WO2025040626A1

WO2025040626A1 - Heater assembly with microchannel array

Info

Publication number: WO2025040626A1
Application number: PCT/EP2024/073219
Authority: WO
Inventors: Fernando CARBAJO FUERTES; Bo Jiang
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2023-08-24
Filing date: 2024-08-19
Publication date: 2025-02-27
Anticipated expiration: 2026-02-24

Abstract

The invention relates to a heater assembly for an aerosol-generating device. The heater assembly comprises a heating element (10) for heating a liquid aerosol-forming substrate (12) and a liquid transport structure (14) configured to transport the liquid aerosol-forming substrate towards the heating element. The liquid transport structure comprises a plurality of microchannels (16, 18, 20) arranged in an ordered array. The invention further relates to an aerosol-generating device. The invention further relates to an aerosol-generating system comprising the aerosol-generating device and an aerosol-forming substrate. The invention further relates to a method for manufacturing a heater assembly for an aerosol-generating device.

Description

HEATER ASSEMBLY WITH MICROCHANNEL ARRAY

The present disclosure relates to a heater assembly for an aerosol-generating device. The present disclosure further relates to an aerosol-generating device. The present disclosure further relates to an aerosol-generating system comprising the aerosol-generating device and an aerosol-forming substrate. The present disclosure further relates to a method for manufacturing a heater assembly for an aerosol-generating device.

It is known to provide an aerosol-generating device for generating an inhalable vapor. Such devices may heat an aerosol-forming substrate without burning the aerosol-forming substrate. The aerosol-generating device may comprise a heating element for heating the aerosol-forming substrate.

Upon heating to a target temperature, the aerosol-forming substrate vaporises to form an aerosol. The aerosol-forming substrate may be present in solid form or in liquid form. Liquid aerosol-forming substrate may be comprised in a liquid storage portion and may be delivered to the heating element via a wicking component. The liquid storage portion may form part of a replaceable or refillable cartridge.

It would be desirable to provide a durable aerosol-generating device. It would be desirable to provide an aerosol-generating device that may reliably produce aerosol over many heating cycles. It would be desirable to provide an aerosol-generating device that may be used over many heating cycles without substantial material degradation. It would be desirable to provide an aerosol-generating device that may reduce or avoid carbonization of components of the heater assembly.

It would be desirable to provide an aerosol-generating device that enables a homogenized vaporization process. It would be desirable to provide an aerosol-generating device that enables an optimized aerosolization process. It would be desirable to provide an aerosol-generating device that enables precise control of throughput of aerosol-forming substrate.

According to an embodiment of the invention there is provided a heater assembly for an aerosol-generating device. The heater assembly may comprise a heating element for heating a liquid aerosol-forming substrate. The heater assembly may comprise a liquid transport structure. The liquid transport structure may be configured to transport the liquid aerosol-forming substrate towards the heating element. The liquid transport structure may comprise a plurality of microchannels arranged in an ordered array.

According to an embodiment of the invention there is provided a heater assembly for an aerosol-generating device. The heater assembly comprises a heating element for heating a liquid aerosol-forming substrate. The heater assembly comprises a liquid transport structure. The liquid transport structure is configured to transport the liquid aerosol-forming substrate towards the heating element. The liquid transport structure comprises a plurality of microchannels arranged in an ordered array.

By the heater assembly of the invention, a durable aerosol-generating device may be provided. An aerosol-generating device that reliably produces aerosol over many heating cycles may be provided. An aerosol-generating device that can be used over many heating cycles without substantial material degradation may be provided. An aerosol-generating device that reduces or avoids carbonization of components of the heater assembly may be provided.

An aerosol-generating device that enables a homogenized vaporization process may be provided. An aerosol-generating device that enables an optimized aerosolization process may be provided. An aerosol-generating device that enables precise control of throughput of aerosol-forming substrate may be provided.

The liquid transport structure comprising the ordered array of microchannels may allow for a precisely predefined amount of liquid aerosol-forming substrate to be transported to the heating element and thus to be volatized.

The liquid transport structure comprising the ordered array of microchannels may allow for an optimized design of the heater assembly in view of a specific device. The aerosolization process may be optimized for each specific application. Carbon deposition may be reduced or avoided. The product lifetime may be enhanced. An aerosol-generating device that may reliably produce aerosol over many heating cycles may be provided.

The liquid aerosol-forming substrate may be transported through the microchannels provided in the liquid transport structure. The liquid aerosol-forming substrate may be transported through the microchannels provided in the liquid transport structure via capillary forces. The liquid transport structure may be configured to transport the liquid aerosolforming substrate to the heating element. The liquid transport structure may be configured to transport the liquid aerosol-forming substrate from a liquid reservoir towards the heating element. The liquid transport structure may be configured to transport the liquid aerosolforming substrate from a liquid reservoir to the heating element.

As used herein, the term “microchannel” relates to a straight hollow channel in the liquid transport structure, the hollow channel having a diameter in the micrometer range, preferably in the range of 1 micrometer to 1000 micrometers, more preferably in the range of 1 micrometer to 999 micrometers. A length of the microchannel may exceed the micrometer range.

As used herein, a continuous hollow path having a diameter in the micrometer range and comprising, along its length, one or more changes of direction between a plurality of straight portions, is defined as a plurality of microchannels. For example, a continuous hollow path having a diameter in the micrometer range and comprising, along its length, two straight portions fluidly connected by a turn of 90 degrees between them, is defined as two microchannels which are fluidly connected to each other at the position of the turn of 90 degrees.

A first microchannel of the liquid transport structure may be fluidly connected to a second microchannel of the liquid transport structure. For example, an open end of a first microchannel extending along a first direction may coincide with an open end of a second microchannel extending in a second direction.

As used herein, the term “ordered array” refers to a predefined arrangement of the microchannels.

The predefined arrangement may comprise microchannels having predefined dimensions. The predefined dimensions may comprise one or more of a predefined length of the microchannel, a predefined diameter of the microchannel, a predefined position of the microchannel in the liquid transport structure, and a predefined orientation of the microchannel in the liquid transport structure.

The predefined arrangement may comprise one or more microchannels extending along a straight line. By “extending along a straight line”, it is meant that the channel is a linear channel extending in one linear direction.

