WO2024149655A1

WO2024149655A1 - Aerosol generating system

Info

Publication number: WO2024149655A1
Application number: PCT/EP2024/050103
Authority: WO
Inventors: Grzegorz Aleksander PILATOWICZ; Alec WRIGHT
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2023-01-11
Filing date: 2024-01-03
Publication date: 2024-07-18
Anticipated expiration: 2025-07-11
Also published as: EP4648634A1; KR20250131803A

Abstract

An aerosol generating system (1) is described which includes an aerosol generating article (2) and an aerosol generating device (6). The aerosol generating article (2) includes aerosol generating material (16) with a first outer surface (16a) and a second outer surface (16b) substantially opposite the first outer surface (16a). The aerosol generating material (16) is substantially cuboid and the first and second outer surfaces (16a, 16b) are the surfaces of the cuboid with the largest surface area. The aerosol generating article (2) also includes a first electrically conductive layer (18a) adjacent to and fully covering the first outer surface (16a). The device (6) includes a first electrode (8) adjacent the first electrically conductive layer (18a).

Description

AEROSOL GENERATING SYSTEM

Technical Field

The present disclosure relates generally to an aerosol generating article, and in particular to an aerosol generating article adapted to be received in an aerosol generating device for generating an aerosol for inhalation by a user. The present disclosure also relates to an aerosol generating system comprising the aerosol generating article and the aerosol generating device.

The present disclosure is particularly applicable to a portable (hand-held) aerosol generating device.

Technical Background

Devices which heat, rather than bum, an aerosol generating material to produce an aerosol for inhalation have become popular with consumers in recent years. A commonly available reduced-risk or modified-risk device is the heated material aerosol generating device, or so-called heat-not-bum device. Devices of this type generate an aerosol or vapour by heating an aerosol generating material to a temperature typically in the range 150°C to 300°C. This temperature range is quite low compared to an ordinary cigarette. Heating the aerosol generating material to a temperature within this range, without burning or combusting the aerosol generating material, generates a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device.

Such devices may use one of a number of different approaches to provide heat to the aerosol generating material. One approach may be designed to heat an electrically conductive aerosol generating material, for example a tobacco material that has been doped with an electrically conductive material such as a carbon-based material to make it electrically conductive, by applying an electric current to the aerosol generating material. The aerosol generating material is therefore heated directly by the electric current that flows through the aerosol generating material (Joule heating) instead of being heated indirectly by an external heater or by one or more susceptors located outside of the aerosol generating material in the case of an induction heating system, for example. The aerosol generating material may be part of an aerosol generating article which the user inserts into the device in use. Heating the aerosol generating material normally requires at least part of the aerosol generating material to be exposed on a surface of the aerosol generating article so that an electrical connection may be made with the device. This may not be acceptable to the user, for example because of the situation that their fingers may come into contact with the exposed aerosol generating material, or because some of the aerosol generating material may escape from the article. Embodiments of the present disclosure therefore seek to solve this problem by providing alternative ways of heating the aerosol generating material by constructing an aerosol generating system as a capacitor and applying an electric field across the aerosol generating material that is surrounded by a wrapper. At least part of the wrapper is electrically conductive. The present disclosure provides an embodiment where the aerosol generating material is electrically conductive so that the electric field causes an electric current to flow through the aerosol generating material, and an embodiment where the aerosol generating material is electrically non-conductive, i.e., where the aerosol generating material is not doped with an electrically conductive material, and acts as a dielectric.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided an aerosol generating system comprising: aerosol generating material with a first outer surface and a second outer surface substantially opposite the first outer surface, wherein the aerosol generating material is substantially cuboid and the first and second outer surfaces are the surfaces of the cuboid with the largest surface area; a first electrically conductive layer adjacent to and fully covering the first outer surface; and a first electrode adjacent the first electrically conductive layer.

