HEATER ASSEMBLY HAVING A FLUID-PERMEABLE HEATER WITH DIRECTLY DEPOSITED TRANSPORT MATERIAL - Patent application

Abstract

A heater assembly (10) for an aerosol generation system, the heater assembly comprising: a fluid-permeable heating element (12) for heating a liquid aerosol-forming substrate to form an aerosol, the fluid-permeable heating element (12) including a plurality of openings (16) that allow a fluid to permeate through the heating element (12); and a transport material (14) including a plurality of channels (18) for transporting the liquid aerosol-forming substrate to the plurality of openings (16) of the fluid-permeable heating element (12), the transport material (14) comprising a ceramic deposited directly on a fluid-permeable surface of the fluid-permeable heating element (12), and for more than 50 percent of the openings (16) of the fluid-permeable heating element (12), the transport material (14) includes corresponding channels (18) for transporting the liquid aerosol-forming substrate to its respective opening (16).

Description

[Technical Field]

[0001] The present invention relates to a heater assembly for an aerosol generating system. In particular, but not exclusively, the present invention relates to a heater assembly for a handheld, electrically operated aerosol generating system for heating an aerosol-forming substrate to generate an aerosol and deliver the aerosol into a user's mouth. The present invention also relates to a cartridge for the aerosol generating system comprising the heater assembly, the aerosol generating system, and a method for manufacturing the heater assembly. [Background technology]

[0002] Handheld, electrically operated aerosol generating devices and systems are known, each comprising a device portion including a battery and control electronics, a portion for housing or receiving a liquid aerosol-forming substrate, and an electrically operated heater for heating the aerosol-forming substrate to generate an aerosol. The heater typically comprises a coil of wire wound around an elongated core that transports the liquid aerosol-forming substrate from a liquid storage portion to the heater. Electric current is passed through the coil of wire to heat the heater, thereby generating an aerosol from the aerosol-forming substrate. A mouthpiece portion is also included, which a user can inhale to draw the aerosol into their mouth.

[0003] In addition to the wick, the liquid reservoir may include an absorbent material to hold the liquid aerosol-forming substrate. Thus, manufacturing a heater assembly for known aerosol-generating devices and providing a means for transporting the liquid aerosol-forming substrate to the heating wire may involve the assembly of at least three components. This increases the complexity of the assembly line and the number of manufacturing steps involved.

[0004] Another problem with known aerosol generating devices occurs when a user continues to use the aerosol generating device after the liquid aerosol-forming substrate has been depleted. In this situation, some materials used to form wicking materials are known to degrade when heated in a dry state, releasing unwanted by-products that can be potentially harmful. Furthermore, some fibrous wicking materials are known to release fibers when heated in a dry state.

[0005] It would be desirable to provide a heater assembly for an aerosol generating system that requires fewer parts to be assembled. It would be desirable to provide a heater assembly for an aerosol generating system that is simpler to manufacture. It would also be desirable to provide a heater assembly that reduces the risk of producing undesirable by-products. Summary of the Invention

[0006] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generation system. The heater assembly may include a fluid-permeable heating element for heating a liquid aerosol-forming substrate to form an aerosol. The heater assembly may include a transport material for transporting the liquid aerosol-forming substrate to the fluid-permeable heating element. The transport material may include a ceramic. The ceramic may be deposited on a fluid-permeable surface of the fluid-permeable heating element. The ceramic may be deposited directly on the fluid-permeable surface of the fluid-permeable heating element.

[0007] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generation system, the heater assembly comprising: a fluid-permeable heating element for heating a liquid aerosol-forming substrate to form an aerosol; and a transport material for transporting the liquid aerosol-forming substrate to the fluid-permeable heating element, the transport material comprising a ceramic deposited directly on a fluid-permeable surface of the fluid-permeable heating element.

[0008] As used herein, the term "deposited" is intended to mean that the transport material is formed on the surface of the fluid-permeable heating element by some form of physical, chemical, or electrodeposition process. The term "deposited" is not intended to encompass forming the transport material as a separate, discrete piece that is simply attached to or placed in contact with the fluid-permeable heating element. For the avoidance of doubt, the term "deposited" includes electrophoretic deposition.

[0009] As used herein, the term "directly deposited" means that the transport material is deposited onto the surface of the fluid-permeable heating element in direct contact with the fluid-permeable heating element, with no intervening components disposed between the transport material and the fluid-permeable heating element.

[0010] Advantageously, by depositing the transport material directly onto the fluid-permeable heating element, the transport material is integrally formed with the fluid-permeable heating element. In other words, the transport material and the fluid-permeable heating element are formed as a single piece or part. Instead of two components, i.e., a separate transport material and heating element, the heater assembly comprises only a single component. This reduces the number of individual parts of the heater assembly that need to be assembled, making assembly easier. It also eliminates the need for additional components to assemble the heater assembly, such as a frame or holder to hold the components together. Furthermore, other components of the heater assembly can be directly connected to the heater assembly. For example, electrical contacts can be directly connected to the fluid-permeable heating element. Furthermore, forming the fluid-permeable heating element and the transport material as a single, integral component ensures that the fluid-permeable heating element is in fluid communication with the transport material, assisting in supplying the liquid aerosol-forming substrate to the heating element.

[0011] An advantage of forming the transport material from a ceramic is that it mitigates some of the problems that can arise from using fibrous wicking materials, such as the production of undesirable by-products caused by dry, heated conditions. Compared to some polymer-based fibers, ceramics are relatively inert and are thermally and structurally stable over a wider temperature range. The use of ceramic transport materials also reduces the risk of releasing fiber segments into the device.

[0012] The fluid-permeable heating element may include a plurality of gaps or openings extending from a first side to a second side of the heating element, which advantageously allow fluid to permeate through the heating element.

[0013] The transport material may include a plurality of channels for conveying the liquid aerosol-forming substrate to the plurality of openings of the fluid-permeable heating element. Each channel of the plurality of channels may be a capillary channel that transports the liquid from one end of the transport material to another by capillary action. The transport material may include any suitable ceramic. The transport material may include any suitable inert or biocompatible ceramic. Examples of suitable ceramics include Al2O3, ZrO2, and calcium phosphate ceramics, including hydroxyapatite.