The predefined arrangement may comprise one or more microchannels having a constant diameter along their length. The predefined arrangement may comprise a plurality of microchannels having the same length. The predefined arrangement may comprise a plurality of microchannels having the same diameter. The predefined arrangement may comprise a plurality of microchannels all having the same length and the same diameter. The predefined arrangement may comprise a plurality of identical microchannels.

The predefined arrangement may comprise microchannels being arranged in predefined orientations. The predefined arrangement may comprise microchannels being arranged in parallel to one another. The predefined arrangement may comprise microchannels being arranged in perpendicular to one another.

The microchannels in the ordered array are thus not random microchannels of a microcapillary material, but are artificially created, for example by a manufacturing method as described herein.

At least two microchannels of the ordered array may each extend along a straight line, and the straight lines may be arranged in parallel. The “straight line” along which the channel extends refers to a longitudinal center axis of a respective channel. At least three microchannels of the ordered array may each extend along a straight line, and the straight lines may be arranged in parallel. The at least three parallelly arranged microchannels may be equidistantly spaced.

At least two microchannels of the ordered array may each extend along a straight line and the straight lines be arranged in perpendicular.

A first microchannel may extend along a first straight line and a second microchannel may extend along a second straight line, the first straight line may be arranged in perpendicular to the second straight line, and an open end of the first microchannel may be in direct fluid connection with an open end of the second microchannel.

At least two microchannels of the ordered array may have the same length.

At least two microchannels of the ordered array may have the same diameter.

The ordered array may comprise an ordered structure of at least a portion of the microchannels.

At least a portion of the microchannels may be arranged in a regular pattern.

As used herein, the term “ordered structure” refers to a set of building blocks arranged in predefined structural relationship, for example a regular pattern. As used herein, the term “regular pattern” refers to a symmetric arrangement of building blocks that repeat along the principal directions of three-dimensional space. The set of building blocks may be a plurality of microchannels.

A diameter of the microchannels may be in the range of 1 micrometer to 2000 micrometers. A diameter of the microchannels may be in the range of 300 micrometers to

2000 micrometers. A diameter of the microchannels may be in the range of 1 micrometer to

1000 micrometers, preferably 10 micrometers to 500 micrometers, more preferably 20 micrometers to 400 micrometers, more preferably 50 micrometers to 200 micrometers. A diameter of the microchannels may be below 100 micrometers.

The ordered array may comprise at least 5 microchannels, preferably at least 10 microchannels, more preferably at least 15 microchannels, more preferably at least 20 microchannels, more preferably at least 25 microchannels, more preferably at least 30 microchannels, more preferably at least 35 microchannels, more preferably at least 40 microchannels, more preferably at least 45 microchannels, more preferably at least 50 microchannels.

The liquid transport structure may comprise less than 500 microchannels, preferably less than 400 microchannels, more preferably less than 350 microchannels, more preferably less than 300 microchannels, more preferably less than 250 microchannels, more preferably less than 200 microchannels, more preferably less than 150 microchannels, more preferably less than 100 microchannels. All microchannels of the liquid transport structure may form part of the ordered array.

The liquid transport structure comprising the plurality of microchannels may be a monolithic structure. A compact heater assembly may be provided. A robust heater assembly may be provided. A heater assembly that can be easily handled during manufacturing of the aerosol-generating device may be provided.

The liquid transport structure comprising the plurality of microchannels may be made of glass, silica, or a ceramic material.

The heating element may comprise a metallic film provided on an outer surface of the liquid transport structure. The metallic film may be a planar metallic film.

The plurality of microchannels may comprise a plurality of outlet-microchannels. Each outlet-microchannel may extend from an interior of the liquid transport structure to the surface of the liquid transport structure comprising the metallic film.

Each outlet-microchannel may extend from a transversal manifold channel arranged within the liquid transport structure to the surface of the liquid transport structure comprising the metallic film. The transversal manifold channel may extend substantially in perpendicular to the outlet-microchannels.

The plurality of microchannels may comprise a plurality of supply-microchannels. Each supply-microchannel may extend from a surface of the liquid transport structure opposing the surface of the liquid transport structure comprising the metallic film to the transversal manifold channel. The transversal manifold may channel extend substantially in perpendicular to the supply-microchannels. The supply-microchannels may be fluidly connected to a liquid storage portion. The transversal manifold channel may extend substantially in parallel to the surface of the liquid transport structure comprising the metallic film.

The heating element may be embedded within the liquid transport structure. A compact heater assembly may be provided. A robust heater assembly may be provided. A heater assembly that can be easily handled during manufacturing of the aerosol-generating device may be provided.

The liquid transport structure comprising the plurality of microchannels may be a monolithic structure and the heating element may be embedded within the monolithic liquid transport structure. The combination of a monolithic liquid transport structure and the heating element being embedded in the liquid transport structure may synergistically provide a particularly compact heater assembly. The combination of a monolithic liquid transport structure and the heating element being embedded in the liquid transport structure may synergistically provide a particularly robust heater assembly. The combination of a monolithic liquid transport structure and the heating element being embedded in the liquid transport structure may synergistically provide a heater assembly that can be particularly easily handled during manufacturing of the aerosol-generating device. By the combination of a monolithic liquid transport structure and the heating element being embedded in the liquid transport structure, a particularly durable heater assembly may be provided.

The embedded heating element may be provided on an inner surface of the liquid transport structure. For example, the embedded heating element may be provided on a surface of a vaporization channel of the liquid transport structure.

As used herein, the term ‘vaporization channel’ may refer to a channel of the liquid transport structure of the heater assembly which is configured such that liquid aerosolforming substrate is vaporized or volatized in the vaporization channel during use.

The embedded heating element may be encapsulated by a material layer of the liquid transport structure. For example, the embedded heating element may be provided within the material of the liquid transport structure below a surface of a vaporization channel of the liquid transport structure.

The heating element may comprise a metallic film embedded within the liquid transport structure. The metallic film embedded within the liquid transport structure may be a planar metallic film.

