EP4654846A1

EP4654846A1 - Heater assembly and method

Info

Publication number: EP4654846A1
Application number: EP24703416.8A
Authority: EP
Inventors: Howard ROTHWELL
Original assignee: Nicoventures Trading Ltd
Current assignee: Nicoventures Trading Ltd
Priority date: 2023-01-27
Filing date: 2024-01-25
Publication date: 2025-12-03
Also published as: AR131687A1; GB202301169D0; TW202512951A; WO2024157017A1

Abstract

Described is a heater assembly for an aerosol provision system, the heater assembly including: a substrate, having a first end and a second end; a heater layer configured to generate heat when supplied with energy, the heater layer provided on a first surface of the substrate; and one or more capillary tubes extending from a second surface of the substrate through the heater layer provided at the first surface of the substrate, the second surface opposite the first surface. The substrate is arranged such that at least a part of at least one of the first surface and second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate. Also described is an aerosol provision system comprising the heater assembly and a method for manufacturing a heater assembly.

Description

HEATER ASSEMBLY AND METHOD

Field

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

Background

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

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

So-called microfluidic heater assemblies have been proposed to try to address some of the issues of the abovementioned heater assemblies. However, some microfluidic heater assemblies may not provide desired heating characteristics for certain applications.

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

Summary According to a first aspect of certain embodiments there is provided a heater assembly for an aerosol provision system, the heater assembly including: a substrate, having a first end and a second end; a heater layer configured to generate heat when supplied with energy, the heater layer provided on a first surface of the substrate; and one or more capillary tubes extending from a second surface of the substrate through the heater layer provided at the first surface of the substrate, the second surface opposite the first surface. The substrate is arranged such that at least a part of at least one of the first surface and second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate.

According to a second aspect of certain embodiments there is provided an aerosol provision system comprising the heater assembly of the first aspect.

According to a third aspect of certain embodiments there is provided a method for manufacturing a heater assembly for an aerosol provision system, the method including: providing a substrate having a first end and a second end; providing a heater layer configured to generate heat when supplied with energy, the heater layer provided on a first surface of the substrate; and providing one or more capillary tubes extending from a second surface of the substrate through the heater layer provided at the first surface of the substrate, the second surface opposite the first surface. The substrate is arranged such that at least a part of at least one of the first surface and the second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate.

According to a fourth aspect of certain embodiments there is provided a heater means for an aerosol provision system, the heater means including: a substrate having a first end and a second end; heater layer means configured to generate heat when supplied with energy, the heater layer means provided on a first surface of the substrate; and capillary means extending from a second surface of the substrate through the heater layer means provided at the first surface of the substrate, the second surface opposite the first surface. The substrate is arranged such that at least a part of at least one of the first surface and the second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate.

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

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

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

Figure 2 is a cross-sectional view of a cartomiser suitable for use in the aerosol provision system of Figure 1 ;

Figures 3a and 3b schematically show a heater assembly according to a first implementation in which a first major surface of the heater assembly is curved in a convex manner and a second major surface of the heater assembly is curved in a concave manner: Figure 3a shows a perspective view of the heater assembly , while Figure 3b shows a side-on view of the heater assembly;

Figures 4a and 4b schematically show a heater assembly according to a second implementation in which a first major surface of the heater assembly is curved in a concave manner and a second major surface of the heater assembly is curved in a convex manner: Figure 4a shows a perspective view of the heater assembly , while Figure 4b shows a side- on view of the heater assembly;

Figures 5a and 5b are schematic representations of a heater assembly according to a third implementation in which the capillary tubes are provided at an angle to a central axis of the heater assembly; Figure 5a shows the heater assembly in a side-on view where the first major surface is convex and capillary tubes are angled away from the central axis, while Figure 5b shows the heater assembly in a side-on view where the first major surface is concave and capillary tubes are angled toward the central axis;

Figure 6a schematically represents a further heater assembly according to a fourth implementation, whereby the major surfaces of the substrate I heater assembly are curved in at least two directions;

Figure 6b shows a further example of a heater assembly in cross-section where the first major surface and the second major surface have parts of the surface that are curved to follow a curved path defined between points on the respective surfaces that are located between ends of the heater assembly;

Figure 6c shows a modification of the heater assembly of Figure 4a and 4b, where Figure 6c shows a side-on cross-sectional view of the modified heater assembly, wherein the modified heater assembly includes a part of the first major surface of the substrate that has a different radius of curvature compared to the concave first major surface; and Figure 7 is a method in accordance with aspects of the present disclosure for forming a heater assembly.

Detailed Description

Aspects and features of certain examples and embodiments are discussed I described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed I described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

According to the present disclosure, a “non-combustible” aerosol provision system is one where a constituent aerosol-generating material of the aerosol provision system (or component thereof) is not combusted or burned in order to facilitate delivery of at least one substance to a user.

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

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

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

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

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

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

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

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

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

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

In some embodiments, the flavour may comprise a sensate, which is intended to achieve a somatosensorial sensation which are usually chemically induced and perceived by the stimulation of the fifth cranial nerve (trigeminal nerve), in addition to or in place of aroma or taste nerves, and these may include agents providing heating, cooling, tingling, numbing effect. A suitable heat effect agent may be, but is not limited to, vanillyl ethyl ether and a suitable cooling agent may be, but not limited to eucolyptol, WS-3. The aerosol-former material may comprise one or more constituents capable of forming an aerosol. In some embodiments, the aerosol-former material may comprise one or more of glycerine, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-butylene glycol, erythritol, meso-Erythritol, ethyl vanillate, ethyl laurate, a diethyl suberate, triethyl citrate, triacetin, a diacetin mixture, benzyl benzoate, benzyl phenyl acetate, tributyrin, lauryl acetate, lauric acid, myristic acid, and propylene carbonate.

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

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

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

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

In some embodiments, the non-combustible aerosol provision system, such as a non- combustible aerosol provision device thereof, may comprise a power source and a controller. The power source may, for example, be an electric power source.

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

In some embodiments, the consumable for use with the non-combustible aerosol provision device may comprise aerosol-generating material, an aerosol-generating material storage area, an aerosol-generating material transfer component, an aerosol generator, an aerosol generation area, a housing, a mouthpiece, and/or an aerosol-modifying agent. An aerosol generator is an apparatus configured to cause aerosol to be generated from the aerosol-generating material. In some embodiments, the aerosol generator is a heater configured to subject the aerosol-generating material to heat energy, so as to release one or more volatiles from the aerosol-generating material to form an aerosol.

In accordance with the present disclosure, a heater assembly, that comprises an electrically resistive layer capable of generating heat when a current is applied thereto and a substrate on a surface of which is disposed the electrically resistive layer, is configured such that at least one surface of the heater assembly (either the surface comprising the electrically resistive layer or the opposite surface) is curved or follows a curved path that extends between side or end surfaces of the heater assembly. Providing curved surfaces can influence the performance characteristics of the heater assembly, thereby offering improved or different user experiences depending on the particular heater assembly used. Therefore, more flexibility may be afforded to a designer of an aerosol provision system to produce certain user experiences.

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

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

The cartomiser 3 comprises a reservoir which stores an aerosol-generating material. Accordingly, the reservoir may also be referred to as an aerosol-generating material storage portion. In the following, the aerosol-generating material is a liquid aerosol-generating material. The liquid aerosol-generating material (herein sometimes referred to simply as liquid, source liquid or e-liquid) may be a conventional e-liquid which may or may not contain nicotine. However, it should be appreciated that other liquids and I or aerosol-generating materials may be used in accordance with the principles of the present disclosure. The cartomiser 3 is able to be removed from the aerosol provision device 2 when, for example, the cartomiser 3 requires refilling with liquid or replacement with another (full) cartomiser 3. The aerosol provision device 2 comprises a power source (such as a rechargeable battery) and control electronics. As will be described below, the cartomiser 3 comprises an electrically powered heater assembly. When the cartomiser 3 is coupled to the aerosol provision device 2, the control electronics of the aerosol provision device 2 are configured to supply electrical power to the heater assembly of the cartomiser 3 to cause the heater assembly to generate an aerosol from the liquid aerosol-generating material supplied thereto. The control electronics may be provided with various components to facilitate I control the supply of power to the cartomiser 3. For example, the control electronics may be provided with an airflow sensor (not shown) configured to detect when a user of the aerosol provision system 1 inhales on the aerosol provision system and to supply power in response to such a detection and / or a push button (not shown) which is pressed by the user and to supply power in response to such a detection. Additional functions may be controlled by the control electronics depending on the configuration of the aerosol provision device 2 (for example, the control electronics may be configured to control I regulate recharging of the power source, or to facilitate wireless communication with another electronic device, such as a smartphone). The features and functions of the aerosol provision device 2 are not of primary significance in respect of the present disclosure.

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

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

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

The upper clamping unit 5 is an intermediate component of the stack of components. The upper clamping unit 5 includes a foot 51 in the form of a block. The foot 51 includes a well 53 which descends from a flat top surface to a flat bottom surface of the foot 51. At the bottom surface, the well 53 is open. As will be described in more detail below, the heater assembly 6 extends across the opening of the well 531 foot 51, effectively sealing the opening of the well 531 foot 51. The foot 51 is designed to engage with the outer housing 4 (more specifically, such that the outer circumferential surface of the foot is pressed against an inner circumferential surface of the outer housing 4). The foot 51 may have a suitable shape and include suitable sealing components to reduce or prevent liquid from leaking between the outer surface of the foot 51 and the inner surface of the housing 4.