[0014] For each opening of the fluid-permeable heating element, or for at least a majority (e.g., more than 50 percent) of each opening of the fluid-permeable heating element, the transport material may include a corresponding channel for delivering the liquid aerosol-forming substrate to that respective opening. For more than 60 percent, preferably more than 70 percent, and more preferably more than 80 percent of the openings of the fluid-permeable heating element, the transport material may include a corresponding channel for delivering the liquid aerosol-forming substrate to that respective opening. For 50 to 85 percent, preferably 60 to 85 percent, and more preferably 70 to 85 percent of the openings of the fluid-permeable heating element, the transport material may include a corresponding channel for delivering the liquid aerosol-forming substrate to that respective opening. This means that each opening, or at least a majority of the openings, has its own dedicated channel that helps supply the liquid aerosol-forming substrate to the fluid-permeable heating element. It also means that the liquid aerosol-forming substrate may be supplied to all openings, or at least a majority of the openings. This helps ensure that all portions of the fluid-permeable heating element having apertures, or at least the majority of all portions of the fluid-permeable heating element having apertures, receive the supply of liquid aerosol-forming substrate, and that the supply is evenly distributed across the fluid-permeable heating element.

[0015] The transport material may have a thickness defined between a first surface of the transport material and an opposing second surface of the transport material. The fluid-permeable heating element may be disposed on the first surface, and the second surface may be disposed to receive the liquid aerosol-forming substrate. A plurality of channels may extend through the thickness of the transport material between the first and second surfaces of the transport material. The plurality of channels extending through the thickness of the transport material may assist in supplying the liquid aerosol-forming substrate from the liquid reservoir to the fluid-permeable heating element. The thickness of the transport material may be 0.5 to 6 mm.

[0016] The plurality of channels may be arranged to allow unidirectional flow of the liquid aerosol-forming substrate between the first and second surfaces of the transport material. Advantageously, this may result in more efficient transfer of the liquid aerosol-forming substrate to the fluid-permeable heating element. In standard porous ceramic materials, the pores are isotropically interconnected, allowing liquid to permeate through the ceramic in any direction, not necessarily toward the heating element. By providing channels through the ceramic, liquid is encouraged to flow unidirectionally through the transport material, i.e., from the second surface where the liquid aerosol-forming substrate is received to the fluid-permeable heating element.

[0017] The plurality of channels may extend substantially linearly in a direction substantially perpendicular to the first surface of the transport material. Advantageously, this may result in more efficient transport of the liquid aerosol-forming substrate to the fluid-permeable heating element, as the liquid will take the shortest route, i.e., a straight line, to the fluid-permeable heating element.

[0018] Each of the plurality of openings in the fluid-permeable heating element may have a cross-sectional dimension of 20 microns to 300 microns, which has been found to be a particularly effective size range that allows the liquid aerosol-forming substrate to penetrate into the openings in the fluid-permeable heating element and to provide particularly effective aerosol generation upon heating by the fluid-permeable heating element.

[0019] Preferably, each of the plurality of apertures in the fluid-permeable heating element may have a cross-sectional dimension of between 20 microns and 200 microns, more preferably between 20 microns and 100 microns, more preferably between 50 microns and 80 microns, and even more preferably about 70 microns.

[0020] The cross-sectional dimension of each of the plurality of channels along the length of the channel may be substantially the same as the cross-sectional dimension of the opening in the fluid-permeable heating element, thereby allowing unimpeded flow of the liquid aerosol-forming substrate through the channel.

[0021] The cross-sectional dimension of each of the plurality of channels along the length of the channel may be substantially the same as the cross-sectional dimension of its corresponding opening in the fluid-permeable heating element, thereby allowing unimpeded flow of the liquid aerosol-forming substrate through the channel.

[0022] The heater assembly may further include electrical contacts for supplying power to the fluid-permeable heating element. The electrical contacts may be connected directly to the fluid-permeable heating element. Advantageously, connecting the electrical contacts directly to the fluid-permeable heating element further reduces the number of components that need to be assembled and connected on an assembly line.

[0023] The electrical contacts may be located on both ends of the fluid-permeable heating element. The electrical contact portions may comprise two conductive contact pads. The conductive contact pads may be located in the edge regions of the fluid-permeable heating element. Preferably, at least two conductive contact pads may be located at the tip of the heating element. The conductive contact pads may be affixed directly to the conductive filaments of the fluid-permeable heating element. The conductive contact pads may include tin patches. Alternatively, the conductive contact pads may be integral with the fluid-permeable heating element.

[0024] The transport material may include a first transport material disposed on a first side of the fluid-permeable heating element. The heater assembly may further include a second transport material disposed on a second side of the fluid-permeable heating element. This effectively sandwiches the fluid-permeable heating element between the first and second transport materials, which may help improve robustness of the heater assembly.

[0025] The fluid-permeable heating element may include an electrically resistive heating element.

[0026] The fluid-permeable heating element may be made from any suitable electrically conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable alloys include stainless steel, constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timetal®, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The fluid-permeable heating elements are preferably made from stainless steel, more preferably 300 series stainless steel such as AISI 304, 316, 304L, 316L, etc.

[0027] Additionally, the fluid-permeable heating element may include a combination of the above materials. A combination of materials may be used to improve control of the resistance of the substantially planar heating element. For example, a material with a high resistivity may be combined with a material with a low resistivity. This may be advantageous when one of the materials is more advantageous from another perspective, such as price, machinability, or other physical and chemical parameters. Advantageously, a heater with a high resistivity allows for more efficient use of battery energy.

