Heating element having a thermally conductive filament and a wicking filament

Abstract

A heating element (10) for an aerosol generating system, the heating element (10) including a plurality of first filaments (16) and a plurality of second filaments (18), the plurality of first filaments (16) configured to heat a liquid aerosol-forming substrate, and the plurality of second filaments (18) configured to convey the liquid aerosol-forming substrate and wet at least a portion of the heating element (10) with the liquid aerosol-forming substrate.

Description

[Technical Field]

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

[0002] Handheld electrically operated aerosol generating devices and systems are known that include 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 assembly for heating the aerosol-forming substrate to generate an aerosol. The heater assembly typically includes a heating element in the form of a coil of wire wound around an elongated wick that transports the liquid aerosol-forming substrate from a liquid storage portion to the heater. In use, an electric current is passed through the coil of wire to heat the heater assembly, thereby generating an aerosol from the liquid aerosol-forming substrate. A mouthpiece portion is also included, which a user can puff on to draw the aerosol into their mouth.

[0003] It is generally desirable for an aerosol generating system to be able to produce a consistent aerosol over successive uses of the system and between different aerosol generating systems of the same type. Variations in the quality and quantity of aerosol produced can detract from the user's experience. In particular, it is desirable to reduce the likelihood of a "dry heat" condition occurring, which can result from a heating element being heated in the presence of insufficient liquid aerosol-forming substrate. This situation, also known as "dry puff," can result in overheating and potentially thermal decomposition of the liquid aerosol-forming substrate, which can produce undesirable by-products.

[0004] To generate a consistent aerosol, the heating element needs to be consistently wetted with the liquid aerosol-forming substrate by the user for each puff on the aerosol-generating system. However, with conventional wick and coil heater assemblies, achieving consistent wetting can be difficult due to variations between different wicks. Wetting of the heating element also depends on the orientation of the aerosol-generating system and the amount of aerosol-forming substrate remaining in the liquid reservoir.

[0005] Furthermore, the ability to accurately and consistently manufacture heater assemblies is important in maintaining consistent performance among different aerosol generating systems of the same type. For example, in heater assemblies having heater coils, the heater coils must be manufactured to the same dimensions to reduce variability between products. In known systems, manufacturing a heater assembly can require numerous manufacturing steps, some of which may need to be performed, for example, manually. Manual assembly increases the likelihood of variability among different heater assemblies and also increases the cost and complexity of the manufacturing process.

[0006] It would be desirable to provide a heating element for an aerosol generating system that allows for more consistent wetting of the heating element. It would also be desirable to provide a heating element that can be manufactured more easily and consistently. Summary of the Invention

[0007] According to one embodiment of the present disclosure, there is provided a heating element for an aerosol generating system. The heating element may include a first filament. The first filament may be configured to heat a liquid aerosol-forming substrate. The heating element may include a second filament. The second filament may be configured to transport the liquid aerosol-forming substrate so as to wet at least a portion of the heating element with the liquid aerosol-forming substrate.

[0008] According to one embodiment of the present disclosure, there is provided a heating element for an aerosol generating system. The heating element may include a plurality of first filaments. The plurality of first filaments may be configured to heat a liquid aerosol-forming substrate. The heating element may include a plurality of second filaments. The plurality of second filaments may be configured to convey the liquid aerosol-forming substrate so as to wet at least a portion of the heating element with the liquid aerosol-forming substrate.

[0009] According to one embodiment of the present disclosure, a heating element of an aerosol generation system is provided, the heating element comprising a plurality of first filaments and a plurality of second filaments, the plurality of first filaments being configured to heat a liquid aerosol-forming substrate, and the plurality of second filaments being configured to convey the liquid aerosol-forming substrate to wet at least a portion of the heating element with the liquid aerosol-forming substrate.

[0010] Thus, the heating element is a hybrid heating element including two different types of filaments: a plurality of first filaments configured to heat the liquid aerosol-forming substrate and a plurality of second filaments configured to transport the liquid aerosol-forming substrate. Advantageously, the plurality of second filaments transport the liquid aerosol-forming substrate along the first filaments. Thus, the second filaments act as a wick within the body of the heating element, increasing the area of ​​the first filaments in contact with the liquid aerosol-forming substrate and thereby helping to wet the heating element with the liquid aerosol-forming substrate. The second filaments distribute the aerosol-forming substrate throughout the heating element, helping to achieve improved wetting of the first filaments and an increased evaporation area. The heating element of the present disclosure helps ensure that a consistent area of ​​the heating element is wetted during each use of the aerosol generating system, thus helping to produce a consistent amount of aerosol across successive uses and between different aerosol generating systems of the same type. The second filaments may also help to improve the integration of the heating element into porous materials or other forms of transport materials used to transport the liquid aerosol-forming substrate to the heating element. Additionally, the second filament serves to increase the contact area between the heating element and the transport material.

[0011] The heating element may be a fluid-permeable heating element. The first filament may be a heating filament. The second filament may be a wicking filament.

[0012] The plurality of first filaments may be formed from an electrically conductive material that allows the heating element to be heated resistively or inductively.

[0013] The plurality of first filaments may comprise electrically resistive filaments.

[0014] The plurality of first filaments may be formed from a metallic material. The first filaments may be formed from any suitable 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. Preferably, the plurality of first filaments are made of stainless steel, more preferably a 300 series stainless steel such as AISI 304, 312, 316, 304L, or 316L, or a 400 series stainless steel such as AISI 410, 420, or 430.

[0015] Furthermore, the plurality of first filaments may comprise a combination of the above materials. A combination of materials may be used to improve control of the resistance of the 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 resistance allows for more efficient use of battery energy.

[0016] The plurality of first filaments may include wires. The plurality of first filaments may include conductive yarns.

[0017] The plurality of second filaments may be hydrophilic. The plurality of second filaments may be made of a hydrophilic material. Alternatively, the plurality of second filaments may be made of another material and coated with a hydrophilic material. A hydrophilic material has an affinity for water and is more easily wetted by an aqueous solution than a non-hydrophilic material. The hydrophilic second filaments help transport the liquid aerosol-forming substrate within the heating element and wet the heating element.

[0018] The plurality of second filaments may be formed from a metallic material. The plurality of second filaments may be formed from a non-metallic material. The plurality of second filaments may be made from or coated with any suitable hydrophilic material. Suitable materials include, but are not limited to, polymers such as polyester, cotton made from wood and agricultural products, cellulose fibers such as rayon or other recycled fibers, glass, ceramics, and composites made from combinations of the foregoing. In one example, the second filaments may be made from a ductile material such as rayon, as opposed to a more brittle material such as glass, because ductile materials are more flexible and more amenable to mass production techniques.

[0019] The plurality of second filaments may be fibrous. Each second filament may include one or more fibers. Each second filament may include yarns. The plurality of second filaments may include glass fiber yarns.