The lower support unit 7 is in the form of a block having a broadly flat top surface 71 and a flat bottom surface 72. The flat top surface 71 includes a trench or recessed portion into which the heater assembly 6 is located. In accordance with the principles of the present disclosure, and as seen in Figure 2, the trench or recessed portion is curved to accommodate the curved heater assembly 6. A central air passage 73 extends upwardly from the bottom surface 72 towards the top surface 71 and is in fluid communication with the trench or recessed portion, and hence with a surface of the heater assembly 6 when the heater assembly 6 is located in the trench or recessed portion. On each side of the air passage 73, the block of the lower support unit 7 includes a through hole. In the example cartomiser 3 of Figure 2, a co-moulded contact pad 75 in the form of a pin is inserted into the through holes. More specifically, each contact pad 75 is a press fit in its respective through hole. Each contact pad 75 provides an electrical connection path from the bottom surface 72 to a respective end portion of the heater assembly 6 when the heater assembly 6 is positioned between the top surface 71 of the lower support unit 7 and the bottom surface of the upper clamping unit 5.

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

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

It would be possible to omit the end cap 8 (in order to reduce the component count) by arranging for the lower support unit 7 to form a snap-fit type connection with the bottom end of the side wall 44 of the outer housing 4. Additionally, the cartomiser 3 could be provided with indentations which engage with projections at the top end 21 of the main housing 2, so that a releasable connection is provided between the cartomiser and the main housing.

In any case, the cartomiser 3 is provided what may more generally be referred to as a device interface which is a part of the cartomiser 3 that interfaces with the main housing 2 (or aerosol-generating device). In the above example, the device interface may include the metal cap 8 including the bottom wall 81 and circumferential side wall 83 and I or the lower support unit 7 including the bottom surface 72. More generally, the device interface of the cartomiser 3 may encompass any part or parts of the cartomiser 3 that contact, abut, engage or otherwise couple to the main housing 2.

When the components of the cartomiser 3 have been assembled together, an overall air passage exists from the bottom end 32 to the top end 31 of the cartomiser 3. The overall air passage is formed by the air passage 73 leading to a not-shown air tube provided as part of the upper clamping unit 5 which, in turn, leads to the mouthpiece orifice 41. In this regard, air enters the cartomiser 3 through the opening to air passage 73 formed in the bottom surface 72 of the lower support unit 7, and passes to a region directly below the heater assembly 6. Here, vaporised liquid aerosol-generating material is capable of being entrained in the airflow past the heater assembly 6. The upper clamping unit 5 and/or lower support unit 7 are provided with one or more passages that are in fluid communication with the air channel 73 and extend around the heater assembly 6. For example, with reference to Figure 2, the one or more passages extend into and/or out of the cross-sectional plane of Figure 2 and pass upwards towards the mouthpiece orifice 41 on either side of the heater assembly 6. In some implementations, air that enters the air channel 73 impacts the heater assembly 6 and subsequently bifurcates as it is directed around the side edges of the heater assembly 6 by at least two passages. The not-shown air tube of the upper clamping unit 5 extends from the one or more passages to an air tube 47 which extends downwards from the mouthpiece orifice 41 in the top face 43 of the outer housing 4. That is to say, the not-shown air tube connects the one or more passages to the air tube 47. The not-shown air tube may extend at least in part along the central axis L1 of the cartomiser 3 or may extend along an inside surface of the outer housing 44.

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

When the components of the cartomiser 3 have been assembled, the heater assembly 6 is arranged such that at least a surface thereof is in fluid communication with the well 53. Liquid aerosol-generating material in the reservoir 46 is therefore able to pass to the surface of the heater assembly 6 via the well 53. In some implementations, a wicking material, such as cotton or glass fibres, e.g., formed as a layer, may be provided between the heater assembly 6 and the reservoir 46 and I or upper clamping unit 5, where the wicking material is in contact with the wells 53. The wicking material may act to control the flow of liquid aerosol-generating material in the direction towards the heater assembly 6 and I or may facilitate the flow of liquid aerosol-generating material in the lateral direction (e.g., along the surface of the heater assembly). Additionally or alternatively, the heater assembly 6 itself may be formed with one or more channels permitting the transport of liquid aerosolgenerating material in the lateral direction of the heater assembly 6. For example, in some implementations, the heater assembly 6 may be formed from a porous substrate (such as a sintered material or a ceramic) and I or have channels formed (such as through drilling or other machining) along the length of the heater assembly 6.

Turning now to the heater assembly 6, the heater assembly 6 is a microfluidic heater assembly. Figures 3a and 3b illustrate the microfluidic heater assembly 6 in more detail in accordance with a first example. Figure 3a shows the heater assembly 6 in perspective view, while Figure 3b shows the heater assembly 6 in a side-on view viewing the longitudinal axis L2 of the heater assembly 6.

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

The substrate 62 is formed from a non-conductive material, such as quartz (silicon dioxide); however, it should be appreciated that other suitable non-conductive materials may be used, such as ceramics or silicon oxide, for example. As noted above, the substrate 62 in some implementations may be formed from a porous material. The porous substrate 62 may be formed from naturally porous materials, such as sponges, porous stones or ceramics etc., or via materials that are engineered to be porous, such as sintered metals or other materials. These materials, either formed naturally or engineered, have pores or hollow regions which are interconnected and define passages that follow a substantially random pathway through the material. In other implementations, the substrate 62 may be considered substantially impermeable. The materials of the substrate 62 is not of primary significance to the principles of the present disclosure.

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

The heater assembly 6 is broadly in the form of a rectangular cuboidal block, elongate in the direction of a longitudinal axis L2. Figure 3a includes a Cartesian co-ordinate reference for the heater assembly 6 shown in Figure 3a, where the x-axis of the Cartesian co-ordinate reference is parallel to the longitudinal axis L2. The heater assembly 6 has the shape of a strip and has parallel sides. The heater assembly 6 has parallel upper and lower major surfaces and parallel side surfaces and parallel end surfaces. However, in accordance with the present disclosure, the heater assembly 6 is arranged such that at least a surface of the heater assembly 6 follows a curved path defined between the two parallel end surfaces of the heater assembly 6.

With reference to Figures 3a and 3b, the heater assembly 6 is shown as having a curved structure. More particularly, the substrate 62, which forms the majority of the heater assembly 6, is arranged such that the major surfaces of the substrate 62 (shown as surfaces 62a, 62b in Figures 3a and 3b) are curved. The major surfaces 62a, 62b are curved along a curved path which extends between the two parallel end surfaces of the substrate 62 (shown as surfaces 62c, 62d in Figures 3a and 3b). That is, a curved path is defined between the two end surfaces 62c, 62d of the substrate 62, and the major surfaces 62a, 62b of the substrate 62 are arranged to follow that curved path. It should be understood that the curved path that the first major surface 62a of the substrate 62 follows is displaced (i.e., in the z- direction) from the curved path that the second major surface 62b of the substrate 62 follows. However, in the implementation shown, the curved paths that the first and second major surfaces 62a, 62b follow are identical with the exception of being displaced in the z- axis direction. In addition, it should be understood that the electrically resistive layer 64 is disposed on the first major surface 62a of the substrate 62 and therefore an exposed surface of the electrically resistive layer 64 (i.e., the surface of the electrically resistive layer 64 opposite the surface that contacts the substrate 62) also follows the curved path defined between the two parallel end surfaces 62c, 62d of the substrate 62 (although again, this curved path is displaced in the z-axis direction).

The heater assembly has a length along the x-axis direction, a width along the y-axis direction and a thickness along the z-axis direction. In the shown implementation of Figure 3, the length of the heater assembly 6 is 10 mm and its width is 1 mm, while the thickness of the heater assembly is on the order of 0.12 mm (where the thickness of the substrate 62 is approximately 0.10 mm, and the thickness of the electrically resistive layer 64 is approximately 0.02 mm). The small size of the heater assembly 6 enables the overall size of the cartomiser 3 to be reduced and the overall mass of the components of the cartomiser 3 to be reduced. However, it should be appreciated that in other implementations, the heater assembly 6 may have different dimensions depending upon the application at hand. For example, in some implementations, the heater assembly 6 may be a 3 x 3 mm chip.

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

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

The capillary tubes 66 are configured so as to transport liquid from the second major surface 62b of the substrate 62 (i.e., the surface of the substrate 62 opposite the electrically resistive layer 64) to the electrically resistive layer 64 disposed on the first major surface 62a of the substrate 62. The capillary tubes 66 may be formed based in part on the liquid aerosolgenerating material to be stored in the reservoir 46 of the cartomiser 3 and subsequently used with the heater assembly 6. For example, the properties of the liquid aerosolgenerating material (e.g., viscosity) in the reservoir 46 of the cartomiser 3 may dictate the configuration of the capillary tubes 66 to ensure that a suitable flow of liquid is provided to the electrically resistive layer 64. Broadly speaking, in some implementations, the capillary tubes 66 may have a diameter on the order to tens of microns, e.g., between 10 pm to 100 pm. However, it should be appreciated that capillary tubes 66 in other implementations may be sized differently.

