aerosol-generating material supplied thereto.

The control electronics may be provided with various components to facilitate I control the supply of power to the cartomiser 3. For example, the control electronics may be provided with an airflow sensor (not shown) configured to detect when a user of the aerosol provision system 1 inhales on the aerosol provision system and to supply power in response to such a detection and / or a push button (not shown) which is pressed by the user and to supply power in response to such a detection. Additional functions may be controlled by the control electronics depending on the configuration of the aerosol provision device 2 (for example, the control electronics may be configured to control I regulate recharging of the power source, or to facilitate wired or wireless communication with another electronic device, such as a smartphone). The features and functions of the aerosol provision device 2 are not of primary significance in respect of the present disclosure.

Figure 2 shows an example cartomiser 3 suitable for use in the aerosol provision system of Figure 1. From the exploded view of Figure 2, it may be seen that the cartomiser 3 is assembled from a stack of components: an outer housing 4, an upper clamping unit 5, a heater assembly 6, a lower support unit 7 and an end cap 8.

The cartomiser 3 has a top end 31 and a bottom end 32 which are spaced apart along the longitudinal axis L1 , which is the longitudinal axis of the cartomiser as well as being the longitudinal axis of the aerosol provision system 1. The top end 31 of the cartomiser 3 defines a mouthpiece 33 of the aerosol provision system 1 (around which a user may place their mouth and inhale). The mouthpiece 33 includes a mouthpiece orifice 41 which is provided at the top end 42 of outer housing 4 in the centre of a top face 43.

The outer housing 4 includes a circumferential side wall 44 which leads down from the top end 42 to a bottom end 45 of the outer housing 4 and which defines an internal reservoir 46 for holding the liquid aerosol-generating material (and may be referred to as an aerosolgenerating material storage area). Prior to assembly of the cartomiser 3, the bottom end 45 of the outer housing is open, but upon assembly the bottom end 45 is closed by a plug formed by the upper clamping unit 5 and the lower support unit 7 which are stacked together with the heater assembly 6 sandwiched therebetween.

The upper clamping unit 5 is an intermediate component of the stack of components. The upper clamping unit 5 includes a foot 51 in the form of a block and an upwardly extending air tube 52. On each side of the air tube 52, the foot 51 includes a well 53 which descends from a flat top surface 54 to a flat bottom surface (not shown in Figure 2) of the foot 51. At the bottom surface, each well 53 is open and, specifically, opens into an elongate recess formed in the bottom surface, with the depth of the recess broadly matching the size I shape and thickness of the heater assembly 6. The foot 51 is designed to engage with the outer housing 4 (more specifically, such that the outer circumferential surface of the foot is pressed against an inner circumferential surface of the outer housing 4). The foot 51 may have a suitable shape and include suitable sealing components to reduce or prevent liquid from leaking between the outer surface of the foot 51 and the inner surface of the housing 4. The air tube 52 extends up from the bottom of the wells 53 and defines an internal air passage 58. When the upper clamping unit 5 is engaged with the outer housing 4, the air tube 52 extends up to and encircles the mouthpiece orifice 41. The outer housing 4 and/or the air tube 52 may be suitably configured so as to provide a liquid- (and optionally air-) tight seal between the two. As will be understood below, air I aerosol is intended to pass along the air tube 52 and out of the mouthpiece orifice 41, while the space around the air tube 52 and within the outer housing 4 defines the reservoir 46 for storing the liquid aerosolgenerating material. Hence, it should be understood that, with the exception of the openings of the wells 53, the reservoir 46 is a sealed volume defined by the outer housing 4, the outer surface of the air tube 52, and the foot 51.

The lower support unit 7 is in the form of a block having a broadly flat top surface 71 and a flat bottom surface 72. A central air passage 73 extends upwardly from the bottom surface 72 to the top surface 71. On each side of the air passage 73, the block of the lower support unit 7 includes a through hole 74. In the example cartomiser 3 of Figure 2, a co-moulded contact pad 75 in the form of a pin is inserted into the through holes 74. More specifically, each contact pad 75 is a press fit in its respective through hole 74. Each contact pad 75 provides an electrical connection path from the bottom surface 72 to a respective end portion of the heater assembly 6 when the heater assembly 6 is sandwiched between the top surface 71 of the lower support unit 7 and the recess of the bottom surface 55 of the upper clamping unit 5.

Much like the upper clamping unit 5, the lower support unit 7 is designed to engage with the outer housing 4 (more specifically, such that the outer circumferential surface of the lower support unit 7 is pressed against an inner circumferential surface of the outer housing 4). The lower support unit 7 may have a suitable shape and include suitable sealing components to reduce or prevent liquid from leaking between the outer surface of the lower support unit 7 and the inner surface of the housing 4. The foot 51 of the upper clamping unit 5 and the lower support unit 7 (with its block-like form) combine together to form a plug which seals the bottom end of the reservoir 46.

As shown in Figure 2, the cartomiser 3 includes an end cap 8 at its bottom end. The end cap 8 is made of metal and serves to assist with retaining the cartomiser 3 in the aerosol provision device 2 when the cartomiser 3 is plugged in to the top end of the aerosol provision device 2, because, in this example, the aerosol provision device 2 is provided with magnets which are attracted to the metal of the end cap 8. The end cap 8 has a bottom wall 81 with a central opening (not shown in Figure 2). The end cap 8 also has a circumferential side wall 83 which has two opposed cut-outs 84 which latch onto corresponding projections 49 on the outer surface of the bottom end of the side wall 44 of the outer housing 4, so that the end cap 8 has a snap-fit type connection onto the bottom end of the outer housing 4. When the end cap 8 has been fitted in position, it holds in position the lower support unit 7, the upper clamping unit 5 and the heater assembly 6 which is sandwiched between the lower support unit 7 and the upper clamping unit 5.

It would be possible to omit the end cap 8 (in order to reduce the component count) by arranging for the lower support unit 7 to form a snap-fit type connection with the bottom end of the side wall 44 of the outer housing 4. Additionally, the cartomiser 3 could be provided with indentations which engage with projections at the top end 21 of the main housing 2, so that a releasable connection is provided between the cartomiser and the main housing. However, the way in which the cartomiser 3 is configured to engage with and couple to the aerosol provision device 2 (and subsequently how the aerosol provision device 2 is correspondingly configured to engage with the cartomiser 3) is not significant to the principles of the present disclosure. In any case, the cartomiser 3 is provided what may more generally be referred to as a device interface which is a part of the cartomiser 3 that interfaces with the main housing 2 (or aerosol-generating device). In the above example, the device interface may include the metal cap 8 including the bottom wall and circumferential side wall 83 and I or the lower support unit 7 including the bottom surface 72. More generally, the device interface of the cartomiser 3 may encompass any part or parts of the cartomiser 3 that contact, abut, engage or otherwise couple to the main housing 2.

When the components of the cartomiser 3 have been assembled together, an overall air passage exists from the bottom end 32 to the top end 31 of the cartomiser 3 and it is formed by the air passage 73 leading to the air passage 58 which, in turn, leads to the mouthpiece orifice 41. Where the air passage 73 meets the air passage 58, the air flow bifurcates as it passes around the side edges of the heater assembly 6.

With reference back to Figure 1, the top end 21 of the aerosol provision device 2 includes an air inlet hole 22 on each side of the aerosol provision device 2 (with one of the two air inlet holes 22 being visible in Figure 1). Air can enter the air inlet holes 22 and flow transversely inwards to the longitudinal axis L1 so as to enter the bottom end of the air passage 73 of the lower support unit 7 and to start to flow in the direction of the longitudinal axis L1 towards the mouthpiece 33.

In addition, when the components of the cartomiser 3 have been assembled, the heater assembly 6 is arranged such that the ends thereof are in fluid communication with the wells 53 (or openings to the wells 53). Liquid aerosol-generating material in the reservoir 46 is therefore able to pass to the ends of the heater assembly 6 via the wells 53. Liquid aerosolgenerating material is also permitted to travel along the longitudinal direction of the heater assembly 6, e.g., to regions of the heater assembly 6 that are not in direct contact with the reservoir 46, such as a region of the heater assembly that is provided in the air passage 73 or air passage 58. Any suitable arrangement may be provided to facilitate the transfer of liquid along the longitudinal direction. For example, in some implementations, a wicking material, such as cotton or glass fibres, formed as a layer may be provided between the heater assembly 6 and the upper clamping unit 5, where the wicking material is in contact with the wells 53 and capable of transporting the liquid aerosol-generating material in the longitudinal direction. Additionally or alternatively, the heater assembly 6 itself may be formed with one or more channels permitting the transport of liquid aerosol-generating material along the length of the heater assembly 6. For example, in some implementations, the heater assembly 6 may be formed from a porous substrate (such as a sintered material or a ceramic) and/or have channels formed (such as through drilling or other machining) along the length of the heater assembly 6. Accordingly, even though only a part of the heater assembly 6 in Figure 2 is shown in contact with the wells 53, liquid is capable of travelling along the length of the heater assembly.

Turning now to the heater assembly 6, the heater assembly 6 is a microfluidic heater assembly. Figure 3 illustrates the microfluidic heater assembly 6 in more detail.

The microfluidic heater assembly 6 comprises a substrate 62 and an electrically resistive layer 64 disposed on a surface of the substrate 62.

In this implementation, the substrate 62 is formed from a non-conductive material, such as quartz (silicon dioxide); however, it should be appreciated that other suitable non-conductive materials may be used, such as ceramics, for example. As noted above, the substrate 62 in some implementations may be formed from a porous material. The porous substrate 62 may be formed from naturally porous materials, such as sponges, porous stones or ceramics etc., or via materials that are engineered to be porous, such as sintered metals or other materials. These materials, either formed naturally or engineered, have pores or hollow regions which are interconnected and define passages that follow a random or substantially random pathway through the material (where substantially in this context means that, considering the bulk material of the substrate 62 as a whole, there may be some general trend in the direction that the pathways extend, e.g., left to right, but from the perspective of liquid I fluid passing through the substrate 62, the pathway is a series of random selections of e.g., pores or hollow regions). In other implementations, the substrate 62 may be considered impermeable or substantially impermeable (where substantially in this context means that the substrate 62 may have some degree of absorption of fluid, e.g., e-liquid; for example, the substrate 62 may be capable of absorbing up to 2 % or up to 1 % of the total volume of the substrate 62 of a volume of fluid). The way in which the substrate 62 is formed and the materials it is made therefrom is not of primary significance to the principles of the present disclosure.

The electrically resistive layer 64 is formed from any suitable electrically conductive material, for example a metal or a metal alloy such as titanium or nickel chromium. The electrically resistive layer 64 may be formed on a first surface 62a of the substrate 62 in any suitable way. For example, the electrically resistive layer 64 may be provided as a film that is adhered or otherwise bonded to the first surface 62a of the substrate 62. Alternatively, the electrically resistive layer 64 may be formed though a deposition technique, such as chemical or vapour deposition. The way in which the electrically resistive layer 64 is formed and the materials it is made therefrom is not of primary significance to the principles of the present disclosure.

The heater assembly 6 is planar and in the form of a rectangular cuboidal block, elongate in the direction of a longitudinal axis L2. The heater assembly 6 has the shape of a strip and has parallel sides. The planar heater assembly 6 has parallel upper and lower major (planar) surfaces, herein denoted as the first surface 62a and second surface 62b of the substrate 62, and parallel side surfaces and parallel end surfaces. In the shown implementation of Figure 3, the length of the heater assembly 6 is 10 mm, its width is 1 mm, and its thickness is 0.12 mm (where the thickness of the substrate 62 is approximately 0.10 mm, and the thickness of the electrically resistive layer 64 is approximately 0.02 mm). The small size of the heater assembly 6 enables the overall size of the cartomiser 3 to be reduced and the overall mass of the components of the cartomiser 3 to be reduced.

However, it should be appreciated that in other implementations, the heater assembly 6 may have different dimensions depending upon the application at hand. For example, in some implementations, the heater assembly 6 may be a 3 x 3 mm chip.

Along the longitudinal axis L2, the heater assembly 6 has a central portion 67 and first and second end portions 68, 69. In Figure 3, the length of the central portion 67 (relative to the lengths of the end portions 68, 69) has been exaggerated for reasons of visual clarity. When the vaporizer is in situ in the cartomiser, the central portion 67 is positioned in the air passage 73. The central portion 67 extends across the top end of the air passage 73 of the lower support unit 7, and across the bottom end of the air passage 58 of the upper clamping unit 5. The end portions 68, 69 are clamped between the upper clamping unit 5 and the lower support unit 7.

In the central portion 67 of the heater assembly 6, a plurality of capillary tubes 66 are provided. Only the openings of the capillary tubes 66 are shown in Figure 3 (and in an exaggerated way for clarity), but the capillary tubes 66 extend from one side of the heater assembly 6 to the other. More specifically, the capillary tubes extend from the second surface 62b of the substrate 62, through the substrate 62 toward the first surface 62a of the substrate 62 on which the electrically resistive layer 64 is disposed, and then through the electrically resistive layer 64. The plurality of capillary tubes 66 extend substantially linearly through the heater assembly 6 (that is, the capillary tubes 66 follow substantially linear paths). By substantially, it is meant that the capillary tubes 66 follow pathways that are within 5 %, within 2 % or within 1 % of a straight line. This measure may be obtained in any suitable way, e.g., by comparison of the length of the distance from a first point to a second point along the extent of the capillary tube 66 and the corresponding distance that the central axis of the capillary tube 66 extends between the same two points. The capillary tubes 66 are formed in the heater assembly 66 via a manufacturing process. That is to say, the capillary tubes 66 do not naturally exist in the substrate material 62 or electrically resistive layer 64, but rather, the capillary tubes 66 are formed in the substrate material 62 and electrically resistive layer 64 through a suitable process. A suitable process for forming the capillary tubes 66, particularly when forming capillary tubes that substantially follow a linear path, is laser drilling. However, any other suitable technique may be employed in order to generate the capillary tubes 66.