[0028] The fluid-permeable heating element may include a substantially flat heating element to allow for simple manufacturing. Geometrically, the term "substantially flat" heating element is used to refer to a heating element that is in the form of a substantially two-dimensional topological manifold. In some embodiments, a substantially flat heating element may extend substantially in two dimensions along a surface rather than in three dimensions. In some embodiments, the dimension of the substantially flat heating element in two dimensions within its surface may be at least five times larger than the dimension in the third dimension perpendicular to the surface. In some embodiments, a substantially flat fluid-permeable heating element may include two substantially flat parallel imaginary surfaces. In some embodiments, a substantially flat heating element may be a structure between two substantially flat parallel imaginary surfaces, where the distance between these two imaginary surfaces is substantially less than the extension within the surface. In some embodiments, only one of the two substantially parallel imaginary surfaces may be flat. In some embodiments, a substantially flat heating element may be planar. In other embodiments, a substantially flat heating element may be curved along one or more dimensions, for example, forming a dome or bridge shape.

[0029] The fluid-permeable heating element may include one or more electrically conductive filaments. The term "filament" is used to refer to an electrical path disposed between two electrical contacts. The filament may arbitrarily branch and diverge into several paths or filaments, respectively, or several electrical paths may merge into one path. The filaments may have a cross section that is round, square, flat, or of any other shape. The filaments may be arranged in a straight or curved manner.

[0030] The fluid-permeable heating element may be, for example, an array of filaments arranged parallel to one another. Preferably, the filaments may form a mesh. The mesh may be woven or non-woven. The mesh may be formed using different types of weave or lattice structures. Alternatively, the conductive heating element comprises an array of filaments or a woven fabric of filaments. A mesh, array, or woven fabric of conductive filaments may also be characterized by its ability to retain liquid.

[0031] In one preferred embodiment, the substantially flat heating element may be constructed of wires formed into a wire mesh. The mesh preferably has a plain weave design. The heating element is preferably a wire grill made from mesh strips.

[0032] The conductive filaments may define gaps between them, which may have a width of 10 micrometers to 100 micrometers. The filaments preferably create capillary action within the gaps so that liquid to be vaporized in use is drawn into the gaps, increasing the contact area between the heating element and the liquid aerosol-forming substrate.

[0033] The conductive filaments may form a mesh with a size of 60 to 240 filaments per centimeter (±10 percent). The mesh density is preferably 100 to 140 filaments per centimeter (±10 percent). More preferably, the mesh density is approximately 115 filaments per centimeter. The gap width may be 20 micrometers to 300 micrometers, preferably 50 micrometers to 100 micrometers, and more preferably approximately 70 micrometers. The open area of ​​the mesh, which is the ratio of the gap area to the total area of ​​the mesh, may be 40 percent to 90 percent, preferably 85 percent to 80 percent, and more preferably approximately 82 percent.

[0034] The conductive filaments may have a width or diameter of 10 micrometers to 100 micrometers, preferably 10 micrometers to 50 micrometers, more preferably 12 micrometers to 25 micrometers, and most preferably approximately 16 micrometers. The filaments may have a round or flattened cross section.

[0035] The area of ​​the conductive filament mesh, array, or woven fabric may be small, for example, 50 square millimeters or less, preferably 25 square millimeters or less, and more preferably approximately 15 square millimeters. The size is selected to allow the heating element to be incorporated into a handheld system. Sizing the conductive filament mesh, array, or woven fabric to 50 square millimeters or less reduces the total amount of power required to heat the conductive filament mesh, array, or woven fabric while still ensuring that the conductive filament mesh, array, or woven fabric is in sufficient contact with the liquid aerosol-forming substrate. The conductive filament mesh, array, or woven fabric may be rectangular, for example, and may have a length of 2 to 10 millimeters and a width of 2 to 10 millimeters. The mesh preferably has dimensions of approximately 5 millimeters by 3 millimeters.

[0036] Preferably, the filament is made of wire, more preferably the wire is made of metal, most preferably stainless steel.

[0037] The electrical resistance of the mesh, array, or woven conductive filaments of the heating element may be between 0.3 ohms and 4 ohms. Preferably, the electrical resistance is 0.5 ohms or greater. More preferably, the electrical resistance of the mesh, array, or woven conductive filaments is between 0.6 ohms and 0.8 ohms, and most preferably about 0.68 ohms. The electrical resistivity of the mesh, array, or woven conductive filaments is preferably at least one order of magnitude greater, and more preferably at least two orders of magnitude greater, than the electrical resistivity of any conductive contacts. This ensures that heat generated by passing current through the heating element is localized to the mesh or array of conductive filaments. If the system is battery-powered, a low overall resistance to the heating element is advantageous. A low-resistance, high-current system allows for high power delivery to the heating element, allowing the heating element to quickly heat the conductive filaments to the desired temperature.

[0038] Alternatively, the fluid-permeable heating element may include a heating plate or membrane having an array of apertures formed therein. The apertures may be formed, for example, by etching or machining. The plate or membrane may be formed from any material having suitable electrical properties, such as those materials described above with respect to the fluid-permeable heating element.

[0039] According to another embodiment of the present disclosure, there is provided a cartridge for an aerosol generation system. The cartridge may include a heater assembly according to any of the exemplary heater assemblies described above. The cartridge may include a liquid reservoir or compartment for holding a liquid aerosol-forming substrate.

[0040] According to another embodiment of the present disclosure, there is provided a cartridge for an aerosol generation system, the cartridge comprising a heater assembly according to any of the exemplary heater assemblies described above and a liquid reservoir or compartment for holding a liquid aerosol-forming substrate.

[0041] The terms "liquid storage portion" and "liquid storage compartment" are used interchangeably herein. A liquid storage portion or compartment may have first and second storage portions in communication with each other. The first storage portion of the liquid storage compartment may be on an opposite side of the heater assembly from the second storage portion of the liquid storage compartment. A liquid aerosol-forming substrate is held in both the first and second storage portions of the liquid storage compartment.

[0042] Advantageously, the first storage portion of the storage compartment is larger than the second storage portion of the liquid storage compartment. The cartridge may be configured to allow a user to draw from or suck on the cartridge to inhale the aerosol generated by the cartridge. In use, the opening at the mouth end of the cartridge is typically positioned above the heater assembly, and the first storage portion of the storage compartment is positioned between the opening at the mouth end and the heater assembly. By making the first storage portion of the liquid storage compartment larger than the second storage portion of the liquid storage compartment, liquid is ensured to be delivered from the first storage portion of the liquid storage compartment to the second storage portion of the storage compartment and to the heater assembly under the influence of gravity during use.