The heater assembly may comprise a thin layer of wicking material arranged on top of the heating element. The heater assembly may comprise a thin layer of wicking material arranged on top of the metallic film. The thickness of the thin layer may be equal to or less than 500 micrometers, preferably equal to or less than 300 micrometers, more preferably equal to or less than 150 micrometers, more preferably equal to or less than 100 micrometers. The thin layer of wicking material may promote wetting of the liquid.

The thin layer of wicking material may be provided directly on the metallic film The thin layer of wicking material may be in direct physical contact with the metallic film. Alternatively, a material layer of the liquid transport structure may be arranged spatially between the layer of wicking material and the metallic film. The thin material layer of the liquid transport structure may be arranged spatially between the layer of wicking material and the metallic film, such that the layer of wicking material and the metallic film are in thermal proximity. The layer of wicking material and the metallic film may be in thermal proximity such that the metallic film may heat the layer of wicking material to volatilize aerosol-forming substrate soaked by the thin layer of wicking material. For example, the heating element may be encapsulated by a layer of the liquid transport structure. The heating element may be surrounded by the liquid transport structure. The heating element may be entirely surrounded by the liquid transport structure. The liquid transport structure may comprise a vaporization channel spatially arranged between the metallic film and at least one supply-microchannel.

The at least one supply-microchannel may be at least one micro dispenser unit. The at least one micro dispenser unit may comprise a valve control means. The micro dispenser unit may allow to provide a predefined quantity of liquid aerosol-forming substrate onto the thin layer of wicking material.

The liquid transport structure may comprise at least one inlet-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel. The at least one inlet-microchannel may extend substantially in perpendicular to the vaporization channel.

The liquid transport structure may comprise at least one outlet-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel. The at least one outlet microchannel may extend substantially in parallel to the vaporization channel.

A diameter of the at least one inlet-microchannel may exceed a diameter of the at least one outlet-microchannel. A ratio of the diameter of the at least one outlet-microchannel to the diameter of the at least one inlet-microchannel may be equal to or less than 0.8.

The liquid transport structure may comprise a vaporization channel spatially arranged between the metallic film and at least one inlet-and-supply-microchannel. The at least one inlet-and-supply-microchannel may extend from an outer surface of the liquid transport structure to the vaporization channel. The at least one inlet-and-supply-microchannel may be configured to direct both air and liquid-aerosol-forming substrate into the vaporization channel. The at least one inlet-and-supply-microchannel may extend substantially in perpendicular to the vaporization channel. The heater assembly may comprise at least one outlet-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel. The at least one outlet-microchannel may extend substantially in perpendicular to the vaporization channel. Both the at least one inlet-and-supply- microchannel and the at least one outlet-microchannel may extend from a common planar boundary surface of the liquid transport structure to the vaporization channel.

The heater assembly may comprise a liquid storage portion. The liquid storage portion may be in contact with the liquid transport structure. The liquid storage portion may be configured for feeding a liquid aerosol-forming substrate to the liquid transport structure.

The heating element may be a resistive heating element. The heating element may be electrically fed by electrodes.

The invention further relates to an aerosol-generating device comprising the heater assembly as described herein. The invention further relates to an aerosol-generating system comprising the aerosolgenerating device as described herein and an aerosol-forming substrate.

The invention further relates to a method for manufacturing a heater assembly for an aerosol-generating device. The method may comprise providing a plurality of substrate layers for forming a liquid transport structure. The method may comprise creating cavities in the substrate layers, preferably by means of one or more of: wet etching, dry etching, laser induced wet etching, lasering, and micro embossing. The method may comprise stacking the substrate layers with cavities to form the liquid transport structure.

The invention further relates to a method for manufacturing a heater assembly for an aerosol-generating device. The method comprises providing a plurality of substrate layers for forming a liquid transport structure. The method comprises creating cavities in the substrate layers. The method comprises stacking the substrate layers with cavities to form the liquid transport structure. The method steps may be conducted consecutively in accordance to the sequence of mentioning above. The cavities may be created in the substrate layers by means of one or more of: wet etching, dry etching, laser induced wet etching, lasering, and micro embossing.

The method may comprise, before or after one or both of creating cavities in the substrate layers and stacking the substrate layers with cavities to form the liquid transport structure, a step of applying an electrically conductive film onto at least one of the substrate layers. The electrically conductive film may be applied by using a thin-film fabrication process. The electrically conductive film may be applied by using a thin-film fabrication process selected form one or both of physical vapor deposition and chemical vapor deposition.

The substrate layers may comprise glass or silica, and the cavities may be created by one or more of: wet etching and dry etching. The stacked substrate layers may be connected by means of an anodic bonding process and or a glass frit bonding process.

The substrate layers may be ceramic green tapes and the cavities may be created by one or more of: lasering and micro embossing. The stacked substrate layers may be connected by means of a lamination process. The method may further comprise a step of firing the stacked and laminated substrate layers at a temperature of at least 800 degrees Celsius and densifying the fired substrate layers to form a monolithic piece.

The invention further relates to a heater assembly for an aerosol-generating device, manufactured by the method as described herein.

The invention further relates to a method for manufacturing an aerosol-generating device. The method may comprise manufacturing a heater assembly for an aerosol- generating device according to a method as described herein and providing an aerosolgenerating device comprising the heater assembly.

The invention further relates to an aerosol-generating device, manufactured by the method as described herein.

The heater assembly may form part of the aerosol-generating device. The heater assembly may comprise the liquid storage portion.

The heater assembly may form part of the aerosol-generating device and the liquid storage portion may form part of a replaceable or refillable cartridge.

The heater assembly may form part of a replaceable or refillable cartridge comprising the liquid storage portion.

The heater assembly comprises at least one heating element. The at least one heating element may be any suitable type of heating element.

The heating element may be a resistive heating element which receives electrical power and transforms at least part of the received electrical power into heat energy. A current may be passed through one or more electrically conductive tracks or wires or an electrically conductive film of the heating element to heat the heating element and the aerosol-forming substrate.

Alternatively, or in addition, the heating element may be a susceptor that is inductively heated by a time varying magnetic field. The heating element may comprise only a single heating element or a plurality of heating elements. The temperature of the heating element or elements is preferably controlled by electric circuitry.

Suitable materials for forming the at least one resistive heating element include but are not limited to: semiconductors such as doped ceramics, electrically ‘conductive’ ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum and metals from the platinum group. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai® and iron- manganese-aluminium based alloys.