The capillary tubes 66 are configured so as to transport liquid from one surface of the heater assembly 6 (i.e., the second surface 62b of the substrate 62) to the electrically resistive layer 64. The capillary tubes 66 may be formed based in part on the liquid to be stored in the reservoir 46 of the cartomiser 3 and subsequently used with the heater assembly 6, as will be explained in more detail below. Broadly speaking, however, in some implementations, the capillary tubes 66 may have a diameter on the order to tens of microns, e.g., between 10 pm to 100 pm. However, it should be appreciated that capillary tubes 66 in other implementations may be set differently.

With reference back to Figure 2, the heater assembly 6 is shown positioned between the upper clamping unit 5 and the lower support unit 7. In particular, the heater assembly 6 is oriented such that the electrically resistive layer 64 faces towards the lower support unit 7, while the substrate 62 (and in particular the second surface 62b) faces towards the upper clamping unit 5. It should be understood from Figure 2 that the end portions 68, 69 of the heater assembly 6 overlap the through holes 74 and the contact pads 75. More specifically, the electrically resistive layer 64 is provided in contact with the contact pads 75, and therefore the end portions 68, 69 of the electrically resistive layer 64 act to form an electrical connection with the contact pads 75 (and thus with any power source subsequently attached to the contact pads 75, such as from the aerosol provision device 2). For example, the aerosol provision device 2 may have two power supply pins (not shown) which make contact with the bottom ends of the contact pads 75. The top ends of the contact pads 75 are in electrical contact with the heater assembly 6, as above. In use, electrical power supplied by the power supply of the aerosol provision device 2 passes through the electrically resistive layer 64, by virtue of the electrical connection between the end portions 68, 69 and the contact pads 75, to cause heating of the electrically resistive layer 64. The electrically resistive layer 64 may therefore be referred to as a heater layer 64. The amount of heating achieved (i.e. , the temperature of the electrically resistive layer 64 that is able to be reached) may depend in part on the power supplied by the aerosol provision device 2 and the electrical resistance of the electrically resistive layer 64. Equally, the amount of heating (i.e., the temperature necessary to vaporise the liquid supplied to the resistive layer 64) will be dependent in part on the properties of the liquid supplied to the electrically resistive layer 64. Accordingly, the resistance of the electrically resistive layer 64 may be set based on the particular application at hand, whereby the resistance of the electrically resistive layer 64 may be dependent on the material of the electrically resistive layer 64 and the physical dimensions of the electrically resistive layer 64 (e.g., thickness).

In accordance with the principles of the present disclosure, the aerosol provision system 1 is configured to simultaneously store (at least) two different aerosol-generating materials, and subsequently the heater assembly 6 used in the aerosol provision system 1 (or more specifically, the cartomiser 3 thereof) is configured to aerosolise the different aerosolgenerating materials. By different aerosol-generating materials it is meant that the different aerosol-generating materials have at least one different characteristic, and in particular, the viscosity of the aerosol-generating materials. In particular, the second aerosol-generating material has a higher viscosity than the first aerosol-generating material. This may be realised, for example, by providing the aerosol-generating materials with different constituents and/or ratios of constituents. For instance, a first aerosol-generating material may comprise a liquid containing nicotine, a first flavourant and a first ratio of propylene glycol to glycerol, while a second aerosol-generating material may also comprise a liquid containing a second, different flavourant and a second ratio of propylene glycol to glycerol. The viscosity of the aerosol-generating materials may be different owing in part to the different ratios of propylene glycol to glycerol. For example, a liquid formulation that predominately comprise water as the majority component (by weight) may have a mean dynamic viscosity, measured at 25°C, in the range of 0.005 to 0.007 Pa s. A liquid formulation having around 65% by weight propylene glycol may have mean dynamic viscosities in the range of 0.088 to 0.174 Pa s, while a liquid formulation having around 50% by weight propylene glycol may have mean dynamic viscosities in the range 0.100 to 0.216 Pa s. Viscosity is a measure of resistance of a fluid to deformation at a given rate. Therefore, it can be said that more viscous aerosol-generating material, i.e., a higher mean dynamic viscosity, tends to face more resistance to flow and therefore flows generally at a slower rate than a less viscous material. It should be appreciated that the above provide examples of liquid formulations and their viscosities only, and the present disclosure should not be considered limited to the liquid formulations or viscosities denoted above.

In some examples, the liquid formulation may comprise 50% water by weight and 50% glycerol by weight. For such a formulation, the dynamic viscosity is measured at 0.00525 Pa s at 25°C. When a flavourant is added to the liquid formulation, the liquid formulation may comprise between 35-50% water by weight, between 35% to 50% glycerol by weight, and between 0 to 30% by weight of a flavourant component. The flavourant component may comprise a solvent (such as propylene glycol) in addition to any flavour imparting components. The dynamic viscosity for such a formulation is at least 0.00525 Pa s at 25°C. It is noted that the % by weight of water has a large impact on the measured dynamic viscosity and by reducing the % by weight of water the dynamic viscosity is expected to increase. In some examples, the liquid formulation may comprise an active ingredient and/or functional materials. In such cases, the % by weight of the constituents listed above varies in accordance with the amount of active ingredient and/or functional materials.

In some other examples, the liquid formulation may comprise 60% propylene glycol by weight and 40% glycerol by weight. For such a formulation, the dynamic viscosity is measured at 0.155 Pa s at 25°C. When a flavourant is added to the liquid formulation, the liquid formulation may comprise 40% glycerol by weight, between 30% to 60% propylene glycol by weight, and between 0 to 30% by weight of a flavourant component. The flavourant component may comprise a solvent (such as propylene glycol) in addition to any flavour imparting components. The dynamic viscosity for such a formulation is at least 0.1 Pa s at 25°C, and may be in the range of 0.10-0.17 Pa s at 25°C. In some examples, the liquid formulation may comprise an active ingredient and/or functional materials. In such cases, the % by weight of the constituents listed above varies in accordance with the amount of active ingredient and/or functional materials. For example, a specific liquid formulation comprises 30% flavourant component, 30% propylene glycol, 36.8% glycerol, 1.7% nicotine and 1.5% acid(s). This formulation is observed to have a dynamic viscosity of 0.1496 Pa s at 25°C.

In some other examples, the liquid formulation may comprise 50% propylene glycol by weight and 50% glycerol by weight. For such a formulation, the dynamic viscosity is measured at 0.2045 Pa s at 25°C. When a flavourant is added to the liquid formulation, the liquid formulation may comprise 50% glycerol by weight, between 20% to 50% propylene glycol by weight, and between 0 to 30% by weight of a flavourant component. The flavourant component may comprise a solvent (such as propylene glycol) in addition to any flavour imparting components. The dynamic viscosity for such a formulation is at least 0.2 Pa s at 25°C.

The different aerosol-generating materials are stored in the reservoir 46 of the cartomiser 3. In some implementations, the reservoir 46 may comprise a dividing wall that divides the reservoir 46 into separate chambers. For example, with reference to Figure 2, the central air tube 52 may act as a dividing wall to separate the left-hand side and right-hand side of the reservoir 46 such that, when the cartomiser 3 is assembled, the central air tube 52 acts to keep the left- and right-hand sides of the reservoir 46 separate. Accordingly, the first aerosol-generating material may be provided in the left-hand side of the reservoir 46 and the second aerosol-generating material may be provided in the right-hand side of the reservoir 46. However, in other implementations, the two aerosol-generating materials may be provided in a common reservoir 46 (or alternatively in both the left- and right-hand sides of the reservoir 46) provided the two aerosol-generating materials are not immiscible.

As should be appreciated, the reservoir 46 is in fluid communication with the heater assembly 6 through wells 53. Liquid aerosol-generating material that exits the reservoir 46 through the wells 53 passes to the capillary tubes 66 (potentially also via wicking material disposed between the heater assembly 6 and the upper clamping unit 5). The liquid aerosolgenerating material is then able to pass, under capillary action, from the surface of the substrate 62 to the electrically resistive layer 64 where it is subsequently vaporised. However, as should be appreciated, whether or not a liquid aerosol-generating material passes through the capillary tube 66 and the rate at which it passes from one end to the other of the capillary tube 66 may depend on a variety of factors.

In accordance with the present disclosure, the heater assembly 6 is provided with a first set of one or more capillary tubes 66 having a first characteristic and extending from the second surface 62b of the substrate 62 through the substrate 62 to the electrically resistive layer 64 and a second set of one or more capillary tubes 66 also extending from the second surface 62b of the substrate 62 through the substrate 62 to the electrically resistive layer 64 but having a second characteristic different from the first characteristic. Accordingly, based on the differences in the first and second characteristics, the first set of one or more capillary tubes 66 are configured to impede the flow of the second aerosol-generating material. More particularly, the first set of capillary tubes 66 are configured to impede (or in some instances prevent) the flow of the second aerosol-generating material through the first set of capillary tubes 66, such that a reduced amount (or in some instances none) of the second aerosol generating material flows through the first set of capillary tubes 66 to the electrically resistive layer 64. Providing the first and second set of capillary tubes 66, whereby the first set of capillary tubes 66 is configured to impede the flow of the second aerosol-generating material through the first set of capillary tubes 66, means that the heater assembly 6 is able to passively control the flow of the second aerosol-generating material to the electrically resistive layer 64 of the heater assembly 6, and thus the vaporisation of the second aerosol-generating material. It should be appreciated that although the first set of capillary tunes 66 are configured to impede the flow of the second aerosol-generating material, the second set of capillary tubes 66 are correspondingly configured to facilitate the flow of the second aerosolgenerating material. That is to say, the second aerosol-generating material is capable of flowing through the second set of capillary tubes 66. Therefore, the second set of capillary tubes 66 may be suitably configured to not impede (or at least impede to a lesser extent) the flow of the second aerosol-generating material through the second set of the capillary tubes 66.

Accordingly, the control of the flow of the second aerosol-generating material to the electrically resistive layer 64 can be controlled in at least two ways. In one example, the rate and/or amount of the second aerosol-generating material can be controlled by the heater assembly 6. For example, the amount and/or rate that the second aerosol-generating material is supplied to the electrically resistive layer 64 can be controlled by altering the number of the second set of capillary tubes 66. For example, a relatively larger number of the second set of capillary tubes 66 allows for a relatively larger amount of the second aerosol-generating material to be provided to the electrically resistive layer 64 and vaporised. This means the aerosol generated and provided to the user via the mouthpiece orifice has an increased amount of the second aerosol-generating material. In addition, it should also be appreciated that this may alter the proportion of the aerosol that is formed from the second aerosol-generating material to the proportion of the aerosol that is formed from the first aerosol-generating material. For example, increasing the number of the second set of capillary tubes 66, thus allowing for a relatively larger amount of the second aerosolgenerating material to be provided to the electrically resistive layer 64 and vaporised, will mean that a greater proportion of the aerosol is provided by the second aerosol-generating material than, for example, where there is a relatively lower number of the second set of capillary tubes 66. Note that the second capillary tubes 66 are likely to also allow the first aerosol-generating material to travel therethrough. That is to say, the second set of one or more capillary tubes 66 are configured to permit the first aerosol-generating material and the second aerosol-generating material to flow along the second set of one or more capillary tubes 66. So, in some examples, the generated aerosol may have a ratio of aerosol generated by the first aerosol-generating material to aerosol generated by the second aerosol-generating material anywhere between (and excluding) the ratio of 1 :1 (i.e., 50% from the first aerosol-generating material and 50% from the second aerosol-generating material) to 1 :0 (i.e., 100% from the first aerosol-generating material). For example, the heater assembly 6 may be configured to provide a ratio of between and including 1:0.99 to 1 :0.01.

Accordingly, in this way, it can be seen that the heater assembly 6 can be configured to provide an aerosol to the user having different proportions of the aerosol generated from the first aerosol-generating material and the second aerosol-generating material. This affects the composition, and subsequently the user’s perception of, the aerosol delivered via the heater assembly 6.

In another example, providing the first and second set of capillary tubes 66 having different characteristics which influence the extent to which the second, more viscous aerosolgenerating material is able to flow through the first set of the capillary tubes 66 may mean that the second aerosol-generating material is (additionally or alternatively) able to be selectively provided to certain locations of the electrically resistive layer 64 for vaporisation. This may have an impact on the aerosol that is generated and subsequently delivered to the user via the orifice 41, and thus also impacts the user experience. That is to say, heater assembly 6 may be configured such that the first aerosol-generating material when aerosolised by electrically resistive layer 64 produces an aerosol having different characteristics compared to the second aerosol-generating material when aerosolised by the electrically resistive layer 64.

In some examples, during use of the heater assembly 6, that is when an electrical current is applied to the electrically resistive layer 64 of the microfluidic heater assembly 6, the temperatures reached across the electrically resistive layer 64 may not be uniform. That is to say, different regions of the electrically resistive layer 64 may reach higher temperatures than other regions of the electrically resistive layer 64 when operated. These regions of the electrically resistive layer 64 where the temperature is relatively higher may be referred to as “hot-spots” of the electrically resistive layer 64. These “hot-spots” may be the result of one or more features of the heater assembly 6 and/or the cartomiser 3 (e.g., such as the airflow past the heater assembly 6). For example, “hot-spots” may occur due to the application of an electric current to the electrically resistive layer 64, whereby variations in the flow of current across the electrically resistive layer 64 and/or variations in the resistance of the electrically resistive layer 64 may cause certain regions of the electrically resistive layer 64 to reach greater temperatures than others. By way of example, it may be that hot-spots appear within a central region of the central portion 67 of the heater assembly 6. That is to say, of the central portion 67, a central region of the central portion 67 may be at a generally higher temperature during operation than an outer or peripheral region of the central portion 67 that surrounds the central region of the central portion 67. More generally, the electrically resistive layer 64 may be configured such that one or more regions of the electrically resistive layer 64 have a different operational characteristic (i.e. , temperature) compared to the rest of the electrically resistive layer 64.

