Heater assembly with expansion member

Abstract

A heater assembly (10) for an aerosol-generating system, the heater assembly (10) comprising: an electrical heating element (12) for heating a liquid aerosol-forming substrate to form an aerosol; a porous body (14) for supplying the liquid aerosol-forming substrate to the electrical heating element (12), the electrical heating element (12) being arranged on a porous outer surface (14a) of the porous body (14); and an expansion member (16) arranged inside the porous body (14) such that a liquid aerosol-forming substrate can be supplied to the expansion member (16) wherein the expansion member (16) is configured to expand upon drying to exert pressure on the inside of the porous body (14) such that the liquid aerosol-forming substrate can be supplied to the expansion member (16), the expansion member (16) is supplied with a liquid aerosol-forming substrate such that the expansion member (16) ruptures the porous body (14) and irreversibly disables the heater assembly (10) in case the expansion member (16) is not supplied with the liquid aerosol-forming substrate.

Description

Technical Field

[0001] The present disclosure relates to a heater assembly for an aerosol-generating system. In particular, but not exclusively, the present disclosure relates to a heater assembly for a hand-held electrically-operated aerosol-generating system for heating an aerosol-forming substrate to generate an aerosol and for delivering the aerosol to a user's mouth. The present disclosure further relates to a cartridge and an aerosol-generating system comprising the heater assembly and also to a method of manufacturing the heater assembly. Background Art

[0002] Aerosol-generating systems for heating a liquid aerosol-forming substrate to generate an aerosol for delivery to a user are generally known in the art. These systems typically comprise an aerosol-generating device and a replaceable cartridge. The cartridge comprises a liquid aerosol-forming substrate that is capable of releasing volatile compounds upon heating. The cartridge generally also comprises a heater for heating the liquid aerosol-forming substrate. In known aerosol-generating systems, the heater comprises a resistive heating element wound around a core that supplies the liquid aerosol-forming substrate to the heating element. The aerosol-generating device or the cartridge also comprises a mouthpiece. When a user draws on the mouthpiece, an electric current passes through the heating element such that it is heated by resistive or Joule heating, which in turn heats the liquid aerosol-forming substrate supplied by the core. This causes volatile compounds to be released from the liquid aerosol-forming substrate, which cool to form an aerosol. The aerosol is then inhaled into the user's mouth via the mouthpiece.

[0003] Such known aerosol-generating systems have a number of disadvantages. For example, they may be difficult to manufacture with consistent manufacturing tolerances, which can result in inconsistent vapor production and flavor generation. Inconsistent manufacturing tolerances may also affect the heat transfer from the heating element to the core, thereby reducing the energy efficiency of such devices. Another problem encountered by such known aerosol-generating systems is "dry heating" or "dry puffing", which occurs when the heating element is heated in the absence of sufficient liquid aerosol-forming substrate being supplied to the heating element. For example, this may occur when a user has consumed all of the liquid aerosol-forming substrate in the cartridge such that the liquid aerosol-forming substrate in the cartridge has been depleted and the cartridge needs to be replaced. During operation, it is preferred to maintain the supply of liquid aerosol-forming substrate to the heating element such that the heating element remains in a wet state, as this helps to ensure that a satisfactory aerosol is produced when the user draws. Dry heating may cause the heating element to overheat and may cause thermal decomposition of the liquid aerosol-forming substrate, which may produce undesirable by-products and an unsatisfactory aerosol. Allowing the aerosol-generating system to continue operating when the liquid aerosol-forming substrate is not being supplied to the heating element may result in a poor user experience. SUMMARY OF THE INVENTION

[0004] There is a desire to provide a more energy-efficient heater assembly that can generate a more stable aerosol. There is a desire to provide a heater assembly that reduces the likelihood of a user experiencing dry heating or dry puffing and that restricts continued use of the aerosol-generating system when a liquid aerosol-forming substrate is not supplied to the heating element.

[0005] According to an example of the present disclosure, there is provided a heater assembly for an aerosol-generating system. The heater assembly may include an electric heating element for heating a liquid aerosol-forming substrate to form an aerosol. The heater assembly may include a porous body for supplying the liquid aerosol-forming substrate to the electric heating element. The electric heating element may be disposed on a porous outer surface of the porous body. The heater assembly may include an expansion member disposed within the interior of the porous body such that the liquid aerosol-forming substrate may be supplied to the expansion member. The expansion member may be configured to expand upon drying to apply a pressure or force on the interior of the porous body such that, in the absence of the liquid aerosol-forming substrate being supplied to the expansion member, the expansion member causes the porous body to rupture and irreversibly disable the heater assembly.

[0006] According to an example of the present disclosure, there is provided a heater assembly for an aerosol-generating system. The heater assembly includes an electric heating element for heating a liquid aerosol-forming substrate to form an aerosol. The heater assembly further includes a porous body for supplying the liquid aerosol-forming substrate to the electric heating element. The electric heating element is disposed on a porous outer surface of the porous body. The heater assembly includes an expansion member disposed within the interior of the porous body such that the liquid aerosol-forming substrate may be supplied to the expansion member. The expansion member is configured to expand upon drying to apply a pressure or force on the interior of the porous body such that, in the absence of the liquid aerosol-forming substrate being supplied to the expansion member, the expansion member causes the porous body to rupture and irreversibly disable the heater assembly.

[0007] The term "porous" is used herein to refer to an element or material that is permeable to a liquid aerosol-forming substrate and that permits the liquid aerosol-forming substrate to migrate therethrough.

[0008] Providing the electric heating element on the porous outer surface of the porous body has the advantage of helping to alleviate manufacturing tolerance issues encountered by wick and coil heaters. This is because the electric heating element is fixed to and in contact with the porous body, which helps to supply the liquid aerosol-forming substrate to the electric heating element. This also helps to transfer heat from the electric heating element to the liquid aerosol-forming substrate, which helps to improve energy efficiency. The size and arrangement of the electric heating element relative to the porous body are also fixed, which helps to produce a more stable aerosol.