In some embodiments, the at least one resistive heating element comprises one or more stamped portions of electrically resistive material, such as stainless steel. Alternatively, the at least one resistive heating element may comprise a heating wire or filament, for example a Ni-Cr (Nickel-Chromium), platinum, tungsten or alloy wire. In some embodiments, the at least one heating element comprises an electrically insulating substrate, wherein the at least one resistive heating element is provided on the electrically insulating substrate.

The heating element may comprise an electrically insulating substrate with one or more electrically conductive tracks, or electrically conductive wires, or electrically conductive films disposed on its surface.

The electrically insulating substrate may be rigid. The electrically insulating substrate may be the liquid transport structure as disclosed herein.

The electrically insulating substrate may comprise any suitable material. For example, the electrically insulating substrate may comprise one or more of: paper, glass, ceramic, anodized metal, coated metal, and Polyimide. The ceramic may comprise mica, Alumina (AI2O3) or Zirconia (ZrO2). Preferably, the electrically insulating substrate has a thermal conductivity of less than or equal to about 40 Watts per meter Kelvin, preferably less than or equal to about 20 Watts per meter Kelvin and ideally less than or equal to about 2 Watts per meter Kelvin.

As used herein, the term ‘aerosol-forming substrate’ relates to a substrate capable of releasing volatile compounds that can form an aerosol or a vapor. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may be in liquid form. The terms ‘aerosol’ and ‘vapor’ are used synonymously.

The aerosol-forming substrate may be nicotine-free. The aerosol-forming substrate may comprise a pharmaceutically active substance. The aerosol-forming substrate may comprise a medicament. The aerosol-forming substrate may comprise nicotine.

The aerosol-forming substrate may be part of a cartridge. The aerosol-forming substrate may be part of the liquid held in the liquid storage portion of the cartridge. The liquid storage portion may contain a liquid aerosol-forming substrate.

Preferably, a liquid nicotine or flavor/flavorant containing aerosol-forming substrate may be employed in the liquid storage portion of the cartridge.

The aerosol-forming substrate may comprise nicotine.

The aerosol-forming substrate may comprise at least one aerosol-former. An aerosolformer is any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and that is substantially resistant to thermal degradation at the temperature of operation of the device. Suitable aerosol-formers are well known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, 1 ,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1, 3-butanediol. Preferably, the aerosol former is glycerine.

As used herein, the term ‘cartridge’ refers to an article comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. For example, a cartridge may be an article that generates an aerosol that is directly inhalable by the user drawing or puffing on a mouthpiece at a proximal or user-end of the device or at a mouthpiece of the cartridge itself. A cartridge may be disposable. A cartridge may be reusable. A cartridge may be refillable. The cartridge may be insertable into a cavity of the aerosol-generating device.

As used herein, the term ‘liquid storage portion’ refer to a storage portion comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. The liquid storage portion may be configured as a container or a reservoir for storing the liquid aerosol-forming substrate.

The liquid storage portion may be configured as a replaceable tank or container. The liquid storage portion may be any suitable shape and size. For example, the liquid storage portion may be substantially cylindrical. The cross-section of the liquid storage portion may, for example, be substantially circular, elliptical, square or rectangular. The liquid storage portion may form part of the cartridge.

As used herein, the term ‘aerosol-generating device’ may refer to a device that interacts with one or both of an aerosol-generating article and a cartridge to generate an aerosol. The aerosol-generating device may be a medical inhaler. The aerosol-generating device may be an electronic cigarette.

As used herein, the term ‘aerosol-generating system’ may refer to the combination of an aerosol-generating device with one or both of a cartridge and an aerosol-generating article. In the system, the aerosol-generating device and one or both of the aerosolgenerating article and the cartridge cooperate to generate a respirable aerosol.

Preferably, the aerosol-generating device is portable. The aerosol-generating device may have a size comparable to a conventional cigar or cigarette. The device may be an electrically operated smoking device. The device may be a handheld aerosol-generating device. The aerosol-generating device may have a total length between 30 millimeters and 150 millimeters. The aerosol-generating device may have an external diameter between 5 millimeters and 30 millimeters.

The aerosol-generating device may comprise a housing. The housing may be elongate. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of those materials, or thermoplastics that are suitable for food or pharmaceutical applications, for example polypropylene, polyetheretherketone (PEEK) and polyethylene. Preferably, the material is light and non-brittle.

The housing may comprise at least one air inlet. The housing may comprise more than one air inlet.

The aerosol-generating device may comprise the heater assembly and its heating element.

Operation of the heating element may be triggered by a puff detection system. Alternatively, the heating element may be triggered by pressing an on-off button, held for the duration of the user’s puff. The puff detection system may be provided as a sensor, which may be configured as an airflow sensor to measure the airflow rate. The airflow rate is a parameter characterizing the amount of air that is drawn through the airflow path of the aerosol-generating device per time by the user. The initiation of the puff may be detected by the airflow sensor when the airflow exceeds a predetermined threshold. Initiation may also be detected upon a user activating a button. The sensor may also be configured as a pressure sensor.

The aerosol-generating device may include a user interface to activate the aerosolgenerating device, for example a button to initiate heating of the aerosol-generating device or a display to indicate a state of the aerosol-generating device or of the aerosol-forming substrate.

The aerosol-generating device may include additional components, such as, for example a charging unit for recharging an on-board electric power supply in an electrically operated or electric aerosol-generating device.

As used herein, the term ‘proximal’ refers to a user-end, or mouth-end of the cartridge, the aerosol-generating device or system or a part or portion thereof, and the term ‘distal’ refers to the end opposite to the proximal end. When referring to the cavity or heating chamber, the term ‘proximal’ refers to the region closest to the open end of the cavity and the term ‘distal’ refers to the region closest to the closed end.

As used herein, the terms ‘upstream’ and ‘downstream’ are used to describe the relative positions of components, or portions of components, of the cartridge or the aerosolgenerating device in relation to the direction in which a user draws on the aerosol-generating device during use thereof.