[0043] The cartridge may have a mouth end through which a user can draw generated aerosol and a connection end configured to connect to an aerosol generating device, with a first side of the heater assembly facing the mouth end and a second side of the heater assembly facing the connection end.

[0044] The cartridge may define an enclosed airflow path or passageway from the air inlet past the first side of the heater assembly to an opening at the mouth end of the cartridge. The enclosed airflow passageway may pass through the first or second storage portion of the liquid storage compartment. In one embodiment, the airflow path extends between the first and second storage portions of the liquid storage compartment. Additionally, the airflow passageway may extend through the first storage portion of the liquid storage compartment. For example, the first storage portion of the liquid storage compartment may have an annular cross-section and have an airflow passageway extending through the first storage portion of the liquid storage compartment from the heater assembly to the mouth end. Alternatively, the airflow passageway may extend from the heater assembly to an opening at the mouth end adjacent the first storage portion of the liquid storage compartment.

[0045] Alternatively, or additionally, the cartridge may include a retaining material for retaining the liquid aerosol-forming substrate. The retaining material may be in the first storage portion of the liquid storage compartment, the second storage portion of the liquid storage compartment, or both the first and second storage portions of the liquid storage compartment. The retaining material may be a foam, a sponge, or a collection of fibers. The retaining material may be formed of a polymer or copolymer. In one embodiment, the retaining material is a spun polymer. The liquid aerosol-forming substrate may be released into the retaining material during use. For example, the liquid aerosol-forming substrate may be provided in a capsule.

[0046] The cartridge advantageously contains a liquid aerosol-forming substrate. As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing a volatile compound capable of forming an aerosol. The volatile compound may be released by heating the aerosol-forming substrate.

[0047] The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may contain both liquid and solid components. The liquid aerosol-forming substrate may contain nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may contain plant-derived material. The liquid aerosol-forming substrate may contain tobacco. The liquid aerosol-forming substrate may contain tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate on heating. The liquid aerosol-forming substrate may contain homogenised tobacco material. The liquid aerosol-forming substrate may contain non-tobacco-containing material. The liquid aerosol-forming substrate may contain homogenised plant-derived material.

[0048] The liquid aerosol-forming substrate may contain one or more aerosol formers. The aerosol former is any suitable, well-known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Examples of suitable aerosol formers include glycerin and propylene glycol. Suitable aerosol formers are well-known in the art and include, but are not limited to, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate). The liquid aerosol-forming substrate may contain water, solvents, ethanol, plant extracts, and natural or artificial flavors.

[0049] The liquid aerosol-forming substrate may comprise nicotine and at least one aerosol former. The aerosol former may be glycerin or propylene glycol. The aerosol former may comprise both glycerin and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of about 0.5% to about 10% (e.g., about 2%).

[0050] The cartridge may include a housing. The housing may be formed from a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET). The housing may form some or all of the walls of one or both portions of the liquid storage compartment. The housing and the liquid storage compartment may be integrally formed. Alternatively, the liquid storage compartment may be formed separately from the housing and assembled to the housing.

[0051] According to another embodiment of the present disclosure, an aerosol generation system is provided. The aerosol generation system may include a cartridge according to any of the exemplary cartridges described above. The aerosol generation system may include an aerosol generation device. The cartridge may be removably coupled to the aerosol generation device. The aerosol generation device may include a power source for a heater assembly.

[0052] According to another embodiment of the present disclosure, there is provided an aerosol generation system comprising a cartridge according to any of the exemplary cartridges described above and an aerosol generation device, wherein the cartridge is removably coupled to the aerosol generation device, and the aerosol generation device comprises a power source for the heater assembly.

[0053] The aerosol generating device may further include a control circuit configured to control the supply of power to the heater assembly.

[0054] The control circuit may comprise a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuit capable of providing control. The control circuit may comprise additional electronic components. For example, in some embodiments, the control circuit may comprise a sensor, a switch, or a display element. Power may be supplied to the heater assembly continuously after activation of the device, or may be supplied intermittently, for example, between puffs. Power may be supplied to the heater assembly in the form of current pulses, for example, by pulse width modulation.

[0055] The power source may be a DC power source. The power source may be a battery. The battery may be a lithium-based battery, such as a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. The battery may be a nickel-metal hydride battery or a nickel-cadmium battery. The power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and configured for numerous charge-discharge cycles. The power source may have a capacity that allows for storage of sufficient energy for one or more user experiences; for example, the power source may have a capacity sufficient to allow continuous generation of aerosol for a period of approximately six minutes, corresponding to the typical time it takes to smoke a conventional cigarette, or a multiple of six minutes. In another embodiment, the power source may have a capacity sufficient to allow for a predetermined number of puffs or discontinuous activation of the heater assembly.

[0056] The aerosol generating device may include a housing. The housing may be elongated. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), or polyethylene. Preferably, the material is lightweight and not brittle.

[0057] The aerosol generation system may be a handheld aerosol generation system. The aerosol generation system may be a handheld aerosol generation system configured to allow a user to draw on the mouthpiece and draw the aerosol through an opening in the mouth end. The aerosol generation system may have a size comparable to a conventional cigar or cigarette. The aerosol generation system may have a total length of about 30 mm to about 150 mm. The aerosol generation system may have an outer diameter of about 5 mm to about 30 mm.

[0058] According to another embodiment of the present disclosure, there is provided a method of manufacturing a heater assembly for an aerosol-generating system. The method may include providing a fluid-permeable heating element. The method may include providing a transport material for transporting the liquid aerosol-forming substrate to the fluid-permeable heating element. The transport material may be provided by depositing a ceramic on the fluid-permeable heating element. The transport material may be provided by depositing a ceramic directly on the fluid-permeable heating element.