[0020] The second filaments may be formed from a non-hydrophilic or hydrophobic material and may be surface-treated to increase the hydrophilicity of the material. Any suitable surface treatment that increases the surface energy of the material may be used, including, but not limited to, plasma treatment and sandblasting. In one example, the second filaments may be made from polyetheretherketone (PEEK) that has been surface-treated to make it hydrophilic and improve its wettability. An advantage of using PEEK filaments is that they can be used to incorporate a heating element into a heater mount made of PEEK or another suitable polymer. By placing the heating element on the PEEK heater mount and heating both to at least the glass transition temperature of the PEEK, the heating element filament bonds to the PEEK heater mount, holding the heating element on the heater mount.

[0021] The plurality of first filaments may comprise inductive heating filaments such that the plurality of first filaments are inductively heated when the heating element is placed in a changing magnetic field, the plurality of first filaments preferably being aligned with or substantially parallel to the direction of the changing magnetic field.

[0022] The plurality of first filaments may be formed from a susceptor material. As used herein, the term "susceptor" refers to a material capable of converting magnetic energy into heat. When the susceptor is placed in a changing magnetic field, such as a changing magnetic field generated by an inductor coil, the susceptor heats up. The heating of the susceptor can be the result of at least one of hysteresis losses and eddy currents induced within the susceptor, which depend on the electrical and magnetic properties of the susceptor material.

[0023] The susceptor material may be or include any material that can be inductively heated to a temperature sufficient to release volatile compounds from the aerosol-forming substrate. Preferred susceptor materials may be heated to temperatures exceeding 100, 150, 200, or 250 degrees Celsius. A preferred susceptor material may be an electrically conductive material. Suitable materials for the susceptor assembly include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Preferred susceptor materials include metal or carbon. Some preferred susceptors may be ferromagnetic materials, such as ferritic iron, ferromagnetic alloys such as ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrites. The susceptor may include at least 5 percent, at least 20 percent, at least 50 percent, or at least 90 percent ferromagnetic or paramagnetic material. Preferred susceptor materials may include or be formed from, for example, 400 series stainless steel, such as AISI 410, 420, or 430. Different materials dissipate different amounts of energy when placed in electromagnetic fields having similar values ​​of frequency and field strength. Thus, susceptor material parameters, such as material type, size, etc., may be modified to provide a desired power dissipation within a known electromagnetic field.

[0024] In one example, the plurality of first filaments may be formed from a magnetic metallic material. The plurality of second filaments may be formed from a non-metallic hydrophilic material. The heating element may further include a plurality of third filaments formed from a non-magnetic metallic material. Advantageously, providing a plurality of third filaments formed from a non-magnetic material creates regions of the heating element that are not significantly inductively heated when placed in a changing magnetic field, because the non-magnetic material does not generate as much heat as the magnetic material. This is because the non-magnetic material heats due to eddy currents within the material, particularly in regions of the material near its surface (the so-called "skin" effect), while the magnetic material heats due to eddy currents within the skin and hysteresis losses in the magnetic material. The additional hysteresis losses in the magnetic material help generate more heat. For example, when a stainless steel filament is placed in a changing magnetic field having a frequency of approximately 6.78 megahertz and a field strength of approximately 1 to 10 amperes per meter, the magnetic stainless steel generates approximately 10 times more heat than the non-magnetic stainless steel. The plurality of third filaments may have a structural function. For example, the multiple third filaments can form part of a heating element that connects to or contacts a heater mount or mesh holder. Such an arrangement reduces the amount of heat from the heating element that is dissipated into the heater mount and also reduces the possibility of thermal damage to the heater mount. The frequency and field strength of the magnetic field can be adapted depending on the materials used.

[0025] In another embodiment, the plurality of first filaments may be formed from a magnetic metallic material. The plurality of second filaments may be formed from a magnetic metallic material. The heating element may further include a plurality of third filaments formed from a non-magnetic metallic material. The plurality of third filaments may extend in the same direction as the plurality of second filaments. The plurality of third filaments may be arranged in two sections or groups on opposite sides of the heating element. The plurality of third filaments may form part of a heating element that connects to or contacts a heater mount or mesh holder. The plurality of second heating elements may form part of a heating element that is disposed within or across openings or channels in a heater mount or mesh holder. The plurality of second and third filaments may be more closely spaced or more densely packed than the plurality of first filaments. Each of the plurality of second filaments may contact an adjacent one of the plurality of second filaments at one or more points along its length. Each of the plurality of third filaments may contact an adjacent one of the plurality of third filaments at one or more points along its length.

[0026] The plurality of first filaments may be made from 400 series stainless steel, such as AISI 410, 420, or 430. 400 series stainless steels are generally magnetic. The plurality of third filaments may be made from 300 series stainless steel, such as AISI 304, 312, 316, 304L, or 316L. 300 series stainless steels are generally non-magnetic.

[0027] Each second filament may extend along a respective one of the first filaments and serve to transport or draw the liquid aerosol-forming substrate along the first filament. Each second filament may extend into the space between two adjacent first filaments and serve to transport or draw the liquid aerosol-forming substrate into the space between adjacent first filaments and along the first filament. Each second filament may substantially fill the space between two adjacent first filaments. The second filaments may transport the liquid aerosol-forming substrate by capillary action or wicking. The second filaments may transport the liquid aerosol-forming substrate by capillary action or wicking within the body of the filament itself, for example, between the fibers of the second filament. Alternatively, or additionally, the space between the first filament and the second filament may act as a capillary channel to transport the liquid aerosol-forming substrate.

[0028] The plurality of first filaments and the plurality of second filaments may extend in the same direction. The plurality of first filaments and the plurality of second filaments may be crossed. By "crossed," we mean that the plurality of first filaments and the plurality of second filaments are arranged in an alternating arrangement of the first and second filaments. The plurality of first filaments and the plurality of second filaments may be arranged parallel to one another. This arrangement helps to transport or draw the liquid aerosol-forming substrate into the spaces between the first filaments and along the first filaments, which in turn helps to wet the heating element. As a result, the area of ​​the first filaments in contact with the liquid aerosol-forming substrate is increased, which helps improve the vaporization of the liquid aerosol-forming substrate.

[0029] The heating element may include an array of filaments or fibers of filaments. In one example, a plurality of first filaments may be arranged to form a mesh. As used herein, the term "mesh" refers to a network of filaments having a plurality of gaps or openings therein. The mesh may include a portion of the plurality of first filaments arranged in a first direction and another portion of the plurality of first filaments arranged in a second direction. The second direction may be transverse to the first direction. The second direction may be substantially perpendicular to the first direction. Other filaments of the plurality of second filaments may be arranged between at least some of the first filaments. Other filaments of the plurality of second filaments may be arranged in at least either the first direction or the second direction. In this arrangement, the second filaments serve to transport or draw the liquid aerosol-forming substrate into the gaps or openings in the mesh of the first filaments and along the first filaments, which in turn serves to wet the heating element.