The term ‘airflow path’ as used herein denotes a channel suitable to transport gaseous media. An airflow path may be used to transport ambient air. An airflow path may be used to transport an aerosol. An airflow path may be used to transport a mixture of air and aerosol. The aerosol-generating device may comprise a power supply for powering the heating element. The power supply may comprise a battery. The power supply may be a lithium-ion battery. Alternatively, the power supply may be a nickel-metal hydride battery, a nickel cadmium battery, or a lithium-based battery, for example a lithium-cobalt, a lithium- iron-phosphate, lithium titanate or a lithium-polymer battery. The power supply may require recharging and may have a capacity that enables to store enough energy for one or more usage experiences; for example, the power supply may have sufficient capacity to continuously generate aerosol for a period of around six minutes or for a period of a multiple of six minutes. In another example, the power supply may have sufficient capacity to provide a predetermined number of puffs or discrete activations of the heating element.

Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

Example E1 : A heater assembly for an aerosol-generating device, the heater assembly comprising a heating element for heating a liquid aerosol-forming substrate; and a liquid transport structure configured to transport the liquid aerosol-forming substrate towards the heating element, wherein the liquid transport structure comprises a plurality of microchannels arranged in an ordered array.

Example E2: The heater assembly according to Example E1, wherein at least two microchannels each extend along a straight line, and wherein the straight lines are arranged in parallel.

Example E3: The heater assembly according to Example E2, wherein at least three microchannels each extend along a straight line, and wherein the straight lines are arranged in parallel, preferably wherein the parallel arranged microchannels are equidistantly spaced.

Example E4: The heater assembly according to any of the preceding examples, wherein at least two microchannels each extend along a straight line, and wherein the straight lines are arranged in perpendicular.

Example E5: The heater assembly according to Example E4, wherein a first microchannel extends along a first straight line and a second microchannel extends along a second straight line, wherein the first straight line is arranged in perpendicular to the second straight line, and wherein an open end of the first microchannel is in direct fluid connection with an open end of the second microchannel.

Example E6: The heater assembly according to any of the preceding examples, wherein at least a portion of the microchannels is arranged in a regular pattern. Example E7: The heater assembly according to any of the preceding examples, wherein at least two microchannels have the same length.

Example E8: The heater assembly according to any of the preceding examples, wherein at least two microchannels have the same diameter.

Example E9: The heater assembly according to any of the preceding examples, wherein a diameter of the microchannels is in the range of 1 micrometer to 2000 micrometers, preferably 1 micrometers to 1000 micrometers, more preferably 1 micrometers to 999 micrometers, more preferably 10 micrometers to 500 micrometers, more preferably 20 micrometers to 400 micrometers, more preferably 50 micrometers to 200 micrometers, or wherein a diameter of the microchannels is below 100 micrometers.

Example E10: The heater assembly according to any of the preceding examples, wherein the ordered array comprises at least 5 microchannels, preferably at least 10 microchannels, more preferably at least 15 microchannels, more preferably at least 20 microchannels, more preferably at least 25 microchannels, more preferably at least 30 microchannels, more preferably at least 35 microchannels, more preferably at least 40 microchannels, more preferably at least 45 microchannels, more preferably at least 50 microchannels.

Example E11: The heater assembly according to any of the preceding examples, wherein the liquid transport structure comprising the plurality of microchannels is a monolithic structure.

Example E12: The heater assembly according to any of the preceding examples, wherein the liquid transport structure comprising the plurality of microchannels is made of glass, silica, or a ceramic material.

Example E13: The heater assembly according to any of the preceding examples, wherein the heating element comprises a metallic film provided on an outer surface of the liquid transport structure, preferably wherein the metallic film is a planar metallic film.

Example E14: The heater assembly according to Example E13, wherein the plurality of microchannels comprises a plurality of outlet-microchannels, and wherein each outletmicrochannel extends from an interior of the liquid transport structure to the surface of the liquid transport structure comprising the metallic film.

Example E15: The heater assembly according to Example E14, wherein each outletmicrochannel extends from a transversal manifold channel arranged within the liquid transport structure to the surface of the liquid transport structure comprising the metallic film.

Example E16: The heater assembly according to Example E15, wherein the transversal manifold channel extends substantially in perpendicular to the outletmicrochannels. Example E17: The heater assembly according to Example E16, wherein the plurality of microchannels comprises a plurality of supply-microchannels, and wherein each supplymicrochannel extends from a surface of the liquid transport structure opposing the surface of the liquid transport structure comprising the metallic film to the transversal manifold channel.

Example E18: The heater assembly according to Example E17, wherein the transversal manifold channel extends substantially in perpendicular to the supplymicrochannels.

Example E19: The heater assembly according to Example E17 or Example E18, wherein the supply-microchannels are fluidly connected to a liquid storage portion.

Example E20: The heater assembly according to any of Example E15 to E19, wherein the transversal manifold channel extends substantially in parallel to the surface of the liquid transport structure comprising the metallic film.

Example E21: The heater assembly according to any of Example E1 to E12, wherein the heating element comprises a metallic film embedded within the liquid transport structure, preferably wherein the metallic film is a planar metallic film.

Example E22: The heater assembly according to Example E21 , comprising a thin layer of wicking material arranged on top of the metallic film, preferably wherein a thickness of the thin layer does not exceed 500 micrometers, more preferably does not exceed 300 micrometers, more preferably does not exceed 150 micrometers, more preferably does not exceed 100 micrometers.

Example E23: The heater assembly according to Example E21 or Example E22, wherein the liquid transport structure comprises a vaporization channel spatially arranged between the metallic film and at least one supply-microchannel, preferably wherein the at least one supply-microchannel is at least one micro dispenser unit, more preferably wherein the at least one micro dispenser unit comprises a valve control means.

Example E24: The heater assembly according to Example E23, wherein the liquid transport structure comprises at least one inlet-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel, preferably wherein the at least one inlet-microchannel extends substantially in perpendicular to the vaporization channel.

Example E25: The heater assembly according to Example E24, wherein the liquid transport structure comprises at least one outlet-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel, preferably wherein the at least one outlet microchannel extends substantially in parallel to the vaporization channel.

Example E26: The heater assembly according to Example E25, wherein a diameter of the at least one inlet-microchannel exceeds a diameter of the at least one outlet- microchannel, preferably wherein a ratio of the diameter of the at least one outletmicrochannel to the diameter of the at least one inlet-microchannel does not exceed 0.8.