[0009] Advantageously, by providing an expansion member within the porous body, which expands upon drying to apply a pressure or force on the interior of the porous body in the case where the expansion member is not supplied with a liquid aerosol-forming substrate, when dry heating is encountered, the porous body can be intentionally ruptured or split in a controlled manner. If the expansion member is not supplied with a liquid aerosol-forming substrate, it indicates that the electrical heating element is also not supplied with a liquid aerosol-forming substrate and dry heating is occurring. Rupturing or splitting the porous body may also cause the heating element disposed along the porous outer surface of the porous body to break or crack. Thus, rupturing the porous body irreversibly disables the heater assembly and renders the aerosol-generating system inoperable until the cartridge containing the disabled heater assembly is replaced. Additionally, this can reduce the likelihood that the porous body fails in an uncontrolled manner and breaks into multiple pieces, which may occur due to extreme temperature cycling of the heating element during dry heating. This may contribute to improving the safety of the heater assembly of the aerosol-generating system. Furthermore, compared to known systems that tend to use electronic monitoring and disabling, this may provide a more reliable mechanical disabling means in the event of dry heating.

[0010] The expansion member can comprise a material having a negative drying shrinkage coefficient. Generally, most materials decrease in size upon drying and increase in size upon wetting. Such materials are considered to exhibit dry shrinkage and are characterized by a positive drying shrinkage coefficient. However, some materials decrease in size upon wetting and increase in size upon drying. Such materials are considered to exhibit dry expansion and are characterized by a negative drying shrinkage coefficient. Advantageously, an expansion member made of a material having a negative drying shrinkage coefficient can be used to apply a force on the porous body to rupture the porous body when the expansion member is not supplied with a liquid aerosol-forming substrate. Thus, such materials can provide a simple mechanical means for disabling the heater assembly in the event of dry heating.

[0011] The expansion member can comprise a hydrophobic material. The expansion member can comprise hydrophobic fibers. The expansion member can comprise a material having a contact angle greater than 150 degrees. The expansion member can comprise hydrophobic cellulose or superhydrophobic cellulose. As used herein, the term "hydrophobic cellulose" refers to a cellulose material that has undergone a chemical or physical treatment that renders the surface of the cellulose hydrophobic such that it repels water. For example, this can be achieved by coating the fibers of the cellulose material with a low surface energy material such as a hydrocarbon compound or a fluorinated compound. However, any suitable method can be used to achieve hydrophobicity.

[0012] Advantageously, the hydrophobic cellulose is a material that exhibits dry swelling and is characterized by a negative drying shrinkage coefficient. It has been surprisingly found that an expansion member including hydrophobic cellulose can exert sufficient pressure on a porous body when dry to cause the porous body to rupture and disable the heater assembly. That is, when the expansion member is not supplied with a liquid aerosol-forming matrix, the hydrophobic cellulose swells to rupture the porous body. However, during normal operation or storage, the hydrophobic cellulose is maintained in a saturated wet state by the liquid aerosol-forming matrix supplied by the porous body. The expansion member has a significantly reduced size in its wet state such that it does not exert pressure on the porous body or otherwise interfere with the operation of the heater assembly.

[0013] The expansion member can be substantially planar. Geometrically, the term "planar" is used to refer to an expansion member that extends more in two dimensions along a surface than in a third dimension. Advantageously, being substantially planar, the expansion member can exert pressure both out of the plane and along the plane to assist in rupturing the porous body. Such a configuration may assist in the controlled failure of the porous body along the plane of the expansion member when the expansion member is not supplied with a liquid aerosol-forming matrix.

[0014] The expansion member can pass through at least 50% of the size of the porous body in any one plane. Preferably, the expansion member can pass through at least 60% of the size of the porous body in any one plane. More preferably, the expansion member can pass through at least 70% of the size of the porous body in any one plane. Even more preferably, the expansion member can pass through at least 80% of the size of the porous body in any one plane.

[0015] The expansion member can pass through 50% to 80% of the size of the porous body in any one plane. Preferably, the expansion member can pass through 60% to 80% of the size of the porous body in any one plane. More preferably, the expansion member can pass through 70% to 80% of the size of the porous body in any one plane. Even more preferably, the expansion member can pass through 75% to 80% of the size of the porous body in any one plane. Advantageously, passing through at least 50% of the size of the porous body in any one plane reduces the amount of remaining material in that plane of the porous body that is used to maintain the structural integrity of the porous body. The tensile stress generated by the pressure exerted by the expansion member is concentrated on the reduced cross-sectional area until it exceeds the tensile strength of the material of the porous body, thereby causing the porous body to rupture.

[0016] The expansion member can pass through the length of the porous body in any one plane. The expansion member can pass through the width of the porous body in any one plane. The expansion member can pass through the thickness of the porous body in any one plane.

[0017] The expansion member can be configured to expand to at least 3 times its size, preferably at least 4 times its size, and more preferably at least 5 times its size in its dry state compared to its saturated state. The term "dry" or "dry state" is used herein to refer to an expansion member having a moisture content of less than 20% relative to the dry weight of the material from which the expansion member is made. Advantageously, expanding to at least 3 times its size helps the expansion member apply pressure or force on the porous body to rupture the porous body when the expansion member is not supplied with a liquid aerosol-forming matrix.

[0018] The expansion member can be configured to apply a pressure of at least 0.3 N / mm², preferably at least 0.4 N / mm², and more preferably at least 0.5 N / mm² on the porous body when it is in its expanded state. The expansion member can be configured to apply a pressure of approximately 0.3 to 0.8 N / mm², preferably approximately 0.4 to 0.7 N / mm², and more preferably approximately 0.5 to 0.6 N / mm² on the porous body in its expanded state. It should be understood that the expansion member is in its expanded state when it is in the dry state (i.e., when the expansion member is not supplied with a liquid aerosol-forming matrix). It has been found that these pressures are sufficient to rupture the porous body according to the present disclosure.

[0019] The expansion member can have a first major surface. The expansion member can have a second major surface. The second major surface can be opposite to the first major surface. The second major surface can be separated from the first major surface by the thickness of the expansion member. The major surfaces of the expansion member can have a surface area of 6 to 16 mm², preferably 7 to 14 mm², and more preferably 8 to 12 mm². It has been found that these surface areas are sufficient to rupture the porous body according to the present disclosure.