[0059] According to another embodiment of the present disclosure, there is provided a method of manufacturing a heater assembly for an aerosol generating system, the method comprising: providing a fluid-permeable heating element; and providing a transport material for transporting a liquid aerosol-forming substrate to the fluid-permeable heating element, wherein the transport material is provided by depositing a ceramic directly onto the fluid-permeable heating element.

[0060] Advantageously, by depositing the transport material directly onto the fluid-permeable heating element, the transport material is integrally formed with the fluid-permeable heating element. In other words, the transport material and the fluid-permeable heating element are formed as a single piece or part. The transport material and the fluid-permeable heating element are formed as a single piece or part in a single manufacturing process. Instead of two components, i.e., a separate transport material and heating element, the heater assembly comprises only a single component. This reduces the number of individual parts of the heater assembly that need to be assembled, making assembly easier. It also eliminates the need for additional components to assemble the heater assembly, such as a frame or holder to hold the components together. Furthermore, other components of the heater assembly can be directly connected to the heater assembly. For example, electrical contacts can be directly connected to the fluid-permeable heating element.

[0061] The transport material may be deposited directly onto the fluid-permeable heating element by electrophoretic deposition.

[0062] As used herein, the term "electrophoretic deposition" refers to a process in which colloidal particles suspended in a liquid medium migrate under the influence of an electric field (electrophoresis) and are deposited onto a conductive substrate, such as a fluid-permeable heating element, which acts as an electrode.

[0063] Electrophoretic deposition can help impart several properties to a heater assembly. Advantageously, a ceramic transport material is bonded to a fluid-permeable heating element to create a single-piece heater assembly comprising a fluid-permeable heating element and an integral transport material. The ceramic transport material is deposited in the shape of the underlying fluid-permeable heating element, which acts as an electrode in the electrophoretic deposition process. Furthermore, the deposited ceramic transport material maintains this shape as the thickness of the deposited ceramic layer increases during the deposition process. Thus, the ceramic transport material has substantially linear channels extending away from the fluid-permeable heating element. The channels have substantially the same shape and dimensions as the underlying openings in the fluid-permeable heating element. Thus, the channels allow unidirectional liquid flow through the transport material toward the fluid-permeable heating element by capillary action.

[0064] The transport material may be deposited by depositing ceramic particles onto a fluid-permeable heating element, the ceramic particles having an average particle size of 0.05 microns to 0.7 microns, which particle size range of ceramic particles has been found to be particularly effective for producing a transport material with favorable properties.

[0065] The particle size of the ceramic particles can depend on the type of ceramic used. For example, for inert ceramics such as Al2O3 and ZrO2, the particle size can be 0.2 to 0.7 microns. For biocompatible ceramics such as hydroxyapatite, the particle size can be 50 to 600 nanometers.

[0066] The method may use particles of different types of ceramic to build up different ceramic layers within the deposited transport material. Different types of ceramic can be used to impart different properties to the transport material.

[0067] The method may further include annealing the heater assembly after the transport material is deposited. The method may further include sintering the heater assembly after the transport material is deposited. Sintering fuses the ceramic particles together, reducing voids or spaces between them. This may help reduce lateral flow of the liquid aerosol-forming substrate from the channels through the ceramic body and instead maintain the liquid aerosol-forming substrate within the channels so that liquid flows efficiently within the channels to openings in the fluid-permeable heating element. [Example]

[0068] The present invention is defined in the claims. However, the following provides a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0069] Example 1: A heater assembly for an aerosol generation system, the heater assembly comprising: a fluid-permeable heating element for heating a liquid aerosol-forming substrate to form an aerosol; and a transport material for transporting the liquid aerosol-forming substrate to the fluid-permeable heating element. Example 2: The heater assembly according to example 1, wherein the transport material comprises a ceramic deposited directly onto the fluid-permeable surface of the fluid-permeable heating element. Example 3: The heater assembly according to example 1 or example 2, wherein the fluid-permeable heating element includes a plurality of openings that allow fluid to permeate through the heating element. Example 4: A heater assembly according to example 3, wherein the transport material comprises a plurality of channels for conveying the liquid aerosol-forming substrate to the plurality of openings of the fluid-permeable heating element. Example 5: A heater assembly according to Example 4, wherein for each opening of the fluid-permeable heating element, the transport material includes a corresponding channel for conveying the liquid aerosol-forming substrate to its respective opening. Example 6: 6. A heater assembly according to any of Examples 1-5, wherein the transport material has a thickness defined between a first surface of the transport material and an opposing second surface of the transport material, the fluid-permeable heating element is disposed on the first surface, the second surface is disposed to receive a liquid aerosol-forming substrate, and the plurality of channels extend through the thickness of the transport material between the first surface and the second surface of the transport material. Example 7: The heater assembly according to example 6, wherein the plurality of channels are arranged to allow unidirectional flow of the liquid aerosol-forming substrate between the first surface and the second surface of the transport material. Example 8: The heater assembly according to example 6 or example 7, wherein the plurality of channels extend substantially linearly in a direction substantially perpendicular to the first surface of the transport material. Example 9: A heater assembly according to any of Examples 1-8, wherein each of the plurality of openings in the fluid-permeable heating element has a cross-sectional dimension between 20 microns and 300 microns. Example 10: A heater assembly according to any of Examples 5-9, wherein a cross-sectional dimension of each of the plurality of channels along the length of the channel is substantially the same as a cross-sectional dimension of its corresponding opening in the fluid-permeable heating element. Example 11: 11. The heater assembly according to any of Examples 1-10, further comprising electrical contacts for supplying power to the fluid-permeable heating element, the electrical contacts being directly connected to the fluid-permeable heating element. Example 12: A heater assembly according to any of Examples 1-11, wherein the fluid-permeable heating element is substantially flat. Example 13: A heater assembly according to any of Examples 1-12, wherein the transport material comprises a ceramic selected from one or more of aluminum oxide, zirconium oxide, and hydroxyapatite. Example 14: The heater assembly according to any of Examples 5-13, wherein each opening in the fluid-permeable heating element is substantially aligned with its corresponding channel. Example 15: A heater assembly according to any of Examples 4-14, wherein the cross-sectional shape of the channel is substantially the same as the cross-sectional shape of the opening. Example 16: A heater assembly according to any of Examples 11-15, wherein the electrical contacts are disposed on opposite sides of the fluid-permeable heating element. Example 17: 17. The heater assembly according to any of Examples 1-16, wherein the transport material comprises a first transport material disposed on a first side of the fluid-permeable heating element, and the heater assembly comprises a second transport material disposed on a second side of the fluid-permeable heating element. Example 18: A heater assembly according to any of Examples 1-17, wherein the fluid-permeable heating element comprises a mesh heater comprising a plurality of intersecting heating filaments. Example 19: The heater assembly according to example 18, wherein the width or diameter of the heating filament is 10 to 100 microns. Example 20: A cartridge for an aerosol-generating system, the cartridge comprising a heater assembly according to any one of Examples 1 to 19 and a liquid reservoir for holding a liquid aerosol-forming substrate. Example 21: An aerosol generation system comprising: a cartridge according to Example 20; and an aerosol generation device, wherein the cartridge is removably coupled to the aerosol generation device, and the aerosol generation device comprises a power source for the heater assembly. Example 22: A method of manufacturing a heater assembly for an aerosol generating system, the method comprising: providing a fluid-permeable heating element; and providing a transport material for transporting a liquid aerosol-forming substrate to the fluid-permeable heating element. Example 23: The method according to example 22, wherein the transport material is provided by depositing a ceramic directly onto the fluid-permeable heating element. Example 24: The method according to example 23, wherein the transport material is deposited directly onto the fluid-permeable heating element by electrophoretic deposition. Example 25: The method according to Example 23 or Example 24, wherein the transport material is deposited by depositing ceramic particles onto the fluid-permeable heating element, and the ceramic particles have an average particle size of 0.05 microns to 0.7 microns. Example 26: The method according to any of examples 23-25, further comprising sintering the heater assembly after the transport material is deposited. [Brief explanation of the drawings]