[0030] The plurality of second filaments may be arranged in only one of the first and second directions. The plurality of second filaments may be arranged in both the first and second directions. The plurality of second filaments may be arranged between the plurality of first filaments such that each space between adjacent ones of the plurality of first filaments contains a second filament.

[0031] In another example, the heating element may be arranged to form a mesh. A plurality of first filaments may be arranged in a first direction. A plurality of second filaments may be arranged in a second direction. The second direction may be transverse to the first direction. The second direction may be substantially perpendicular to the first direction. This arrangement helps to transport or draw the liquid aerosol-forming substrate towards the heating element, which helps to wet the heating element.

[0032] The mesh may be woven or non-woven. The mesh may be formed using different types of weave or lattice structures.

[0033] The heating element may include a woven mesh. The weaving of the first filaments and the second filaments helps to improve the strength of the mesh. Furthermore, the woven mesh causes at least one of the first filaments and the second filaments to have an undulating configuration as it weaves through the other filaments. This undulating configuration can help incorporate the heating element into the transport material, as the undulating portions of the filaments can be embedded in the transport material.

[0034] When the heating element comprises a woven mesh, the first direction of the filaments may be the warp direction and the second direction of the filaments may be the weft direction.

[0035] In embodiments in which the filaments of the heating element are made from the same material, the filaments arranged in the weft direction may have a diameter or thickness equal to or less than the diameter or thickness of the filaments arranged in the warp direction. This arrangement makes the weft filaments at least as flexible and deformable as the warp filaments, and preferably more flexible and deformable than the warp filaments. This aids in weaving the weft filaments around the warp filaments.

[0036] In another embodiment where the heating element includes both metallic and non-metallic filaments, the metallic filaments may be the warp filaments and the non-metallic filaments may be the weft filaments. In this case, the non-metallic filaments may be selected to be more flexible and deformable than the metallic filaments. This aids in weaving the weft filaments around the warp filaments.

[0037] The mesh heating element may include a plurality of first filaments formed from a magnetic metallic material. The mesh heating element may include a plurality of second filaments formed from a magnetic metallic material. The mesh heating element may further include a plurality of third filaments formed from a non-magnetic metallic material so that the plurality of third filaments are not inductively heated to a significant extent when placed in a changing magnetic field. The plurality of third filaments may be woven in the same direction as the plurality of second filaments. The plurality of third filaments may form at least a portion of the heating element that connects to or contacts the heater mount or mesh holder. This arrangement reduces heat loss from the heater mount. The plurality of second heating elements may be included in a portion of the heating element that is disposed within or across an opening or channel in the heater mount or mesh holder. The plurality of second and third filaments may be more closely spaced or more densely packed than the plurality of first filaments. Each of the plurality of second filaments may contact or be in contacting engagement with an adjacent one of the plurality of second filaments at one or more points along its length. Each of the plurality of third filaments may be in contact or contacting engagement with an adjacent one of the plurality of third filaments at one or more points along its length. By arranging the plurality of second and third filaments in contact with each other, no spaces will be visible between the filaments when viewed at an angle perpendicular to the plane of the mesh. Such a dense mesh pattern aids in transporting the liquid aerosol-forming substrate within the mesh.

[0038] The plurality of first filaments may define gaps or openings between the filaments, and the gaps may have a width of 10 micrometers to 300 micrometers, preferably 20 micrometers to 100 micrometers, preferably 50 micrometers to 100 micrometers, and more preferably about 70 micrometers.

[0039] The plurality of first filaments may form a mesh having a size of 60 to 240 filaments per centimeter (±10 percent). Preferably, the mesh density is 100 to 140 filaments per centimeter (±10 percent). More preferably, the mesh density is approximately 115 filaments per centimeter.

[0040] The open area of ​​the mesh, which is the ratio of the area of ​​the gaps and openings to the total area of ​​the mesh, may be between 40 percent and 90 percent, preferably between 85 percent and 80 percent, and more preferably about 82 percent.

[0041] Each of the first filaments or wires of the heating element may have an average diameter of at least 10, 16, 17, 25, or 30 microns. Each of the first filaments or wires may have an average diameter of less than 100, 90, 80, 70, 60, 50, 40, or 30 microns. Each of the first filaments or wires may have an average diameter of 10 to 80 microns, preferably 10 to 50 microns, more preferably 15 to 30 microns, for example, about 25 microns.

[0042] The plurality of second filaments may have a modified or flattened cross-sectional profile. Each of the second filaments may have a width approximately equal to the opening size of the mesh so that the second filament occupies substantially all, or at least 80%, of the space between adjacent first filaments. Each of the second filaments may have a thickness approximately equal to the diameter or thickness of the first filament.

[0043] The second filament or fiber may have an average diameter that is 80% to 120% of the average diameter of the first filament or wire. The first filament and the second filament may have substantially the same average diameter.

[0044] Each of the second filaments or fibers may have an average diameter of at least 10, 16, 17, 25, or 30 microns. Each of the second filaments or fibers may have an average diameter of less than 100, 90, 80, 70, 60, 50, 40, or 30 microns. Each of the second filaments or fibers may have an average diameter of 10 to 80 microns, preferably 10 to 50 microns, more preferably 15 to 30 microns, e.g., about 25 microns.

[0045] The heating element may be substantially flat. The heating element may be substantially planar. Advantageously, a flat or planar heating element is easier to handle during manufacturing and provides a robust heater assembly structure.

[0046] As used herein, the term "flat" refers to a substantially two-dimensional topological manifold. A flat heating element therefore extends in two dimensions, along a surface, much more than in the third dimension. In particular, the dimensions of a planar heating element in two dimensions within its surface may be at least 2, 5, or 10 times greater than its dimensions in the third dimension perpendicular to the surface. An example of a substantially flat heating element is a structure with two substantially parallel surfaces, where the distance between these two imaginary surfaces is significantly less than the extent within the surface. In some embodiments, a substantially flat heating element may engage the surface of a transport material, such as a porous ceramic body.

[0047] In other embodiments, the heating element may be curved along one or more dimensions, for example forming a dome or bridge shape.

[0048] The area of ​​the heating element may be small, for example, 50 square millimeters or less, preferably 25 square millimeters or less, and more preferably about 15 square millimeters. The size is selected to allow the heating element to be incorporated into a handheld system. Sizing the heating element to 50 square millimeters or less reduces the total amount of power required to heat the heating element while ensuring sufficient contact of the heating element with the liquid aerosol-forming substrate. The heating element may be, for example, rectangular and may have a length of 2 to 10 millimeters and a width of 2 to 10 millimeters. Preferably, the heating element has dimensions of approximately 5 millimeters by 3 millimeters.

[0049] The electrical resistance 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 heating element is between 0.6 and 0.8 ohms, and most preferably about 0.68 ohms. The electrical resistance of the heating element is preferably at least one order of magnitude greater, and more preferably at least two orders of magnitude greater, than the electrical resistance of any conductive contact points. This ensures that heat generated by passing current through the heating element is localized to the heating element. 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. This allows the heating element to quickly heat the conductive filament to the desired temperature.