Example E27: The heater assembly according to Example E21 or Example E22, wherein the liquid transport structure comprises a vaporization channel spatially arranged between the metallic film and at least one inlet-and-supply-microchannel, the at least one inlet-and-supply-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel, the at least one inlet-and-supply-microchannel being configured to direct both air and liquid-aerosol-forming substrate into the vaporization channel, preferably wherein the at least one inlet-and-supply-microchannel extends substantially in perpendicular to the vaporization channel.

Example E28: The heater assembly according to Example E27, comprising at least one outlet-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel, preferably wherein the at least one outlet-microchannel extends substantially in perpendicular to the vaporization channel.

Example E29: The heater assembly according to Example E28, wherein both the at least one inlet-and-supply-microchannel and the at least one outlet-microchannel extend from a common planar boundary surface of the liquid transport structure to the vaporization channel.

Example E30: The heater assembly according to any of the preceding examples, comprising a liquid storage portion provided in contact with the liquid transport structure and being configured for feeding a liquid aerosol-forming substrate to the liquid transport structure.

Example E31: The heater assembly according to any of the preceding examples, wherein the heating element is a resistive heating element.

Example E32: An aerosol-generating device comprising the heater assembly according to any of the preceding examples.

Example E33: An aerosol-generating system comprising the aerosol-generating device according to Example E32 and an aerosol-forming substrate.

Example E34: A method for manufacturing a heater assembly for an aerosolgenerating device, the method comprising providing a plurality of substrate layers for forming a liquid transport structure; creating cavities in the substrate layers, preferably by means of one or more of: wet etching, dry etching, laser induced wet etching, lasering, and micro embossing; and stacking the substrate layers with cavities to form the liquid transport structure. Example E35: The method according to Example E34, comprising, before or after one or both of creating cavities in the substrate layers and stacking the substrate layers with cavities to form the liquid transport structure, applying an electrically conductive film onto at least one of the substrate layers, preferably by using a thin-film fabrication process, more preferably by using a thin-film fabrication process selected form one or both of physical vapor deposition and chemical vapor deposition.

Example E36: The method according to Example E34 or Example E35, wherein the substrate layers comprise glass or silica, wherein the cavities are created by one or more of: wet etching and dry etching, and wherein the stacked substrate layers are connected by means of an anodic bonding process and or a glass frit bonding process.

Example E37: The method according to Example E34 or Example E35, wherein the substrate layers are ceramic green tapes, wherein the cavities are created by one or more of: lasering and micro embossing, wherein the stacked substrate layers are connected by means of a lamination process, and wherein the method further comprises a step of firing the stacked and laminated substrate layers at a temperature of at least 800 degrees Celsius and densifying the fired substrate layers to form a monolithic piece.

Example E38: The method according to any of Examples E34 to E37, wherein the method comprises a step of providing a heating element.

Example E39: A method for manufacturing an aerosol-generating device, the method comprising, manufacturing a heater assembly for an aerosol-generating device in accordance to any of Example E34 to E38; and providing an aerosol-generating device comprising the heater assembly.

Example E40: A heater assembly for an aerosol-generating device, manufactured by the method of any of Examples E34 to E38.

Example E41: An aerosol-generating device, manufactured by the method of Example E39.

Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 shows a heater assembly for an aerosol-generating device;

Fig. 2 shows a heater assembly for an aerosol-generating device; and

Fig. 3 shows a heater assembly for an aerosol-generating device.

Fig. 1 shows a heater assembly for an aerosol-generating device in cross-sectional view. The heater assembly comprises a heating element 10 for heating a liquid aerosolforming substrate 12. The heating element 10 is configured as a planar metallic film 10 being resistively heated and being fed by electrodes (not shown).

The heater assembly comprises a liquid transport structure 14. The liquid transport structure 14 is configured to transport the liquid aerosol-forming substrate 12 towards the heating element 10. The liquid transport structure 14 comprises a plurality of microchannels arranged in an ordered array. The microchannels are thus not random microchannels of a microcapillary material, but are artificially created, for example by a manufacturing method as described herein. The liquid transport structure 14 may be a monolithic structure. The liquid transport structure 14 may be made of glass, silica, or a ceramic material.

The plurality of microchannels comprises a plurality of outlet-microchannels 16. Fig. 1 shows six outlet-microchannels 16. Each outlet-microchannels 16 extends along a first straight line, and the first straight lines are arranged in parallel and are equidistantly spaced. Thus, the linear microchannels 16 are oriented in parallel and are equidistantly spaced. The outlet-microchannels 16 are thus arranged in a regular pattern. All outlet-microchannels 16 have the same length and the same diameter. Each outlet-microchannel 16 extends from an interior of the liquid transport structure 14 to the surface of the liquid transport structure 14 comprising the metallic film 10. Particularly, each outlet-microchannel 16 extends from a transversal manifold channel 18 arranged within the liquid transport structure 14 to the surface of the liquid transport structure 14 comprising the metallic film 10. An open end of each outlet-microchannel 16 is in direct fluid connection with the transversal manifold channel 18. Particularly, a first end of each outlet-microchannel 16 is fluidly connected to the transversal manifold channel 18. A second end of each outlet-microchannel 16 is fluidly connected to the outside of the liquid transport structure 14.

The transversal manifold channel 18 extends substantially in parallel to the surface of the liquid transport structure 14 comprising the metallic film 10. The transversal manifold channel 18 extends along a second straight line, the second straight line being substantially in perpendicular to the first straight lines of the outlet-microchannels 16.

The plurality of microchannels comprises a plurality of supply-microchannels 20. Fig. 1 shows two supply-microchannels 20. The supply-microchannels 20 extend along parallelly arranged straight lines. The supply-microchannels 20 are thus arranged in a regular pattern.

Each supply-microchannel 20 extends from a surface of the liquid transport structure 14 opposing the surface of the liquid transport structure 14 comprising the metallic film 10 to the transversal manifold channel 18. The transversal manifold channel extends substantially in perpendicular to the supply-microchannels 20. An open end of each supply-microchannel 20 is in direct fluid connection with the transversal manifold channel 18. An opposing open end of each supply-microchannel 20 is in direct fluid connection with a liquid storage portion 22.