Accordingly, in some examples, the heater assembly 6 may be configured such that the second aerosol-generating material is supplied to these “hot-spots” (e.g., a central region of the central portion 67 of the electrically resistive layer 64). That is, the first set of capillary tubes 66, which impede the flow of the second aerosol-generating material, may be provided at locations around the central region of the central portion 67 (i.e., in the peripheral region of the central portion 67), while the second set of capillary tubes 66, which relative to the first set of capillary tubes 66 permit the flow of the second aerosol-generating material therethrough, may be provided in the central region of the central portion 67. Accordingly, the second aerosol-generating material may, generally, be aerosolised at a slightly higher temperature by being directed to the “hot-spots” of the heater assembly 6. This may subsequently affect the aerosol that is generated from the second aerosol-generating material when vaporised by the electrically resistive layer 64, for example, in terms of particle size or the like. For example, generally speaking, greater aerosolisation temperatures are understood to generally result in the formation of aerosols having a smaller particle size.

Alternatively, it should be appreciated that in some implementations, the second aerosolgenerating material may be directed to the cooler, peripheral region of the central portion 67 of the heater assembly 6 (e.g., by providing the first set of capillary tubes 66 in the central region of the central portion 67 of the heater assembly 6). Again, this may subsequently affect the aerosol that is generated from the second aerosol-generating material when vaporised by the electrically resistive layer 64, for example, in terms of particle size or the like. For example, generally speaking, lower aerosolisation temperatures are understood to generally result in the formation of aerosols having a larger particle size.

It should also be understood that in some implementations, the second aerosol-generating material may be selectively provided to regions of the heater assembly 6 irrespective of the operating temperature of the electrically resistive layer 64. That is, there may be other reasons to direct the second aerosol-generating material to certain locations of the heater assembly 6, which may affect the properties of the aerosol generated. For example, with reference to Figure 2, air flowing through the central air passage 73 bifurcates around the longitudinal edges of the heater assembly 6. This may mean, for example, that there is relatively lower turbulence in the air flow at the regions proximate the longitudinal edges of the heater assembly 6 than the central region of the centre portion 67. A greater turbulence may lead to greater particles sizes for any aerosol generated in that region (e.g., owing to a longer dwell time and/or a greater chance of coalescing). Thus, depending on the desired result to be achieved, the second aerosol-generating material may be directed to the edges of the electrically resistive layer 64 (by placing the first set of capillary tubes in the centre region of the central portion 67) or to the centre of the electrically resistive layer 64 (by placing the first set of capillary tubes 66 in the peripheral region of the central portion 67).

Hence, more generally, the first set of one or more capillary tubes 66 are provided in one (or more regions) of the heater assembly 6 such that the second aerosol-generating material is impeded or prevented from being provided to the electrically resistive layer 64 in the one or more regions of the heater assembly 6. This may be because the heater assembly 6 is observed to have different operating characteristics in different regions of the electrically resistive layer 64, either as a result of the configuration of the heater assembly 6 itself (such as the resistance of the electrically resistive layer 64 in different regions thereof) or as a result of the configuration of the cartomiser 31 aerosol provision system 1 (such as in terms of the airflow to I over I through the heater assembly 6). By selectively providing the second aerosol-generating material to certain regions of the electrically resistive layer 64, the desired aerosol generated from the second aerosol-generating material may be generated.

Hence, it should be appreciated that providing a heater assembly 6 with first and second sets of capillary tubes 66 allows for the heater assembly 6 (i.e. , a single heater assembly 6) to simultaneously generate aerosol from both the first aerosol-generating material and the second aerosol-generating material in a controlled manner. In particular, one or both of the relative proportion of the aerosol formed from the second aerosol-generating material and the characteristics of the aerosol formed from the second aerosol-generating material may be controlled or set based on suitable provision of the first and second sets of capillary tubes 66. Accordingly, the characteristics of the aerosol generated can be appropriately configured to achieve a particular outcome - e.g., such as flavour mixing, or targeted delivery to the user through particle size.

In accordance with the resent disclosure, the first set of one or more capillary tubes 66 differ from the second set of one or more capillary tubes 66 by at least one of: a size of a cross- sectional area of the capillary tubes 66, the shape of the cross-sectional area of the capillary tubes 66, and the properties of side surfaces of the one or more capillary tubes 66. However, it should be appreciated that in other implementations the first set of capillary tubes 66 may differ from the second set of capillary tubes 66 in any suitable way that subsequently impedes the flow of the second aerosol-generating material along the first set of capillary tubes 66. Figures 4 to 6 schematically and respectively represent three examples of a heater assembly 6 provided with a first set of capillary tubes 66a and a second set of capillary tubes 66b according to the principles of the present disclosure.

Figures 4 and 5 show a part of the central portion 67 of the heater assembly 6 as viewed from above (i.e., looking down onto the electrically resistive layer 64). A first set of a plurality of capillary tubes 66a are shown across the central portion 67 of the heater assembly 6, where, as above, the first set of capillary tubes 66a extend through to the second surface 62b of the heater assembly 6 (i.e., the surface opposite the electrically resistive layer 64) and have a first characteristic. Figures 4 and 5 also show a second set of a plurality of capillary tubes 66b provided in a central region 67a of the central portion 67 of the heater assembly 6. The central region 67a is highlighted via a dashed-line. As above, the second set of capillary tubes 66b extend through to the second surface 62b of the heater assembly 6 (i.e., the surface opposite the electrically resistive layer 64) and have a second characteristic different from the first characteristic.

Figure 4 represents a first example of a heater assembly 6 according to the present disclosure.

In Figure 4, the size of the cross-sectional area of the first set of capillary tubes 66a differs from the size of the cross-sectional area of the second set of capillary tubes 66b. In the example of Figure 4, the cross-sectional shape of both the first and second set of capillary tubes 66a, 66b is circular. However, the diameter of the second set of capillary tubes 66b is larger than the diameter of the first set of capillary tubes 66a (or alternatively, the diameter of the first set of capillary tubes 66a is smaller than the diameter of the second set of capillary tubes 66b). It should be appreciated that in other implementations the cross-sectional shape of the capillary tubes 66a, 66b may be different, e.g., square or hexagonal, etc. and in such cases at least one dimension of the cross-sectional area of the second set of capillary tubes 66b may be different (i.e., larger) than the equivalent dimension of the first set of capillary tubes 66a.

As stated above, several factors can influence how a liquid aerosol-generating material interacts with a capillary tube and subsequently the capillary forces that the aerosolgenerating material experiences. One of these factors is the size of the cross-sectional area of the capillary tubes 66, or in the context of the example of Figure 4, the diameter of the capillary tubes 66. Noting that the second aerosol-generating material is more viscous than the first aerosol-generating material, by appropriately setting the diameter of the first set of capillary tubes 66a to a small enough value, the second, more viscous, aerosol-generating material may not be able to sufficiently penetrate into the first set of capillary tubes 66a (for example, the surface tension of the second aerosol-generating material may prevent or reduce the chance for the second aerosol-generating material to enter the first set of capillary tubes 66a). Accordingly, as described above, by setting the diameter of the first set of capillary tubes 66a to a suitable (i.e., small enough) value, the first set of capillary tubes 66a can be configured to impede the flow of the second aerosol-generating material through the first set of capillary tubes 66a.

Additionally, it should be appreciated that the size (i.e., diameter) of the first set of capillary tubes 66a is also configured so as to suitably allow the first aerosol-generating material to pass into and through the first set of capillary tubes 66a. In other words, the size I diameter of the first set of capillary tubes 66a is set so as to be small enough to impede the flow of the second aerosol-generating material therethrough but large enough to allow the first aerosol - generating material to pass into and through the first set of capillary tubes 66a. Additionally, it should also be appreciated that the second set of capillary tubes 66b have a size (i.e., diameter) that is configured so as to suitably allow the second aerosol-generating material to pass into and through the second set of capillary tubes 66b.

In the example of Figure 4, the second set of capillary tubes 66b are provided in the first region 67a of the central portion 67 of the heater assembly 6. Hence, according to the above, it should be appreciated that the second aerosol-generating material is able to pass through the second capillary tubes 66b to the electrically resistive layer 64 in the first region 67a, but is prevented or impeded, or substantially prevented or impeded, from passing to the region of the electrically resistive layer 64 other than the first region 67a (where substantially in this context means that a small amount of the second aerosol-generating material may be capable of passing through the second capillary tubes 66b relative to the first aerosolgenerating material; e.g., in a ratio of 10:1 or greater in respect of the first aerosol-generating material to the second aerosol-generating material). Therefore, the second aerosolgenerating material is predominantly provided to the first region 67a which may correspond to a hot spot, for example, of the electrically resistive layer 64. Alternatively, although not shown, it should be appreciated that in other implementations, the second set of capillary tubes 66b may be distributed differently, e.g., uniformly, across the central portion 67.

Hence, accordingly by setting the size of the cross-sectional area of the capillary tubes 66a, 66b, the supply of the second aerosol-generating material to the electrically resistive layer 64 can be controlled or set accordingly.

Figure 5 represents a second example of a heater assembly 6 according to the present disclosure. In Figure 5, the shape of the cross-sectional area of the first set of capillary tubes 66a differs from the shape of the cross-sectional area of the second set of capillary tubes 66b. In the example of Figure 5, the cross-sectional shape of the first set of capillary tubes 66a is circular. However, the cross-sectional shape of the second set of capillary tubes 66b is, in this case, triangular. It should be appreciated that in other implementations the cross- sectional shapes of both the first and second sets of capillary tubes 66a, 66b may be different to those shown, e.g., square or hexagonal, etc.

As stated above, several factors can influence how a liquid aerosol-generating material interacts with a capillary tube and subsequently the capillary forces that the aerosolgenerating material experiences. Not only the size of the cross-sectional area of the capillary tubes 66, but in some instances the shape of the cross-sectional area may also influence whether the liquid aerosol-generating material is capable of flowing along the capillary tube 66. In the example of Figure 5, the shape and diameter of the first set of capillary tubes 66a to set such the second, more viscous, aerosol-generating material may not be able to sufficiently penetrate into the first set of capillary tubes 66a (for example, the surface tension of the second aerosol-generating material may prevent or reduce the chance for the second aerosol-generating material to enter the first set of capillary tubes 66a). Accordingly, as described above, by setting the shape and/or diameter of the first set of capillary tubes 66a to a suitable (i.e. , small enough) value, the first set of capillary tubes 66a can be configured to impede the flow of the second aerosol-generating material through the first set of capillary tubes 66a.

In the example of Figure 5, the second set of capillary tubes 66b have a triangular cross- sectional shape. Different cross-sectional shapes of the capillary tubes may impart different capillary forces on liquid aerosol-generating material that is capable of passing through the capillary tubes 66 and, additionally, the way in which the cross-sectional shape interacts with the surface tension of the liquid aerosol-generating material. In other words, owing to the cross-sectional shape, the shape of the capillary tubes 66 may be sufficient to cause the aerosol generating material to pass into the capillary tube 66. In Figure 5, the second capillary tubes 66b are provided so as to allow the second aerosol-generating material to pass into the capillary tubes 66b. It should be appreciated that in other examples, the cross- sectional shapes of the first capillary tubes 66a may alternatively be set to be a triangular shape or the like. The precise shapes and dimensions may depend on the properties of the aerosol-generating materials used and whether the first set of capillary tubes 66a are able to impede the flow of the second aerosol generating material along the first set of capillary tubes 66a. As with Figure 4, in Figure 5 the second set of capillary tubes 66b are provided in the first region 67a of the central portion 67 of the heater assembly 6. Therefore, similarly, the second aerosol-generating material is able to pass through the second capillary tubes 66b to the electrically resistive layer 64 in the first region 67a, but is prevent or impeded, or substantially prevented or impeded, from passing to the region of the electrically resistive layer 64 other than the first region 67a (where substantially again in this context means that a small amount of the second aerosol-generating material may be capable of passing through the second capillary tubes 66b relative to the first aerosol-generating material; e.g., in a ratio of 10:1 or greater in respect of the first aerosol-generating material to the second aerosol-generating material). Alternatively, although not shown, it should be appreciated that in other implementations, the second set of capillary tubes 66b may be distributed differently, e.g., uniformly, across the central portion 67.

Hence, accordingly by setting the cross-sectional shape of the capillary tubes 66a, 66b, the supply of the second aerosol-generating material to the electrically resistive layer 64 can be controlled or set accordingly.

Figure 6 represents a third example of a heater assembly 6 according to the present disclosure.

Figure 6 schematically shows an example heater assembly 6 in cross-section. Two capillary tubes 66a, 66b are shown for the purposes of illustrating the present example, although it should be appreciated that in practical terms the heater assembly 6 may comprise more than two capillary tubes 66a, 66b. As can be seen, the capillary tubes 66a, 66b extend from the second surface 62b of the substrate 62 through the electrically resistive layer 64.

When considering the heating assembly 6 of the present disclosure, it should be appreciated that liquid is supplied to the electrically resistive layer 64 via the capillary tubes 66a, 66b. Liquid that contacts these surfaces has a certain contact angle that is associated with the respective surfaces. By changing or setting the contact angle for a given liquid aerosolgenerating material in respect of the abovementioned surfaces, the liquid flow properties of the abovementioned surfaces can equally be set or changed.

In the example of Figure 6, the first and second sets of capillary tubes 66a, 66b may have the same or similar cross-sectional shapes and sizes, but the first set of capillary tubes 66a is provided with a surface modification 91 along the side walls of the first set of capillary tubes 66a. The surface modification 91 that is configured to adjust (i.e. , set or change) the flow of aerosol-generating material capable of flowing along the side walls of the first set of capillary tubes 66a. In the example of Figure 6, the surface modification 91 is provided to impede (i.e., decrease) the rate of liquid flow along the respective surface relative to surfaces or parts of surfaces that do not comprise the surface modification 91. In combination with the diameter (size) and/or shape of the first set of capillary tubes 66a, the surface modification 91 may be set in such a way to impede or substantially impede the flow of the second aerosol-generating material along the second capillary tube 66b (where substantially again in this context means that a small amount of the second aerosolgenerating material may be capable of passing through the second capillary tubes 66b relative to the first aerosol-generating material; e.g., in a ratio of 10:1 or greater in respect of the first aerosol-generating material to the second aerosol-generating material). In other words, in the absence of a surface modification 91 (e.g., such as in the second set of capillary tubes 66b), both the first aerosol-generating material and the second aerosolgenerating are able to flow into and along the capillary tube; however, in the presence of the surface modification 91 , such as in the first set of capillary tubes 66a, the surface energy of the side walls of the first set of capillary tubes 66a are changed to an extent that the second aerosol-generating material is now unable to pass into or through the first set of capillary tubes 66a, while the first aerosol-generating material is still capable of passing into and through the first capillary tubes 66a (albeit potentially at a reduced rate).