[0050] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol-generating system. The heater assembly may include a heating element according to any of the embodiments described above. The heater assembly may also include a transport material for transporting the liquid aerosol-forming substrate to the heating element.

[0051] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generation system, the heater assembly including a heating element according to any of the above-described embodiments, and a transport material for transporting a liquid aerosol-forming substrate to the heating element.

[0052] The transport material may include a capillary material. As used herein, "capillary material" refers to a material that transports liquid from one end of the material to another by capillary action. The capillary material may have a fibrous or porous structure. Preferably, the capillary material includes a bundle of capillaries. For example, the capillary material may include multiple fibers or threads or other fine tubes. The fibers or threads may be generally aligned to transport the liquid aerosol-forming substrate in a specific direction, such as toward a heating element. Alternatively, the capillary material may include a spongy or foam-like material. The structure of the capillary material forms multiple small holes or tubes through which the liquid aerosol-forming substrate can be transported by capillary action. The capillary material may extend into gaps or openings in the heater. The heater may draw the liquid aerosol-forming substrate into the gaps or openings by capillary action.

[0053] The transport material may comprise any suitable material or combination of materials. Examples of suitable materials include sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, expanded metal or plastic materials, fibrous materials made of, for example, spun or extruded fibers, such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene, or polypropylene fibers, nylon fibers, or ceramics. The transport material may have any suitable capillary and porosity for use with different liquid properties. The liquid aerosol-forming substrate has physical properties, including, but not limited to, viscosity, surface tension, density, thermal conductivity, boiling point, and vapor pressure, that allow the liquid aerosol-forming substrate to move through the transport material by capillary action. The transport material may also comprise a porous ceramic body.

[0054] Some portions of the second filaments may be integrated into the transport material. Some portions of the second filaments may have portions extending away from the plane or body of the heating element, and these portions may be integrated into the transport material. For example, some of the second filaments may have undulating shapes or loops, or loose ends that may be incorporated or embedded in the transport material. The advantage of incorporating portions of the second filaments into the transport material is that it helps improve contact between the heating element and the transport material and transport of the liquid aerosol-forming substrate to the heating element.

[0055] The heating element may be fixedly attached to the transport material. The heating element may be welded or soldered to the transport material. The heating element may be attached to the transport material by a bond site formed between a portion of the second filament and the transport material. The bond site may be formed by thermal fusion. Alternatively, the transport material may be deposited directly onto the heating element by some form of chemical, vapor, or electrodeposition process.

[0056] The heater assembly may further include at least two electrical contacts for supplying power to the heating element. Each of the electrical contacts may be connected to at least one of the plurality of first filaments. Each of the electrical contacts may be connected to a plurality of first filaments. Each of the electrical contacts may be connected to substantially all of the first filaments. The electrical contacts may be connected directly to one or more of the first filaments. The electrical contacts may be connected to one or more of the first filaments by solder.

[0057] When the heater assembly has a heating element in which electrical contacts are directly connected to one or more of the first filaments, the plurality of first filaments may be arranged in the weft direction. As discussed above, the plurality of first filaments are heating filaments, that is, filaments through which current flows. By arranging the plurality of first filaments as weft filaments, the undulating nature of the weft filaments around the warp filaments helps to connect the first filaments directly with the electrical contacts. This helps to improve the electrical connection between the heating element and the electrical contacts and reduce heat loss that may be caused by an indirect connection.

[0058] Each of the electrical contacts may be connected to at least one of the plurality of third filaments. The electrical contacts may be connected to areas of the heating element that do not heat up to a significant extent during use, thereby reducing thermal stress on the electrical contacts.

[0059] The electrical contacts may be located on opposite ends or sides of the heating element. The electrical contact portions may include two conductive contact pads. The conductive contact pads may be located at end regions of the heating element. Preferably, at least two conductive contact pads may be located at the tip of the heating element. The conductive contact pads may include tin patches. Alternatively, the conductive contact pads may be integral with the fluid-permeable heating element.

[0060] According to one embodiment of the present disclosure, there is provided a cartridge for an aerosol generating system. The cartridge may include a heater assembly according to any of the above-described embodiments. The cartridge may include a liquid reservoir for holding a liquid aerosol-forming substrate.

[0061] According to one embodiment of the present disclosure, there is provided a cartridge for an aerosol generation system, the cartridge including a heater assembly according to any of the embodiments described above and a liquid reservoir for holding a liquid aerosol-forming substrate.

[0062] 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.

[0063] 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 in 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. Having the first storage portion of the liquid storage compartment above the second storage portion of the liquid storage compartment ensures that liquid is delivered from the first storage portion of the liquid storage compartment to the second storage portion of the liquid storage compartment of the storage compartment and then delivered to the heater assembly under the influence of gravity during use.

[0064] 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.

[0065] 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.

[0066] The cartridge may include a retaining material for retaining the liquid aerosol-forming substrate. The retaining material may be in a first storage portion of the liquid storage compartment, a 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.

[0067] 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.

[0068] 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 liquid aerosol-forming substrate containing nicotine 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 upon 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.

[0069] The liquid aerosol-forming substrate may include one or more aerosol formers. The aerosol former is any suitable 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 include water, solvents, ethanol, plant extracts, and natural or artificial flavors.

[0070] 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%, for example about 2%.

[0071] 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.

[0072] According to one embodiment of the present disclosure, there is provided an aerosol generation system. The aerosol generation system may include a cartridge according to any of the above-described embodiments. The aerosol generation system may include an aerosol generation device. The cartridge may be configured to be removably connectable to the aerosol generation device. The aerosol generation device may include a power source for providing power to the heating element.

[0073] According to one embodiment of the present disclosure, there is provided an aerosol generation system including a cartridge according to any of the above-described embodiments and an aerosol generation device, wherein the cartridge is configured to be removably coupled to the aerosol generation device, and the aerosol generation device includes a power source for supplying power to the heating element.

[0074] The aerosol generating device may further include a control circuit configured to control the supply of power to the heater assembly.

[0075] The aerosol generating device may be configured to inductively heat the heating element. The aerosol generating device may comprise an inductor for inductively heating the heating element. The inductor may be an induction coil.

[0076] The control circuit may comprise a microprocessor. The microcontroller 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.

[0077] 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.

[0078] 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), and polyethylene. Preferably, the material is lightweight and not brittle.

[0079] 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 outer diameter of the aerosol generation system may be about 5 mm to about 30 mm.

[0080] According to one embodiment of the present disclosure, there is provided a method of manufacturing a heating element for an aerosol generating system. The method may include providing a plurality of first filaments. The plurality of first filaments may be configured to heat a liquid aerosol-forming substrate. The method may include providing a plurality of second filaments. The plurality of second filaments may be configured to carry the liquid aerosol-forming substrate along at least a portion of their length to distribute the liquid aerosol-forming substrate across at least a portion of the heating element.