The system may further comprise a second electrically conductive layer adjacent to and fully covering the second outer surface, and a second electrode adjacent the second electrically conductive layer. It is typically advantageous that the first and second electrically conductive layers fully cover the respective outer surface of the aerosol generating material. If the aerosol generating material is an electrically conductive material, such an arrangement means that the vectors of electric current that flow through the aerosol generating material are aligned. This helps to provide more uniform heating and, in particular, may prevent the formation of “hot spots” or “cold spots” within the aerosol generating material (i.e. , areas where the aerosol generating material is heated too much or too little). Such hot and cold spots may affect the taste of the generated aerosol. If the aerosol generating material is an electrically non-conductive material, such that it may function as a dielectric for an aerosol generating system that is constructed generally as a capacitor - see below - efficiency of aerosol generation may be increased by making sure that the respective outer surfaces of the aerosol generating material are fully covered by the first and second electrically conductive layers, thereby maximising the available capacitance.

A surface area of the first electrically conductive layer may be larger than the surface area of the first outer surface and/or a surface area of the second electrically conductive layer may be larger than the surface area of the second outer surface. Making the first electrically conductive layer and/or the second electrically conductive layer slightly larger than the adjacent outer surface of the aerosol generating material may further increase available capacitance and provide more uniform heating of the aerosol generating material while also accommodating manufacturing tolerances.

The aerosol generating material and the first electrically conductive layer may be part of an aerosol generating article (or consumable). The aerosol generating article may also comprise the second electrically conductive layer. In such an aerosol generating article there is good adhesion and contact between the aerosol generating material and the first electrically conductive layer and/or between the aerosol generating material and the second electrically conductive layer. This may improve the efficiency of aerosol generation. The first electrode may be part of an aerosol generating device adapted to receive, in use, the aerosol generating article. The aerosol generating device may also comprise the second electrode. When the aerosol generating article is received in the aerosol generating device, for example in an aerosol generating space or heating chamber of the device, the first electrode will be positioned adjacent the first electrically conductive layer and the second electrode will be positioned adjacent the second electrically conductive layer. The first electrode may be in electrical contact with the first electrically conductive layer and the second electrode may be in electrical contact with the second electrically conductive layer. The first electrode and the first electrically conductive layer may form a first electrode assembly that is arranged adjacent the first outer surface of the aerosol generating material. The second electrode and the second electrically conductive layer may form a second electrode assembly that is arranged adjacent the second outer surface of the aerosol generating material.

The first and second electrodes (or the first and second electrode assemblies) may be substantially planar and may define a pair of electrically conductive parallel capacitor plates that may be separated by a dielectric that includes the aerosol generating material when an electrically non-conductive material. The aerosol generating system may therefore be constructed generally as a capacitor.

The first electrode may be connected to a first terminal (e.g., a positive terminal) and the second electrode may be connected to a second terminal (e.g., a negative terminal). When a voltage is applied across the first and second terminals to charge the capacitor, for example if the aerosol generating device further comprises a circuit electrically connected between the first and second terminals with a power source (e.g., a battery), a net positive charge will collect on the positive electrode (e.g., the first electrode or electrode assembly) and a net negative charge will collect on the negative electrode (e.g., the second electrode or electrode assembly). An electric field is generated between the first and second electrodes or electrode assemblies. The capacitor can be charged until its voltage value is substantially equal to the voltage across the first and second electrodes. If the capacitor is fully charged, the current will stop flowing in the circuit. The capacitor can be discharged, e.g., through a resistor. As described in more detail below, charging and discharging the capacitor heats the aerosol generating material to generate an aerosol for inhalation by a user.

If the aerosol generating material is an electrically conductive material, the aerosol generating device may further comprise a circuit electrically connected between the first and second terminals with a power source (e.g., a battery) that can be used to generate an electric field between the first and second electrodes or electrode assemblies and cause an electric current to flow through the aerosol generating material to heat the aerosol generating material by Joule heating to generate an aerosol for inhalation by a user.

The circuit may further comprise a switching device (e.g., one or more switches). The switching device may be closed to charge the capacitor or cause an electric current to flow through the aerosol generating material, and opened to discharge the capacitor or stop the flow of electric current through the aerosol generating material. The one or more switches may be semiconductor switching devices. The one or more switches may be opened or closed (or switched on and off) by a controller.