[0070] The embodiments will now be further described with reference to the following figures:

[0071] [Figure 1] FIG. 1 is a schematic perspective view of a heater assembly according to an embodiment of the present disclosure. [Figure 2] 2 is a schematic cross-sectional side view of the heater assembly of FIG. 1 taken along line AA of FIG. [Figure 3] FIG. 3 is a schematic diagram of an exemplary aerosol generation system including a cartridge and an aerosol generator. [Figure 4] FIG. 4 is a schematic diagram of the apparatus used for electrophoretic deposition. [Figure 5A] FIG. 5A is a schematic illustration of electrophoretic deposition of ceramic particles on a portion of a mesh heater, according to an embodiment of the present disclosure. [Figure 5B] FIG. 5B is a schematic diagram showing the ceramic particles of FIG. 4A after a sintering process. DETAILED DESCRIPTION OF THE INVENTION

[0072] Referring to Figure 1, there is shown a heater assembly 10 comprising a mesh heating element 12 and a ceramic transport material 14. The mesh heating element 12 includes an array of conductive filaments 13 made from stainless steel and is fluid-permeable. The ceramic transport material 14 is deposited directly onto the fluid-permeable bottom surface (not shown in Figure 1) of the mesh heating element 12 by electrophoretic deposition. Any suitable ceramic may be used to form the transport material 14, and examples of suitable ceramics are discussed below.

[0073] A ceramic transport material 14 is fixedly attached to the bottom surface of the mesh heating element 12 to form a single-piece heater assembly 10. The ceramic transport material 14 is arranged to transport a liquid aerosol-forming substrate (not shown) to the mesh heating element 12. A plurality of gaps or openings 16 are defined between the filaments 13 of the mesh heating element 12. During heating, the vaporized aerosol-forming substrate can be released from the heater assembly 10 through the openings 16 to generate an aerosol.

[0074] Heater assembly 10 further includes a pair of electrical contacts 15 for supplying power to mesh heating element 12. Electrical contacts 15 are bonded directly to the mesh heating element and include a pair of tin pads disposed on opposing sides of the mesh. While the electrical contacts cover a portion of the openings in mesh heating element 12, this is only a small percentage of the total openings in the mesh heating element and does not significantly affect aerosol generation.

[0075] FIG. 2 shows a cross-sectional view through heater assembly 10 taken along line AA in FIG. 1 . Mesh heating element 12 is disposed on a first surface 14a of ceramic transport material 14. An opposing second surface 14b of ceramic transport material 14 is disposed to receive or contact a liquid aerosol-forming substrate. Ceramic transport material 14 includes a plurality of channels 18 for conveying the liquid aerosol-forming substrate to a plurality of openings 16 disposed between filaments 13 of mesh heating element 12. The plurality of channels 18 extend through a thickness T of ceramic transport material 14 between first surface 14a and second surface 14b of ceramic transport material 14. For each opening 16 in mesh heating element 12, ceramic transport material 14 includes a corresponding channel 18 for conveying the liquid aerosol-forming substrate to its respective opening 16. Note that FIG. 2 is not to scale. For clarity, the channels 18, filaments 13, and openings 16 are enlarged and fewer channels 18, filaments 13, and openings 16 are shown than would be present in an actual heater assembly.

[0076] As discussed in more detail below, the ceramic transport material 14 is formed by electrophoretic deposition of ceramic particles onto the mesh heating element 12. When deposited, the ceramic particles are deposited only on the conductive filaments 13 of the mesh heating element 12, not within the spaces of the openings 16, so that the ceramic transport material 14 assumes the same shape and dimensions as the mesh heating element 12. Thus, as the thickness T of the ceramic transport material 14 deposited during the electrophoretic deposition process increases, multiple channels 18 are formed through the thickness T of the ceramic transport material, each channel 18 corresponding to its respective opening 16. Of course, due to manufacturing tolerances in the electrophoretic deposition process, clear channels 18 through the thickness T of the transport material 14 may not be formed for all openings 16 of the heating element 12. However, channels 18 are formed for the majority of the openings 16, i.e., more than 50 percent of the openings 16, and typically the percentage of openings 16 in which channels 18 are formed is much higher, e.g., more than 80 or 90 percent of the openings 16.