[0081] According to one embodiment of the present disclosure, there is provided a method of manufacturing a heating element for an aerosol-generating system, the method comprising: providing a plurality of first filaments configured to heat a liquid aerosol-forming substrate; and providing a plurality of second filaments configured to convey the liquid aerosol-forming substrate along at least a portion of its length to distribute the liquid aerosol-forming substrate across at least a portion of the heating element.

[0082] Advantageously, multiple second filaments are arranged to transport the liquid aerosol-forming substrate to and along the first filaments. Thus, the second filaments, while remaining within the body of the heating element and acting as a wick, help wet the heating element with the liquid aerosol-forming substrate by increasing the area of ​​the first filaments in contact with the liquid aerosol-forming substrate. The second filaments distribute the aerosol-forming substrate throughout the heating element, helping to achieve improved wetting of the first filaments and increased evaporation area. The heating elements of the present disclosure help ensure that a consistent area of ​​the heating element is wetted during each use of the aerosol generating system, thus helping to produce a consistent amount of aerosol over successive uses and between different aerosol generating systems of the same type. The second filaments can also help improve the integration of the heating element into porous materials or other forms of transport materials used to transport the liquid aerosol-forming substrate to the heating element. Furthermore, the second filaments help increase the contact area between the heating element and the transport material.

[0083] Advantageously, incorporating multiple secondary filaments into the heating element can improve the consistency of aerosol delivery and reduce product-to-product variation. The heating element can also be simply and consistently manufactured using mass production techniques.

[0084] In some embodiments, the heating element may comprise a mesh. The method may include alternating first and second filaments in a first direction and disposing the first filaments in a second direction. Alternatively, the method may include alternating first and second filaments in a second direction.

[0085] In various embodiments, the heating element may comprise a mesh. The method may include arranging a plurality of first filaments in a first direction and a plurality of second filaments in a second direction.

[0086] Features described with respect to one of the above embodiments may equally be applied to other embodiments of the present disclosure.

[0087] The present invention is defined in the claims. However, the following non-limiting examples are provided in a non-exhaustive manner. Any one or more features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0088] Example 1: A heating element for an aerosol-generating system, the heating element comprising: a first filament configured to heat a liquid aerosol-forming substrate; and a second filament configured to convey the liquid aerosol-forming substrate and wet at least a portion of the heating element with the liquid aerosol-forming substrate. Example 2: 10. A heating element according to example 1, comprising a plurality of first filaments and a plurality of second filaments. Example 3: 3. The heating element according to example 1 or 2, wherein the first filament is formed from an electrically conductive material. Example 4: The heating element according to any one of Examples 1 to 3, wherein the first filament is formed from a metal material. Example 5: The heating element according to any one of Examples 1 to 4, wherein the second filament is hydrophilic. Example 6: The heating element according to any one of Examples 1 to 5, wherein the second filament is formed from a non-metallic material. Example 7: The heating element according to example 2, wherein the plurality of first filaments are formed from a magnetic metallic material, the plurality of second filaments are formed from a non-metallic hydrophilic material, and the heating element further comprises a plurality of third filaments formed from a non-magnetic metallic material. Example 8: A heating element according to any one of Examples 2 to 7, wherein the plurality of first filaments and the plurality of second filaments extend in the same direction and intersect. Example 9: A heating element according to any of Examples 2-7, wherein a plurality of first filaments are arranged to form a mesh in which a portion of the plurality of first filaments are arranged in a first direction and another portion of the plurality of first filaments are arranged in a second direction that is transverse to the first direction, and wherein distinct ones of the plurality of second filaments are oriented in at least one of the first direction or the second direction and are disposed between at least a portion of the first filaments. Example 10: The heating element according to Example 9, wherein the plurality of second filaments can be arranged in both the first and second directions. Example 11: The heating element according to example 9 or 10, wherein a plurality of second filaments can be disposed between the plurality of first filaments such that each space between adjacent ones of the plurality of first filaments contains a second filament. Example 12: A heating element according to any of Examples 2-7, wherein the heating element is arranged to form a mesh, a plurality of first filaments arranged in a first direction, and a plurality of second filaments arranged in a second direction, the second direction being transverse to the first direction. Example 13: The heating element of any of Examples 9-12, wherein the heating element comprises a woven mesh. Example 14: The heating element according to any one of Examples 1 to 13, wherein each of the first filaments has an average diameter of 10 to 80 microns, preferably 10 to 50 microns, and more preferably about 25 microns. Example 15: The heating element according to any one of Examples 1 to 14, wherein each of the second filaments has an average diameter of 10 to 80 microns, preferably 10 to 50 microns, and more preferably about 25 microns. Example 16: The heating element of any one of Examples 1 to 15, wherein the heating element is substantially flat. Example 17: A heater assembly for an aerosol-generating system, comprising a heating element according to any one of Examples 1 to 16 and a transport material for transporting a liquid aerosol-forming substrate to the heating element. Example 18: 18. The heater assembly of example 17, wherein a portion of the plurality of second filaments are embedded in the transport material. Example 19: 19. The heater assembly according to example 17 or 18, further comprising at least two electrical contacts for supplying power to the heating element, each of the electrical contacts connected to at least one of the plurality of first filaments. Example 20: A cartridge for an aerosol generating system, comprising the heater assembly according to any one of Examples 17 to 19 and a liquid storage portion for holding a liquid aerosol-forming substrate. Example 21: An aerosol generation system comprising the cartridge according to Example 20 and an aerosol generating device, wherein the cartridge is configured to be removably coupled to the aerosol generating device, and the aerosol generating device comprises a power source for supplying power to the heating element. Example 22: A method of manufacturing a heating element for an aerosol generating system, the method comprising: providing a plurality of first filaments configured to heat a liquid aerosol-forming substrate; and providing a plurality of second filaments configured to transport the liquid aerosol-forming substrate along at least a portion of its length to distribute the liquid aerosol-forming substrate across at least a portion of the heating element. Example 23: 23. The method of example 22, wherein the heating element comprises a mesh, and the method further comprises alternating the first filaments and the second filaments in a first direction and disposing the first filaments in a second direction. Example 24: 24. The method according to example 22 or 23, further comprising alternating the first filaments and the second filaments in a second direction. Example 25: 23. The method of example 22, wherein the heating element comprises a mesh, and the method comprises arranging a plurality of first filaments in a first direction and a plurality of second filaments in a second direction.