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

With reference back to Figure 2, the heater assembly 6 is shown positioned between the upper clamping unit 5 and the lower support unit 7. In particular, the heater assembly 6 is oriented such that the electrically resistive layer 64 faces towards the lower support unit 7, while the second major surface 62b of the substrate 62 faces towards the upper clamping unit 5. It should be understood from Figure 2 that the end portions 68, 69 of the heater assembly 6 overlap the through holes and the contact pads 75. More specifically, the electrically resistive layer 64 is provided in contact with the contact pads 75, and therefore the end portions 68, 69 act to form an electrical connection with the contact pads 75 (and thus any power source subsequently attached to the contact pads 75, such as from the aerosol provision device 2). For example, the aerosol provision device 2 may have two power supply pins (not shown) which make contact with the bottom ends of the contact pads 75. The top ends of the contact pads 75 are in electrical contact with the heater assembly 6, as above. In use, electrical power supplied by the power supply of the aerosol provision device 2 passes through the electrically resistive layer 64, by virtue of the electrical connection between the end portions 68, 69 and the contact pads 75, to cause heating of the electrically resistive layer 64.

The amount of heating achieved (i.e., the temperature of the electrically resistive layer 64 that is able to be reached) may depend in part on the power supplied by the aerosol provision device 2, the electrical resistance of the electrically resistive layer 64 and the heating efficiency of the heater assembly 6 (in particular, how much of the heating energy is lost to the substrate 62 and/or environment around the electrically resistive layer 64). Equally, the amount of heating required (i.e., the temperature necessary to vaporise the liquid supplied to the resistive layer 64) will be dependent in part on the properties of the liquid supplied to the electrically resistive layer 64. For a given current applied to the electrically resistive layer 64 of the heater assembly 6, the resistance of the electrically resistive layer 64 may be set based on the particular implementation, whereby the resistance of the electrically resistive layer 64 may be dependent on the material of the electrically resistive layer 64 and the physical dimensions of the electrically resistive layer 64 (e.g., thickness).

In accordance with the present disclosure, it is considered that by providing at least one surface of the substrate 62 (or more generally the heater assembly 6) such that it is curved, the performance of the heater assembly 6 may be modified (as compared to a heater assembly with a flat or non-curved surface). The performance of the heater assembly 6 may be influenced in a number of ways depending on the particular implementation at hand and also noting that the performance of a given heater assembly 6 may not solely be a result of the properties or configuration of the heater assembly 6. For example, the relative position of the heater assembly 6 with respect to the flow of air through the cartomiser 3, which may provide a localised cooling effect at certain regions of the heater assembly 6, or the properties of the liquid aerosol-generating material to be used with the heater assembly 6, which may affect the rate at which liquid is passed to the electrically resistive layer 64 and thus the vaporisation, may impact the overall performance of the heater assembly 6. However, characteristics of the heater assembly 6, for example in terms of the generated aerosol (e.g., particle size, volume, etc.) or in terms of the distribution of liquid, may be influenced by providing a curved surface as will be explained below in more detail. Accordingly, by varying the structure of the heater assembly 6, and in particular whether the first major surface 62a and/or the second major surface 62b are curved, offers the ability to customise the performance of the heater assembly 6. This may ultimately affect the generated aerosol that is delivered to the user of the aerosol provision system 1 providing the user with a certain experience. It should be appreciated that some implementations may be directed towards providing a certain user experience, while other implementations may be directed towards providing a different user experience.

Turning to particular implementations, as shown in Figures 2, 3a and 3b, the heater assembly 6 is shown in which the first major surface 62a of the substrate 62 curves in a convex manner. That is, between the two parallel end surfaces 62c, 62d, the first major surface 62a curves in an outward direction. Put another way, if one envisages a reference line (a straight line) extending between the centres of the two-parallel end surfaces 62c, 62d, then the distance between a centre point of the first major surface 62a and the centre of the reference line in the z-direction (or thickness direction) is greater when the first major surface 62a is convex compared to when the first major surface 62a is not curved. Additionally, the heater assembly 6 of Figures 2, 3a and 3b is shown in which the second major surface 62b of the substrate 62 curves in a concave manner. That is, between the two parallel end surfaces 62c, 62d, the second major surface 62b curves in an inward direction. Put another way, if one envisages the same reference line above extending between the centres of the two-parallel end surfaces 62c, 62d, then the distance between a centre point of the second major surface 62b and the centre of the reference line in the z-direction (or thickness direction) is less when the first major surface 62a is concave compared to when the first major surface 62a is not curved.

As described with respect to Figure 2, the lower support unit 7 and the upper clamping unit 5 are configured to receive the heater assembly 6 having the shape as described above. In particular, the trench or recessed portion of the lower support unit 7 is curved so as to conform to the convex curvature of the first major surface 62a of the substrate 621 the exposed surface of the electrically resistive layer 64, such that the heater assembly 6 is supported by the trench or recessed portion.

In such implementations, the concave second major surface 62b of the substrate 62 is provided in fluid communication with the reservoir 46 (via the optional wicking material). Configuring the second major surface 62b of the substrate 62 such that it is concaved, and providing this surface in fluid communication with the reservoir 46, means the concaved second major surface 62b forms a trough or well in which the liquid aerosol-generating material may collect. That is, in normal use of the cartomiser 3, the cartomiser 3 is held in a vertical arrangement (where, for instance, the longitudinal axis L1 is substantially parallel to the direction along which gravity acts). In this orientation, any liquid aerosol-generating material is directed towards the centre of the central portion 67 of the heater assembly 6. That is to say, the liquid aerosol-generating material of the reservoir 46 is biased to flow or otherwise be directed towards the centre of the central portion 67 of the heater assembly 6 by virtue of the second major surface 62b of the substrate 62 being curved in a concave manner. This effect may be particularly pronounced when the amount of liquid aerosolgenerating material in the reservoir 46 is relatively low.

Providing the concave second major surface 62b of the substrate 62 may provide certain advantages in some implementations. For example, in some implementations, it may be desirable to generate aerosol at the centre of the central portion 67 of the heater assembly 6. This may be because the centre of the central portion 67 exhibits a particular temperature profile in operation which may be suited for generating aerosol at a certain rate (i.e. , providing a certain concentration of aerosol per second) or may be suited for generating aerosol with certain properties, such as a certain particle size or distribution of particle sizes. Without wishing to be bound by theory, it is considered that if the centre of the central portion 67 exhibits a high temperature profile during operation (i.e., a relatively higher operational temperature than other parts of the heater assembly 6), then aerosol may be generated more quickly and/or with a smaller particle size at the centre of the central portion 67 than compared to the edges of the central portion 67. Conversely, it is considered that if the centre of the central portion 67 exhibits a low temperature profile during operation (i.e., a relatively lower operational temperature than other parts of the heater assembly 6), then aerosol may be generated more slowly and/or with a larger particle size at the centre of the central portion 67 than compared to the edges of the central portion 67. Therefore, depending on the properties of the aerosol to be generated, and the expected operating temperatures of the heater assembly 6, the second major surface 62b may be formed (curved) accordingly. It should also be understood that directing liquid towards the centre of the central portion 67 of the heater assembly 6 may also be desired in implementations where the edges of the central portion 67 exhibit a particular temperature profile which is less suitable for generating aerosol (for example, too warm or too cool). That is to say, liquid aerosol-generating material may be directed towards the centre of the central portion 67 of the heater assembly because the centre of the central portion 67 displays desired characteristics in respect of aerosol generation and/or the edges of the central portion 67 display undesired or less desired characteristics in respect of aerosol generation.

Additionally, providing the concave second major surface 62b may help guide liquid aerosolgenerating material to areas where aerosol generation is more pronounced (e.g., the centre of a heater assembly 6 where the centre of the central portion 67 is operating at a higher temperature) to avoid overloading the capillary tubes 66 in areas of the heater assembly 6 where aerosol generation is less pronounced (e.g., the edges of a heater assembly 6 where the centre of the central portion 67 is operating at a higher temperature). In this way, the chances of the capillary tubes 66 becoming overloaded in regions of the heater assembly 6 where aerosol generation is less pronounced may be reduced or eliminated by providing the concave second major surface 62b. In the implementation of Figures 2, 3a and 3b, when the heater assembly 6 is located in the cartomiser 3, the convex first major surface 62a of the substrate 62 is provided in fluid communication with the air channel 73. Configuring the first major surface 62a of the substrate 62 such that it is convex and providing this surface in fluid communication with the air channel 73 may cause the centre of the central portion 67 of the heater assembly 6, and in particular the electrically resistive layer 64 in the centre of the central portion 67, to protrude into the air channel 73 by a greater extent than the edges of the central portion 67 of the heater assembly 6. Hence, when air is drawn into the cartomiser 3 (e.g., by a user inhaling at the mouthpiece orifice 41), it may be considered that the air flow interacts with the centre of the central portion 67 of the heater assembly 6 to a greater extent than the edges of the central portion 67.