By the outlet-microchannels 16, the transversal manifold channel 18, and the supply- microchannels 20, an ordered array of microchannels is formed.

During use, the liquid aerosol-forming substrate 12 may be transported by capillary forces from the liquid storage portion 22 to the transversal manifold channel 18 via the supply-microchannels 20. This is indicated by black arrows 24 in Fig. 1. The transversal manifold channel 18 may serve as an intermediate liquid reservoir. The liquid aerosolforming substrate 12 may be further transported by capillary forces from the transversal manifold channel 18 towards the heating element 10 via the outlet-microchannels 16. Once the liquid aerosol-forming substrate 12 reaches a heating region at the heating element 10, the liquid aerosol-forming substrate 12 volatizes due to the heat generated by the heating element 10. Volatized components may exit the liquid transport structure 14 via holes 30 in the heating element 10. The volatized components may mix with a stream of air coming from an upstream end of an airflow route of the aerosol-generating device to successively form an aerosol on a route downstream towards an air outlet of the aerosol-generating device.

Fig. 2 shows a heater assembly for an aerosol-generating device in cross-sectional view. The heater assembly comprises a heating element 10 for heating a liquid aerosolforming substrate 12. The heater assembly comprises a liquid transport structure 14. The liquid transport structure 14 is configured to transport the liquid aerosol-forming substrate 12 towards the heating element 10. The liquid transport structure 14 comprises a plurality of microchannels arranged in an ordered array. The microchannels are thus not random microchannels of a microcapillary material, but are artificially created, for example by a manufacturing method as described herein. The liquid transport structure 14 may be a monolithic structure. The liquid transport structure 14 may be made of glass, silica, or a ceramic material.

The heating element 10 is configured as a planar metallic film 10 embedded within the liquid transport structure 14. The heating element 10 embedded within the liquid transport structure 14 may be arranged to be entirely encapsulated by the material of the liquid transport structure 14 as shown in Fig. 2. Alternatively, the heating element 10 embedded within the liquid transport structure 14 may be arranged on an inner surface of the liquid transport structure 14 neighboring an inner channel of the liquid transport structure 14.

The heater assembly may comprise a thin layer of wicking material 32 arranged on top of the metallic film 10. The thin layer of wicking material 32 may promote wetting of the liquid. The thin layer of wicking material 32 is not necessarily in direct physical contact with the metallic film 10. A portion of the liquid transport structure 14 may be arranged in between the layer of wicking material 32 and the metallic film 10. The heating element 10 is electrically fed by electrodes 11.

The liquid transport structure 14 comprises a vaporization channel 34 spatially arranged between the metallic film 10 and at least one supply-microchannel 20. The at least one supply-microchannel 20 may be a micro dispenser unit. The micro dispenser unit may allow to provide a predefined quantity of liquid aerosol-forming substrate 12 onto the thin layer of wicking material 32. For example, for the micro-dispenser unit, a liquid pump may be used which can precisely define the volume of each droplet 40. The micro dispenser unit may comprise a valve control means 36.

The liquid transport structure 14 comprises at least one inlet-microchannel 38 extending from an outer surface of the liquid transport structure 14 to the vaporization channel 34. The at least one inlet-microchannel 38 extends substantially in perpendicular to the vaporization channel 34.

The liquid transport structure 14 comprises at least one outlet-microchannel 16 extending from an outer surface of the liquid transport structure 14 to the vaporization channel 34. The at least one outlet microchannel 16 extends substantially in parallel to the vaporization channel 34.

The heater assembly may be configured such that a diameter 39 of the at least one inlet-microchannel 38 exceeds a diameter 17 of the at least one outlet-microchannel 16. For example, a ratio of the diameter 17 of the at least one outlet-microchannel 16 to the diameter 39 of the at least one inlet-microchannel 38 does not exceed 0.8. Thereby, an optimized back pressure in the airflow route may be provided. Aerosol formation may be optimized.

A first end of each inlet-microchannel 38 is fluidly connected to the vaporization channel 34. A second end of each inlet-microchannel 38 is fluidly connected to the outside of the liquid transport structure 14. A first end of each supply-microchannel 20 is fluidly connected to the liquid storage portion 22. A second end of each supply-microchannel 20 is fluidly connected to the vaporization channel 34. A first end of each outlet-microchannel 16 is fluidly connected to the vaporization channel 34. A second end of each outlet-microchannel 16 is fluidly connected to the outside of the liquid transport structure 14. By the one or more outlet-microchannels 16, the vaporization channel 34, and the one or more supply-microchannels 20, an ordered array of microchannels is formed.

During use, droplets 40 of liquid aerosol-forming substrate 12 may be transported from the liquid storage portion 22 to the vaporization channel 34 via the supply-microchannel 20. This is indicated by a black arrow 24 in Fig. 2. The droplet 40 may be soaked by the thin layer of wicking material 32. Heat produced by the heating element 10 volatizes the liquid aerosol-forming substrate 12 in the thin layer of wicking material 32. Ambient air 28 entering via inlet-microchannel 38 and travelling through the vaporization channel 34 takes up volatized components on the way to an air outlet of the device via outlet microchannel 16 as indicated by arrow 26.

Fig. 3 shows a heater assembly for an aerosol-generating device in cross-sectional view. The heater assembly comprises a heating element 10 for heating a liquid aerosolforming substrate 12. The heater assembly comprises a liquid transport structure 14. The liquid transport structure 14 is configured to transport the liquid aerosol-forming substrate 12 towards the heating element 10. The liquid transport structure 14 comprises a plurality of microchannels arranged in an ordered array. The microchannels are thus not random microchannels of a microcapillary material, but are artificially created, for example by a manufacturing method as described herein. The liquid transport structure 14 may be a monolithic structure. The liquid transport structure 14 may be made of glass, silica, or a ceramic material.

The heating element 10 is configured as a planar metallic film 10 embedded within the liquid transport structure 14. The heating element 10 is electrically fed by electrodes 11.