Hence, by modifying the surface of the first set of capillary tubes 66a via a surface modification 91, the first set of capillary tubes 66a may be configured so as to substantially impede the flow of the second aerosol-generating material through the first set of capillary tubes 66a.

It should also be appreciated that in some other implementations, the surface modification 91 may instead be provided on the second set of capillary tubes 66b and is provided to improve (i.e. , increase) the rate of liquid flow along the respective surface relative to surfaces or parts of surfaces that do not comprise the surface modification 91. In such implementations, the surface modification 91 is provided to effectively enable a capillary tube 66b that would otherwise impede the flow of the second aerosol-generating material.

The surface modification may be any suitable modification that is made to the surface of the underlying bulk material (e.g., the substrate 62) that alters the properties of the surface (such as the surface energy) in the region where the surface modification is provided. In some implementations, the surface modification comprises a surface coating. For example, a surface coating of another material may be applied to the surface(s) of the substrate 62 and/electrically resistive layer. In other implementations, the surface modification comprises a surface treatment. A surface treatment is any treatment made to the corresponding surface of the heater assembly 6 (e.g., the substrate 62) that subsequently alters the properties of the surface (such as the surface energy) of the bulk material. For instance, a surface treatment may include etching, scoring or any other similar treatment that makes the surface rougher. In other examples, a surface treatment may include polishing or otherwise smoothing the surface of the heater assembly 6.

Hence, accordingly by providing a surface modification 91 to the surface(s) of the capillary tubes 66a, 66b, the supply of the second aerosol-generating material to the electrically resistive layer 64 can be controlled or set accordingly.

Figures 4 to 6 represent three examples of how the first and second capillary tubes 66a, 66b can be set such that the first set of capillary tubes 66a impede the flow of the more viscous second aerosol-generating material while the second set of capillary tubes 66b permit the flow of the second aerosol-generating material. As noted above, the way in which a liquid interacts with the capillary tubes 66a, 66b may depend on several factors. Thus, in the process of configuring the first set of capillary tubes 66a to impede the flow of the more viscous second aerosol-generating material, any one or more of the techniques described in Figures 4 to 6 may be used in combination to achieve the desired result. Additionally, it should be appreciated that the precise way in which the first and/or second set of capillary tubes 66a, 66b are configured may depend in part on the properties of the first and second aerosol-generating materials to be used with the heater assembly 6. Suitable configurations may be found through empirical testing and/or computer simulation.

The heater assembly 6 as described above is generally provided as a relatively small component having a relatively small footprint (as compared to more traditional heater assemblies, such as a wick and coil). This is in part due to the fact the capillary tubes 66 are formed via a manufacturing process in the heater assembly 6 (i.e. , the capillary tubes are engineered, e.g., through a laser drilling process), and can therefore be designed to achieve a desired delivery of liquid aerosol-generating material to the electrically resistive layer 64. By providing a smaller component, material wastage (e.g., when the cartomiser 3 is disposed of) can be reduced. Not only can the liquid be provided more efficiently to the electrically resistive layer 64, but by manufacturing the capillary tubes 66, more control is given over the supply of liquid to the electrically resistive layer 64 (that is, the more capillary tubes of a certain diameter, the more liquid per unit time (ml/s) can be delivered to the electrically resistive layer 64).

It should be appreciated that the configuration of the cartomiser 3 accommodating the heater assembly 6 is provided as an example configuration of such a cartomiser 3. The principles of the present disclosure apply equally to other configurations of the cartomiser 3 (for example, comprising similar or different components to those as shown in Figures 1 and 2, and a similar or different layout to that shown in Figure 2). That is, the cartomiser 3 and the relative position of the heater assembly 6 in the cartomiser 3 is not significant to the principles of the present disclosure. Broadly speaking, a cartomiser is likely to comprise a top end (having the mouthpiece orifice 41) and a bottom end. In the examples shown above, the heater assembly 6 is arranged to be below the reservoir 46, horizontal or substantially horizontal (e.g., within 5°) to the longitudinal axis of the cartomiser 3, and arranged in an airflow path that is substantially perpendicular to longitudinal axis of the heater assembly. However, this need not be case, and in other implementations the cartomiser 3 may be configured differently depending on the particular design and application at hand. For example, the heater assembly 6 may be arranged such that airflow is parallel or substantially parallel (e.g., within 5°) to the longitudinal axis of the heater assembly, e.g., along the exposed surface of the electrically resistive layer 64. For example, the upper clamping unit 5 may not be provided with the central air passage 58 and instead the air passage may be provided to one side of the upper clamping unit 5. Air may enter the cartomiser 3 by a suitable inlet and flow along the longitudinal surface of the heater assembly 6 (and along the electrically resistive layer 64) before passing in a vertical or substantially vertical direction (e.g., within 5° of the vertical direction) through the air passage 58 positioned at one end of the upper sealing unit 5 (e.g., the end opposite the air inlet). The outer housing 4 and mouthpiece orifice 41 may be suitably configured. In such an example, the entirely of the lower surface of the heater assembly 6 may be exposed to the reservoir 46. In such implementations, the capillary tubes 66 may be disposed across the heater assembly 6, not just within the central portion 67 of the heater assembly 6 (provided the electrically resistive layer 64 is capable of coupling to a power source). Hence, although the heater assembly 6 has been described in the specific context of the example cartomiser 3 of Figures 1 and 2, the principles described herein can be applied to different heater assemblies for use in different cartomisers 3.

In the example shown in Figure 2, the contact pads 75 directly contact the electrically resistive layer 64 of the heater assembly 6. However, the cartomiser 3 may be provided with any suitable arrangement that facilitates the electrical contact between the aerosol provision device 2 and the heater assembly 6. For example, in some implementations, electrical wiring or other electrically conductive elements may extend between the electrically resistive layer 64 and the contact pads 75 of the cartomiser 3. This may particularly be the case when the heater assembly 6 has its largest dimension (e.g., its length) less than a minimum distance between the contact pads 75. The distance between the contact pads 75 may be dictated by the electrical contacts on the aerosol provision device 2.

In addition, in the described examples, the heater assembly 6 is orientated such that the electrically resistive layer 64 faces towards the bottom of the cartomiser 3. However, the orientation of the heater assembly 6 is not limited to this and, in other implementations, the heater assembly 6 may be provided in alternative orientations, for example, where the electrically resistive layer faces away from the bottom of the cartomiser 3.

It should also be appreciated that while the above has described a cartomiser 3 which includes the heater assembly 6, in some implementations the heater assembly 6 may be provided in the aerosol provision device 2 itself. For example, the aerosol provision device 2 may comprise the heater assembly 6 and a removable cartridge (containing a reservoir of liquid aerosol-generating material). The heater assembly 6 is provided in fluid contact with the liquid in the cartridge (e.g., via a suitable wicking element or via another fluid transport mechanism). Alternatively, the aerosol provision device 2 may include an integrated liquid storage area in addition to the heater assembly 6 which may be refillable with liquid. More broadly, the aerosol provision system (which encompasses a separable aerosol provision device and cartomiser / cartridge or an integrated aerosol provision device and cartridge) includes the heater assembly.

Additionally, the above has described a heater assembly 6 in which an electrically resistive layer 64 is provided on a surface of the respective substrate. In the aerosol provision system 1 of Figure 2, electrical power is supplied to the electrically resistive layer 64 via the contact pads 75. Accordingly, an electrical current is able to flow through the electrically resistive layer 64 from one end to the other to cause heating of the electrically resistive layer 64. However, it should be understood that electrical power for the purposes of causing the electrically resistive layer 64 to heat may be provided via an alternative means, and in particular, via induction. In such implementations, the aerosol provision system 1 is provided with a coil (known as a drive coil) to which an alternating electrical current is applied. This subsequently generates an alternating magnetic field. When the electrically resistive layer 64 is exposed to the alternating magnetic field (and it is of sufficient strength), the alternating magnetic field causes electrical current (Eddy currents) to be generated in the electrically resistive layer 64. These currents can cause Joule heating of the electrically resistive layer 64 owing to the electrical resistance of this layer 64. Depending on the material which the electrically resistive layer 64 is formed, heating may additionally be generated through magnetic hysteresis (if the material is ferro- or ferrimagnetic). More generally, the electrically resistive layer 64 is an example of a heater layer of the heater assembly 6 which is configured to generate heat when supplied with energy (e.g., electrical energy), which, for example, may be provided through direct contact or via induction. Additional ways of causing the heater layer to generate heat are also considered within the principles of the present disclosure.

Moreover, it should be understood that in some implementations, an additional layer or layers, e.g., serving as a protective layer, may be disposed on top of the electrically resistive layer 64. In such implementations, the capillary tubes 66 still extend to an opening on the electrically resistive layer 64 but may additionally extend through the additional layer(s). More broadly, the capillary tubes 66 extend through the heater assembly 6 to an opening at a surface of a side of the heater assembly 6 comprising the electrically resistive layer 64, which includes an opening in the electrically resistive layer 64 itself as well as an opening in any additional layer(s) positioned above the electrically resistive layer 64.

Figure 7 depicts an example method for manufacturing a heater assembly 6.

The method begins at step S1 by providing a substrate 62. The way in which the substrate 62 is formed is not significant to the principles of the present disclosure. For example, the substrate 62 may be cut from a portion of cultured quartz or formed via a sintering process by sintering quartz powders I fibres, for example.

The method then proceeds to step S2 whereby the electrically resistive layer 64 is provided on a surface of the substrate 62. The way in which the electrically resistive layer 64 is formed on the surface of the substrate 62 is not significant to the principles of the present disclosure. For example, the electrically resistive layer 64 may be a sheet of metal (e.g., titanium) adhered, welded, or the like to the substrate 62. Alternatively, the electrically resistive layer 64 may be formed through a vapour or chemical deposition technique using the substrate 62 as a base.

It should also be appreciated that step S2 may alternatively occur before step S1. For example, a further alternative is to grow or culture the substrate 62 using the electrically resistive layer 64 as a base.

In the described example, after step S2, the method proceeds to step S3. At step S3, one or more capillary tubes 66 are formed in the substrate 621 electrically resistive layer 64. As noted above, the capillary tubes 66 extend from a surface of the substrate 62 I heater assembly 6, through the electrically resistive layer 64 provided on the first surface of the substrate 62. That is, the capillary tubes 66 extend all the way through the heater assembly 6. The capillary tubes 66 may be formed by laser drilling, as noted above, or any other suitable technique.

Moreover, in accordance with the present disclosure, step S3 includes forming a first set of one or more capillary tubes 66a and forming a second set of one or more capillary tubes 66b. This may involve drilling (or otherwise forming) the capillary tubes 66a, 66b e.g., with different sizes (diameters) or shapes. Additionally or alternatively, this may including applying a coating or performing a surface treatment, as described above. It should be appreciated that step S3 may be performed prior to step S2 (and equally step S3 may follow step S1 where step S2 is performed prior to step S1). That is to say, the capillary tubes 66 may be formed in the substrate 62 prior to applying the electrically resistive layer 64. At step S4, one or more surface modifications are provided to the heater assembly 6. As noted above, the surface modifications may be provided on at least a portion of one of the surface of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side walls/surfaces of the one or more capillary tubes 66. The surface modifications are provided to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one of the surface of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66. As described above, the surface modifications may comprise a surface coating and/or a surface treatment, and accordingly at step S4 any suitable technique may be employed to provide the surface modifications as desired, e.g., such as CVD or polishing, etc.

Broadly, it should be understood that the method of Figure 7 is an example method only, and adaptations to the steps or ordering of the steps of this method are contemplated within this disclosure, for example, as described above.

After step S3, the heater assembly 6 is formed, and subsequently may be assembled to form the cartomiser 3 (or more generally, the heater assembly 6 may be positioned in an aerosol provision system 1).

In accordance with the principles of the present disclosure, there is also provided an aerosol provision means, which includes the aerosol provision system 1. The aerosol provision means comprises a heater means, which includes the heater assembly 6. The heater means includes a substrate, which includes substrate 62, and a heater layer means, which includes the electrically resistive layer 64, provided on at least a first surface of the substrate and configured to generate heat. The heater means further comprises a first set of capillary means, which includes the first set of capillary tubes 66a, extending from a second surface of the substrate through the substrate and the heater layer means and having a first characteristic, and a second set of capillary means, including the second set of capillary tubes 66b, extending from the second surface of the substrate through the substrate and the heater layer means and having a second characteristic different from the first characteristic. The aerosol provision means further comprises aerosol-generating material storage means, which includes the reservoir 44, in fluid communication with the second surface of the substrate. The aerosol-generating material storage means further comprises a first and second aerosol-generating material. The second aerosol-generating material has a higher viscosity than the first aerosol-generating material. Additionally, the first set of capillary means are configured to impede the flow of the second aerosol-generating material.

Thus, there has been described an aerosol provision system, the aerosol provision system including a heater assembly and an aerosol-generating material storage region. The heater assembly comprises a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat, a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic, and a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic. The aerosol-generating material storage region is in fluid communication with the second surface of the substrate, and includes a first and a second aerosol-generating material. The second aerosolgenerating material has a higher viscosity than the first aerosol-generating material, and the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material. Also described is a consumable for use with an aerosol provision system a method of manufacturing an aerosol provision system or a consumable and aerosol provision means.

Alternatively, the present disclosure may be summarised as an aerosol provision system comprising a heater assembly. The heater assembly comprises a substrate; a heater layer provided on at least a first surface of the substrate and configured to generate heat; a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and to heater layer and having a first characteristic; and a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and to heater layer and having a second characteristic different from the first characteristic. The aerosol provision system further comprises an aerosol-generating material storage region, in fluid communication with the second surface of the substrate, comprising a first and second aerosol-generating material. The second aerosol-generating material has a higher viscosity than the first aerosol-generating material. The first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material.