Providing the convex first major surface 62a of the substrate 62 may provide certain advantages in some implementations. For example, in some implementations, it may be desirable to increase the influence of any inhaled air at the centre of the central portion 67 of the heater assembly 6. This may be to reduce the duration between aerosol or vapour being generated from the electrically resistive layer 64 and being entrained in the air flow. This may influence the particle size of the resulting aerosol by reducing the dwell time near the electrically resistive layer 64. Without wishing to be bound by theory, it is considered that a reduced dwell time may lead to a generated aerosol having smaller particle sizes.

Additionally, or alternatively, the convex first major surface 62a of the substrate 62 may influence the degree of turbulence within the air flow. The way in which the convex first major surface 62a of the substrate 62 influences the turbulence of the airflow may depend in part on the direction of flow of air in the air channel 73. In some implementations, the convex first major surface 62a of the substrate 62 may act to maintain or even decrease the turbulence of the air (e.g., when an air flow is perpendicular to the convex first major surface 62a, or at a sharp angle to the normal of the convex first major surface 62a, e.g., between 45° to 90°). In such cases, air that is incident on the convex first major surface 62a may be guided along the convex surface, thereby providing for a more laminar flow. Without wishing to be bound by theory, it is considered that decreased turbulence may lead to a generated aerosol having smaller particle sizes.

In addition, providing the convex first major surface 62a may help guide liquid aerosol generating material that is not vaporised during use (e.g., a previous use of the heater assembly 6, or when the capillary tubes 66 are oversaturated) away from the centre of the central portion 67 of the heater assembly 6. That is, in such implementations, the convex first major surface 62a can be configured to transport liquid aerosol-generating material to other regions of the heater assembly 6 (and more particularly, of the electrically resistive layer 64). In the particular case of a convex first major surface 62a, these regions are provided at the edges of the central portion 67 or the edge portions 68, 69 of the heater assembly 6. In some implementations, these regions may be provided without capillary tubes 66 (or a lower number of capillary tubes 66). For example, transporting free-standing liquid on the first major surface 62a to one or more regions without capillary tubes 66 may help to ensure consistent performance from one puff to the next (i.e. in terms of the rate at which aerosol is generated), by avoiding a situation in which some capillary tubes 66 generate aerosol during one puff but then become blocked by free-standing liquid during another puff. During operation, when a mass of liquid aerosol-generating material is to be heated/vaporised, for a given heater power (e.g., supplied via the electrically resistive layer 64), the time from heating to initial vapour being formed is based in part on the mass of the liquid aerosol-generating material. Additionally, in some instances, if the mass of liquid aerosol-generating material is too great, the capillary tubes 66 may in effect become blocked by this free-standing liquid on the surface of the electrically resistive layer 64 such that aerosol generation may not occur or may occur with a delay. By directing the liquid aerosolgenerating material to a different region of the electrically resistive layer 64, those regions that the liquid aerosol-generating material is directed away from (i.e., the centre of the central portion 67 in the case of a convex first major surface 62a) may be prevented from being blocked and/or able to generate aerosol more quickly owing to the reduce mass of liquid aerosol-generating material at these regions. Additionally or alternatively, in other implementations, regions of the heater assembly, such as the centre of the central portion 67 (of the electrically resistive layer 64) may experience higher temperatures during operation of the heater assembly 6. In such implementations, the convex first major surface 62a can help guide liquid aerosol-generating material away from the regions of the electrical resistive layer 64 that may experience higher temperatures during operation of the heater assembly 6 to regions of the heater assembly that may experience lower temperatures during operation of the heater assembly (e.g., to the edges of the heater assembly 6). In this way, the liquid aerosol-generating material is able to pool at locations away from the region of the electrical resistive layer 64 that experiences relatively higher operational temperatures, thereby reducing the mass of liquid aerosol-generating material in the centre of the central portion 67 of the electrically resistive layer 64. In such implementations, the relatively low mass of liquid aerosol-generating material at the centre of the central portion 67 and the higher operational temperatures may cause the heater assembly 6 to more quickly vaporise this relatively lower mass of liquid aerosol-generating material, thus reducing the time taken to begin aerosol generation from initiation (e.g., turning on of the heater assembly 6). As the heater assembly 6 is used, pooled liquid aerosol-generating material at the edges of the electrically resistive layer 64 are gradually heated to an extent that vapour may also be generated.

Figures 4a and 4b show a second implementation of the heater assembly 6. Figures 4a and 4b will be understood from Figures 3a and 3b. As with Figure 3a, Figure 4a shows the heater assembly 6 in perspective view. As with Figure 3b, Figure 4b shows the heater assembly 6 in a side-on view viewing the longitudinal axis L2 of the heater assembly 6.

The heater assembly 6 of Figures 4a and 4b is substantially the same as the heater assembly 6 of Figures 3a and 3b with the exception that the first and second major surfaces 62a, 62b of the implementation shown in Figures 4a and 4b are provided with curvature that is opposite to the curvature of the major surfaces 62a, 62b of the implementation of Figures 3a and 3b. That is, Figures 4a and 4b show a heater assembly 6 in which the first major surface 62a of the substrate 62 curves in a concave manner (that is, between the two parallel end surfaces 62c, 62d, the first major surface 62a curves in an inward direction), and the second major surface 62b of the substrate 62 curves in a convex manner (that is, between the two parallel end surfaces 62c, 62d, the second major surface 62b curves in an outward direction).

In order to accommodate these implementations of the heater assembly, the lower support unit 7 and the upper clamping unit 5 are configured to receive the heater assembly 6 having the shape as described above. In some implementations, rather than providing a trench or recessed portion of the lower support unit 7, as in the implementation described in Figure 2, the lower support unit 7 is instead provided with a protrusion that protrudes in the direction of the longitudinal axis L1 of the cartomiser 3 and is curved so as to conform to the concave curvature of the first major surface 62a of the substrate 621 the exposed surface of the electrically resistive layer 64, such that the heater assembly 6 is supported by the protrusion. The protrusion also includes or encompasses the air channel 73. Additionally, the upper clamping unit 5 may be arranged to accommodate the heater assembly 6; for example, the edges of the foot 51 around the well 53 of the upper clamping unit 5 may be flexible and/or curved in an upward direction to accommodate the convex curvature of the second major surface 62b. Alternatively, in other implementations, the trough or recess portion of the lower support unit 7 may be retained but has a curvature that conforms to the concave curvature of the first major surface 62a, while the upper clamping unit 5 is configured to include protrusion(s) that project downwards from the foot 51 to contact the end portions 68, 69 of the convex second major surface 62b when the upper clamping unit 5 is engaged with the lower support unit 7.

As should be appreciated, the convex second major surface 62b of the substrate 62 is provided in fluid communication with the reservoir 46 (via the optional wicking material). Instead of providing the second major surface 62b in a concave manner, as in Figure 3a or 3b, providing the second major surface 62b in a convex manner forms one or more troughs or wells around the edges of the second major surface 62b in which the liquid aerosolgenerating material may collect (when held in a vertical orientation in normal use, as described above). Accordingly, any liquid aerosol-generating material is directed towards the edges of the central portion 67 of the heater assembly 6. That is to say, the liquid aerosolgenerating material of the reservoir 46 is biased to flow or otherwise be directed away from the centre of the central portion 67 and towards the edges of the central portion 67 and/or the edge portions 68, 69 of the heater assembly 6 by virtue of the second major surface 62b of the substrate 62 being curved in a convex manner. This effect may be particularly pronounced when the amount of liquid aerosol-generating material in the reservoir 46 is relatively low.

Providing the convex second major surface 62b of the substrate 62 may provide certain advantages in some implementations. For example, in some implementations, it may be desirable to generate aerosol at the edges of the central portion 67 of the heater assembly 6. This may be because the edges of the central portion 67 exhibit a particular temperature profile in operation which may be suited for generating aerosol at a certain rate (i.e., providing a certain concentration of aerosol per second) or may be suited for generating aerosol with certain properties, such as a certain particle size or distribution of particle sizes. Without wishing to be bound by theory, it is considered that if the edges of the central portion 67 exhibit a high temperature profile during operation (i.e., a relatively higher operational temperature than the centre of the central portion 67), then aerosol may be generated more quickly and/or with a smaller particle size at the edges of the central portion 67 than compared to the centre of the central portion 67. Conversely, it is considered that if the edges of the central portion 67 exhibit a low temperature profile during operation (i.e., a relatively lower operational temperature than the centre of the central portion 67), then aerosol may be generated more slowly and/or with a larger particle size at the edges of the central portion 67 than compared to the centre of the central portion 67. Therefore, depending on the properties of the aerosol to be generated, and the expected operating temperatures of the heater assembly 6, the second major surface 62b may be formed (curved) accordingly. It should also be understood that directing liquid towards the edges of the central portion 67 of the heater assembly 6 may also be desired in implementations where the centre of the central portion 67 exhibits a particular temperature profile which is less suitable for generating aerosol (for example, too warm or too cool). That is to say, liquid aerosol-generating material may be directed towards the edges of the central portion 67 of the heater assembly because the edges of the central portion 67 display desired characteristics in respect of aerosol generation and/or the centre of the central portion 67 displays undesired or less desired characteristics in respect of aerosol generation.