The first electrode may have a surface area substantially the same as the surface area of the first outer surface of the aerosol generating material or the first electrically conductive layer that fully covers the first outer surface. The second electrode may have a surface area substantially the same as the surface area of the second outer surface of the aerosol generating material or the second electrically conductive layer that fully covers the second outer surface. It will be understood that the capacitance of a parallel plate capacitor is proportional to the area of the smallest of the first and second electrodes and inversely proportional to the distance or separation between them. The first and second outer surfaces are the surfaces of the cuboid with the largest surface area so as to maximise the capacitance. Maximising the capacitance may improve the efficiency of aerosol generation. In other arrangements, the first electrode may have a surface area that is larger or smaller than the surface area of the first outer surface of the aerosol generating material or the first electrically conductive layer and/or the second electrode may have a surface area that is larger or smaller than the surface area of the second outer surface of the aerosol generating material or second electrically conductive layer, for example. The first electrode and/or the second electrode may be designed simply to provide an electrical connection between the circuit and the respective electrically conductive layer of the aerosol generating article when the article is received in the aerosol generating space or heating chamber of the device. In particular, it must be emphasised that the first electrode does not need to fully cover the first outer surface of the aerosol generating material and the second electrode does not need to fully cover the second outer surface of the aerosol generating material. A narrower or smaller positive and/or negative electrode may therefore be used. This may mean that the positive and/or negative electrodes are not exposed at the proximal end of the aerosol generating device. It may also prevent the transfer of electrostatic charge from the user to the positive and/or negative electrodes.

The first and second electrodes may be formed from any suitable electrically conductive material such as aluminium, for example.

The aerosol generating material may comprise a plant derived material, and in particular may comprise a tobacco material.

The aerosol generating material may be an electrically non-conductive material or it may be an electrically conductive material and may further comprise a carbon-based material such as charcoal, for example, or a metal such as aluminium. In particular, the aerosol generating material may comprise an electrically non-conductive material such as a plant derived material or a tobacco material as a substrate that is then doped with an electrically conductive material such as the carbon-based material or metal particles to make it electrically conductive.

When heated, the aerosol generating material may release one or more volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco or other flavouring.

The aerosol generating material may be part of an aerosol precursor section of the aerosol generating article. The aerosol generating article may further comprise a cooling section (or filter section) at a proximal end. The first and second electrodes preferably do not extend over or overlap with the cooling section when the article is received in the device. In other words, at least part of the cooling section is preferably positioned outside the space defined between the first and second electrodes when the article is received in the device. The cooling section may comprise cellulose acetate fibres, for example. The cooling section may constitute a mouthpiece filter. One or more vapour collection regions, cooling regions, and other structures may also be included in some designs. The vapour cooling region may advantageously allow the vapour to cool and condense to form an aerosol with suitable characteristics for inhalation by a user, for example through the filter segment. In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour may be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification.

The aerosol generating article may further comprise an electrically non-conductive wrapper such as a paper wrapper that extends substantially around the cooling section.

The first electrically conductive layer and/or the second electrically conductive layer may comprise a substrate (e.g., a paper substrate) doped with electrically conductive particles such as carbon-based or metal particles, or impregnated with an electrically conductive electrolyte such as a sodium chloride-based electrolyte. In another arrangement, the first electrically conductive layer and/or the second electrically conductive layer may be formed on a surface of an electrically non-conductive substrate (e.g. a paper substrate). The aerosol generating material may be substantially surrounded by a substrate such as a paper substrate or wrapper, for example, that extends around the outer surfaces of the aerosol generating material and which is only made electrically conductive - by doping or impregnating with electrically conductive particles or electrolyte, or by forming an electrically conductive layer - in those parts of the substrate or wrapper that are adjacent the first and second outer surfaces to form the first and second electrically conductive layers. The electrically conductive layers are separated by electrically non-conductive parts of the substrate or wrapper, for example those parts of the substrate or wrapper that are adjacent the other outer surfaces of the aerosol generating material. This ensures that the first and second electrically conductive layers are electrically isolated from each other. It is generally preferred that at least the aerosol generating material is completely surrounded by the substrate or wrapper so that none of the aerosol generating material is exposed.