In accordance with another aspect of the present disclosure, a heater assembly is provided which includes surface modifications (comprising surface coatings and/or surface treatments) configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of the heater assembly. Specifically, along one or more of a surface of the heater layer, a surface of the substrate facing the aerosol generating material storage area, and the side surfaces of one or more capillary tubes extending between the second surface and the heater layer. By providing surface modifications, the characteristics of the heater assembly in respect of liquid flow or transport can be varied or adjusted. In this way, a designer of a heater assembly is permitted more freedom in terms of the materials available to produce the heater assembly, as the surface modifications can be used to fine tune the performance of the heater assembly in the event that the underlying materials used to produce the heater assembly do not have the desired characteristics in terms of liquid flow.

With reference to Figure 3, in accordance with the another aspect of the present disclosure, the capillary tubes 66 are configured so as to transport liquid from one surface of the heater assembly 6 (i.e. , the second surface 62b of the substrate 62) to the electrically resistive layer 64. The capillary tubes 66 may be formed based in part on the liquid to be stored in the reservoir 46 of the cartomiser 3 and subsequently used with the heater assembly 6. For example, the properties of the liquid aerosol-generating material (e.g., viscosity) in the reservoir 46 of the cartomiser 3 may influence the configuration of the capillary tubes 66 to help ensure that a suitable flow of liquid is provided to the electrically resistive layer 64. Broadly speaking, in some implementations, the capillary tubes 66 may have a diameter on the order to tens of microns, e.g., between 10 pm to 100 pm. However, it should be appreciated that capillary tubes 66 in other implementations may be configured differently.

In accordance with the another aspect of the present disclosure, the heater assembly 6 is configured to facilitate the transport of liquid aerosol-generating material from the reservoir 46 to the electrically resistive layer 64 such that the liquid aerosol-generating material may be vaporised to form an aerosol. The liquid aerosol-generating material is able to contact the heater assembly 6 at several locations. In particular, the liquid aerosol-generating material is able to contact the second surface 62b of the substrate 62 (which faces the reservoir 64 when the heater assembly is sandwiched between the upper clamping unit 5 and the lower support unit 7), the surfaces of the capillary tubes 66, and the exposed surface 64a of the electrically resistive layer 64 (e.g., either when the liquid escapes the end of the capillary tube 66 in liquid form or as a result of condensing on the exposed surface 64a of the electrically resistive layer 64 after being vaporised). Accordingly, it should be appreciated that the liquid aerosol-generating material is capable of flowing along any one or more of these surfaces.

When a liquid interacts with a surface, the contact angle is a parameter that determines the degree to which a liquid droplet will spread out across the surface. A relatively larger contact angle means a liquid is less likely to spread out across the surface, while a smaller contact angle means a liquid is more likely to spread out across the surface. The contact angle is dependent, in part, on the properties of the material forming the surface. Typically, surfaces can be characterised by their surface energy. For a given liquid, a surface with a higher surface energy leads to a greater spread of the liquid across the surface, whereas a surface with a lower surface energy leads to a lower spread of the liquid across the surface.

When considering the heating assembly 6 of the present disclosure, it should be appreciated that liquid is supplied to the electrically resistive layer 64 via the capillary tubes 66 and, potentially, via the second surface 62b. Liquid that contacts these surfaces has a certain contact angle, and thus a degree of spreading, that is associated with the respective surfaces. By changing or setting the contact angle for a given liquid in respect of the abovementioned surfaces, the liquid flow properties of the abovementioned surfaces can equally be set or changed. For example, in some instances, it may be desirable to improve the flow of liquid along the second surface 62b and/or along the capillary channels 66 to thereby increase the rate at which liquid is fed to the electrically resistive layer 64. In some instances, it may be desirable to decrease the flow of liquid along the second surface 62b and/or along the capillary tubes 66 to thereby decreases the rate at which liquid is set to the electrically resistive layer 64.

Equally, liquid that contacts the electrically resistive layer 64 also forms a certain contact angle with the surface of the electrically resistive layer 64. In this case, the surface area of liquid supplied from the capillary tubes 66 that contacts the electrically resistive layer 64 during heating I vaporisation of the liquid may be governed in part by the contact angle the liquid forms with the surface of the electrically resistive layer 64. By changing or setting the contact angle for a given liquid in respect of the surface of the electrically resistive layer 64, the liquid flow properties of the surface of the electrically resistive layer 64 can equally be set or changed. For example, the degree to which a droplet spreads out across the electrically resistive layer 64 (and hence the surface area of a liquid droplet that contacts the electrically resistive layer 64) can be increased or decreased based on the properties of the surface of the electrically resistive layer 64. This may subsequently impact the rate or amount of aerosol generated during vaporisation. Additionally, condensed liquid (i.e. , liquid that has already been vaporised and subsequently condenses in the region below the heater assembly 6) may also collect on the surface of the electrically resistive layer 64. This liquid may also form a contact angle (which may be the same or different to the contact angle for the pre-vaporised liquid) with the surface of the electrically resistive layer 64. By changing or setting the contact angle for a given liquid in respect of the surface of the electrically resistive layer 64, the liquid flow properties of the surface of the electrically resistive layer 64 can equally be set or changed. For example, in some instances, it may be desirable to set the flow of condensed liquid along the electrically resistive layer 64 to thereby set the rate at which liquid is fed back to the capillary tubes 66 (or the openings thereof) at the electrically resistive layer 64. Hence, more generally, it should be understood that the contact angle that the liquid forms with respective surfaces of the heater assembly 6 can influence the liquid flow properties of the respective surface of the heater assembly 6.

In accordance with the principles of the another aspect of the present disclosure, the heater assembly 6 comprises a surface modification that is configured to adjust (i.e. , set or change) the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the electrically resistive layer 64 (or more generally, the heater layer), the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66 through the substrate 62. By providing a surface modification at at least a portion of one or more of the surface of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66 through the substrate 62, the liquid flow properties of liquid contacting any of the abovementioned surfaces can be altered relative to the surfaces in the absence of a surface modification. In some implementations, a surface modification may be provided to improve (i.e., increase) the rate of liquid flow along the respective surface relative to surfaces or parts of surfaces that do not comprise the surface modification. This may help increase the amount of aerosol generated during vaporisation and/or the rate at which aerosol is generated during vaporisation. Additionally or alternatively, a surface modification may be provided to impede (i.e., decrease) the rate of liquid flow along the respective surface relative to surfaces or parts of surfaces that do not comprise the surface modification. This may help decrease the amount of aerosol generated during vaporisation and/or the rate at which aerosol is generated during vaporisation.

The surface modification may be any suitable modification that is made to the surface of the underlying bulk material (e.g., the substrate 62 and/or the electrically resistive layer 64) that alters the properties of the surface (such as the surface energy) in the region where the surface modification is provided.

In some implementations, the surface modification comprises a surface coating. For example, a surface coating of another material may be applied to the surface(s) of the substrate 62 and/electrically resistive layer. Depending upon the properties of the material applied and/or the way in which it is applied, the surface coating may either increase or decrease certain properties of the underlying bulk material to which the coating is applied. In particular, surface coatings may increase the surface energy or decrease the surface energy of the surface of the underlying bulk material.

In some implementations, a surface coating may be applied using plasma treatment (such as used in the manufacture of silicon wafers). In such implementations, the underlying substrate 62 and/or electrically resistive layer 64 can be bombarded with ions to adjust the surface energy of the underlying material, e.g., to make the surface more hydrophobic or hydrophilic as desired. A mixture of inert gasses, such as krypton or argon, may be used to form the plasma, although other gasses may be used. The mixture of gasses may be selected to provide certain properties to the surface of the underlying material. In other implementations, spin coating may be used to apply an organic surface coating to the underlying material (e.g., the substrate 62 and/or the electrically resistive layer 64). Coatings or films applied by spin coating may be a few nanomicrons thick, which may be appropriate for certain applications.

Any suitable material may be applied as the surface coating to the heater assembly 6. However, it should be appreciated that the characteristics of the material of the surface coating may be different when applied to different parts of the heater assembly 6. For example, the electrically resistive layer 64 is intended to receive current and generate heat in operation, so a surface coating applied to the surface of the electrically resistive layer 64 may be chosen to be electrically non-conductive and/or heat resistant (up to typical operating temperatures of the electrically resistive layer 64). Additionally, any suitable technique for applying the surface coating to the heating assembly 6 may be used. For example, techniques such as chemical vapour deposition (CVD) may be used to deposit a suitable material on the surface of the heater assembly 6 using broadly conventional techniques.

In other implementations, the surface modification comprises a surface treatment. A surface treatment is any treatment made to the corresponding surface of the heater assembly 6 (e.g., the substrate 62 and/or the electrically resistive layer 64) that subsequently alters the properties of the surface (such as the surface energy) of the bulk material. For instance, a surface treatment may include etching, grinding, scoring or any other similar treatment that makes the surface rougher. In other examples, a surface treatment may include polishing or otherwise smoothing the surface of the heater assembly 6. In some implementations, laser ablation may be used to provide roughness to the surface of the underlying material or to remove rough or uneven regions (depending on the state of the underlying material prior to treatment). In other implementations, UV ozone treatment can be used to treat the surface of the underlying substrate 62 and/or electrically resistive layer 64, whereby this technique provides a temporary cleaning of the surface (thereby removing any contaminants or the like that may otherwise impact the surface energy of the material). Again, broadly conventional techniques may be used to make the surface treatment on the corresponding surface of the heater assembly 6. In some implementations, the surface modification is provided on the entire of a respective surface of the heater assembly 6. That is, the surface modification may be provided on the entirety of the second surface 62b of the substrate and/or on the entirety of the side walls of the capillary tubes 66 and/or the entirety of the electrically resistive layer 64. This may be implemented where the bulk material of the substrate 62, the capillary tubes 66 and/or the electrically resistive layer 64 displays unsuitable properties in respect of liquid flow (but perhaps desired qualities in respect of other properties, e.g., heat conduction/insulation, electrical resistivity, etc.). In other implementations, the surface modification may be provided on only a portion of the corresponding surface of the heater assembly 6. That is, the surface modification may be provided on a portion of the second surface 62b of the substrate and/or on a portion of the side walls of the capillary tubes 66 and/or on a portion of the electrically resistive layer 64. By providing the surface modification on only a portion of the corresponding surface, it is possible to provide portions on the corresponding surface where flow of aerosol-generating material may be improved/impeded with respect to other portions of the corresponding surface. For example, it may be possible to provide the surface modification so as to facilitate flow of aerosol-generating material to a particular region of the heater assembly 6. That is, it may be possible to target areas of the heater assembly 6 with increased (or reduced) liquid flow properties so that those areas may received an increased (or decreased) amount of liquid aerosol-generating material.

Additionally, in implementations where there are a plurality of capillary tubes 66, the surface modification need not be provided to each capillary tube 66. That is, for example, the side walls (or portions thereof) of certain capillary tubes 66 of the plurality of capillary tubes 66 may be provided with a surface modification, whereas other ones of the capillary tubes 66 may not be provided with a surface modification (or the side walls or portions thereof may be provided with a different surface modification). In this way, it is possible to selectively adjust the liquid flow properties of certain capillary tubes 66 of the plurality of capillary tubes 66. For example, it may be possible to relatively improve the liquid flow properties of capillary tubes 66 towards the centre of the heater assembly, and to relatively decrease the liquid flow properties of capillary tubes 66 of capillary tubes towards the peripheral of the heater assembly 6. There may be certain factors that determine which of the capillary tubes 66 to apply a surface feature to (e.g., the operational temperature of the electrically resistive layer 64 in the vicinity of the ends/openings of the capillary tube 66, etc.).

As noted above, in some implementations, the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the surface of the at least one of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66. For instance, by applying a surface coating or performing a surface treatment, it is possible to relatively increase the surface energy of the surface as compared to the underlying bulk material. For a given liquid, this results in a relatively shallower contact angle, and thus greater spreading of a liquid droplet across the surface. Such surfaces may be said to have a high wettability. Such surfaces may be said to facilitate or enable transport of liquid across the surface to a greater degree than surfaces without such a surface modification. Furthermore, depending on the type of liquid to be used with the heater assembly 6, the surface modification may be said to have different qualities. In implementations where the liquid is a water or water-based, the surface modification can be said to make the surface relatively more hydrophilic. In implementations where the liquid is an oil or oil-based, the surface modification can be said to make the surface relatively more oleophilic. In this regard, it should be appreciated that the surface energy of a material is not the only factor that determines the contact angle for a liquid. Indeed, the contact angle is also dependent on at least the surface tension for a given liquid droplet (i.e., an inherent property of the liquid). Therefore, in the context of the present disclosure, it should be appreciated that particular surface modifications may be made to the heater assembly 6 taking account of the liquid (or liquids) that the heater assembly 6 is to be used with. Hence, it should be appreciated that a given surface modification may have different effects on different liquids, and the extent to which a surface may need to be modified may depend on the liquid to be used with the heater assembly 6.

In some other implementations, the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the surface of the at least one of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66. For instance, by applying a surface coating or performing a surface treatment, it is possible to relatively decrease the surface energy of the surface as compared to the underlying bulk material. For a given liquid, this results in a relatively greater contact angle, and thus a lesser spreading out of a liquid droplet across the surface. Such surfaces may be said to have a low wettability (sometimes referred to as “dewetting”). Such surfaces may be said to impede the transport of liquid across the surface to a greater degree than surfaces without such a surface modification. Furthermore, depending on the type of liquid to be used with the heater assembly 6, the surface modification may be said to have different qualities. In implementations where the liquid is a water or waterbased, the surface modification can be said to make the surface relatively more hydrophobic. In implementations where the liquid is an oil or oil-based, the surface modification can be said to make the surface relatively more oleophobic. As noted above, it should be appreciated that the surface energy of a material is not the only factor that determines the contact angle for a liquid (and this may be dependent on the liquid to be used with the heater assembly 6).