[0020] The expansion member can be arranged perpendicular to the porous outer surface on which the electric heating element is located. Optionally, the expansion member can be arranged parallel to the porous outer surface on which the electric heating element is located. It has been found that these two configurations of the expansion member are sufficient to rupture the porous body according to the present disclosure.

[0021] The porous outer surface on which the electric heating element is arranged can include a first porous outer surface of the porous body. Thus, the first porous outer surface includes the heating surface or the aerosolization surface of the heater assembly. The porous body can have a second porous outer surface configured to receive a liquid aerosol-forming matrix. Thus, the second porous outer surface includes the liquid absorption surface of the heater assembly. The second porous outer surface can be opposite to the first porous outer surface. The porous body is configured to supply the liquid aerosol-forming matrix from the liquid absorption side to the aerosolization side of the porous body.

[0022] The porous body may include a heat-resistant material. The porous body may include a material having a thermal decomposition temperature of at least 250 degrees Celsius.

[0023] The porous body may be formed of a brittle material. As used herein, the term "brittle" refers to a material that fractures without undergoing substantial elastic or plastic deformation. The porous body may be formed of a material that has a tensile strength that is less than the pressure or force that can be exerted by the expansion member for a given cross-sectional area. However, it should be understood that brittle materials, such as ceramics, typically fail at tensile stresses that are lower than their theoretical tensile strength due to inherent weaknesses or defects in their structure.

[0024] The porous body may include a ceramic. The porous body may include any suitable inert or biocompatible ceramic. Examples of suitable ceramics are ceramics including aluminum oxide, zirconium oxide, silicon oxide, calcium silicate, and calcium phosphate (including hydroxyapatite). The porous body may include a ceramic comprising one or more of Al2O3, ZrO2, SiO2, and Ca2SiO3. In a preferred example, the porous body includes a ceramic comprising one or both of SiO2 and Ca2SiO3. The advantage of using ceramic materials is that they are thermally stable at the temperatures at which the heater assembly typically operates and generally have a significantly higher thermal decomposition temperature than conventional cores. This may help reduce the risk of generating unwanted by-products during dry heating.

[0025] The porous body may include a plurality of interconnected open pores.

[0026] The porous body may include a wicking material that transports a liquid through the material by capillary action. The porous body may have a fibrous or porous structure. The porous body may include a bundle of capillary tubes. For example, the porous body may include a plurality of fibers or threads or other microporous tubes. The porous body may include fibers or threads of cotton or treated cotton (e.g., acetylated cotton). Other suitable materials may also be used, such as ceramic- or graphite-based fibrous materials or materials made from spun, drawn, or extruded fibers, such as fiberglass, cellulose acetate, or any suitable heat-resistant polymer.

[0027] The porous body may include a slot for receiving the expansion member. The slot may be located in the porous outer surface of the porous body. The slot may be located in the second porous outer surface of the porous body. The second porous outer surface may be opposite the first porous outer surface. The slot may be located in the porous side surface of the porous body. The slot may extend into the interior of the porous body.

[0028] The porous body may include weakened lines or fracture lines or weak points. The weakened lines, fracture lines or weak points may include features that cause the porous body to break or rupture at a stress or force value below the expected or theoretical tensile strength of the material of the porous body. The expansion member may be arranged to cause the porous body to break along the weakened line. The weakened lines, fracture lines or weak points may include regions of reduced cross-sectional area that cause stress to concentrate in the regions of reduced cross-sectional area when the expansion member applies a force to the porous body. The expansion member may be aligned with the weakened line, fracture line or weak point. The weakened lines, fracture lines or weak points may include notches. Advantageously, the weakened lines or fracture lines or weak points help to reduce the tensile stress when the material of the porous body fails. This means that when the expansion member is not supplied with the liquid aerosol-forming matrix, the expansion member only needs to apply a smaller pressure or force to break the porous body.

[0029] The electric heating element may include discrete, solid, preformed components. The electric heating element may have any suitable shape or form. Examples of suitable shapes and forms include, but are not limited to, strips, bands, wires, filaments, meshes, flat spiral coils, fibers or fabrics. The heating element may be fluid-permeable.

[0030] In some instances, the electric heating element may be at least partially embedded in the porous outer surface of the porous body. In other words, at least a portion of the electric heating element may extend into the porous body. This arrangement may help to secure the electric heating element to the porous body and increase the contact between the electric heating element and the porous body to improve the heating of the liquid aerosol-forming matrix and the transfer of the aerosol.

[0031] In some preferred instances, the heating element is planar. The planar heating element may extend substantially in a plane.

[0032] In some preferred instances, the heating element includes a mesh. The heating element may include an array of wires forming the mesh. As used herein, the term "mesh" encompasses gratings and arrays of wires having spaces therebetween. The term mesh also includes woven and non-woven fabrics.

[0033] The wires may be formed by etching a sheet material such as foil. This may be particularly advantageous when the heater assembly includes an array of parallel wires. If the heating element includes a mesh or fabric of wires, the wires may be formed individually and woven together.

[0034] The heating element may include a resistive heating element. The heating element may be made of any suitable electrically conductive material. Suitable materials include, but are not limited to: semiconductors (such as doped ceramics), "electrically conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys, and composite materials made of ceramic materials and metal materials. Such composite materials may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel; constantan; nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, and iron-containing alloys; and nickel-, iron-, cobalt-based superalloys; stainless steel, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. is a registered trademark of Titanium Metals Corporation. The heating element may be made of stainless steel, such as 300 series stainless steel, such as AISI 304, 316, 304L, 316L. In a preferred example, the electric heating element may include one or more of NiCr and TiZr.

[0035] Additionally, the heating element may include a combination of the above materials. The combination of materials may be used to improve the control of the resistance of the heating element. For example, a material with a high intrinsic resistance may be combined with a material with a low intrinsic resistance. This may be advantageous if one of the materials is more favorable in other aspects, such as price, processability, or other physical and chemical parameters. Advantageously, high resistivity heating allows for more efficient use of battery energy.