[0077] The plurality of channels 18 extend substantially linearly in a direction substantially perpendicular to the first surface 14a of the ceramic transport material. After electrophoretic deposition of the ceramic transport material 14, the heater assembly is typically sintered, which fuses the ceramic particles and reduces the size of any voids between the particles. This helps reduce lateral flow of the liquid aerosol-forming substrate from the channels through the ceramic body and instead maintains the liquid aerosol-forming substrate within the channels 18. Thus, the plurality of channels 18 allows the liquid aerosol-forming substrate to flow unidirectionally from the second surface 14b of the ceramic transport material 14, which receives or is in contact with the liquid aerosol-forming substrate, to the first surface 14a of the ceramic transport material 14, on which the mesh heating element 12 is disposed.

[0078] 2, the cross-sectional dimensions of each of the plurality of channels 18 along the length of the channel are substantially the same as the cross-sectional dimensions of the corresponding openings 16 in the channel of the mesh heating element 12. Depending on the spacing of the filaments 13 in the mesh heating element 12, the openings 16 may have cross-sectional dimensions between 20 microns and 300 microns. In this size range, the plurality of channels 18 act as capillaries or capillary channels, transporting the liquid aerosol-forming substrate to the mesh heating element 12 by capillary action.

[0079] FIG. 3 is a schematic diagram of an exemplary aerosol generation system. The aerosol generation system comprises two main components: a cartridge 100 and a main body or aerosol generation device 200. A connecting end 115 of the cartridge 100 is removably connected to a corresponding connecting end 205 of the aerosol generation device 200. The connecting end 115 of the cartridge 100 and the connecting end 205 of the aerosol generation device 200 each have electrical contacts or connections (not shown) arranged to cooperate to provide electrical connection between the cartridge 100 and the aerosol generation device 200. The aerosol generation device 200 includes a power source in the form of a battery 210 (which in this embodiment is a rechargeable lithium-ion battery) and a control circuit 220. The aerosol generation system is portable and has a size comparable to a conventional cigar or cigarette. A mouthpiece 125 is disposed at the end of the cartridge 100 opposite the connecting end 115.

[0080] The cartridge 100 includes a housing 105 containing the heater assembly 10 of FIGS. 1 and 2 and a liquid storage compartment or portion having a first storage portion 130 and a second storage portion 135. A liquid aerosol-forming substrate is held within the liquid storage compartment. Although not shown in FIG. 1 , the first storage portion 130 of the liquid storage compartment is connected to the second storage portion 135 of the liquid storage compartment such that liquid in the first storage portion 130 can transfer to the second storage portion 135. The heater assembly 10 receives liquid from the second storage portion 135 of the liquid storage compartment. At least a portion of the ceramic transport material of the heater assembly 10 extends into the second storage portion 135 of the liquid storage compartment and contacts the liquid aerosol-forming substrate therein.

[0081] Airflow passages 140, 145 extend through the cartridge 100 from an air inlet 150 formed in the side of the housing 105, past the mesh heating element of the heater assembly 10, and from the heater assembly 10 to a mouthpiece opening 110 formed in the housing 105 at the end of the cartridge 100 opposite the connecting end 115.

[0082] The components of the cartridge 100 are arranged so that the first storage portion 130 of the liquid storage compartment is between the heater assembly 10 and the mouthpiece opening 110, and the second storage portion 135 of the liquid storage compartment is positioned on the side of the heater assembly 10 opposite the mouthpiece opening 110. In other words, the heater assembly 10 is positioned between the two portions 130 and 135 of the liquid storage compartment and receives liquid from the second storage portion 135. The first storage portion 130 of the liquid storage compartment is closer to the mouthpiece opening 110 than the second storage portion 135 of the liquid storage compartment. Airflow passages 140, 145 extend past the mesh heating element of the heater assembly 10 and between the first and second portions 130, 135 of the liquid storage compartment.

[0083] The aerosol generating system is configured to allow a user to inhale or withdraw the cartridge mouthpiece 125, drawing aerosol into their mouth through the mouthpiece opening 110. In operation, when a user inhales on the mouthpiece 125, air is drawn from the air inlet 150, through the airflow passages 140, 145, past the heater assembly 10, and into the mouthpiece opening 110. A control circuit 220 controls the supply of power from the battery 210 to the cartridge 100 when the system is activated, which in turn controls the amount and characteristics of vapor produced by the heater assembly 10. The control circuit 220 may include an airflow sensor (not shown), and may supply power to the heater assembly 10 when the airflow sensor detects a user puff. This type of control arrangement is well established in aerosol generating systems such as inhalers and e-cigarettes. When a user draws on mouthpiece opening 110 of cartridge 100, heater assembly 10 is activated, generating a vapor that is entrained in the airflow passing through airflow passage 140. The vapor cools within the airflow in passage 145, forming an aerosol that is then drawn through mouthpiece opening 110 into the user's mouth.

[0084] In operation, the mouthpiece opening 110 is typically the highest point in the system. The construction of the cartridge 100, and in particular the arrangement of the heater assembly 10 between the first storage portion 130 and the second storage portion 135 of the liquid storage compartment, is advantageous because it utilizes gravity to ensure that liquid substrate is delivered to the heater assembly 10 even when the liquid storage compartment is beginning to empty, yet prevents oversupply of liquid to the heater assembly 10, which may lead to leakage of liquid into the airflow passage 140.

[0085] 4 is a schematic diagram of an apparatus 300 used for electrophoretic deposition of ceramic transport material onto a mesh heating element. The apparatus 300 includes a container 302 that holds a suspension 304 of ceramic particles 306 in a solvent at a low pH. The ceramic particles 306 are electrically charged so that they move under an applied electric field. In this example, the ceramic particles 306 are negatively charged. The ceramic particles 306 are kept well dispersed throughout the solvent by magnetic stirring 308. Additionally, additives (not shown), such as dispersants or stabilizers, are typically added to prevent aggregation or flocculation.