Additionally, providing the convex second major surface 62b may help guide liquid aerosolgenerating material to areas where aerosol generation is more pronounced (e.g., the edges of a heater assembly 6 where the centre of the edges of the central portion 67 are operating at a higher temperature) to avoid overloading the capillary tubes 66 in areas of the heater assembly 6 where aerosol generation is less pronounced (e.g., the centre of a heater assembly 6 where the centre of the central portion 67 is operating at a lower temperature). In this way, the chances of the capillary tubes 66 becoming overloaded in regions of the heater assembly 6 where aerosol generation is less pronounced may be reduced or eliminated by providing the convex second major surface 62b.

In the implementation of Figure 4a and 4b, when the heater assembly 6 is located in the cartomiser 3, the concave first major surface 62a of the substrate 62 is provided in fluid communication with the air channel 73. Configuring the first major surface 62a of the substrate 62 such that it is concave and providing this surface in fluid communication with the air channel 73 may cause the centre of the central portion 67 of the heater assembly 6, and in particular the electrically resistive layer 64 in the centre of the central portion 67, to be withdrawn from the air channel 73. That is to say, the edges of central portion 67 of the heater assembly 6 may extend into the air channel 73 by a greater amount than the centre of the central portion 67 of the heater assembly 6. Hence, when air is drawn into the cartomiser 3 (e.g., by a user inhaling at the mouthpiece orifice 41), it may be considered that the air flow interacts with the centre of the central portion 67 of the heater assembly 6 to a lesser extent than it does with the edges of the central portion 67.

Providing the concave first major surface 62a of the substrate 62 may provide certain advantages in some implementations. For example, in some implementations, it may be desirable to decrease the influence of any inhaled air at the centre of the central portion 67 of the heater assembly 6. This may be to increase the duration between aerosol (or vapour) being generated from the electrically resistive layer 64 and being entrained in the air flow through channel 73. The dwell time may influence the particle size of the resulting aerosol. For example, increasing the dwell time near the electrically resistive layer 64 may therefore provide a greater period of time for the generated aerosol (or vapour) to cool. Without wishing to be bound by theory, it is considered that an increased dwell time may lead to a generated aerosol having larger particle sizes as more time is provided for the generated aerosol to cool and coalesce. Additionally, or alternatively, the concave first major surface 62a of the substrate 62 may influence the degree of turbulence within the air flow. The way in which the concave first major surface 62a of the substrate 62 influences the turbulence of the airflow may depend in part on the direction of flow of air in the air channel 73. In some implementations, the concave first major surface 62a of the substrate 62 may act to increase the turbulence of the air (e.g., when an air flow is perpendicular to the concave first major surface 62a, or at a sharp angle to the normal of the concave first major surface 62a, e.g., between 45° to 90°). In this case, the concave first major surface 62a may deflect air towards the normal of the concave first major surface 62a, thereby providing for a more turbulent air flow. Without wishing to be bound by theory, it is considered that increased turbulence may lead to a generated aerosol having larger particle sizes.

In addition, providing the concave first major surface 62a may help guide liquid aerosol generating material that is not vaporised during use (e.g., a previous use of the heater assembly 6, or when the capillary tubes 66 are oversaturated) away from the edges of the central portion 67 of the heater assembly 6. That is, in such implementations, the concave first major surface 62a can be configured to transport liquid aerosol-generating material to other regions of the heater assembly 6 (and more particularly, of the electrically resistive layer 64). In the particular case of a concave first major surface 62a, these regions are provided at the centre of the central portion 67 of the heater assembly 6. In some implementations, these regions may be provided without capillary tubes 66 (or a lower number of capillary tubes 66). As described above, transporting free-standing liquid on the first major surface 62a to one or more regions without capillary tubes 66 may help to ensure consistent performance from one puff to the next (i.e. in terms of the rate at which aerosol is generated), by avoiding a situation in which some capillary tubes 66 generate aerosol during one puff but then become blocked by free-standing liquid during another puff. During operation, when a mass of liquid aerosol-generating material is to be heated/vaporised, for a given heater power (e.g., supplied via the electrically resistive layer 64), the time from heating to initial vapour being formed is based in part on the mass of the liquid aerosolgenerating material. Additionally, in some instances, if the mass of liquid aerosol-generating material is too great, the capillary tubes 66 may in effect become blocked by this freestanding liquid on the surface of the electrically resistive layer 64 such that aerosol generation may not occur or may occur with a delay. By directing the liquid aerosolgenerating material to a different region of the electrically resistive layer 64, those regions that the liquid aerosol-generating material is directed away from (i.e., the edges of the central portion 67 in the case of a concave first major surface 62a) may be prevented from being blocked and/or able to generate aerosol more quickly owing to the reduce mass of liquid aerosol-generating material at these regions. Additionally or alternatively, in other implementations, regions of the heater assembly, such as the edges of the central portion 67 (of the electrically resistive layer 64), may experience higher temperatures during operation of the heater assembly 6. In such implementations, the concave first major surface 62a can help guide liquid aerosol-generating material away from the regions of the electrical resistive layer 64 that may experience higher temperatures during operation of the heater assembly 6 to regions of the heater assembly that may experience lower temperatures during operation of the heater assembly (e.g., the centre of the central portion 67 of the heater assembly 6). In this way, the liquid aerosol-generating material is able to pool at locations away from the region of the electrical resistive layer 64 that experiences relatively higher operational temperatures, thereby reducing the mass of liquid aerosol-generating material at the edges of the central region 67 of the electrically resistive layer 64. In such implementations, the relatively low mass of liquid aerosol-generating material and the higher operational temperatures may cause the heater assembly 6 to more quickly vaporise this relatively lower mass of liquid aerosol-generating material, thus reducing the time taken to begin aerosol generation from initiation (e.g., turning on of the heater assembly 6). As the heater assembly 6 is used, pooled liquid aerosol-generating material at the centre of the electrically resistive layer 64 is gradually heated to an extent that vapour may also be generated.

Hence, it has been shown above that by providing a heater assembly 6 with curved major surfaces 62a, 62b, the performance characteristics of the heater assembly 6 may be altered or customised. Providing the first major surface 62a with a curvature may impact the dwell time (i.e., the duration or time between aerosol, or vapour, being generated from the electrically resistive layer 64 to becoming entrained in an air flow) and/or the degree of turbulence of the air flow. In the implementations described above, providing a convex first major surface 62a may decrease dwell time and/or decrease turbulence (particularly for airflows which are substantially perpendicular to the first major surface 62a) leading to smaller particle sizes, while providing a concave first major surface 62a may increase dwell time and/or increase turbulence (particularly for airflows which are substantially perpendicular to the first major surface 62a), leading to larger particle sizes. However, it should be understood that in some implementations, the effects of providing a concave or convex first major surface 62a may be different depending on the specific implementation at hand and other factors influencing the characteristics of the generated aerosol. Providing the second major surface 62b with a curvature may impact the liquid flow bias (i.e., the bias experience by liquid aerosol-generating material to flow to a particular part of the heater assembly). In the implementations described above, providing a concave second major surface 62b biases liquid aerosol-generating material to the centre of the central portion 67 of the heater assembly 6, while providing a convex second major surface 62b biases liquid aerosol-generating material to the edges of the central portion 67 of the heater assembly 6. The precise way this may affect the performance characteristics of the heater assembly 6 will depend on the implementation at hand, but as described above, the performance characteristics of the heater assembly 6 can be altered by configuring the curvature of the second major surface 62b of the heater assembly 6 accordingly.

It should be appreciated that the degree of curvature (or put another way, the radius of curvature) of the first and second major surfaces 62a, 62b may be set as desired in order to impact the performance characteristics of the heater assembly to a desired extent. For example, providing a small radius of curvature (that is, where the curvature is more apparent) may impact the performance characteristics (e.g., liquid bias, turbulence, dwell time) to a greater extent that providing a larger radius of curvature (that is, where the curvature is less apparent). Accordingly, it should be understood that the curvature of the first and second major surfaces 62a, 62b may be set as desired.

The heater assembly 6 described above may be formed so as to provide curved first and second major surfaces 62a, 62b in any suitable manner. For example, the heater assembly 6 may be formed as a flat, planar structure (e.g., a rectangular cuboid strip) and subsequently bent into a curved shape using a suitable technique, e.g., such as stamping. Alternatively, the heater assembly 6 may be constructed to have a particular shape, e.g., such as by carving, etching or otherwise machining a block material to the curved structure.

It has been described above that the heater assembly 6 includes first and second major surfaces 62a, 62b that each follow curved paths that are identical to one another with the exception of being displaced in the z-axis direction. However, in other implementations, this is not the case and the curved paths may be different; for example, the curved paths may have different radii of curvature. For example, the first major surface 62a may follow a curved path having a greater or smaller radius of curvature than the second major surface 62b. Moreover, it should be understood that only one of the first major surface 62a or the second major surface 62b may follow a curved path. For example, the first major surface 62a may follow a curved path while the second major surface 62b may be substantially flat (or put another way, have a radius of curvature equal to infinity), or vice versa. In this regard, it should be understood that for any of the above, bending of flat, planar structure may be unsuitable in order to form the heater assembly 6 where the first and second major surfaces 62a, 62b have different radii of curvature.