[0036] The electric heating element may be formed of an electrically conductive material deposited onto a porous outer surface. As used herein, the term "electrically conductive material" refers to a material having a resistivity of 1x10 -2 Ωm or less. As used herein, the term "deposited" means to apply as a layer or coating through a physical or chemical process, such as in liquid, plasma, or vapor form, and subsequently condensing or aggregating said form to form the electric heating element, rather than simply laying or fixing a solid, preformed component onto or to the porous body.

[0037] The electric heating element may be directly deposited onto the porous outer surface. In other words, the electrically conductive material forming the electric heating element is deposited onto the porous outer surface of the porous body such that the electric heating element is in direct contact with the porous outer surface.

[0038] In some instances, the conductive material of the electroheating element can at least partially diffuse into the porous outer surface of the porous body. As used herein, the term "diffuse into the porous outer surface" means that the conductive material interlaces with the material of the porous outer surface at the interface between the conductive material and the porous body, for example, by extending into the pores of the porous outer surface. Such an arrangement can help to fix the electroheating element to the porous body and increase the contact between the electroheating element and the porous body to improve the heating of the liquid aerosol-forming matrix and the transfer of the aerosol.

[0039] The conductive material forming the electroheating element can be deposited onto the porous outer surface in any suitable manner. For example, the conductive material can be deposited as a liquid onto the porous outer surface of the porous body using a dispensing pipette or syringe, or using a fine-tip transfer device such as a needle.

[0040] In some instances, at least one heating element comprises a printable conductive material printed on the porous outer surface of the porous body. In such embodiments, any suitable known printing technique can be used. For example, one or more of screen printing, gravure printing, flexographic printing, inkjet printing. Such printing processes may be particularly suitable for high-speed production processes.

[0041] Alternatively, the conductive material forming the electroheating element can be deposited onto the porous outer surface of the porous body by one or more vacuum deposition processes such as evaporation deposition and sputtering.

[0042] At least one heating element can be formed from any suitable conductive material. In certain preferred embodiments, the conductive material comprises one or more of metals, conductive polymers, and conductive ceramics.

[0043] Suitable conductive metals include but are not limited to aluminum, silver, nickel, gold, platinum, copper, tungsten, and their alloys. In some embodiments, the conductive material comprises metal powder suspended in a glue such as epoxy resin. In one embodiment, the conductive material comprises silver-containing epoxy resin.

[0044] Suitable conductive polymers include PEDOT (poly(3,4-ethylenedioxythiophene)), PSS (poly(phenylene sulfide)), PEDOT:PSS (a mixture of both PEDOT and PSS), PANI (polyaniline), PPY (poly(pyrrole)), PPV (poly(phenylene vinylene)), or any combination thereof.

[0045] Suitable conductive ceramics include ITO (indium tin oxide), SLT (strontium titanate doped with lanthanum), SYT (strontium titanate doped with yttrium), or any combination thereof.

[0046] The conductive material may also include one or more additives selected from the group consisting of a solvent, a curing agent, an adhesion promoter, a surfactant, a viscosity reducer, and an aggregation inhibitor. Such additives can be used, for example, to assist in the deposition of the conductive material on the porous outer surface of the porous body, to increase the amount of the conductive material diffusing into the porous outer surface of the porous body, to reduce the time required for the conductive material to solidify, to increase the adhesion level between the conductive material and the porous body, or to reduce the amount of aggregation of suspended particles (such as metal particles or powders) in the conductive material before being applied to the porous outer surface of the porous body.

[0047] The heater assembly may also include a first electrical contact and a second electrical contact connected to the electrical heating element. Each electrical contact may be disposed at opposite sides of the porous outer surface. The electrical heating element may extend between the electrical contacts. The electrical heating element may form an electrical connection therebetween.

[0048] The electrical contacts may be formed of any suitable material. Examples of suitable materials for the electrical contacts include, but are not limited to, copper, zinc, and gold.

[0049] In one example, the first electrical contact and the second electrical contact may be formed of the conductive material directly deposited on the porous outer surface of the porous body.

[0050] The electrical heating element may extend between the electrical contacts in a wavy or serpentine manner. This helps to increase the length of the heating element in contact with the porous outer surface between the electrical contacts, which helps to improve the heating of the liquid aerosol-forming substrate.

[0051] The heater assembly may include a plurality of expansion members. Advantageously, the plurality of expansion members may help to increase the amount of pressure or force applied to the porous body to assist in rupturing the porous body when the expansion members are not supplied with the liquid aerosol-forming substrate.

[0052] According to another example of the present disclosure, there is provided a cartridge for an aerosol-generating system. The cartridge may include any one of the above-described heater assemblies. The cartridge may include a liquid storage portion or reservoir configured to hold a liquid aerosol-forming substrate. The liquid storage portion may be disposed on a side of the heater assembly opposite to the porous outer surface.

[0053] According to another example of the present disclosure, there is provided a cartridge for an aerosol-generating system. The cartridge includes any one of the above-described heater assemblies and a liquid storage portion or reservoir configured to hold a liquid aerosol-forming substrate. The liquid storage portion is disposed on a side of the heater assembly opposite to the porous outer surface.

[0054] As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds can be released by heating the liquid aerosol-forming substrate.

[0055] The aerosol-forming substrate can be liquid at room temperature. The aerosol-forming substrate can include both liquid and solid components. The liquid aerosol-forming substrate can include nicotine. The nicotine-containing liquid aerosol-forming substrate can be a nicotine salt substrate. The liquid aerosol-forming substrate can include plant-based materials. The liquid aerosol-forming substrate can include tobacco. The liquid aerosol-forming substrate can include a tobacco-containing material comprising volatile tobacco flavor compounds that are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate can include homogenized tobacco materials. The liquid aerosol-forming substrate can include tobacco-free materials. The liquid aerosol-forming substrate can include homogenized plant-based materials.