If an electrically conductive layer is formed on a surface of an electrically non- conductive substrate, such as a paper substrate or wrapper, for example, it may be in electrical contact with the opposite surface of the substrate or wrapper by means of one or more electrically conductive connections extending through the substrate or wrapper - e.g., by means of one or more vias. These electrically conductive connections (or vias) allow electric current to pass through the non-electrically conductive substrate or wrapper. The electrically conductive connections may also function as air inlet holes for allowing air to be drawn into the aerosol generating material, for example. Such electrically conductive connections might be similar to those used to connect the electrically conductive layers of a printed circuit board (PCB). In a PCB, for example, a via may include a pair of pads on different conductive layers of the board that are electrically connected by a hole through the board. The hole may be made electrically conductive by electroplating or may be lined with a tube of electrically conductive material. Each electrically conductive connection of the present disclosure may have a similar construction, e.g., with an electrically conductive tube that connects to a pair of pads or electrically conductive layers on opposite surfaces of the substrate or wrapper.

An electrically conductive layer may be formed on the substrate surface by partial dip coating or by printing such as by printing a conductive ink on the substrate surface, for example.

If the aerosol generating material is an electrically non-conductive material, the aerosol generating material functions as a dielectric between the first and second electrodes or electrode assemblies. Charging and discharging the capacitor dissipates heat in the first and second electrodes or electrode assemblies, which heats the adjacent aerosol generating material. When the capacitor is charged, i.e., when a voltage is applied across the first and second terminals, and an electric field is generated between the first and second electrodes or electrode assemblies, an electric current does not flowthrough the aerosol generating material. Instead, the aerosol generating material is polarised such that positive charges within the aerosol generating material are displaced slightly in the direction of the electric field, and the negative charges are displaced slightly in the direction opposite to the electric field. The polarisation is released when the capacitor is discharged and the charges may revert to their original positions. The moving positive and negative charges interact with the internal resistance of the aerosol generating material to provide direct heating of the aerosol generating material.

If the aerosol generating material is an electrically conductive material, when a voltage is applied across the first and second terminals, the electric field that is generated between the first and second electrodes or electrode assemblies will cause an electric current to flow through the aerosol generating material. Because of the internal resistance of the aerosol generating material, the electric current that flows through the aerosol generating material provides direct heating of the aerosol generating material by Joule heating.

In both arrangements, direct heating is provided without having to expose part of the aerosol generating material. The aerosol generating material may therefore be surrounded by a wrapper such as a paper wrapper, which may form the first and second electrically conductive layers. There is no risk that the fingers of the user will come into contact with exposed aerosol generating material, nor that some of the aerosol generating material will escape from the aerosol generating article.

Brief Description of the Drawings

Figure 1 is a diagrammatic view of an aerosol generating system with an aerosol generating device and an aerosol generating article;

Figure 2 is a diagrammatic perspective view of the aerosol generating article of Figure i; Figure 3 is a diagrammatic side view of the aerosol generating article of Figure 1 showing an aerosol precursor section and a cooling section;

Figure 4 is a diagrammatic top view of the aerosol generating article of Figure 1 showing the aerosol precursor section and the cooling section;

Figure 5 is a diagrammatic cross section view of the aerosol generating system of Figure 1 where a first aerosol generating article is received in the aerosol generating device; Figure 6 is a diagrammatic cross section view along line A-A of Figure 5;

Figure 7 is a diagrammatic cross section view of the aerosol generating system of Figure 1 where a second aerosol generating article is received in the aerosol generating device; Figure 8 is a diagrammatic cross section view along line A-A of Figure 7;

Figure 9 is a diagrammatic view showing an example of a wrapper; and Figure 10 is a diagrammatic view showing another example of a wrapper.

Detailed Description of Embodiments

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring initially to Figure 1, there is shown diagrammatically an example of an aerosol generating system 1 that includes an aerosol generating article 2 (or consumable) that is adapted to be received in an aerosol generating space or heating chamber 4 of an aerosol generating device 6.

The aerosol generating device 6 includes a positive electrode 8 and a negative electrode 10 adjacent the aerosol generating space 4. The positive and negative electrodes 8, 10 may be formed from any suitable electrically conductive material such as aluminium, for example.

As shown in Figures 1 to 4, the aerosol generating article 2 has a substantially cuboid construction and includes a first outer surface 2a and a second outer surface 2b opposite the first outer surface 2a. The first and second outer surfaces 2a, 2b are the surfaces of the cuboid with the largest surface area so as to maximise the capacitance - see below. Maximising the capacitance may improve the efficiency of aerosol generation. The aerosol generating article 2 also has:

- a third outer surface 2c,

- a fourth outer surface 2d opposite the third outer surface 2c,

- a fifth outer surface 2e at a distal end of the aerosol generating article 2, and

- a sixth outer surface 2f opposite the fifth outer surface 2e at a proximal end of the aerosol generating article 2.