[0089] The embodiments will now be further described with reference to the figures. [Brief explanation of the drawings]

[0090] [Figure 1] FIG. 1 is a schematic plan view of a heating element according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic plan view of a heating element according to another embodiment of the present disclosure. [Figure 3A] FIG. 3A is a schematic diagram of one arrangement of filaments of the heating element of FIG. [Figure 3B] FIG. 3B is a schematic diagram of an alternative arrangement of filaments in the heating element of FIG. [Figure 4] FIG. 4 is a perspective view of a heater assembly according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a plan view of a heater assembly according to another embodiment of the present disclosure. [Figure 6A] FIG. 6A is an enlarged cross-sectional view through a portion of a heater assembly according to an embodiment of the present disclosure. [Figure 6B] FIG. 6B is an enlarged cross-sectional view through a portion of a heater assembly according to another embodiment of the present disclosure. [Figure 7] FIG. 7 is a schematic diagram of an exemplary aerosol generation system including a cartridge and an aerosol generation device according to one embodiment of the present disclosure. [Figure 8A] FIG. 8A is a schematic diagram of the apparatus used to measure the wicking performance of a heating element. [Figure 8B] FIG. 8B is a graph showing the absorption of liquid aerosol-forming substrate versus time for three different heating element samples. DETAILED DESCRIPTION OF THE INVENTION

[0091] Referring to FIG. 1 , a schematic plan view of a heating element 1 is shown. The heating element 1 is a hybrid heating element including a plurality of first filaments 2 configured to heat a liquid aerosol-forming substrate (not shown) and a plurality of second filaments 4 configured to carry the liquid aerosol-forming substrate and wet at least a portion of the heating element 1 with the liquid aerosol-forming substrate. The plurality of first filaments 2 and the plurality of second filaments 4 extend in the same direction and are interdigitated. In other words, each second filament 4 is disposed between adjacent ones of the plurality of first filaments 2. The plurality of first filaments 2 and the plurality of second filaments 4 are held in place by attaching them to an underlying substrate or transport material (not shown).

[0092] The plurality of first filaments 2 are electrically conductive and made from stainless steel wire. The plurality of second filaments 4 are made from hydrophilic glass fiber yarn. The liquid aerosol-forming substrate is transported or drawn along the length of the plurality of second filaments 4 by capillary action between the fibers of the glass fiber yarn. This, in turn, serves to draw or transport the liquid aerosol-forming substrate along the plurality of first filaments 2. Furthermore, the spaces 6 between the first filaments 2 and the second filaments 4 act as capillary channels that serve to transport and draw the liquid aerosol-forming substrate along the plurality of first filaments 2. Thus, the plurality of second filaments 4 serve to consistently wet the heating element 1 by distributing the liquid aerosol-forming substrate within or on the heating element 1.

[0093] In use, the plurality of first filaments 2 of the heating element 1 may be inductively or resistively heated. The heat generated by the plurality of first filaments 2 vaporizes the liquid aerosol-forming substrate, which is emitted from the heating element 1 in the space 6 between the first filaments 2 and the second filaments 4. The glass fiber yarn of the plurality of second filaments 4 can withstand the temperature of the plurality of first filaments 2 during heating.

[0094] FIG. 2 shows a schematic plan view of another exemplary heating element 10. The heating element 10 includes a woven mesh 12 including a plurality of first filaments and a plurality of second filaments with gaps or openings 14 therein. FIGS. 3A and 3B illustrate different arrangements of the plurality of first and second filaments of the heating element 10. Each of FIGS. 3A and 3B shows only an enlarged portion of the heating element 10 for clarity. Similar to the heating element 1 of FIG. 1, the plurality of first filaments are made of conductive stainless steel wire and are configured to heat a liquid aerosol-forming substrate (not shown). The plurality of second filaments 14b are made of hydrophilic glass fiber yarn and are configured to convey the liquid aerosol-forming substrate and wet at least a portion of the heating element 1 with the liquid aerosol-forming substrate.

[0095] 3A, the plurality of first filaments 16a, 16b, i.e., heating filaments, are arranged in a mesh configuration. Half 16a of the plurality of first filaments are arranged in a first direction of the woven mesh, and the remaining half 16b of the plurality of first filaments are arranged in a second direction of the woven mesh that is substantially perpendicular to the first direction. The opening 14 is disposed between and surrounded by the plurality of first filaments 16a, 16b.

[0096] In the arrangement of FIG. 3A, the plurality of second filaments 18a, 18b, i.e., wicking filaments, are arranged between the plurality of first filaments 16a, 16b in both the first and second directions, such that each space between adjacent ones of the plurality of first filaments 16a, 16b contains a second filament 18a, 18b. In other words, the woven mesh heating element of FIG. 3A contains alternating first filaments 16a and second filaments 18a in the first direction and alternating first filaments 16b and second filaments 18b in the second direction. The first and second directions are substantially perpendicular to each other. The plurality of second filaments 18a, 18b intersect within the openings 14 between the plurality of first filaments 16a, 16b, occupying at least a portion of each opening 14 area. In this arrangement, the plurality of second filaments 18a, 18b serve to convey or draw the liquid aerosol-forming substrate between and along the plurality of first filaments 16a, 16b and into the spaces or openings 14, which in turn serve to wet the heating element 10.

[0097] 3B, the heating element 10 is arranged in a mesh configuration. The plurality of first filaments 16, i.e., heating filaments, are arranged in a first direction, and the plurality of second filaments 18, i.e., wicking filaments, are arranged in a second direction. The second direction is substantially perpendicular to the first direction. In this arrangement, the plurality of second filaments 18 serve to transport or draw the liquid aerosol-forming substrate into the spaces 14 between the plurality of first filaments 16, which serves to wet the heating element 10.

[0098] It should be noted that Figures 1, 2, 3A, and 3B are schematic and not to scale. For clarity, the figures have been simplified and feature sizes have been altered. For example, filaments have been enlarged and aspect ratios have been changed. Additionally, fewer filaments are shown than would be present in an actual heating element.

[0099] FIG. 4 is a perspective view of a heater assembly 100 including the mesh heating element 10 of FIG. 2 and a transport material 102. The mesh heating element 10 may have either of the filament arrangements of FIG. 3A or 3B described above. The transport material is made from a porous ceramic. Any suitable ceramic can be used for the transport material. The heating element 10 is fixedly attached to the top surface of the transport material 102. Any suitable fastening method can be used to attach the heating element 10 to the transport material.

[0100] Transport material 102 is positioned to carry a liquid aerosol-forming substrate (not shown) to mesh heating element 10. As discussed above with respect to Figure 2, a plurality of gaps or openings are defined between the filaments of mesh heating element 10. During heating, vaporized aerosol-forming substrate can be released from heater assembly 100 through the openings to generate an aerosol.

[0101] Heater assembly 100 further includes a pair of electrical contacts 104 for supplying power to mesh heating element 10. Electrical contacts 104 are bonded directly to mesh heating element 10 and include a pair of tin pads located on opposing sides of the mesh. While the electrical contacts cover a portion of mesh heating element 10, sufficient area of ​​mesh heating element 10 remains so that it does not affect aerosol generation.