[0056] The liquid aerosol-forming substrate can include one or more aerosol-forming agents. An aerosol-forming agent is any suitable known compound or mixture of compounds that promotes the formation of a dense and stable aerosol during use and is substantially heat-resistant to degradation at the operating temperature of the system. Examples of suitable aerosol-forming agents include glycerol and propylene glycol. Suitable aerosol-forming agents are well known in the art and include, but are not limited to: polyols such as triethylene glycol, 1,3-butanediol, and glycerol; esters of polyols such as glycerol mono-, di-, or triacetate; and aliphatic esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. The liquid aerosol-forming substrate can include water, solvents, ethanol, plant extracts, and natural or artificial flavorants.

[0057] The liquid aerosol-forming substrate can include nicotine and at least one aerosol-forming agent. The aerosol-forming agent can be glycerol or propylene glycol. The aerosol-forming agent can include both glycerol and propylene glycol. The liquid aerosol-forming substrate can have a nicotine concentration between about 0.5% and about 10%, for example about 2%.

[0058] The liquid storage portion can be provided at a first side of the heater assembly. The airflow channel can be provided at a side of the heater assembly opposite the first side. The airflow channel can be adjacent to the electrical heating element. The airflow path can extend through the electrical heating element. The airflow path can be configured to convey the aerosol. The cartridge body can be configured such that the airflow passing through the heater assembly entrains the vaporized aerosol-forming substrate.

[0059] The porous outer surface can include a first porous outer surface or aerosolization surface of the porous body. The porous body can include a second porous outer surface or liquid absorption surface. The second porous outer surface or liquid absorption surface can be opposite the first porous outer surface. The liquid storage portion can be disposed on the same side of the heater assembly as the second porous outer surface or liquid absorption surface.

[0060] The aerosolization chamber can be arranged on the same side of the heater assembly as the first porous outer surface or aerosolization surface. The aerosolization chamber can be in fluid communication with the first porous outer surface or aerosolization surface to receive aerosol from the heater assembly. The aerosolization chamber can be in fluid communication with the airflow path to entrain the aerosol in the airflow.

[0061] The cartridge can have a mouthpiece disposed at the mouth end of the cartridge. The mouthpiece can have an aerosol outlet through which a user can draw the generated aerosol. The cartridge can have a connection end configured to couple the cartridge to the aerosol generating device.

[0062] The cartridge can include an air inlet. The cartridge can include a closed airflow passage from the air inlet to the aerosol outlet. The closed airflow passage can extend from the air inlet through the heater assembly to the aerosol outlet. The closed airflow passage can bypass the outer surface of the liquid storage portion. Alternatively, the closed airflow passage can pass through the liquid storage portion. For example, the liquid storage portion can have an annular cross-section defining an internal passage, and the airflow passage can extend through the internal passage of the liquid storage portion.

[0063] The cartridge can include a first airflow path that extends from the air inlet towards the heater assembly in a first direction. The cartridge can include a second airflow path that extends through the electrical heating element and is configured to entrain the aerosol. The cartridge can include a third airflow path that extends from the heater assembly to the aerosol outlet in a second direction. The second direction can be opposite to the first direction. The second airflow path can provide a fluid connection between the first airflow path and the third airflow path.

[0064] The cartridge can include a cartridge housing. The cartridge housing can be formed of a durable material. The cartridge housing can be formed of a liquid-impermeable material. The cartridge housing can be formed of a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET). The cartridge housing of the cartridge can define a part of the liquid storage portion or reservoir. The cartridge housing can define the liquid storage portion. The cartridge housing and the liquid storage portion can be integrally formed. Alternatively, the liquid storage portion can be separately formed from an external housing and disposed within the external housing.

[0065] According to another example of the present disclosure, an aerosol generating system is provided. The aerosol generating system can include any of the above-described cartridges. The aerosol generating system can include an aerosol generating device. The aerosol generating device can include a power source for supplying power to the heater assembly. The aerosol generating device can include control circuitry for controlling the power supply from the power source to the heater assembly. The cartridge can be removably coupled to the aerosol generating device.

[0066] According to another example of the present disclosure, there is provided an aerosol generating system including any one of the above-described cartridges and an aerosol generating device. The aerosol generating device includes a power source for supplying power to the heater assembly and a control circuitry for controlling the power supply from the power source to the heater assembly. The cartridge is removably coupled to the aerosol generating device.

[0067] The aerosol generating device may include a housing. The housing may be elongate. The housing may include any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of those materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is lightweight and non-brittle.

[0068] The aerosol generating device housing may define a cavity or recess for receiving a portion of the cartridge. The aerosol generating device may have a connection end configured to removably connect the aerosol generating device to the cartridge. The connection end may include a cavity or recess for receiving the cartridge.

[0069] The aerosol generating device may have a distal end opposite the connection end. The distal end may include an electrical connector configured to connect the aerosol generating device to an electrical connector of an external power source for charging the power source of the aerosol generating device.

[0070] The aerosol generating system may include an air inlet. The air inlet may be disposed at an interface between the cartridge and the aerosol generating device. The aerosol generating system may include a closed air flow path from the air inlet to an aerosol outlet in a mouthpiece. The closed air flow path may extend from the air inlet through the heater assembly to the aerosol outlet.

[0071] The aerosol generating system may include a first air flow path that extends from the air inlet towards the heater assembly in a first direction. The aerosol generating system may include a second air flow path that extends through the electrically heated element and is configured to entrain aerosol. The aerosol generating system may include a third air flow path that extends from the heater assembly to the aerosol outlet in a second direction. The second direction may be opposite to the first direction. The second air flow path may provide a fluid connection between the first air flow path and the third air flow path.

[0072] The power source can be any suitable power source. Preferably, the power source is a DC power source. The power source can be a battery. The battery can be a lithium-based battery, such as a lithium cobalt, lithium iron phosphate, lithium titanate, or lithium polymer battery. The battery can be a nickel-metal hydride battery or a nickel-cadmium battery. The power source can be another form of charge storage device, such as a capacitor. The power source can be rechargeable and configured for a number of charge and discharge cycles. The power source can have a capacity that allows it to store enough energy for one or more user experiences of the aerosol generation system; for example, the power source can have enough capacity to allow continuous aerosol generation for a period of about six minutes (corresponding to the typical time taken to smoke a conventional cigarette), or for a period that is a multiple of six minutes. In another example, the power source can have enough capacity to allow a predetermined number of puffs or discontinuous activation of the aerosol generation system.