In addition, it has been described above that the first and second major surfaces 62a, 62b have opposite curvatures; e.g., as in Figures 3a, 3b the first major surface 62a is convex while the second major surface 62b is concave, and vice versa in Figures 4a, 4b. In other implementations, however, the first and second major surfaces 62a, 62b may have the same curvature; e.g., both the first and second major surfaces 62a, 62b may be concave, or both the first and second major surfaces 62a, 62b may be convex. Again, it should be understood that for any of the above, bending of flat, planar structure may be unsuitable in order to form the heater assembly 6 where the first and second major surfaces 62a, 62b have the same curvatures.

Furthermore, it has been described above that the first major surface 62a and I or the second major surface 62b of the entire substrate 621 heater assembly 6 is curved (or rather, follows a curved path). However, this need not be the case in all implementations. For example, in some implementations, the parts of the first and second major surfaces 62a, 62b corresponding to the central portion 67 of the heater assembly 6 may follow a curved path while the parts of the first and second major surfaces 62a, 62b corresponding to the end portions 68, 69 of the heater assembly 6 may follow a linear path. Figure 6b schematically shows such an implementation whereby only parts of the first and second major surfaces 62a, 62b are curved (or rather follow a curved path). In this regard, Figure 6b shows a convex curved surface 62a’ provided at the first major surface 62a and a concave second surface 62b’ provided at the second major surface 62b. Such implementations may enable improved electrical contact between the contact pads 75 and the electrically resistive layer 64 at the end portions 68, 69, as well as enable regions of the heater assembly to benefit from the above-mentioned effects. For example, the convex curved surface 62a’ provided at the first major surface 62a may allow liquid aerosol-generating material on the surface of the electrically resistive layer 64 to be directed away from the centre of the central portion 67 to reduce blockage of the capillary tubes 66 in this region, while the concave second surface 62b’ provided at the second major surface 62b may allow liquid to preferentially collect and be directed to the electrically resistive layer 64 at the centre of the central portion 67.

In addition, it should be appreciated that although Figure 6b shows a convex curved surface 62a’ provided at the first major surface 62a and a concave second surface 62b’ provided at the second major surface 62b, in other implementations, the curved surface 62a’ provided at the first major surface 62a may be concave and the second surface 62b’ provided at the second major surface 62b may be convex. In regards to the concave first surface 62a’, this may allow liquid aerosol-generating material on the surface of the electrically resistive layer 64 to be directed toward from the centre of the central portion 67 to reduce blockage of the capillary tubes 66 at the remaining parts of the electrically resistive layer 64 (i.e., the edges of the central portion 67), while the convex second surface 62b’ provided at the second major surface 62b may allow liquid to preferentially collect at the edges of the central portion 67 and be directed to the electrically resistive layer 64 at the edges of the central portion 67.

Furthermore, it should be appreciated that although Figure 6b shows portions of both the first major surface 62a and the second major surface 62b following a curved path, in some implementations, only portions of one of these major surfaces 62a, 62b may follow a curved path.

For the avoidance of doubt, such major surfaces 62a’, 62b’ still follow a curved path defined between the two ends of the substrate 62c, 62d. That is to say, the curved path need not start at the two ends of the substrate, but is nonetheless defined between the two ends of the substrate (or more specifically, between points on the respective major surface(s) located between the two ends of the substrate).

In addition, it has been shown, in Figures 3a, 3b, 4a and 4b, that the heater assembly 6 comprises capillary tubes 66 that all extend along the same direction (e.g., the z-axis direction). However, this may not necessarily be the case and the capillary tubes may extend along different directions.

Figures 5a and 5b show two different implementations in which the capillary tubes 66 extend along different directions. Figure 5a is a side-on view of a heater assembly 6 similar to heater assembly 6 of Figure 3b where the first major surface 62a is convex and the second major surface 62b is concave, while Figure 5b is a side-on view of a heater assembly 6 similar to heater assembly 6 of Figure 4b where the first major surface 62a is concave and the second major surface 62b is convex. The heater assemblies of Figures 5a and 5b are substantially the same as their counterparts of Figures 3b and 4b respectively, and only the differences are described herein.

In Figure 5a, capillary tubes 66a extend from the second major surface 62b to the first major surface 62a. Each of the capillary tubes 66a follows a substantially straight line (as do capillary tubes 66 of Figures 3a to 4b). However, in the implementation of Figure 5a, at least some of the straight lines along which the capillary tubes 66a extend are provided at an angle with respect to the z-axis direction. In Figure 5a, the capillary tubes 66a are angled such that, with respect to the first major surface 62a (comprising the electrically resistive layer 64) the straight lines along which the capillary tubes 66a extend are angled away from the z-axis direction. That is to say, when the first major surface 62a is curved in a convex manner, at least some of the capillary tubes 66a follow a linear direction which is angled away from a central axis extending through the centre of the heater assembly from the second major surface 62b to the first major surface 62a.

In this regard, it should be understood that aerosol that is generated at the electrically resistive layer 64 may be broadly directed along the linear direction of the respective capillary tubes 66a when it leaves I exits the capillary tube 66a. This is schematically illustrated by the arrows pointing in the direction from the capillary tubes 66a in Figure 5a. As these capillary tubes 66a are angled away from the z-axis direction, it can be seen that the generated aerosol is distributed in a more diffuse manner (i.e., within a greater volume). This may cause the generated aerosol to form with smaller particle sizes as the average distance between droplets of aerosol is increased owing to the diffuse distribution (that is, there is a reduced chance of droplets coalescing). Hence, providing the capillary tubes 66a at an angle to the z-axis direction (thickness direction) in combination with the curved (convex) first major surface 62a, the performance characteristics of the heater assembly 6 may be further modified. In this implementation, the particle size may be further decreased as compared, e.g., to the heater assembly of Figure 3b.

Conversely, in Figure 5b, capillary tubes 66b are angled such that, with respect to the first major surface 62a (comprising the electrically resistive layer 64) the straight lines along which the capillary tubes 66b extend are angled toward the z-axis direction. That is to say, when the first major surface 62a is curved in a concave manner, at least some of the capillary tubes 66b follow a linear direction which is angled toward a central axis extending through the centre of the heater assembly from the second major surface 62b to the first major surface 62a.

As above, aerosol that is generated at the electrically resistive layer 64 may be broadly directed along the linear direction of the respective capillary tubes 66b when it leaves I exits the capillary tube 66b. This is schematically illustrated by the arrows pointing in the direction from the capillary tubes 66b in Figure 5b. However, as these capillary tubes 66b are angled toward the z-axis direction, it can be seen that the generated aerosol is distributed in a more concentrated manner (i.e., within a smaller volume). This may cause the generated aerosol to form with greater particle sizes as the average distance between droplets of aerosol is decreased owing to the concentrated distribution (that is, there is an increased chance of droplets coalescing). Hence, providing the capillary tubes 66b at an angle to the z-axis direction (thickness direction) in combination with the curved (concave) first major surface 62a, the performance characteristics of the heater assembly 6 may be further modified. In this implementation, the particle size may be further increased as compared, e.g., to the heater assembly of Figure 4b. In the examples of Figures 5a and 5b above, the capillary tubes 66a, 66b are shown broadly extending along a linear direction that is normal to the local area of the curved first and second major surfaces 62a, 62b. However, this need not be the case, and the capillary tubes 66a, 66b may be provided at any desired angle that is offset from the z-axis direction, provided that the capillary tubes 66a, 66b extend from the second major surface 62b to the first major surface 62a.

In addition, it should be appreciated that in some implementations, the capillary tubes 66a, 66b may be tapered such that the opening on one surface (e.g., first major surface 62a) is larger than the opening on another surface (e.g., second major surface 62b). Providing such tapered capillary tubes 66a, 66b may alter the liquid flow rate and/or the aerosol generation of these capillary tubes 66a, 66b. Broadly speaking, increasing the size of the opening of the capillary tubes 66a, 66b at the electrically resistive layer 64 may relatively increase the amount of aerosol that is generated from that capillary tube 66a, 66b. In some implementations, only certain ones of the capillary tubes 66a, 66b are tapered. For example, the capillary tubes 66a in the centre of the implementation of Figure 5a or the capillary tubes 66b at the edges of the implementation of Figure 5b may be provided with a taper, such that the openings of said capillary tubes 66b on the first major surface 62a are larger than the openings on the second major surface 62b. In the example of Figure 5a, because the aerosol jets are directed away from a centre point provided a distance from the electrically resistive layer 64, the temperature is likely to be lower at the centre of the electrically resistive layer 64 (or conversely higher at the edges). By tapering the capillary tubes 66a at the centre of the heater assembly 6 in this way, more consistent aerosol generation may be realised across the electrically resistive layer 64 (i.e. more aerosol being generated at the centre, even though the centre of the electrically resistive layer 64 may be operating at lower temperatures). In the example of Figure 5b, because the aerosol jets are directed towards a centre point provided a distance from the electrically resistive layer 64, the temperature is likely to be higher at the centre of the electrically resistive layer 64. By tapering the capillary tubes 66b at the edges of the heater assembly 6 such that the openings of said capillary tubes 66b on the first major surface 62a are larger than the openings on the second major surface 62b, more consistent aerosol generation may be realised across the electrically resistive layer 64 (i.e. more aerosol being generated at the edges, even though the edges of the electrically resistive layer 64 may be operating at lower temperatures).