[0102] 5 is a plan view of another example heater assembly 200 including a heater mount 202 and a woven mesh heating element 204. A rectangular opening 206 is formed in the upper end 202a of the heater mount 202 and leads through the upper end 202a of the heater mount 202 into an interior compartment (not shown) containing a liquid aerosol-forming substrate (not shown). The liquid aerosol-forming substrate can travel through the rectangular opening 206 to the mesh heating element 204. A transport material (not shown) may be disposed within the rectangular opening 206 in contact with the mesh heating element 204 to transport the liquid aerosol-forming substrate to the mesh heating element 204. The mesh heating element 204 extends across the rectangular opening 206 and is fixedly attached to the upper surface 202a of the heater mount 202 on the opposite side of the heater mount 202. Any suitable fastening method can be used to attach the heating element 204 to the heater mount 202. The heater mount 202 is made of PEEK.

[0103] The heater mount 202 is configured to be received in an induction coil (not shown) of an aerosol generating device (not shown) so that the mesh heating element 204 can be inductively heated. The mesh heating element 204 includes a plurality of first filaments 204a made from magnetic stainless steel wire, such as AISI 430. The plurality of first filaments 204a is configured to be inductively heated to heat a liquid aerosol-forming substrate. The plurality of first filaments 204a are arranged in a first direction of the woven mesh heating element 204, which is aligned with the direction of an applied changing magnetic field provided by the induction coil. The mesh heating element 204 also includes a plurality of second filaments 204b made from glass fiber yarn. The plurality of second filaments 204b are configured to transport the liquid aerosol-forming substrate so as to wet at least a portion of the mesh heating element 204 with the liquid aerosol-forming substrate. The plurality of second filaments 204b are arranged in a second direction of the woven mesh heating element 204. The second direction is substantially perpendicular to the first direction. The mesh heating element 204 further includes two third filaments 204c made from non-magnetic stainless steel wire, such as AISI 304. The third filaments 204c are configured not to be inductively heated. The third filaments 204c are also arranged in a first direction of the woven mesh heating element 204 and are located on either side of the region of the mesh heating element 204 formed by the first filaments 204a.

[0104] The mesh heating element 204 is fixedly attached to the heater mount in the region of the mesh heating element 204 formed by the plurality of third filaments 204c. Because the plurality of third filaments 204c, made from non-magnetic stainless steel wire, are not heated by the induction coil of the aerosol generating device, significant heating of the region of the mesh heating element 204 formed by the plurality of third filaments 204c is avoided. This helps to reduce heating and thermal stress in the region where the mesh heating element 204 is fixedly attached to the heater mount 202, which in turn helps to reduce damage to the heater mount 202 caused by heating of the mesh heating element 204.

[0105] FIG. 6A shows an enlarged cross-sectional view of a portion of an exemplary heater assembly 300a including the mesh heating element 10 of FIG. 2 and a transport material 302. The mesh heating element 10 has the filament arrangement of FIG. 3B described above. That is, the mesh heating element 10 includes a plurality of first or heating filaments 16 arranged in a first (warp) direction and a plurality of second or wicking filaments 18 arranged in a second (weft) direction substantially perpendicular to the first direction. However, the filament arrangement of FIG. 3B, or any other suitable filament arrangement, may be used. The transport material is made from a porous ceramic. Any suitable ceramic may be used for the transport material. The heating element 10 is fixedly attached to the upper surface 302a of the transport material 302. Any suitable fastening method may be used to attach the heating element 10 to the transport material 302.

[0106] The plurality of second filaments 18 transport or wick the liquid aerosol-forming substrate from the transport material 302 into the spaces 14 between the plurality of first filaments 16 of the mesh heating element 10, as shown by arrow A in FIG. 6A . This aids in wetting of the mesh heating element 10, improves contact between the plurality of first filaments 16 and the transport material 302, and improves transfer of the liquid aerosol-forming substrate from the transport material 302 to the plurality of first filaments 16. The plurality of first filaments 16 heat and vaporize the liquid aerosol-forming substrate, and the vaporized aerosol-forming substrate escapes the heater assembly 300a through the spaces 14 of the mesh heating element 10. The mesh heating element 10 is consistently wetted between uses, which promotes improved and more consistent aerosol production.

[0107] FIG. 6B shows an enlarged cross-sectional view of a portion of another exemplary heater assembly 300b. The arrangement in FIG. 6B is identical to that in FIG. 6A, except that the mesh heating element 10 is embedded or embedded within the ceramic transport material 302 so that the upper surface 302a of the transport material 302 now contacts the plurality of first filaments 16, i.e., heating filaments. Portions of the plurality of second filaments 18, i.e., wicking filaments, underlying the plurality of first filaments 16 are embedded within the ceramic. The undulating shape of the plurality of second filaments 18 helps achieve integration of the mesh heating element 10 with the transport material by providing portions that can be embedded in the ceramic. Portions of the plurality of second filaments 18 underlying the plurality of first filaments 16 may be embedded in pores of a porous ceramic transport material, or the transport material may be formed with grooves or depressions to receive portions of the plurality of second filaments 16. Alternatively, the transport material may be deposited directly onto the underside of the mesh heating element 10 by some form of physical, vapor, or electrodeposition process.

[0108] 7 is a schematic diagram of an exemplary aerosol generation system. The aerosol generation system comprises two main components: a cartridge 400 and a main body portion, an aerosol generation device 500. A connecting end 415 of the cartridge 400 is removably connected to a corresponding connecting end 505 of the aerosol generation device 500. The connecting end 415 of the cartridge 400 and the connecting end 505 of the aerosol generation device 500 each have electrical contacts or connections (not shown) arranged to cooperate to provide an electrical connection between the cartridge 400 and the aerosol generation device 500. The aerosol generation device 500 comprises a power source in the form of a battery 510, which in this example is a rechargeable lithium-ion battery, and a control circuit 520. The aerosol generation system is portable and has a size comparable to that of a conventional cigar or cigarette. A mouthpiece 425 is disposed at the end of the cartridge 400 opposite the connecting end 415.

[0109] The cartridge 400 comprises the heater assembly 100 of FIG. 4 and a housing 405 including a liquid storage compartment or portion having a first storage portion 430 and a second storage portion 435. A liquid aerosol-forming substrate is held in the liquid storage compartment. Although not shown in FIG. 7, the first portion 430 of the liquid storage compartment is connected to the second storage portion 435 of the liquid storage compartment such that liquid in the first storage portion 430 can transfer to the second storage portion 435. The heater assembly 100 receives liquid from the second storage portion 435 of the liquid storage compartment. At least a portion of the ceramic transport material of the heater assembly 100 extends into the second storage portion 435 of the liquid storage compartment and contacts the liquid aerosol-forming substrate therein.

[0110] Airflow passages 440, 445 extend from an air inlet 450 formed in the side of the housing 405, past the mesh heating element of the heater assembly 100, and from the heater assembly 100 through the cartridge 400 to a mouthpiece opening 410 formed in the housing 405 at the end of the cartridge 400 opposite the connecting end 415.