[0073] The control circuitry can include any suitable controller or electrical component. The controller can include a memory. Information for performing the above methods can be stored in the memory. The control circuitry can include a microprocessor. The microprocessor can be a programmable microprocessor, a microcontroller, or an application-specific integrated circuit (ASIC) or other electronic circuitry capable of providing control. The control circuitry can be configured to continuously supply power to the heating element after the device is activated, or can be configured to supply power intermittently, such as on a puff-by-puff basis. The power can be supplied to the heating element in the form of current pulses, for example, by means of pulse width modulation (PWM).

[0074] The control circuitry can include additional electronic components. For example, in some embodiments, the control circuitry can include any one of a sensor, a switch, a display element.

[0075] The aerosol generation system can include a puff detector. The puff detector can be configured to detect when a user is puffing on the aerosol generation system. The puff detector can be any suitable sensor capable of detecting when a user is puffing on the aerosol generation device. For example, the puff detector can be an airflow sensor. The control circuitry can be configured to supply power to the heating element when the puff detector detects that a user is puffing on the aerosol generation system.

[0076] According to another example of the present disclosure, a method of manufacturing a heater assembly for an aerosol generating system is provided. The method may include compressing an expansion member. The method may include maintaining the expansion member in a compressed state during the manufacture of the heater assembly. The method may include disposing the compressed expansion member within a porous body. The porous body may be configured to supply a liquid aerosol-forming substrate to a porous outer surface of the porous body. The expansion member may be disposed within the porous body. The liquid aerosol-forming substrate may be supplied to the expansion member. The expansion member may be configured to expand when dry during use. The expansion member may be configured to apply pressure on an interior of the porous body when dry during use. The method may include providing an electrical heating element for heating the liquid aerosol-forming substrate. The electrical heating element may be provided on the porous outer surface.

[0077] According to another example of the present disclosure, a method of manufacturing a heater assembly for an aerosol generating system is provided. The method includes: compressing an expansion member and maintaining the expansion member in a compressed state during the manufacture of the heater assembly; disposing the compressed expansion member within a porous body, the porous body being configured to supply a liquid aerosol-forming substrate to the porous outer surface of the porous body, the expansion member being disposed within the porous body such that the liquid aerosol-forming substrate can be supplied to the expansion member, the expansion member being configured to expand when dry during use to apply pressure on an interior of the porous body; and providing an electrical heating element for heating the liquid aerosol-forming substrate, the electrical heating element being provided on the porous outer surface.

[0078] The expansion member may be compressed in a dry state. The step of compressing the expansion member may include mechanically compressing the expansion member. The expansion member may be compressed by a press. The expansion member may be maintained in a compressed state in the press until inserted into the porous body of the heater assembly. The compressed expansion member may be maintained in a compressed state by impregnating it with a resin in the compressed state such that once the resin has cured, the expansion member is held in a compressed state. The resin may be soluble in the liquid aerosol-forming substrate. The resin may be configured to dissolve when in contact with the liquid aerosol-forming substrate once the heater assembly is installed within a liquid-filled cartridge.

[0079] The expansion member may be compressed by wetting the expansion member. During manufacture, the expansion member may be maintained in a compressed state by keeping the expansion member wet.

[0080] The step of disposing the compressed expansion member within the porous body of the heater assembly may include molding the porous body around the expansion member. The expansion member may include a heat-protective coating that is soluble in a liquid to protect the ceramic porous body when it is cured or fired. Alternatively, the expansion member may be inserted into a slot in the porous body in a wet state.

[0081] The step of providing an electrical heating element for heating a liquid aerosol-forming substrate on the porous outer surface of the porous body may include depositing a conductive material on the porous outer surface using any suitable physical or chemical deposition process.

[0082] Features described with respect to one example among the above examples may equally apply to other examples of the present disclosure.

[0083] The present invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0084] Example Ex1: A heater assembly for an aerosol-generating system, the heater assembly comprising: an electrical heating element for heating a liquid aerosol-forming substrate to form an aerosol; and a porous body for supplying the liquid aerosol-forming substrate to the electrical heating element.

[0085] Example Ex2: The heater assembly according to Example Ex1, wherein the electrical heating element is disposed on the porous outer surface of the porous body.

[0086] Example Ex3: The heater assembly according to Example Ex1 or Ex2, further comprising an expansion member disposed within the porous body such that a liquid aerosol-forming substrate can be supplied to the expansion member, wherein the expansion member is configured to expand when dry to apply pressure on the interior of the porous body such that, in the case where the expansion member is not supplied with the liquid aerosol-forming substrate, the expansion member causes the porous body to rupture and irreversibly disable the heater assembly.

[0087] Example Ex4: The heater assembly according to Example Ex3, wherein the expansion member comprises a material having a negative dry shrinkage coefficient. 3]

[0088] Example Ex5: The heater assembly according to Example Ex3 or Ex4, wherein the expansion member comprises a hydrophobic material.

[0089] Example Ex6: The heater assembly according to Example Ex4 or Ex5, wherein the expansion member comprises hydrophobic cellulose.

[0090] Example Ex7: A heater assembly according to any one of Examples Ex3 to Ex6, wherein the expansion member is substantially planar.

[0091] Example Ex8: A heater assembly according to any one of Examples Ex3 to Ex7, wherein the expansion member extends through at least 50% of the size of the porous body in any one plane.

[0092] Example Ex9: A heater assembly according to Example Ex8, wherein the expansion member extends through at least 60% of the size of the porous body in any one plane.

[0093] Example Ex10: A heater assembly according to Example Ex9, wherein the expansion member extends through at least 70% of the size of the porous body in any one plane.

[0094] Example Ex11: A heater assembly according to Example Ex10, wherein the expansion member extends through at least 80% of the size of the porous body in any one plane.

[0095] Example Ex12: A heater assembly according to any one of Examples Ex3 to Ex7, wherein the expansion member extends through 50% to 80% of the size of the porous body in any one plane.