In terms of forming the capillary tubes 66, 66a or 66b in the heater assembly 6, the capillary tubes 66, 66a or 66b may be formed in a heater assembly that already comprises some curvature (e.g., has been formed to have curvature) or in a flat, planar structure that is, e.g., bent in order to provide some curvature. In the case of bending the heater assembly, the capillary tubes 66a, 66b may be formed prior to bending the heater assembly or after bending the heater assembly. However, in some implementations, for example where the capillary tubes are formed by laser drilling, it may be advantageous to form the capillary tubes prior to bending the heater assembly. This is because, in some implementations, a diffraction technique may be used to drill multiple capillary tubes at any one time. Thus, it may be more efficient from a manufacturing perspective to form the capillary tubes such that all capillary tubes are aligned and extend along the same direction, and then to vary the angle of some of the capillary tubes relative to the z-axis direction by bending the flat, planar heater assembly after the capillary tubes have been formed. However, it should be appreciated that other techniques may be utilised to form the capillary tubes and these techniques may be more or less suitable for providing a plurality of capillary tubes at different angles to the z-axis direction.

It has also broadly been described that the first and second major surfaces 62a, 62b of the heater assembly follow a single curved path. For example, the first and second major surfaces 62a, 62b of Figures 3a to 5b, follow a curved path that is defined between the two parallel end surfaces 62c, 62d. However, in other implementations, the first and second major surfaces 62a, 62b of the heater assembly 6 may be curved so as to follow a plurality of curved paths.

Figure 6a schematically shows an example of a heater assembly 6, in perspective view, in which the first and second major surfaces 62a, 62b are curved in at least two directions (that is, they follow a plurality of curved paths). Figure 6a will be understood from Figures 3a and 4a and like components are labelled with the same reference signs. Only the differences will be explained herein.

In Figure 6a, the first and second major surfaces 62a, 62b are curved along a curved path extending along a first direction (i.e. , the y-axis direction) defined between the parallel ends 62c and 62d of the substrate 62, as described above with respect to e.g., Figure 3a and 3b. However, in Figure 6a, the first and second major surfaces 62a, 62b are additionally curved along a curved path extending along a second direction (i.e., the x-axis direction, or width direction), where the second direction is substantially perpendicular (or perpendicular) to the first direction. The second curved path in this instance is defined between the two parallel side surfaces, 62e and 62f (obscured from view in Figure 6a), of the heater assembly 6.

In this way, it should be appreciated that the effects of the curvature of the first and second major surfaces 62a, 62b described above may be further modified or enhanced in particular regions of the heater assembly 6. For example, the second major surface 62b may be modified to bias liquid towards a central (oval) portion of the centre portion 67, as the concave surface forms a bowl-like structure. Alternatively, the bowl-like structure may direct liquid towards the outer edges (in both directions) of the central portion if the second major surface 62b is provided with convex curvature.

Accordingly, the characteristics of the heater assembly 6 may be further modified by curving the major surfaces 62a, 62b of the heater assembly 6 along directions that extent in at least two directions.

Further, it should be understood that in some implementations, a single major surface may be arranged to be curved in a concave manner in one direction and a convex direction in another (e.g., providing a saddle-like shape). The way in which the first and second surfaces are curved may depend in part on the implementation at hand and the cartomiser 3 in which the heater assembly 6 is to be used.

It should be understood that the cartomiser 3 (e.g., the lower support unit 7 and the upper clamping unit 5) may be adapted accordingly to accommodate a heater assembly where the first and second major surfaces 62a, 62b follow a plurality of curved paths.

Figure 6c schematically shows a modification to the heater assembly 6 of Figures 4a and 4b (where a first major surface 62a of the heater assembly 6 is curved in a concave manner and a second major surface 62b of the heater assembly 6 is curved in a convex manner). Figure 6c shows the heater assembly 6 in cross-section.

As stated above, the heater assembly 6 of Figure 6c is broadly similar to the heater assembly of Figures 4a and 4b. However, there are two differences.

Firstly, the capillary tubes 66 are arranged such that there is a region 67a of the central portion 67 of the heater assembly 6 that does not comprise capillary tubes 66 (this is indicated schematically by the double-headed arrow in Figure 6c). This region 67a may extend the entire width of the heater assembly 6 (e.g., from the side surfaces 62e to 62f) or only part of the width of the heater assembly 6.

Secondly, a depression 62a” is formed in the first major surface 62a. The depression 62a” may take the form of a bowl-shaped depression (providing a hemi-spherical depression or well, for example) in the first major surface 62a. However, more generally, the depression 62a” is an example of the first major surface 62a following a second curved path at least in the same direction as the first curved path. More broadly, at least a part of at least one of the first major surface 62a and the second major surface 62b follows a first curved path defined along a first direction (e.g., between the ends of the substrate 62), and a different part (e.g., 62a”) of one of the first major surface 62a and the second major surface 62b follows a second curved path defined along the same direction defined between points on the respective surface (for example, the points defined on the respect surface, are those points at the edges of the capillary tubes 66 shown in Figure 6c). The radius of curvature of the second curved path is different (e.g., smaller) that the radius of curvature of the first curved path. In this way, any given surface (e.g., the first major surface or the second major surface) of the heater assembly 6 may comprise parts that follow a first curved path having a first radius of curvature, and parts that follow a second curved path having a second radius of curvature.

In the example of Figure 6c, the radius of curvature of the depression 62a” is smaller than the radius of curvature of the rest of the first major surface 62a. In addition, it should be understood that the depression 62a” may follow curved paths in other directions (e.g., in the width direction) to form the bowl-shape mentioned above; however, the rest of the first major surface 62a may or may not be curved along a curved path in a second direction.

In the example of Figure 6c, the depression 62a” (or more generally, the part of the surface having a different radius of curvature) is located firstly in the middle of the first major surface 62a, and secondly in the region 67a of the central portion 67 of the heater assembly 6 where no capillary tubes 66 are formed. However, in other implementations, this may not be the case - that is the depression (or more generally, the part of the surface having a different radius of curvature) may not be located at the centre of the respective surface or the depression (or more generally, the part of the surface having a different radius of curvature) may not be located at the region of no capillary tubes 66.

In the present example of Figure 6c, the depression 62a” acts as a reservoir for collecting liquid that is otherwise present on the surface of the electrically resistive layer 64 (i.e., that is condensed liquid or liquid that has leaked from the capillary tubes 66 due to oversaturation). As described above in respect of Figures 4a and 4b, the concave first major surface 62a may help guide liquid aerosol generating material that is not vaporised during use (e.g., a previous use of the heater assembly 6, or when the capillary tubes 66 are oversaturated) away from the edges of the central portion 67 of the heater assembly 6 and towards the centre. In the example of Figure 6c, such liquid aerosol-generating material is firstly directed to a region (e.g., region 67a) where no capillary tubes 66 are present and secondly to a part (e.g., depression 62a”) that is adapted to hold a volume of liquid aerosol generating material, allowing more liquid aerosol-generating material to be stored in this region than a region having an equivalent two-dimensional extent in the implementation of Figure 4a and 4b. As described above, transporting free-standing liquid on the first major surface 62a to one or more regions without capillary tubes 66 may help to ensure consistent performance from one puff to the next (i.e. in terms of the rate at which aerosol is generated), by avoiding a situation in which some capillary tubes 66 generate aerosol during one puff but then become blocked by free-standing liquid during another puff. By providing the depression 62a”, this effect may be enhanced (or rather, a greater amount of liquid may be held in the depression and thus guided away from the capillary tubes 66) as compared to the implementation of Figure 4a and 4b.

It should be appreciated that Figure 6c shows one implementation where a surface (the first major surface 62a) is provided with a part that follows a different curved path. In other implementations, the second major surface 62b may comprise a part that follows a different curved path (e.g., a depression or the like). Equally, it should be appreciated that parts of the same surface may have different types of curvature - that is, instead of providing a depression 62a” in the concave first major surface 62a, a protrusion (following a convex curved path) may be provided instead of the depression 62a”. Different implementations may utilise different combinations of the curvatures as desired.