Hence, by utilising a surface modification such as those described above, the heater assembly 6 can be modified or adjusted to provide certain characteristics in terms of the performance of liquid flow to certain parts of the heater assembly 6. This offers a greater freedom to designers of the heater assembly 6, whereby certain bulk materials may be selected for certain performance characteristics but be unsatisfactory in terms of other (i.e. , liquid flow) performance characteristics. Additionally, surface modifications can be provided at certain locations of the heater assembly 6 to provide more selective liquid flow I transport to certain locations of the heater assembly 6. This may be used to fine tune the performance of the heater assembly 6. For example, in terms of aerosol generation, the surface modifications may be provided to supply relatively more liquid (or supply liquid at a greater rate) to the centre of the heater assembly 6 which may be where the conditions for aerosol generation are more suitable compared to e.g., the edges of the heater assembly 6.

Figures 8a and 8b schematically represent a first implementation of a heater assembly 6 comprising a surface modification according to the another aspect of the present disclosure. In particular, Figures 8a and 8b schematically represent a heater assembly 6 having a surface modification provided on the second surface 62b of the substrate 62. Figure 8a shows a top-down view of the second surface 62b of the substrate 62, while Figure 8b shows a perspective view of the heater assembly 6. As compared to Figure 3, Figure 8b shows the heater assembly 6 rotated 180° about the longitudinal axis L2 so as to be able to view the second surface 62b. (Note that Figure 8b shows the heater assembly 6 in the orientation it would be in the cartomiser 3 of Figure 2 when assembled.)

As should be appreciated, the second surface 62b of the substrate 62 faces towards the reservoir 46 and is therefore provided, at least partially, in fluid contact with the liquid aerosol-generating material within the reservoir 46. Liquid that exits the reservoir 46 contacts the second surface 62b of the heater assembly 6 as the first point of contact with the heater assembly 6.

In the arrangement of the cartomiser 3 described in Figures 1 and 2, the heater assembly 6 is provided such that the end portions 68, 69 overlap openings to the wells 53 in the upper clamping unit 5. In some implementations, there may be provided a wicking material between the openings of the wells 53 and the second surface 62b which may facilitate the transport of liquid in a direction along the second surface 62b (i.e., broadly along the longitudinal direction L2 of the heater assembly 6). However, regardless of whether or not the wicking material is provided, it is expected that at least some liquid from the reservoir 46 will be delivered to the parts of the second surface 62b at the end portions 68, 69 of the heater assembly 6 overlapping the openings to the wells 53. As the end portions 68, 69 do not have any capillary tubes 66 and do not communicate with the central air passage 73, it is desirable to direct this liquid towards the central portion 67 when the capillary tubes 66 are located and hence to ultimately deliver the liquid to the electrically resistive layer 64.

In accordance with the first example, the heater assembly 6, and more particularly the second surface 62b of the substrate 62, is provided with a first surface modification 191 at each of the end portions 68, 69 of the second surface 62b of the substrate 62. The first surface modification 191 is provided to relatively increase the surface energy of the bulk material, i.e. , the substrate 62, at the portions where the first surface modification 191 is provided as compared to those portions of the second surface 62b where the first surface modification 191 is not provided. In terms of the liquid itself, this results in a relatively smaller contact angle being formed with the surface 62b in the regions having the first surface modification 191 and therefore the liquid experiences a greater spread across the surface 62b. Hence, the first surface modification 191 is provided to increase or improve the liquid flow characteristics of the second surface 62b in the region where the first surface modification 191 is provided. In particular, the first surface modification 191 is capable of facilitating liquid flow towards the capillary tubes 66 adjacent the first surface modification 191. In this regard, it can be seen from Figures 8a and 8b that the first surface modification 191 is provided having a broadly truncated cone shape, with the narrower part of the truncated cone shape facing towards the capillary tubes 66 of the central portion 67 of the heater assembly 6. Therefore, owing to the first surface modification 191, liquid exiting the wells 53 is capable of flowing towards the capillary tubes 66 and hence to the electrically resistive layer 64.

In addition, it should be appreciated that the capillary tubes 66 are the primary route through which liquid is supplied to the electrically resistive layer 64. That is to say, in order for liquid aerosol-generating material to pass to the electrically resistive layer 64, it primarily passes through the capillary tubes 66. One way to improve the flow of liquid to the electrically resistive layer 64 is to improve flow of liquid to the capillary tubes 66.

Hence, in the described implementation of Figures 8a and 8b, the second surface 62b is provided with a plurality of second surface modifications 92. The second surface modifications 92 are provided on the second surface 62b at locations around the openings to the capillary tubes 66. In the example of Figures 8a and 8b, the openings to the capillary tubes 66 are circular, and thus the second surface modifications 92 are also circular (although have a larger diameter) and are coaxial with the openings of the capillary tubes 66. In a similar manner to the first surface modifications 191, the second surface modifications 92 are provided to relatively increase the surface energy of the bulk material, i.e., the substrate 62, at the portions where the second surface modification 92 is provided as compared to those portions of the second surface 62b where either the first or second surface modifications 191, 92 are not provided. In terms of the liquid itself, this again results in a relatively smaller contact angle being formed with the surface 62b in the regions having the second surface modification 92 and therefore the liquid experiences a greater spread across the surface 62b. Hence, the second surface modification 92 is provided to increase or improve the liquid flow characteristics of the second surface 62b in the region where the second surface modification 92 is provided. In particular, the second surface modification 92 is capable of facilitating liquid flow towards the openings of the capillary tubes 66. Therefore, owing to the second surface modifications 92, liquid that is in the vicinity of the openings of the capillary tubes 66 is capable of more easily or more readily flowing towards the openings of the capillary tubes 66 and hence to the electrically resistive layer 64.

Hence, it can be seen that the first and second surface modifications 191 , 92 are configured to improve the flow of aerosol-generating material capable of flowing along the second surface 62b of the substrate 62, such that aerosol-generating material is more easily or more readily capable of flowing towards the capillary tubes 66 (or more specifically the openings of the capillary tubes 66).

Further, the heater assembly 6 of Figures 8a and 8b is provided with a third surface modification 93. Unlike the first and second surface modifications 191, 92, the third surface modification 93 is provided to relatively decrease the surface energy of the bulk material, i.e., the substrate 62, at the portions where the third surface modification 93 is provided as compared to those portions of the second surface 62b where the third surface modification

93 is not provided (and additionally also portions where the first and second surface modifications 191 , 92 are not provided). In terms of the liquid itself, this results in a relatively larger contact angle being formed with the surface 62b in the regions having the third surface modification 93 and therefore the liquid experiences a relatively smaller spread across the surface 62b. Hence, the third surface modification 93 is provided to inhibit or reduce the liquid flow characteristics of the second surface 62b in the region where the third surface modification 93 is provided.

The third surface modification 93 is provided on the edges of the second surface 62b in the centre of the central portion 67. More particularly, the third surface modification 93 is provided at a position between the edge of the second surface 62b (and hence the edge of the heating assembly 6) and the capillary tubes 66. The third surface modification 93 acts to impede liquid flow in the direction towards the edge of the second surface 62b (and hence away from the capillary tubes 66). Accordingly, the third surface modification can be thought of as a barrier acting to retain liquid that has managed to reach the centre of the central portion 67 in that region, which may therefore increase the chances of the liquid finding its way to the capillary tubes 66. Therefore, owing to the third surface modification 93, liquid that has reached the centre of the central portion 67 is capable of being retained or held in that region such that it is able to more readily supply the capillary tubes 66.

Hence, according to the first example of Figures 8a and 8b, the second surface 62b of the substrate 62 of the heater assembly 6 is provided with one or more surface modifications 191 , 92, 93 arranged so as to alter the flow of liquid aerosol-generating material across the surface of the second surface 62b. In the example described, the first and second surface modifications 191 , 92 are provided to relatively improve the flow of liquid aerosol-generating material across the second surface 62b in order to facilitate a relative increase in the amount of and/or rate of supply of aerosol-generating material to certain portions of the second surface 62b (namely towards the capillary tubes 66), while the third surface modification 93 is provided to relatively decrease the flow of liquid aerosol-generating material across the second surface 62b in order to facilitate a relative decrease in the amount of and/or rate of supply of aerosol-generating material to certain portions of the second surface 62b (namely away from the capillary tubes 66). However, it should be appreciated that the implementation shown in Figures 8a and 8b is an example only, and in other implementations the provision of surface modifications 191 , 92, 93 may be different from that shown.

For example, in some implementations, it may be desired to switch the relative increase and decrease in surface energy of the second surface 62b offered by the first to third surface modifications 191 , 92, 93. That is, the first and second surface modifications 191, 92 may instead be configured to relatively decrease the surface energy as compared to the portions of the second surface 62b that do not comprise a surface modification, while the third surface modification 93 may instead be configured to relatively increase the surface energy as compared to the portions of the second surface 62b that do not comprise a surface modification. This may be implemented in situations where the flow of liquid aerosolgenerating material across the second surface 62b is too great (i.e., the amount and/or rate of supply of aerosol-generating material is too high for the heater assembly resulting in flooding and/or poor vaporisation at the electrically resistive layer 64). Thus, the first and second surface modifications 191, 92 may be provided to effectively slow the supply of aerosol-generating material to the capillary tubes 66. That is to say, the first and second surface modifications are configured to impede the flow of aerosol-generating material capable of flowing along the second surface 62b of the substrate 62, such that the flow of aerosol-generating material toward openings of the one or more capillary tubes 66 is reduced. Equally, the third surface modification 93 may be provided to facilitate the flow of aerosol-generating material away from the capillary tubes 66 to reduce the amount of liquid aerosol-generating material that pools or collects in the centre of the central region 67 of the second surface 62b.

Therefore, it should be appreciated that surface modifications 191, 92, 93 may be provided to the second surface 62b of the heater assembly 6 to influence the flow or transport of liquid aerosol-generating material across the second surface 62b. Depending on the specific characteristics of the heater assembly 6 and its interaction with the liquid aerosol-generating material, the surface modifications 191 , 92, 93 may be provided in any desired configuration to achieve a particular outcome. While the example of Figure 8a and 8b shows surface modifications for increasing the surface energy (i.e., the first and second surface modifications 191 , 92) and for decreasing the surface energy (i.e., the third surface modification 93), it should be appreciated that certain implementations may only employ one type of surface modification. Additionally, while Figures 8a and 8b show a particular shape and distribution of the surface modifications 191, 92, 93, it should be understood that this is an example only and other implementations may have surface modifications with different shapes and/or different distributions across the second surface 62b. Furthermore, as noted above, in some implementations, a surface modification may be provided across the entirety of the second surface 62b.

Figures 9a and 9b schematically represent second and third implementations of a heater assembly 6 comprising a surface modification according to the another aspect of the present disclosure. In particular, Figures 9a and 9b schematically represent a heater assembly 6 having a surface modification provided on the side walls of the capillary tubes 66. The capillary tubes 66 are formed in the substrate 62 and thus it should be appreciated that the side walls of the capillary tubes 66 are also side walls of the substrate 62. Figures 9a and 9b show a cross-sectional view through the heater assembly 6 and illustrate an example capillary tube 66 for explaining the principles of the present disclosure.

In respect of the capillary tubes 66, as noted above, it should be understood that the capillary tubes 66 are the primary mechanism by which liquid aerosol-generating material is fed to the electrically resistive layer 64 for vaporisation. The extent to which liquid aerosolgenerating material travels through the capillary tubes 66 may be dependent on a number of factors, such as the geometry of the capillary tube 66 (e.g., the radius of the capillary tube 66) and the properties of the liquid aerosol-generating material (such as the surface tension). An additional factor is the contact angle of a liquid droplet (or meniscus) formed with the side wall of the capillary tube 66. In a broadly similar manner to as described above, the contact angle or surface energy of the side walls of the capillary tube 66 can be adjusted using a surface modification to the side wall of the capillary tubes 66. By adjusting the contact angle or surface energy, the flow of liquid aerosol-generating material capable of flowing along at least a portion of the side walls of the one or more capillary tubes 66 can also be adjusted.

Figure 9a shows a second implementation in which the side wall of the capillary tube 66 is provided with a fourth surface modification 94. The fourth surface modification 94 is similar to the first and second surface modifications 191 , 92 described above in that the fourth surface modification 94 is provided to relatively increase the surface energy of the bulk material, i.e. , the substrate 62, at the portions where the fourth surface modification 94 is provided as compared to those portions of the side walls of the capillary tubes 66 where the fourth surface modification 94 is not provided. Similarly, in terms of the liquid aerosolgenerating material itself, this results in a relatively smaller contact angle being formed with the side walls of the capillary tubes 66 in the regions having the fourth surface modification 94. In the context of capillary tubes 66, in which the liquid aerosol-generating material is more constrained, this effectively means that the liquid aerosol-generating material travels relatively further along the capillary tube 66 or indeed at a faster rate than compared to instances where the fourth surface modification 94 is not provided. Hence, the fourth surface modification 94 is provided to increase or improve the liquid flow characteristics of the capillary tube 66 in the portions thereof where the fourth surface modification 94 is provided.

In the implementation of Figure 9a, the fourth surface modification 94 is provided on a portion of the capillary tube 66 adjacent the opening in the second surface 62b. In other words, the fourth surface modification 94 is provided at the portion of the capillary tube 66 which first receives the liquid aerosol-generating material. In this regard, the fourth surface modification 94 may help facilitate more rapid loading of the capillary tube 66 with liquid aerosol-generating material. This may help improve the supply of liquid aerosol-generating material to the electrically resistive layer 64 during and prior to use of the heating assembly 6. In the example of Figure 9a, the fourth surface modification 94 does not extend to the electrically resistive layer 64 (i.e., the entire length of the capillary tube 66). In this regard, it should be appreciated that in some implementations the relative pressure imparted on a volume of liquid present in the region of the capillary tube 66 not comprising the fourth surface modification 94 (i.e., closest to the electrically resistive layer 64) by the liquid present in the region of the capillary tube 66 comprising the fourth surface modification 94 may impact the liquid flow properties of the liquid in the region closest to the electrically resistive layer 64. In other words, the additional pressure may force the liquid closest to the electrically resistive layer 64 to flow with a greater ease and/or at a greater rate even in the absence of the fourth surface modification 94. Additionally, during use, residual heat from the electrically resistive layer 64 may also warm the volume of liquid in the region of the capillary tube 66 not comprising the fourth surface modification 94 (i.e., closest to the electrically resistive layer 64) to a greater extent that liquid held in the region comprising the fourth surface modification 94. In such cases, the properties of the liquid closest to the electrically resistive layer 64 (such as viscosity) may change causing the liquid closest to the electrically resistive layer 64 to flow with a greater ease and/or at a greater rate even in the absence of the fourth surface modification 94. Put simply, it may not be necessary to include the fourth surface modification 94 along the entire length of the capillary tube 66 as other factors may influence the flow of liquid through the capillary tube 66 at different portions of the capillary tube 66. However, it should also be appreciated that in other implementations, the fourth surface modification 94 may be provided along the entire length of the capillary tube 66, particularly where the abovementioned factors are negligible.