[0096] Example Ex13: A heater assembly according to Example Ex12, wherein the expansion member extends through 60% to 80% of the size of the porous body in any one plane.

[0097] Example Ex14: A heater assembly according to Example Ex13, wherein the expansion member extends through 70% to 80% of the size of the porous body in any one plane.

[0098] Example Ex15: A heater assembly according to Example Ex13, wherein the expansion member extends through 75% to 80% of the size of the porous body in any one plane.

[0099] Example Ex16: A heater assembly according to any one of Examples Ex3 to Ex15, wherein the expansion member is configured to expand to at least 3 times its size in its dry state compared to its saturated state.

[0100] Example Ex17: A heater assembly according to Example Ex16, wherein the expansion member is configured to expand to at least 4 times its size in its dry state compared to its saturated state.

[0101] Example Ex18: A heater assembly according to Example Ex16, wherein the expansion member is configured to expand to at least 5 times its size in its dry state compared to its saturated state.

[0102] Example Ex19: A heater assembly according to any one of Examples Ex3 to Ex18, wherein the expansion member is configured to apply a pressure of at least 0.3 Newtons per square millimeter on the porous body when the expansion member is in its expanded state.

[0103] Example Ex20: A heater assembly according to Example Ex19, wherein the expansion member is configured to apply a pressure of at least 0.4 Newtons per square millimeter on the porous body when the expansion member is in its expanded state.

[0104] Example Ex21: A heater assembly according to Example Ex20, wherein the expansion member is configured to apply a pressure of at least 0.5 Newtons per square millimeter on the porous body when the expansion member is in its expanded state.

[0105] Example Ex22: A heater assembly according to any one of Examples Ex3 to Ex21, wherein the expansion member is configured to apply a pressure of approximately 0.3 to 0.8 Newtons per square millimeter on the porous body in its expanded state.

[0106] Example Ex23: A heater assembly according to Example Ex22, wherein the expansion member is configured to apply a pressure of approximately 0.4 to 0.7 Newtons per square millimeter on the porous body in its expanded state.

[0107] Example Ex24: A heater assembly according to Example Ex22, wherein the expansion member is configured to apply a pressure of approximately 0.5 to 0.6 Newtons per square millimeter on the porous body in its expanded state.

[0108] Example Ex25: A heater assembly according to any one of Examples Ex3 to Ex24,

[0109] wherein a main surface of the expansion member has a surface area of 6 to 16 square millimeters.

[0110] Example Ex26: A heater assembly according to Example Ex25, wherein a main surface of the expansion member has a surface area of 7 to 14 square millimeters.

[0111] Example Ex27: A heater assembly according to Example Ex26, wherein a main surface of the expansion member has a surface area of 8 to 12 square millimeters.

[0112] Example Ex28: A heater assembly according to any one of Examples Ex3 to Ex27, wherein the expansion member is arranged perpendicular to the porous outer surface.

[0113] Example Ex29: A heater assembly according to any one of Examples Ex3 to Ex27, wherein the expansion member is arranged parallel to the porous outer surface.

[0114] Example Ex30: A heater assembly according to any one of Examples Ex1 to Ex29, wherein the porous body comprises a material having a thermal decomposition temperature of at least 250 degrees Celsius.

[0115] Example Ex31: A heater assembly according to any one of Examples Ex1 to Ex30, wherein the porous body comprises ceramics.

[0116] Example Ex32: A heater assembly according to Example Ex31, wherein the porous body comprises ceramics, and the ceramics comprise one or both of SiO2 and Ca2SiO3.

[0117] Example Ex33: A heater assembly according to any one of Examples Ex1 to Ex32, wherein the porous body comprises a slot for receiving the expansion member.

[0118] Example Ex34: A heater assembly according to Example Ex33, wherein the slot is located in the porous outer surface of the porous body.

[0119] Example Ex35: A heater assembly according to Example Ex33, wherein the porous outer surface comprises a first porous outer surface, and the slot is located in a second porous outer surface of the porous body, the second porous outer surface being opposite to the first porous outer surface.

[0120] Example Ex36: A heater assembly according to Example Ex33, wherein the slot is located in a porous side surface of the porous body.

[0121] Example Ex37: A heater assembly according to any one of Examples Ex3 to Ex36, wherein the porous body comprises a weakening line, and the expansion member is arranged to cause the porous body to rupture along the weakening line.

[0122] Example Ex38: A heater assembly according to Example Ex37, wherein the weakening line comprises a notch.

[0123] Example Ex39: A heater assembly according to any one of Examples Ex1 to Ex38, wherein the electric heating element is formed of a conductive material deposited on the porous outer surface.

[0124] Example Ex40: A heater assembly according to any one of Examples Ex1 to Ex38, further comprising electrical contacts connected to the electric heating element, each electrical contact being disposed at an opposite side of the porous outer surface such that the electric heating element extends between the electrical contacts and forms an electrical connection therebetween.

[0125] Example Ex41: The heater assembly according to Example Ex40, wherein the electrical heating element extends between the electrical contacts in a wavy or serpentine manner.

[0126] Example Ex42: The heater assembly according to any one of Examples Ex3 to Ex42, wherein the heater assembly includes a plurality of expansion members.

[0127] Example Ex43: A cartridge for an aerosol generation system, the cartridge comprising: a heater assembly according to any one of Examples Ex1 to Ex42; and a liquid storage portion configured to hold a liquid aerosol-forming substrate; wherein the liquid storage portion is disposed on a side of the heater assembly opposite the porous outer surface.

[0128] Example Ex44: An aerosol generation system comprising: a cartridge according to Example Ex43; and an aerosol generation device including a power source for supplying power to the heater assembly and a control circuitry for controlling the power supply from the power source to the heater assembly; wherein the cartridge is removably coupled to the aerosol generation device.

[0129] Example Ex45: The aerosol generation system according to Example Ex44, further comprising an air inlet.

[0130] Example Ex46: The aerosol generation system according to Example Ex45, wherein the air inlet is disposed at an interface between the cartridge and the aerosol generation device.