The aerosol generating article 2 includes an aerosol precursor section 12 and a cooling section 14 at a proximal end. The aerosol precursor section 12 includes a cuboid of aerosol generating material 16 with:

- a first outer surface 16a,

- a second outer surface 16b opposite the first outer surface 16a,

- a third outer surface 16c,

- a fourth outer surface 16d opposite the third outer surface 16c,

- a fifth outer surface 16e, and

- a sixth outer surface 16f opposite the fifth outer surface 16c and which is in contact with the cooling section 14.

When heated, the aerosol generating material 16 may release one or more volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco or other flavouring. At least the aerosol precursor section 12 is surrounded by a wrapper 18 such as a paper wrapper. In the aerosol generating article 2 as shown, the wrapper 18 extends around the outer surfaces 16a, 16b, ..., 16e of the aerosol generating material 16 such that the material is completely enclosed by the wrapper and the adjacent cooling section 14 of the aerosol generating article 2. The wrapper 18 may also extend around the cooling section 14.

The wrapper 18 defines a first electrically conductive layer 18a adjacent to and fully covering the first outer surface 16a of the aerosol generating material 16 and a second electrically conductive layer 18b adjacent to and fully covering the second outer surface 16b of the aerosol generating material.

The wrapper 18 also defines electrically non-conductive layers 18c, ..., 18e adj acent the third, fourth and fifth outer surfaces 16c, ..., 16e of the aerosol generating material 16. The parts of the wrapper 18 that may extend around the cooling section 14 are also electrically non-conductive. The first and second electrically conductive layers 18a, 18b are therefore not in electrical contact with each other, i.e., they are electrically isolated. It is not essential that the first and second electrically conductive layers 18a, 18b cover at least a part of the cooling section 14.

As shown in Figures 5 to 8, when the aerosol generating article 2 is received in the aerosol generating space 4 of the aerosol generating device 6, the positive electrode 8 is positioned adjacent the first electrically conductive layer 18a and the negative electrode 10 is positioned adj acent the second electrically conductive layer 18b. At least part of the cooling section 14 is positioned outside the aerosol generating space 4 when the aerosol generating article 2 is received in the aerosol generating device 6 such that the positive and negative electrodes 8, 10 do not extend over or overlap with the cooling section 14. The positive electrode 8 is in electrical contact with the first electrically conductive layer 18a and the negative electrode 10 is in electrical contact with the second electrically conductive layer 18b when the aerosol generating article 2 is received in the aerosol generating device 6.

The electrodes 8, 10 are substantially planar and define a pair of electrically conductive parallel capacitor plates. In practice, the positive electrode 8 and the first electrically conductive layer 18a may function as a single common positive electrode and the negative electrode 10 and the second electrically conductive layer 18b may function as a single common negative electrode.

In the arrangement shown in Figures 5 and 6 the aerosol generating material is formed from an electrically non-conductive material (e.g., a plant derived material, and in particular a tobacco material). The aerosol generating system 1 is constructed generally as a capacitor where the aerosol generating material 16 is the dielectric between the positive and negative electrode assemblies.

The positive electrode 8 has a surface area substantially the same as the surface area of the first outer surface 16a of the aerosol generating material 16. The negative electrode 10 has a surface area substantially the same as the surface area of the second outer surface 16b of the aerosol generating material. Alternatively, the positive electrode 8 may be narrower or have a smaller surface area than the surface area of the first outer surface 16a of the aerosol generating material 16 and/or the negative electrode 10 may be narrower or have a smaller surface area than the second outer surface 16b of the aerosol generating material 16. This may mean that the positive and/or negative electrodes 8, 10 are not exposed at the proximal end of the aerosol generating device 6. It may also prevent the transfer of electrostatic charge from the user to the positive and/or negative electrodes 8, 10.