In accordance with the second implementation of Figure 9a, the fourth surface modification

94 is provided to help facilitate the supply of liquid to the electrically resistive layer 64 (i.e. to help prevent or reduce instances where the electrically resistive layer 64 runs dry, i.e., it is not supplied with a sufficient amount of liquid).

Figure 9b shows a third implementation in which the side wall of the capillary tube 66 is provided with a fifth surface modification 95. The fifth surface modification 95 is similar to the third surface modification 93 described above in that the fifth surface modification 95 is provided to relatively decrease the surface energy of the bulk material, i.e., the substrate 62, at the portions where the fifth surface modification 95 is provided as compared to those portions of the side walls of the capillary tubes 66 where the fifth surface modification 95 is not provided. Similarly, in terms of the liquid aerosol-generating material itself, this results in a relatively larger contact angle being formed with the side walls of the capillary tubes 66 in the regions having the fifth surface modification 95. In the context of capillary tubes 66, in which the liquid aerosol-generating material is more constrained, this effectively means that the liquid aerosol-generating material travels a relatively shorter distance along the capillary tube 66 or at a slower rate than compared to instances where the fifth surface modification

95 is not provided. Hence, the fifth surface modification 95 is provided to decrease or impede the liquid flow characteristics of the capillary tube 66 in the portions thereof where the fifth surface modification 94 is provided.

In the implementation of Figure 9b, the fifth surface modification 95 is provided on a portion of the capillary tube 66 adjacent the opening in the electrically resistive layer 64. In other words, the fifth surface modification 95 is provided at the portion of the capillary tube 66 which is directly adjacent the electrically resistive layer 64 and subsequently supplies the liquid material to the electrically resistive layer 64. As noted above, effects such as the relative pressure imparted on a volume of liquid close to the electrically resistive layer 64 and/or residual heat from the electrically resistive layer 64 may relatively increase the flow of liquid aerosol-generating material in the region close to the electrically resistive layer 64.

This may result in effects such as leakage of the liquid aerosol-generating material (e.g., into the central air channel 73) and/or flooding of the electrically resistive layer 64. Hence, in some implementations, providing the fifth surface modification 95 and help to retain at least some of the liquid aerosol-generating material in the capillary tubes 66 (at least while the heater assembly 6 is not operational) thereby helping to reduce or prevent leakage of the liquid aerosol-generating material. In Figure 9b, the fifth surface modification 95 is shown provided at a portion of the side walls of the capillary tube 66 closest to the electrically resistive layer 64, in part because this is where the effects of any residual temperature and pressure are considered to be greatest. However, it should also be appreciated that in other implementations, the fifth surface modification 95 may be provided along the entire length of the capillary tube 66, particularly where the abovementioned factors are negligible and the liquid aerosol-generating may flow too freely along the entire length of the capillary tube 66.

In accordance with the third implementation of Figure 9b, the fifth surface modification 95 is provided to help slow the supply of liquid to the electrically resistive layer 64 (i.e. to help prevent or reduce instances where the liquid aerosol-generating material leaks from the electrically resistive layer 64).

While the arrangements in Figures 9a and 9b show the fourth and fifth surface modifications 94, 95 provided in certain portions of the capillary tubes 66, it should be appreciated that in some implementations, the functions of the fourth and fifth surface modifications 94, 95 may be reversed. For example, in respect of the arrangement in Figure 9a, in some implementations it may be found that the liquid aerosol-generating material passes from the second surface 62b I reservoir 46 at a greater rate than is desired and hence the fourth surface modification 94 may instead be configured to relatively decrease the surface energy of the side walls of the capillary tubes 66 in the region closest to the second surface 62b, and is subsequently not present at the region closest to the electrically resistive layer 64 to not restrict the flow of liquid to the electrically resistive layer 64 during vaporisation.

Alternatively, in respect of the arrangement of Figure 9b, the fifth surface modification 95 may instead be arranged to relative increase the surface energy of the side walls of the capillary tubes 66 in the region closest to the electrically resistive layer 64 to help improve the flow of liquid to the electrically resistive layer 64 during vaporisation.

More generally, it should be appreciated that a surface modification (i.e., the fourth or fifth surface modifications 94, 95) is provided on at least a part of the side surfaces of the one or more capillary tubes 66 to adjust the characteristics of the at least a part of the side surfaces of the one or more capillary tubes 66 with respect to the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes 66. In some implementations, the surface modification may be configured to improve the flow of aerosolgenerating material, such that aerosol-generating material is capable of flowing through the one or more capillary tubes 66 at a greater rate. This may be to ensure that the electrically resistive layer 64 is supplied with sufficient aerosol-generating material and to reduce or avoid instances where the electrically resistive layer 64 runs dry. In some implementations, the surface modification may be configured to impede the flow of aerosol-generating material, such that aerosol-generating material is capable of flowing through the one or more capillary tubes 66 at a lower rate. This may be to help retain liquid within the capillary tubes 661 heater assembly 6 and avoid instances such as leakage. Overall, it should be understood that providing the fourth and fifth surface modifications 94, 95 allows for the performance of the heater assembly 6 to be modified or adjusted as desired to provided for a certain performance or to provide certain characteristics.

As noted above, it should also be appreciated that all of the plurality of capillary tubes 66 may comprise the same surface modification or, in other implementations, only certain ones of the plurality of capillary tubes 66 may be provided with surface modifications or alternatively, different surface modifications may be applied to different capillary tubes 66. This may allow for more selective or targeted control of the liquid flow properties in certain areas of the heater assembly 6. For example, it may be desired to relatively increase the flow of liquid to areas of the heater assembly 6 that are at a greater operational temperature (e.g., the centre of the central portion 67) where the rate of vaporisation may be greatest.

Figures 10a and 10b schematically represent a fourth implementation of a heater assembly 6 comprising a surface modification in accordance with the another aspect of the present disclosure. In particular, Figures 10a and 10b schematically represent a heater assembly 6 having a surface modification provided on the surface of the electrically resistive layer 64. Figure 10a shows a top-down view of the surface of the electrically resistive layer 64, while Figure 10b shows a perspective view of the heater assembly 6.

As should be appreciated, the surface of the electrically resistive layer 64 faces towards the central air passage 73 and is therefore arranged to receive liquid from the capillary tubes 66 and vaporise the liquid to form a vapour that at least initially is provided in the vicinity of the central air passage 73.

In accordance with the fourth implementation, the heater assembly 6, and more particularly the surface of the electrically resistive layer 64, is provided with sixth surface modifications 96 provided on the surface of the electrically resistive layer 64 at locations around the openings to the capillary tubes 66. In principle, the sixth surface modifications 96 are similar to the second surface modifications 92 of Figures 8a and 8b. In a similar manner to the second surface modifications 92, the sixth surface modifications 96 are provided to relatively increase the surface energy of the bulk material, i.e. , the electrically resistive layer 64, at the portions where the sixth surface modification 92 is provided as compared to those portions of the surface of the electrically resistive layer 64 where the sixth surface modification 96 is not provided.

In terms of the liquid itself, this similarly results in a relatively smaller contact angle being formed with the surface of the electrically resistive layer 64 in the portions having the sixth surface modification 96 and therefore the liquid experiences a greater spread across the surface of the electrically resistive layer 64 (particularly in the vicinity of the openings of the capillary tubes 66). Hence, the sixth surface modification 96 is provided to increase or improve the liquid flow characteristics of the surface of the electrically resistive layer 64 in the portion where the sixth surface modification 96 is provided. In particular, the sixth surface modification 96 is capable of causing liquid aerosol-generating material supplied by the capillary tubes 66 to spread over a larger area of the surface of the electrically resistive layer 64. As the electrically resistive layer 64 is responsible for vaporising the liquid to form an aerosol during use of the heater assembly 6, increasing the effective surface area of the electrically resistive layer 64 that contacts the liquid means that the electrically resistive layer 64 can help vaporise the same relative amount of liquid more quickly. In other words, by causing the liquid aerosol-generating material to spread out across the surface of the electrically resistive layer 64, the heater assembly 6 is able to vaporise liquid at a relatively faster rate. Therefore, owing to the sixth surface modifications 96, liquid that is in the vicinity of the openings of the capillary tubes 66 is capable of more easily or more readily flowing across the surface of the electrically resistive layer 64 and therefore being vaporised more readily but the electrically resistive layer 64.

Further, the heater assembly 6 of Figures 10a and 10b is provided with a seventh surface modification 97. The seventh surface modification 97 is provided to relatively decrease the surface energy of the bulk material, i.e., the electrically resistive layer 64, at the portions where the seventh surface modification 97 is provided as compared to those portions of the surface of the electrically resistive layer 64 where the seventh surface modification 97 is not provided (and additionally also portions where the sixth surface modifications 96 are not provided). In terms of the liquid itself, this results in a relatively larger contact angle being formed with the surface of the electrically resistive layer 94 in the regions having the seventh surface modification 97 and therefore the liquid experiences a relatively smaller spread across the surface 62b. Hence, the seventh surface modification 97 is provided to inhibit or reduce the liquid flow characteristics of the surface of the electrically resistive layer 64 in the regions where the seventh surface modification 97 is provided. The seventh surface modification 97 is provided running along the centre of the electrically resistive layer 64 (parallel with the longitudinal axis L2). The seventh surface modification 97 acts to impede liquid flow in the direction towards the centre of the electrically resistive layer 64. Similarly to the third surface modification 93, the seventh surface modification 97 can be thought of as acting as a barrier to restrict the flow of liquid along the surface of the electrically resistive layer 64. In this example, the seventh surface modification 97 acts to retain liquid within the region close to the openings of the capillary tubes 66. The seventh surface modification 97 reduces the chance of liquid passing from one capillary tube to another capillary tube 66. This may be utilised to prevent excess liquid from one capillary tube 66 passing to another capillary tube 66 and causing flooding or otherwise detrimental effects in terms of vaporisation performance. In other instances, the seventh surface modification 97 may cause any condensed liquid formed via aerosol condensing the central air passage 73 but being unable to pass along the air channel 73 that condenses on the surface of the electrically resistive layer 64 to remain in the proximity of the corresponding capillary tube 66 (again, allowing the opportunity for the condensed liquid to pass to the corresponding capillary tube 66 rather than to any capillary tube 66 and/or any other area of the electrically resistive layer 64). Therefore, owing to the seventh surface modification 97, the movement of liquid across the surface of the electrically resistive layer 64 is restricted or limiting such that the liquid is broadly retained in suitable areas of the surface of the electrically resistive layer 64.

Hence, according to the third implementation of Figures 10a and 10b, the surface of the electrically resistive layer 64 of the heater assembly 6 is provided with one or more surface modifications 96, 97 arranged so as to alter the flow of liquid aerosol-generating material across the surface of the electrically resistive layer 64. In the example described, the sixth surface modification 96 is provided to relatively improve the flow of liquid aerosol-generating material across the surface of the electrically resistive layer 64 in order to facilitate a spreading of the liquid aerosol-generating material and thus an improvement in the aerosol generation performance of the heater assembly 6, while the seventh surface modification 97 is provided to relatively decrease the flow of liquid aerosol-generating material across the surface of the electrically resistive layer 64 in order to retain liquid in certain portions of the surface of the electrically resistive layer 64 (namely from passing between certain capillary tubes 66 which may cause overloading of liquid in certain areas). However, it should be appreciated that the implementation shown in Figures 10a and 10b is an example only, and in other implementations the provision of surface modifications 96, 97 may be different from that shown. For example, in some implementations, it may be desired to switch the relative increase and decrease in surface energy of the surface of the electrically resistive layer 64 offered by the sixth and/or seventh surface modifications 96, 97. That is, in some implementations, the sixth surface modification 96 may instead be configured to relatively decrease the surface energy as compared to the portions of the surface of the electrically resistive layer 64 that do not comprise a surface modification, while the seventh surface modification 97 may additionally or alternative be configured to relatively increase the surface energy as compared to the portions of the surface of the electrically resistive layer 64 that do not comprise a surface modification. Thus, the sixth surface modification 96 may be provided to effectively decrease the spreading of the aerosol-generating material across the surface of the electrically resistive layer 64, to reduce the rate of aerosol generation. Equally, the seventh surface modification 97 may be provided to facilitate the flow of aerosol-generating material toward certain areas (e.g., capillary tubes 66) to return any leaked or condensed liquid to the capillary tubes 66.

Therefore, it should be appreciated that surface modifications 96, 97 may be provided to the surface of the electrically resistive layer 64 of the heater assembly 6 to influence the flow or transport of liquid aerosol-generating material across the surface of the electrically resistive layer 64. Depending on the specific characteristics of the heater assembly 6 and its interaction with the liquid aerosol-generating material, the surface modifications 96, 97 may be provided in any desired configuration to achieve a particular outcome. While the example of Figure 10a and 10b shows surface modifications for increasing the surface energy (i.e. , the sixth surface modification 96) and for decreasing the surface energy (i.e., the seventh surface modification 97), it should be appreciated that certain implementations may only employ one type of surface modification. Additionally, while Figures 10a and 10b show a particular shape and distribution of the surface modifications 96, 97, it should be understood that this is an example only and other implementations may have surface modifications with different shapes and/or different distributions across the surface of the electrically resistive layer 64. Furthermore, as noted above, in some implementations, a surface modification may be provided across the entirety of the surface of the electrically resistive layer 64.