[0086] A conductive stainless steel mesh heating element 310 is immersed in the ceramic suspension 304 and connected to the positive pole of a power supply 312. The mesh heating element forms the working electrode and provides a target substrate on which ceramic particles 306 can be deposited. A counter electrode 314, located on the opposite side of the mesh heating element 310, is also immersed in the ceramic suspension 304 and connected to the negative pole of the power supply 312, with the opposite polarity to that of the mesh heating element 310. Additionally, a reference electrode 316 is inserted into the ceramic suspension 304. The reference electrode 316 has a stable and well-defined potential so that the applied voltage can be precisely controlled, and can be used as a reference for measuring the relative potentials of the mesh heating element 310 and the counter electrode.

[0087] A voltage is applied between mesh heating element 310 and counter electrode 314 by power supply 312 such that negatively charged ceramic particles 306 migrate toward positively charged mesh heating element 310 under the influence of the applied electric field. Ceramic particles 306 impinge on the surface of mesh heating element 310, forming a deposited ceramic layer. As electrophoretic deposition continues, the ceramic layer increases in thickness, forming a transport material with unidirectional channels the size of the openings in mesh heating element 310. After deposition, the resulting ceramic layer is annealed and sintered at high temperatures, as discussed in more detail below.

[0088] 5A is a schematic diagram showing a layer of ceramic particles 306 deposited by electrophoretic deposition onto a portion of a mesh heating element 310. The ceramic particles 306 are deposited only on the filaments 310a of the mesh heating element 310. The layer of ceramic particles 306 does not extend to the sides of the filaments 310a into the gaps or openings 310b, leaving the filaments 310a empty and ultimately forming channels within the ceramic transport material.

[0089] 5B is a schematic diagram showing the ceramic particles 306 of FIG. 5A after a sintering process. As can be seen in FIG. 5B, sintering fuses the ceramic particles 306 together and reduces the voids or spaces between them. This helps reduce the lateral flow of the liquid aerosol-forming substrate from the channels through the ceramic body and instead maintains the liquid aerosol-forming substrate within the channels so that the liquid flows efficiently within the channels to its respective openings 310b of the mesh heating element 310.

[0090] Any suitable ceramic may be used to deposit the transport material. For example, inert ceramics such as Al2O3 and ZrO2 may be used. Alternatively, biocompatible ceramics such as hydroxyapatite may be used. The advantage of both of these types of ceramics is that they reduce the risk of producing toxic compounds or unwanted by-products.

[0091] An example is provided below that illustrates the materials and process conditions required to deposit ceramic onto a mesh heating element by electrophoresis. [Table 1] [Table 2]

Claims

1. 1. A heater assembly for an aerosol generating system, the heater assembly comprising: a fluid-permeable heating element for heating a liquid aerosol-forming substrate to form an aerosol, the fluid-permeable heating element including a plurality of openings that allow fluid to permeate through the heating element; a transport material including a plurality of channels for conveying a liquid aerosol-forming substrate to the plurality of openings of the fluid-permeable heating element; the transport material comprises a ceramic deposited directly onto the fluid-permeable surface of the fluid-permeable heating element; A heater assembly wherein, for more than 50 percent of the openings in the fluid-permeable heating element, the transport material includes a corresponding channel for conveying liquid aerosol-forming substrate to its respective opening.

2. 2. The heater assembly of claim 1, wherein for each of the openings in the fluid-permeable heating element, the transport material includes a corresponding channel for conveying a liquid aerosol-forming substrate to its respective opening.

3. 3. The heater assembly of claim 1, wherein the transport material has a thickness defined between a first surface of the transport material and an opposing second surface of the transport material, the fluid-permeable heating element is disposed on the first surface, the second surface is disposed to receive a liquid aerosol-forming substrate, and the plurality of channels extend through the thickness of the transport material between the first and second surfaces of the transport material.

4. 4. The heater assembly of claim 3, wherein the plurality of channels are arranged to allow unidirectional flow of liquid aerosol-forming substrate between the first and second surfaces of the transport material.

5. 5. The heater assembly of claim 3 or 4, wherein the plurality of channels extend substantially linearly in a direction substantially perpendicular to the first surface of the transport material.

6. The heater assembly of any preceding claim, wherein each of the plurality of openings in the fluid-permeable heating element has a cross-sectional dimension between 20 microns and 300 microns.

7. 7. The heater assembly of claim 1, wherein a cross-sectional dimension of each of the plurality of channels along the length of the channel is substantially the same as a cross-sectional dimension of the opening of the fluid-permeable heating element.

8. 8. The heater assembly of claim 1, further comprising electrical contacts for supplying power to said fluid-permeable heating element, said electrical contacts being directly connected to said fluid-permeable heating element.

9. A heater assembly according to any preceding claim, wherein the fluid-permeable heating element is substantially flat.

10. The heater assembly of any preceding claim, wherein the fluid-permeable heating element comprises a mesh heater including a plurality of intersecting heating filaments.

11. A cartridge for an aerosol generating system, comprising the heater assembly of any one of claims 1 to 10 and a liquid reservoir for holding a liquid aerosol-forming substrate.

12. 1. An aerosol generating system comprising: A cartridge according to claim 11; an aerosol generating device, The aerosol generation system, wherein the cartridge is removably coupled to the aerosol generation device, the aerosol generation device including a power source for the heater assembly.

13. 1. A method of manufacturing a heater assembly for an aerosol generating system, the method comprising: providing a fluid-permeable heating element; providing a transport material for transporting the liquid aerosol-forming substrate to said fluid-permeable heating element; the transport material is provided by depositing a ceramic directly onto the fluid-permeable heating element; A method wherein the transport material is deposited directly onto the fluid-permeable heating element by electrophoretic deposition.

14. 14. The method of claim 13, wherein the transport material is deposited by depositing ceramic particles onto the fluid-permeable heating element, the ceramic particles having an average particle size of 0.05 microns to 0.7 microns.

15. 15. The method of claim 13 or 14, further comprising sintering the heater assembly after the transport material is deposited.

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