The positive electrode 8 is connected to a positive terminal 20 and the negative electrode 10 is connected to a negative terminal 22. The aerosol generating device 6 includes a circuit 24 electrically connected between the positive and negative terminals 20, 22 with a power source (not shown) and a switching device (not shown) that is closed to charge the capacitor and opened to discharge the capacitor. When a voltage is applied across the positive and negative terminals 20, 22 to charge the capacitor, a net positive charge will collect on the positive electrode 8 and a net negative charge will collect on the negative electrode 10. An electric field is generated between the positive and negative electrode assemblies. The capacitor can be charged until its voltage value is substantially equal to the voltage across the positive and negative electrode 8, 10. If the capacitor is fully charged, the current will stop flowing in the circuit 24. The capacitor can be discharged, e.g., through a resistor that forms part of the circuit 24. Charging and discharging the capacitor heats the aerosol generating material 16 to generate an aerosol for inhalation by a user.

Charging and discharging the capacitor dissipates heat in the positive and negative electrodes 8, 10 and the first and second electrically conductive layers 18a, 18b of the paper wrapper 18, which heats the adjacent aerosol generating material 16. When the capacitor is charged, i.e., when an electric field is generated between the positive and negative electrodes 8, 10, the aerosol generating material 16 is polarised such that positive charges within the aerosol generating material are displaced slightly in the direction of the electric field, and the negative charges are displaced slightly in the direction opposite to the electric field. The polarisation is released when the capacitor is discharged and the charges may revert to their original positions. The moving positive and negative charges interact with the internal resistance of the aerosol generating material 16 to provide direct heating of the aerosol generating material. In Figure 6, polarisation of the individual dielectric layer(s) during capacitor charging is indicated by the positive and negative signs (“+” and

In the arrangement shown in Figures 7 and 8, the aerosol generating material 16 is formed from an electrically conductive material (e.g., a plant derived material, and in particular a tobacco material, as a substrate that is doped with an electrically conductive material such as a carbon-based material to make it electrically conductive). Generating an electric field between the positive and negative electrode assemblies will cause an electric current to flow through the aerosol generating material 16. Because of the internal resistance of the aerosol generating material 16, the electric current that flows through the aerosol generating material provides direct heating of the aerosol generating material by Joule heating. In Figure 8, current flow is indicated by the vertical arrows.

In both of these arrangements, direct heating is provided without having to expose part of the aerosol generating material 16. There is no possibility that the fingers of the user will come into contact with exposed aerosol generating material 16, nor that some of the aerosol generating material will escape from the aerosol generating article 2.

As described above, the wrapper 18 that surrounds the aerosol generating material 16 includes electrically conductive and non-conductive parts. The electrically conductive parts of the wrapper 18 are defined by the first and second electrically conductive layers 18a, 18b and the electrically non-conductive parts are defined by the third, fourth and fifth electrically non-conductive layers 18c, ..., 18e. The wrapper 18 may comprise a combination of electrically conductive and non-conductive materials, for example. For example, the first and second electrically conductive layers 18a, 18b may be formed from electrically conductive material (e.g., aluminium) and the other layers may be formed from electrically non-conductive material (e.g., paper substrate).

Alternatively, the first and/or second electrically conductive layers 18a, 18b may comprise an electrically conductive part that is adjacent the aerosol generating material 16 and an electrically non-conductive part that is adjacent the cooling section 14. This electrically non-conductive part may provide thermal insulation and prevent the cooling section 14 from becoming too hot for the user to touch. The user may be able to easily remove the aerosol generating article 2 simply by pinching the covered cooling section 14 even just after aerosol has been generated.

As shown in Figure 9, the wrapper 18 may comprise an electrically non-conductive substrate 26 (e.g., a paper substrate) that is selectively doped with electrically conductive particles 28 to make certain parts of the substrate electrically conductive. For example, the part of the substrate 26 that is adjacent the first outer surface 16a of the aerosol generating material 16 may be doped to define the first electrically conductive layer 18a. Although not shown, the part of the substrate 26 that is adjacent the second outer surface 16b of the aerosol generating material 16 may also be doped to define the second electrically conductive layer 18b. The rest of the substrate is not doped and defines the electrically non-conductive layers 18c, ..., 18e. The wrapper 18 may be doped with any suitable electrically conductive particles such as carbon-based or metal particles, for example. The wrapper may also be selectively impregnated with a suitable electrically conductive electrolyte such as sodium chloride-based electrolyte.