The heater assembly 6 as described above is generally provided as a relatively small component having a relatively small footprint (as compared to more traditional heater assemblies, such as a wick and coil). This is in part due to the fact the capillary tubes 66 are formed via a manufacturing process in the heater assembly 6 (i.e., the capillary tubes are engineered, e.g., through a laser drilling process), and can therefore be designed to achieve a desired delivery of liquid aerosol-generating material to the electrically resistive layer 64. By providing a smaller component, material wastage (e.g., when the cartomiser 3 is disposed of) can be reduced. Additionally, by applying one or more surface modifications, the performance of the heater assembly 6 can be tailored to achieve a particular goal or performance.

It should also be appreciated that while the above has described a cartomiser 3 which includes the heater assembly 6, in some implementations, the heater assembly 6 may be provided in the aerosol provision device 2 itself. For example, the aerosol provision device 2 may comprise the heater assembly 6 and a removable cartridge (containing a reservoir of liquid aerosol-generating material). The heater assembly 6 is provided in fluid contact with the liquid in the cartridge (e.g., via a suitable wicking element or via another fluid transport mechanism). Alternatively, the aerosol provision device 2 may include an integrated liquid storage area in addition to the heater assembly 6 which may be refillable with liquid. More broadly, the aerosol provision system (which encompasses a separable aerosol provision device and cartomiser / cartridge or an integrated aerosol provision device and cartridge) includes the heater assembly.

Figure 11 depicts an example method for manufacturing a heater assembly 6.

The method begins at step S11 by providing a substrate 62. The way in which the substrate 62 is formed is not significant to the principles of the present disclosure. For example, the substrate 62 may be cut from a portion of cultured quartz or formed via a sintering process by sintering quartz powders I fibres, for example.

The method then proceeds to step S12 whereby the electrically resistive layer 64 is provided on a surface of the substrate 62. The way in which the electrically resistive layer 64 is formed on the surface of the substrate 62 is not significant to the principles of the present disclosure. For example, the electrically resistive layer 64 may be a sheet of metal (e.g., titanium) adhered, welded, or the like to the substrate 62. Alternatively, the electrically resistive layer 64 may be formed through a vapour or chemical deposition technique using the substrate 62 as a base.

It should also be appreciated that step S12 may alternatively occur before step S11. For example, a further alternative is to grow or culture the substrate 62 using the electrically resistive layer 64 as a base.

In the described example, after step S12, the method proceeds to step S13. At step S13, one or more capillary tubes 66 are formed in the substrate 621 electrically resistive layer 64. As noted above, the capillary tubes 66 extend from a surface of the substrate 62 I heater assembly 6, through the electrically resistive layer 64 provided on the first surface of the substrate 62. That is, the capillary tubes 66 extend all the way through the heater assembly 6. The capillary tubes 66 may be formed by laser drilling, as noted above, or any other suitable technique.

It should be appreciated that step S13 may be performed prior to step S12 (and equally step S13 may follow step S11 where step S12 is performed prior to step S11). That is to say, the capillary tubes 66 may be formed in the substrate 62 prior to applying the electrically resistive layer 64.

At step S14, one or more surface modifications are provided to the heater assembly 6. As noted above, the surface modifications 92-97, 191 may be provided on at least a portion of one of the surface of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side walls/surfaces of the one or more capillary tubes 66. The surface modifications are provided to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one of the surface of the electrically resistive layer 64, the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66. As described above, the surface modifications may comprise a surface coating and/or a surface treatment, and accordingly at step S14 any suitable technique may be employed to provide the surface modifications as desired, e.g., such as CVD or polishing, etc.

Broadly, it should be understood that the method of Figure 11 is an example method only, and adaptations to the steps or ordering of the steps of this method are contemplated within this disclosure, for example, as described above.

After step S14, the heater assembly 6 is formed, and subsequently may be assembled to form the cartomiser 3 (or more generally, the heater assembly 6 may be positioned in an aerosol provision system 1).

In accordance with the principles of the present disclosure, there is also provided heater means, which includes the heater assembly 6, for an aerosol provision means, which includes the aerosol provision system 1. The heater means includes a substrate, which may include the substrate 62, heater layer means, which may include the electrically resistive layer 64, provided on at least a first surface of the substrate and configured to generate heat; and capillary means, which may include the capillary tubes 66, extending from a second surface of the substrate and through the substrate and the heater layer means, the capillary means configured to supply aerosol-generating material from the second surface of the substrate to the heater layer means. The heater means comprises surface modification means, which may include the surface modifications 92-97, 191, configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer means, the second surface of the substrate, and the side surfaces of the capillary means.

Thus, there has been described a heater assembly for an aerosol provision system, the heater assembly including a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat; and one or more capillary tubes extending from a second surface of the substrate and through the substrate and the heater layer, the one or more capillary tubes configured to supply aerosol-generating material from the second surface of the substrate to the heater layer. The heater assembly includes a surface modification configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes. Also described is a consumable for use with an aerosol provision device, an aerosol provision device, an aerosol provision system, a method of manufacturing a heater assembly and heater means.

Alternatively, the present disclosure may be summarised as providing a heater assembly for an aerosol provision system, the heater assembly 6 having a substrate 62; a heater layer 64 provided on at least a first surface of the substrate 62 and configured to generate heat; and one or more capillary tubes 66 extending from a second surface 62b of the substrate 62 and through the substrate 62 to the heater layer 64, the one or more capillary tubes 66 configured to supply aerosol-generating material from the second surface 62b of the substrate to the heater layer 64. The heater assembly 6 further comprises a surface modification 92-97, 191 configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer 64, the second surface 62b of the substrate 62, and the side surfaces of the one or more capillary tubes 66.

While the above described embodiments have in some respects focussed on some specific example aerosol provision systems, it will be appreciated the same principles can be applied for aerosol provision systems using other technologies. That is to say, the specific manner in which various aspects of the aerosol provision system function are not directly relevant to the principles underlying the examples described herein.

In order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. other than those specifically described herein, and it will thus be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims. The disclosure may include other inventions not presently claimed, but which may be claimed in future.

Claims

1. An aerosol provision system, the aerosol provision system comprising: a heater assembly, the heater assembly comprising: a substrate; a heater layer provided on at least a first surface of the substrate and configured to generate heat; a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic; and a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic; and an aerosol-generating material storage region, in fluid communication with the second surface of the substrate, comprising a first and second aerosol-generating material; wherein the second aerosol-generating material has a higher viscosity than the first aerosol-generating material; and wherein the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material.

2. The aerosol provision system of claim 1 , wherein the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material along the first set of one or more capillary tubes.

3. The aerosol provision system of claims 1 or 2, wherein the second set of one or more capillary tubes are configured to permit the first aerosol-generating material and the second aerosol-generating material to flow along the second set of one or more capillary tubes.

4. The aerosol provision system of any of the preceding claims, wherein the first aerosol-generating material when aerosolised by heater layer produces an aerosol having different characteristics compared to the second aerosol-generating material when aerosolised by the heater layer.

5. The aerosol provision system of any of the preceding claims, wherein the first set of one or more capillary tubes are provided in one or more regions of the heater assembly such that the second aerosol-generating material is impeded or prevented from being provided to the heater layer in the one or more regions of the heater assembly.

6. The aerosol provision system of claim 5, wherein the heater layer in the one or more regions of the heater assembly is configured such that, in use, the one or more regions have a different operational characteristic compared to the rest of the heater layer.

7. The aerosol provision system of any of the preceding claims, wherein the first set of one or more capillary tubes differ from the second set of one or more capillary tubes by at least one of: a size of a cross-sectional area, the shape of the cross-sectional area, and the properties of side surfaces of the one or more capillary tubes.

8. The aerosol provision system of any of the preceding claims, wherein the aerosolgenerating material storage portion comprises a first aerosol-generating material storage portion storing the first aerosol-generating material and a second aerosol-generating material storage portion storing the second aerosol-generating material, wherein the first aerosol-generating material storage portion and the second aerosol-generating material storage portion are both provided in fluid communication with the second surface of the substrate of the heater assembly.

9. A consumable for use with an aerosol provision system to generate an aerosol, the consumable comprising: a heater assembly, the heater assembly comprising: a substrate; a heater layer provided on at least a first surface of the substrate and configured to generate heat; a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic; and a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic; and an aerosol-generating material storage region, in fluid communication with the second surface of the substrate, comprising a first and second aerosol-generating material; wherein the second aerosol-generating material has a higher viscosity than the first aerosol-generating material; and wherein the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material.

10. A method of manufacturing an aerosol provision system or a consumable for use with the aerosol provision system, the aerosol provision system or the consumable comprising a heater assembly, the heater assembly comprising a substrate, and a heater layer provided on at least a first surface of the substrate and configured to generate heat, the aerosol provision system or consumable further comprising an aerosol-generating material storage portion comprising a first aerosol-generating material and a second aerosol-generating material, wherein the second aerosol-generating material has a higher viscosity than the first aerosol-generating material, wherein the method includes: providing a first set of one or more capillary tubes extending from a second surface of the substrate through the substrate and the heater layer and having a first characteristic; and providing a second set of one or more capillary tubes extending from the second surface of the substrate through the substrate and the heater layer and having a second characteristic different from the first characteristic, wherein the first set of one or more capillary tubes are configured to impede the flow of the second aerosol-generating material.

11. An aerosol provision means, the aerosol provision means comprising: heater means, the heater means comprising: a substrate; heater layer means provided on at least a first surface of the substrate and configured to generate heat; a first set of capillary means extending from a second surface of the substrate through the substrate and the heater layer means and having a first characteristic; and a second set of capillary means extending from the second surface of the substrate through the substrate and the heater layer means and having a second characteristic different from the first characteristic; and aerosol-generating material storage means, in fluid communication with the second surface of the substrate, comprising a first and second aerosol-generating material; wherein the second aerosol-generating material has a higher viscosity than the first aerosol-generating material; and wherein the first set of capillary means are configured to impede the flow of the second aerosol-generating material.

12. A heater assembly for an aerosol provision system, the heater assembly comprising: a substrate; a heater layer provided on at least a first surface of the substrate and configured to generate heat; and one or more capillary tubes extending from a second surface of the substrate and through the substrate and the heater layer, the one or more capillary tubes configured to supply aerosol-generating material from the second surface of the substrate to the heater layer, wherein the heater assembly comprises a surface modification configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

13. The heater assembly of claim 12, wherein the surface modification comprises at least one of: a surface coating and a surface treatment.

14. The heater assembly of claim 12 or 13, wherein the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the surface of the at least one of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

15. The heater assembly of claim 12 or 13, wherein the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the surface of the at least one of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

16. The heater assembly of any of claims 12 to 15, wherein the surface modification is provided on at least a part of the second surface of the substrate and is configured to adjust the characteristics of the at least a part of the surface of the second surface of the substrate with respect to the flow of aerosol-generating material capable of flowing along the second surface of the substrate.

17. The heater assembly of claim 16, wherein the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the second surface of the substrate, such that aerosol-generating material is capable of flowing towards openings of the one or more capillary tubes.

18. The heater assembly of claim 16, wherein the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the second surface of the substrate, such that the flow of aerosol-generating material toward openings of the one or more capillary tubes is reduced.

19. The heater assembly of claim 17 or 18, wherein the surface modification is provided on at least a part of the second surface of the substrate surrounding the opening of at least one of the one or more capillary tubes.

20. The heater assembly of any of claims 12 to 19, wherein the surface modification is provided on at least a part of the side surfaces of the one or more capillary tubes and is configured to adjust the characteristics of the at least a part of the side surfaces of the one or more capillary tubes with respect to the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes.

21. The heater assembly of claim 20, wherein the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes, such that aerosol-generating material is capable of flowing through the one or more capillary tubes at a greater rate.

22. The heater assembly of claim 20, wherein the surface modification is configured to impede the flow of aerosol-generating material capable of flowing along the side surfaces of the one or more capillary tubes, such that aerosol-generating material is capable of flowing through the one or more capillary tubes at a lower rate.

23. The heater assembly of any of claims 12 to 22, wherein the surface modification is provided on at least a part of the surface of the heater layer and is configured to adjust the characteristics of the at least a part of the surface of the heater layer with respect to the flow of aerosol-generating material capable of flowing along the surface of the heater layer.

24. The heater assembly of claim 23, wherein the surface modification is configured to improve the flow of aerosol-generating material capable of flowing along the surface of the heater layer, such that aerosol-generating material is capable of flowing from openings of the one or more capillary tubes in the heater layer.

25. A consumable for use with an aerosol provision device, the consumable comprising an aerosol-generating material storage portion, an airflow pathway and the heater assembly of any of claims 12 to 24, wherein the heater assembly is configured such that the second surface of the substrate is provided in fluid communication with the aerosol-generating material storage portion and the heater layer is provided in fluid communication with the airflow pathway.

26. An aerosol provision device for use with a consumable, the device comprising an airflow pathway and the heater assembly of any of claims 12 to 24, wherein the heater assembly is configured such that the heater layer is provided in fluid communication with the airflow pathway.

27. An aerosol provision system, the aerosol provision system comprising an aerosolgenerating material storage portion, an airflow pathway and the heater assembly of any of claims 12 to 24, wherein the heater assembly is configured such that the second surface of the substrate is provided in fluid communication with the aerosol-generating material storage portion and the heater layer is provided in fluid communication with the airflow pathway.

28. A method of manufacturing a heater assembly for an aerosol provision system, the heater assembly comprising a substrate, a heater layer provided on at least a first surface of the substrate and configured to generate heat; and one or more capillary tubes extending from a second surface of the substrate and through the substrate and the heater layer, the one or more capillary tubes configured to supply aerosol-generating material from the second surface of the substrate to the heater layer, wherein the method comprises: providing a surface modification configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one of the surface of the heater layer, the second surface of the substrate, and the side surfaces of the one or more capillary tubes.

29. Heater means for an aerosol provision means, the heater means comprising: a substrate; heater layer means provided on at least a first surface of the substrate and configured to generate heat; and capillary means extending from a second surface of the substrate and through the substrate and the heater layer means, the capillary means configured to supply aerosolgenerating material from the second surface of the substrate to the heater layer means, wherein the heater means comprises surface modification means configured to adjust the flow of aerosol-generating material capable of flowing along at least a portion of one or more of the surface of the heater layer means, the second surface of the substrate, and the side surfaces of the capillary means.