It should be appreciated that the configuration of the cartomiser 3 accommodating the heater assembly 6 is provided as an example configuration of such a cartomiser 3. The principles of the present disclosure apply equally to other configurations of the cartomiser 3 (for example, comprising similar or different components to those as shown in Figures 1 and 2, and a similar or different layout to that shown in Figure 2). That is, the cartomiser 3 and the relative position of the heater assembly 6 in the cartomiser 3 is not significant to the principles of the present disclosure. Broadly speaking, a cartomiser is likely to comprise a top end (having the mouthpiece orifice 41) and a bottom end. In the examples shown above, the heater assembly 6 is arranged to be below the reservoir 46, substantially horizontal to the longitudinal axis of the cartomiser 3, and arranged in an airflow path that is substantially perpendicular to longitudinal axis of the heater assembly. However, this need not be case, and in other implementations the cartomiser 3 may be configured differently depending on the particular design and application at hand. For example, the heater assembly 6 may be arranged such that airflow is substantially parallel to the longitudinal axis of the heater assembly, e.g., along the exposed surface of the electrically resistive layer 64. For example, an air passage may be provided to one side of the upper clamping unit 5. Air may enter the cartomiser 3 by a suitable inlet and flow along the longitudinal surface of the heater assembly 6 (and along the electrically resistive layer 64) before passing in a substantially vertical direction through an air tube positioned at one end of the upper clamping unit 5 (e.g., the end opposite the air inlet). The outer housing 4 and mouthpiece orifice 41 may be suitably configured. Hence, although the heater assembly 6 has been described in the specific context of the example cartomiser 3 of Figures 1 and 2, the principles described herein can be applied to different heater assemblies for use in different cartomisers 3. In the example shown in Figure 2, the contact pads 75 directly contact the electrically resistive layer 64 of the heater assembly 6. However, the cartomiser 3 may be provided with any suitable arrangement that facilitates the electrical contact between the aerosol provision device 2 and the heater assembly 6. For example, in some implementations, electrical wiring or other electrically conductive elements may extend between the electrically resistive layer 64 and the contact pads 75 of the cartomiser 3. This may particularly be the case when the heater assembly 6 has its largest dimension (e.g., its length) less than a minimum distance between the contact pads 75. The distance between the contact pads 75 may be dictated by the electrical contacts on the aerosol provision device 2.

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

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

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

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

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

The method begins at step S1 by providing a substrate 62. The way in which the substrate 62 is formed is not significant to the principles of the present disclosure. For example, the substrate 62 may be cut from a portion of cultured quartz or formed via a sintering process by sintering quartz powders I fibres, for example. In the present example method, the substrate 62 is provided broadly as a flat, planar substrate 62 (e.g., such as a rectangular cuboid having major surfaces 62a, 62b, parallel end surfaces 62c, 62d and parallel side surfaces 62e, 62f).

The method then proceeds to step S2 whereby the electrically resistive layer 64 is provided on a surface of the substrate 62. The way in which the electrically resistive layer 64 is formed on the surface of the substrate 62 is not significant to the principles of the present disclosure. For example, the electrically resistive layer 64 may be a sheet of metal (e.g., titanium) adhered, welded, or the like to the substrate 62. Alternatively, the electrically resistive layer 64 may be formed through a vapour or chemical deposition technique using the substrate 62 as a base. It should also be appreciated that step S2 may alternatively occur before step S1. For example, a further alternative is to grow or culture the substrate 62 using the electrically resistive layer 64 as a base.

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

It should be appreciated that step S3 may be performed prior to step S2 (and equally step S3 may follow step S1 where step S2 is performed prior to step S1). That is to say, the capillary tubes 66 may be formed in the substrate 62 prior to applying the electrically resistive layer 64.

The method of Figure 7 shows two additional steps, step S4a and S4b, in which the heater assembly 6 is curved, or put more broadly, is subject to a process which causes the first major surface 62a and the second major surface 62b of the substrate 62 to be curved. As noted above, this may be via any suitable bending technique or other technique, such as stamping. It is expected that only one of steps S4a and S4b are performed. Step S4a is shown occurring after step S3; that is, after the capillary tubes 66 have been formed in the flat, planar substrate at step S3, the substrate 62 and electrically resistive layer 64 (if step S2 has been performed at this stage) are subject to a process which causes the first major surface 62a and the second major surface 62b of the substrate 62 to be curved. Conversely, step S4b is shown occurring before step S3; that is, in this step, before the capillary tubes 66 have been formed in the flat, planar substrate at step S3, the substrate 62 and electrically resistive layer 64 (if step S2 has been performed at this stage) are subject to a process which causes the first major surface 62a and the second major surface 62b of the substrate 62 to be curved. As shown in Figure 7, after step S4b has been performed, step S3 may be implemented on the curved heater assembly 6 to form the capillary tubes 66.

After step S3 (if step S4b is performed) or S4a, the heater assembly 6 is formed, and subsequently may be assembled to form the cartomiser 3 (or more generally, the heater assembly 6 may be positioned in an aerosol provision system 1).

Broadly, it should be understood that the method of Figure 7 is an example method only, and adaptations to the steps or ordering of the steps of this method are contemplated within this disclosure, for example, as described above. Additionally, it should be appreciated that the method of Figure 7 is described in respect of a substrate 62 which is provided as a flat, planar substrate 62. However, variations of the method of Figure 7 may be applied when the substrate 62 is formed in a curved manner; for example, as part of step S1 . As described above, a substrate 62 may be formed, e.g., carved or etched or the like, so as to have curved first and/or second major surfaces 62a, 62b. In such implementations, steps S4a and S4b are not performed.

Thus, there has been described a heater assembly for an aerosol provision system, the heater assembly including: a substrate, having a first end and a second end; a heater layer configured to generate heat when supplied with energy, the heater layer provided on a first surface of the substrate; and one or more capillary tubes extending from a second surface of the substrate through the heater layer provided at the first surface of the substrate, the second surface opposite the first surface. The substrate is arranged such that at least a part of at least one of the first surface and second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate. Also described is an aerosol provision system comprising the heater assembly and a method for manufacturing a heater assembly.

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

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

Claims

1. A heater assembly for an aerosol provision system, the heater assembly comprising: a substrate, having a first end and a second end; a heater layer configured to generate heat when supplied with energy, the heater layer provided on a first surface of the substrate; and one or more capillary tubes extending from a second surface of the substrate through the heater layer provided at the first surface of the substrate, the second surface opposite the first surface, wherein the substrate is arranged such that at least a part of at least one of the first surface and second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate.

2. The heater assembly of claim 1 , wherein the first surface of the substrate is curved.

3. The heater assembly of claim 2, wherein the surface of the heater layer opposite the surface of the heater layer in contact with the first surface of the substrate also follows a curved path defined between the first end and the second end of the substrate.

4. The heater assembly of any one of claims 2 and 3, wherein the first surface of the substrate is curved in a convex manner between the first end and the second end of the substrate.

5. The heater assembly of claim 4, wherein at least some of the one or more capillary tubes are arranged to follow respective linear paths extending from the second surface through the heater layer, wherein the respective linear paths are angled away from a central axis extending through the centre of the heater assembly from the second surface to the first surface.

6. The heater assembly of any one of claims 2 and 3, wherein the first surface of the substrate is curved in a concave manner between the first end and the second end of the substrate

7. The heater assembly of claim 6, wherein at least some of the one or more capillary tubes are arranged to follow respective linear paths extending from the second surface through the heater layer, wherein the respective linear paths are angled toward a central axis extending through the centre of the heater assembly from the second surface to the first surface.

8. The heater assembly of any of the preceding claims, wherein the second surface of the substrate is curved.

9. The heater assembly of claim 8, wherein the second surface of the substrate is curved in a convex manner.

10. The heater assembly of claim 8, wherein the second surface of the substrate is curved in a concave manner.

11. The heater assembly of any of the preceding claims, wherein the at least a part of at least one of the first surface and the second surface is curved in at least two directions.

12. The heater assembly of claim 11 , wherein the at least a part of at least one of the first surface and the second surface is curved in a first direction along the curved path defined between the first end and the second end of the substrate, and the at least one surface is curved along a curved path in a second direction substantially perpendicular to the first direction.

13. The heater assembly of any of the preceding claims, wherein the curved path that the at least a part of at least one of the first surface and the second surface of the substrate is curved along is defined between at least a first and a second point on the respective surface, where the first and second points are located between the first end and the second end of the substrate.

14. The heater assembly of any of the preceding claims, wherein the at least a part of at least one of the first surface and the second surface follows a first curved path defined along a first direction, and a different part of the at least one of the first surface and the second surface follows a second curved path defined along the first direction between at least a third and a fourth point on the respective surface, where radius of curvature of the second curved path is different that the radius of curvature of the first curved path.

15. An aerosol provision system comprising the heater assembly of any one of the preceding claims.

16. A method for manufacturing a heater assembly for an aerosol provision system, the method comprising: providing a substrate having a first end and a second end; providing a heater layer configured to generate heat when supplied with energy, the heater layer provided on a first surface of the substrate; and providing one or more capillary tubes extending from a second surface of the substrate through the heater layer provided at the first surface of the substrate, the second surface opposite the first surface, wherein the substrate is arranged such that at least a part of at least one of the first surface and the second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate.

17. The method of claim 16, wherein the at least a part of one surface of the substrate is curved prior to providing the one or more capillary tubes.

18. The method of claim 16, wherein the at least a part of one surface of the substrate is curved after providing the one or more capillary tubes.

19. A heater means for an aerosol provision system, the heater means comprising: a substrate having a first end and a second end; heater layer means configured to generate heat when supplied with energy, the heater layer means provided on a first surface of the substrate; and capillary means extending from a second surface of the substrate through the heater layer means provided at the first surface of the substrate, the second surface opposite the first surface, wherein the substrate is arranged such that at least a part of at least one of the first surface and the second surface of the substrate is curved along a curved path defined between the first end and the second end of the substrate.