The liquid transport structure comprises a vaporization channel 34 spatially arranged between the metallic film 10 and at least one inlet-and-supply-microchannel 42, for example two inlet-and-supply-microchannels 42 as shown in Fig. 3. The inlet-and-supply- microchannels 42 extend from an outer surface of the liquid transport structure 14 to the vaporization channel 34. The inlet-and-supply-microchannels 42 extend substantially in perpendicular to the vaporization channel 34. The inlet-and-supply-microchannels 42 are configured to direct both air and liquid-aerosol-forming substrate 12 into the vaporization channel 34.

The heater assembly comprises at least one outlet-microchannel 16 extending from an outer surface of the liquid transport structure 14 to the vaporization channel 34. In Fig. 3, five parallelly and equidistantly arranged outlet-microchannels 16 which extend in perpendicular to the vaporization channel 34 are shown. Each outlet-microchannel 16 extends along a first straight line, and the first straight lines are arranged in parallel and are equidistantly spaced. All outlet-microchannels 16 have the same length and the same diameter. The outlet-microchannels 16 are thus arranged in a regular pattern.

Both the at least one inlet-and-supply-microchannel 42 and the outlet-microchannels 16 extend from a common planar boundary surface of the liquid transport structure 14 to the vaporization channel 34.

A first end of at least some of the inlet-and-supply-microchannels 42 is fluidly connected to the liquid storage portion 22. A first end of at least some of the inlet-and-supply- microchannels 42 is fluidly connected to an air inlet for feeding ambient air. A second end of each inlet-and-supply-microchannels 42 is fluidly connected to the vaporization channel 34. A first end of each outlet-microchannel 16 is fluidly connected to the vaporization channel 34. A second end of each outlet-microchannel 16 is fluidly connected to the outside of the liquid transport structure 14.

By the outlet-microchannels 16, the vaporization channel 34, and the inlet-and- supply-microchannels 42, an ordered array of microchannels is formed.

During use, liquid aerosol-forming substrate 12 may be transported from the liquid storage portion 22 to the vaporization channel 34 via the inlet-and-supply-microchannels 42. This is indicated by black arrows 24 in Fig. 3. Heat produced by the heating element 10 volatizes the liquid aerosol-forming substrate 12 in proximity to the heating element 10. Ambient air enters via the inlet-and-supply-microchannels 42 and travels through the vaporization channel 34 to take up volatized components on the way to an air outlet of the device via the outlet microchannels 16 as indicated by arrows 26. Additional ambient air 28 may be added to the airflow downstream of the outlet microchannels 16.

For example, the heater assembly of Fig. 3 may be manufactured by the following method.

First, a plurality of substrate layers 14a, 14b, 14c for forming a liquid transport structure 14 is provided.

Second, cavities in the substrate layers for forming the microchannels 16, 34, 42 are created. For example, the cavities may be created by one or more of wet etching, dry etching, laser induced wet etching, lasering, and micro embossing.

Third, the substrate layers 14a, 14b, 14c with the cavities are stacked to form the liquid transport structure 14.

The heating element 10 may be obtained, for example, by initially providing the substrate layer 14c in two halves, screen printing an electrically conducting film onto one halve substrate layer 14c, and sandwiching the electrically conductive film between the two halves of the substrate layer 14c. This may be done before or after the step of creating cavities in the substrate layers. The heater assemblies of Fig. 1 and Fig. 2 may be manufacturing by similar methods including providing a plurality of substrate layers, creating cavities in the substrate layers, and stacking the substrate layers to form the liquid transport structure 14.

Claims

1. A heater assembly for an aerosol-generating device, the heater assembly comprising a heating element for heating a liquid aerosol-forming substrate; and a liquid transport structure configured to transport the liquid aerosol-forming substrate towards the heating element, wherein the liquid transport structure comprises a plurality of microchannels arranged in an ordered array, wherein the liquid transport structure comprising the plurality of microchannels is a monolithic structure, and wherein the heating element comprises a metallic film embedded within the liquid transport structure.

2. The heater assembly according to claim 1, wherein at least two microchannels each extend along a straight line, and wherein the straight lines are arranged in parallel.

3. The heater assembly according to claim 2, wherein at least three microchannels each extend along a straight line, and wherein the straight lines are arranged in parallel, preferably wherein the parallel arranged microchannels are equidistantly spaced.

4. The heater assembly according to any of the preceding claims, wherein at least two microchannels each extend along a straight line, and wherein the straight lines are arranged in perpendicular.

5. The heater assembly according to claim 4, wherein a first microchannel extends along a first straight line and a second microchannel extends along a second straight line, wherein the first straight line is arranged in perpendicular to the second straight line, and wherein an open end of the first microchannel is in direct fluid connection with an open end of the second microchannel.

6. The heater assembly according to any of the preceding claims, wherein at least a portion of the microchannels is arranged in a regular pattern.

7. The heater assembly according to any of the preceding claims, wherein at least two microchannels have the same length and the same diameter.

8. The heater assembly according to any of the preceding claims, wherein the metallic film is a planar metallic film.

9. The heater assembly according to claim 8, wherein the liquid transport structure comprises a vaporization channel spatially arranged between the metallic film and at least one supply-microchannel, preferably wherein the at least one supply-microchannel is at least one micro dispenser unit, more preferably wherein the at least one micro dispenser unit comprises a valve control means.

10. The heater assembly according to claim 8, wherein the liquid transport structure comprises a vaporization channel spatially arranged between the metallic film and at least one inlet-and-supply-microchannel, the at least one inlet-and-supply-microchannel extending from an outer surface of the liquid transport structure to the vaporization channel, the at least one inlet-and-supply-microchannel being configured to direct both air and liquid- aerosol-forming substrate into the vaporization channel, preferably wherein the at least one inlet-and-supply-microchannel extends substantially in perpendicular to the vaporization channel.

11. An aerosol-generating device comprising the heater assembly according to any of the preceding claims.

12. An aerosol-generating system comprising the aerosol-generating device according to claim 13 and an aerosol-forming substrate.

13. A method for manufacturing a heater assembly for an aerosol-generating device according to any of claims 1 to 10, the method comprising providing a plurality of substrate layers for forming a liquid transport structure; creating cavities in the substrate layers, preferably by means of one or more of: wet etching, dry etching, laser induced wet etching, lasering, and micro embossing; and stacking the substrate layers with cavities to form the liquid transport structure.