[0111] The components of the cartridge 400 are arranged so that the first storage portion 430 of the liquid storage compartment is between the heater assembly 100 and the mouthpiece opening 410, and the second storage portion 435 of the liquid storage compartment is positioned on the heater assembly 100 opposite the mouthpiece opening 410. In other words, the heater assembly 100 is positioned between the two portions 430, 435 of the liquid storage compartment and receives liquid from the second storage portion 435. The first storage portion 430 of the liquid storage compartment is closer to the mouthpiece opening 410 than the second storage portion 435 of the liquid storage compartment. Airflow passages 440, 445 pass past the mesh heating element of the heater assembly 100 and extend between the first storage portion 430 and the second storage portion 435 of the liquid storage compartment.

[0112] The aerosol generation system is configured to allow a user to inhale or withdraw the cartridge mouthpiece 425, drawing aerosol into their mouth through the mouthpiece opening 410. In operation, when a user inhales or withdraws the mouthpiece opening 425, air is drawn from the air inlet 450 through the airflow passages 440, 445, past the heater assembly 100, and into the mouthpiece opening 410. A control circuit 520 controls the supply of power from the battery 510 to the cartridge 400 when the system is activated. This, in turn, controls the amount and characteristics of vapor produced by the heater assembly 100. The control circuit 520 may include an airflow sensor (not shown), and may supply power to the heater assembly 100 when the airflow sensor detects a user puff. This type of control device is well established in aerosol generation systems such as inhalers and e-cigarettes. Thus, when a user draws on mouthpiece opening 410 of cartridge 400, heater assembly 100 is activated to generate vapor that is entrained in the airflow passing through airflow passage 440. The vapor cools within the airflow in passage 445 to form an aerosol, which is then drawn through mouthpiece opening 410 into the user's mouth.

[0113] In operation, the mouthpiece opening 410 is typically the highest point in the system. The construction of the cartridge 400, and in particular the arrangement of the heater assembly 100 between the first storage portion 430 and the second storage portion 435 of the liquid storage compartment, is advantageous because it utilizes gravity to ensure that liquid substrate is delivered to the heater assembly 100 even as the liquid storage compartment begins to empty, but prevents oversupply of liquid to the heater assembly 100, which could lead to leakage of liquid into the airflow passage 440.

[0114] FIG. 8A shows a schematic diagram of an apparatus 600 used to measure the wicking performance of a mesh heating element 602. A 10 mm x 5 mm rectangular sample of the mesh heating element 602 is prepared. The sample mesh heating element 602 is suspended vertically by one of its narrower ends from a scale 604 capable of accurately measuring the weight of objects weighing as little as 0.0001 grams. The scale may be connected to a computer (not shown), which records the weight measured over time. A container 606 containing a quantity of liquid aerosol-forming substrate 608 is located below the sample mesh heating element 602. The mesh heating element 602 is lowered until the bottom, horizontal, narrow end 602a of the sample mesh heating element 602 comes into contact with the liquid aerosol-forming substrate 608 in the container 606. The amount of liquid absorbed by the mesh heating element 602 is then recorded versus the elapsed time from when wicking begins, i.e., when the sample mesh heating element 602 comes into contact with the liquid aerosol-forming substrate. Liquid absorption by the sample mesh heating element 602 is due to vertical wetting of the heating element 602 with the liquid aerosol-forming substrate.

[0115] 8B shows a table of the amount of liquid aerosol-forming substrate absorbed in grams versus elapsed time in milliseconds for three different mesh heating element samples having the materials and dimensions shown in Table 1 below.

[0116] [Table 1] Table 1

[0117] As can be seen from Table 1, Samples 1 and 2 are made from a single material. However, Sample 3 is a hybrid mesh, containing both stainless steel wire as the first filament and glass fiber yarn as the second filament.

[0118] The graph in Figure 8B shows the relative performance of Samples 1-3. As can be seen from the graph, the hybrid mesh of Sample 3 exhibits significantly improved performance compared to Samples 1 and 2 in terms of the rate and amount of liquid absorption. Sample 3 also exhibits a higher rate of liquid absorption of the aerosol-forming substrate compared to Samples 1 and 2. This means that the mesh heating element of Sample 3 rewetted more quickly after the previous puff than the other two samples. Furthermore, after 500 milliseconds, the amount of liquid absorbed by the hybrid mesh of Sample 3 was approximately twice that of its closest competitor, Sample 2, suggesting that Sample 3 exhibits better wicking and wetting performance and achieves faster wicking and wetting. Therefore, it can be concluded from Figure 8B that the provision of a hybrid mesh improves wicking and wetting performance. This helps achieve more consistent aerosol generation between successive puffs and between aerosol generators of the same type.

Claims

1. A heating element for an aerosol generating system, the heating element comprising a plurality of first filaments and a plurality of second filaments; the plurality of first filaments are configured to heat a liquid aerosol-forming substrate; the plurality of second filaments are configured to carry a liquid aerosol-forming substrate and wet at least a portion of the heating element with the liquid aerosol-forming substrate; A heating element, wherein the heating element is arranged to form a mesh, the plurality of first filaments being arranged in a first direction, and the plurality of second filaments being arranged in a second direction, the second direction being transverse to the first direction.

2. The heating element of claim 1 , wherein the plurality of first filaments are formed from an electrically conductive material.

3. The heating element according to claim 1 or 2, wherein the plurality of second filaments are hydrophilic.

4. The heating element according to any one of claims 1 to 3, wherein the plurality of second filaments are formed from a non-metallic material.

5. 10. The heating element of claim 1, wherein the plurality of first filaments are formed from a magnetic metallic material, the plurality of second filaments are formed from a non-metallic hydrophilic material, and the heating element further comprises a plurality of third filaments formed from a non-magnetic metallic material.

6. The heating element of any preceding claim, wherein the heating element comprises a woven mesh.

7. A heater assembly for an aerosol generating system, comprising a heating element as described in any one of claims 1 to 6, and a transport material for transporting a liquid aerosol-forming substrate to the heating element.

8. The heater assembly of claim 7 , wherein a portion of said plurality of second filaments are embedded in said transport material.

9. 9. The heater assembly of claim 7 or claim 8, further comprising at least two electrical contacts for supplying power to the heating element, each of the electrical contacts being connected to at least one of the plurality of first filaments.

10. A cartridge for an aerosol generating system, comprising a heater assembly as described in any one of claims 7 to 9 and a liquid storage portion for holding a liquid aerosol-forming substrate.

11. 1. An aerosol generating system comprising: A cartridge according to claim 10; An aerosol generating system comprising: an aerosol generating device, wherein the cartridge is configured to be removably coupled to the aerosol generating device, and the aerosol generating device comprises a power source for supplying power to the heating element.

12. 1. A method for manufacturing a heating element for an aerosol generating system, comprising: providing a plurality of first filaments configured to heat a liquid aerosol-forming substrate; providing a plurality of second filaments configured to convey a liquid aerosol-forming substrate along at least a portion of its length to distribute the liquid aerosol-forming substrate over at least a portion of the heating element; and arranging the heating element to form a mesh, wherein the plurality of first filaments are arranged in a first direction and the plurality of second filaments are arranged in a second direction, the second direction being transverse to the first direction.

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