In another arrangement, shown in Figure 10, the first electrically conductive layer 18a may be formed on an inner surface of an electrically non-conductive substrate 26 (e.g., a paper substrate). The first electrically conductive layer 18a may be in electrical contact with the outer surface of the substrate 26 by means of one or more electrically conductive connections (or vias) 30 extending through the substrate. Each electrically conductive connection 30 includes a tube 32 that defines an opening or hole 34, which might be an air inlet hole that allows air to be drawn into the aerosol generating material 16. The inner end of the tube 32 is in electrical contact with the first electrically conductive layer 18a. The outer end of the tube 32 is in electrical contact with one or more electrically conductive layers 36 on the outer surface of the substrate 26 - e.g., to define electrically conductive contact pads that provide an electrical contact with the first electrode 10. One or more electrically conductive layers - including the first electrically conductive layer 18a - may be formed on a substrate surface by partial dip coating or by printing such as by printing a conductive ink on the substrate surface, for example. Although not shown, the second electrically conductive layer 18b may be formed in the same way and the article may include one or more electrically conductive connections (or vias) 30 extending through the substrate. The electrically conductive connections 30 may be in electrical contact with one or more electrically conductive layers on the outer surface of the substrate - e.g., to define electrically conductive contact pads that provide an electrical contact with the second electrode 10.

Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

Claims

1. An aerosol generating system (1) comprising: aerosol generating material (16) with a first outer surface (16a) and a second outer surface (16b) substantially opposite the first outer surface (16a), wherein the aerosol generating material (16) is substantially cuboid and the first and second outer surfaces (16a, 16b) are the surfaces of the cuboid with the largest surface area; a first electrically conductive layer (18a) adjacent to and fully covering the first outer surface (16a); and a first electrode (8) adjacent the first electrically conductive layer (18a).

2. An aerosol generating system (1) according to claim 1, wherein a surface area of the first electrically conductive layer (18a) is larger than the surface area of the first outer surface (16a).

3. An aerosol generating system (1) according to claim 1 or claim 2, wherein the aerosol generating material (16) and the first electrically conductive layer (18a) are part of an aerosol generating article (2).

4. An aerosol generating system (1) according to claim 3, wherein the aerosol generating material (16) is part of an aerosol precursor section (12) of the aerosol generating article (2) and the aerosol generating article (2) further comprises a cooling section (14) at a proximal end, and wherein the first electrode (8) and the first electrically conductive layer (18a) do not overlap with the cooling section (14).

5. An aerosol generating system (1) according to claim 4, further comprising an electrically non-conductive wrapper (18) that extends substantially around the cooling section (14).

6. An aerosol generating system (1) according to any of claims 2 to 5, wherein the aerosol generating article (2) further comprises a second electrically conductive layer (18b) adjacent the second outer surface (16b).

7. An aerosol generating system (1) according to any of claims 2 to 5, wherein the first electrode (8) is part of an aerosol generating device (6) adapted to receive, in use, the aerosol generating article (2).

8. An aerosol generating system (1) according to claim 7, wherein the aerosol generating article (2) further comprises a second electrically conductive layer (18b) adjacent the second outer surface (16b), and the aerosol generating device (2) further comprises a second electrode (10) adjacent the second electrically conductive layer (18b).

9. An aerosol generating system (1) according to any preceding claim, wherein the aerosol generating material (16) comprises a tobacco material.

10. An aerosol generating system (1) according to any preceding claim, wherein the aerosol generating material (16) is electrically conductive.

11. An aerosol generating system (1) according to any of claims 1 to 9, wherein the aerosol generating material (16) is electrically non-conductive.

12. An aerosol generating system (1) according to any preceding claim, wherein the first electrically conductive layer (18a) comprises an electrically non-conductive substrate (26) doped with electrically conductive particles (28) or impregnated with an electrically conductive electrolyte.

13. An aerosol generating system (1) according to any of claims 1 to 11, wherein the first electrically conductive layer (18a) is formed on a surface of an electrically non- conductive substrate (26).

14. An aerosol generating system (1) according to claim 13, wherein the first electrically conductive layer (18a) is in electrical contact with the opposite surface of the substrate (26) by means of one or more electrically conductive connections (30) extending through the substrate (26).

15. An aerosol generating system (1) according to claim 13 or claim 14, wherein the first electrically conductive layer (18a) is a partial dip coated layer or a printed layer.