[0131] Example Ex47: The aerosol generation system according to Example Ex45 or Ex46, wherein the aerosol generation system includes a first airflow path extending from the air inlet towards the heater assembly in a first direction; a second airflow path extending through the electrical heating element and configured to entrain an aerosol; and a third airflow path extending from the heater assembly to an aerosol outlet in a second direction opposite to the first direction; and wherein the second airflow path provides a fluid connection between the first airflow path and the third airflow path.

[0132] Example Ex48: A method of manufacturing a heater assembly for an aerosol generating system, the method comprising: compressing an expansion member and maintaining the expansion member in a compressed state during manufacture of the heater assembly; disposing the compressed expansion member within a porous body configured to supply a liquid aerosol-forming substrate to a porous outer surface of the porous body, the expansion member being disposed within the porous body such that the liquid aerosol-forming substrate can be supplied to the expansion member, the expansion member being configured to expand upon drying in use to apply a pressure on an interior of the porous body; and providing an electrical heating element for heating the liquid aerosol-forming substrate, the electrical heating element being provided on the porous outer surface.

[0133] Example Ex49: The method according to Example Ex48, wherein the expansion member is compressed in a dry state.

[0134] Example Ex50: The method according to Example Ex49, wherein the compressed expansion member is maintained in a compressed state by impregnating it with a resin in the compressed state.

[0135] Example Ex51: The method according to Example Ex50, wherein the resin is soluble in the liquid aerosol-forming substrate.

[0136] Example Ex52: The method according to Example Ex48, wherein the expansion member is compressed by wetting the expansion member. BRIEF DESCRIPTION OF THE DRAWINGS

[0137] Several examples will now be further described with reference to the accompanying drawings, in which:

[0138] Figure 1 is a schematic perspective view of a heater assembly according to an example of the present disclosure;

[0139] Figure 2A and 2B are respectively Figure 1 schematic side and plan views of the heater assembly;

[0140] Figure 3 is Figure 1 a schematic perspective view of the heater assembly, where the porous body has ruptured and shows the force applied by the expansion member to rupture the porous body;

[0141] Figures 4A to 4C is a schematic side view of a heater assembly according to another example of the present disclosure;

[0142] Figure 4D is a schematic plan view of a heater assembly according to another example of the present disclosure; and

[0143] Figure 5 Schematic cross-sectional view of an aerosol-generating system according to an example of the present disclosure.

[0144] Figure 6 Flowchart of a method of manufacturing a heater assembly for an aerosol-generating system according to an example of the present disclosure. Detailed description

[0145] It should be understood that the drawings in the present application are schematic and have been simplified for clarity. Accordingly, some features may have been omitted and the features are not necessarily drawn to scale.

[0146] When describing the features of the present disclosure, references to orientations such as vertical, horizontal, above, below, upper, and lower are not intended to imply any limitation on the orientation of these features, but are merely intended to show the relative spatial arrangement of the features, particularly with reference to the drawings or the relative spatial arrangement in normal use. It should be understood that the features of the present disclosure may have different orientations in use.

[0147] Reference Figure 1 , there is shown a heater assembly 10 which includes a heating element 12 for heating a liquid aerosol-forming substrate to form an aerosol and a cuboid-shaped porous body 14 for supplying the liquid aerosol-forming substrate from a reservoir or liquid storage part (not shown) to the electrically heated element 12. The electrically heated element 12 is disposed on a first porous outer surface 14a of the porous body 14. In Figure 1 an exemplary heater assembly 10 of, the electrically heated element 12 has been deposited on the first porous outer surface 14a of the porous body 14 by a suitable physical or vapor deposition process or printing process. The electrically heated element 12 includes a nickel-chromium (NiCr) alloy, but it should be understood that other suitable electrically conductive materials suitable for resistive heating may be used. The porous body includes a ceramic formed of silica (SiO2) or calcium silicate (Ca2SiO3), but other suitable ceramics may be used.

[0148] A substantially planar expansion member 16 is disposed inside the porous body 14. This arrangement means that when a liquid aerosol forming matrix is available for supply to the electroheating element 12, it is also supplied to the expansion member 16. Conversely, if the liquid aerosol forming matrix is not available for supply to the electroheating element 12, the expansion member 16 will not be supplied with the liquid aerosol forming matrix either. The expansion member 16 is made of hydrophobic cellulose, and the hydrophobic cellulose exhibits dry expansion, that is, the hydrophobic cellulose has a smaller size when wet and expands when dry. Therefore, the hydrophobic cellulose is characterized by a negative dry shrinkage coefficient. If the expansion member 16 is not supplied with the liquid aerosol forming matrix, for example, if dry heating occurs due to exhaustion of the liquid aerosol forming matrix in the reservoir or liquid storage portion, the expansion member 16 will expand. This exerts a pressure or force on the interior of the porous body 14 such that the expansion member 16 intentionally ruptures the porous body 14 in a controlled manner and irreversibly disables the heater assembly 10.

[0149] As can be seen in Figure 1 the expansion member 16 passes through more than 50% of the height and width of the porous body 14 in the vertical plane. Thus, in the vertical plane in which the expansion member 16 is located, less than 50% of the material of the remaining porous body 14 remains. Therefore, the stress generated by the pressure or force applied by the expansion member 16 in the porous body 14 is concentrated in the remaining material of the porous body 14, which helps to rupture the porous body 14 in a controlled and specific manner (i.e., along the vertical plane in which the expansion member 16 is located).

[0150] Compared to its size when the hydrophobic cellulose is saturated with the liquid aerosol forming matrix, the hydrophobic cellulose expands to at least five times its size when dry. In Figure 1 the exemplary heater assembly 10, the dimensions of the porous body are 9.2×4.1×4.6 mm. The dimensions of the expansion member 16 when wet are 3×3×1.5 mm. It was found that when dry, the expansion member 16 had expanded to 15×15×7.5 mm, that is, the size of the expansion member 16 in the dry state is five times its size in the wet state. It was found that the expansion of the expansion member 16 exerts a pressure of 0.5 N / mm² or a tensile force of 4.5 N, which is sufficient to rupture the porous body 14. Expansion members of other dimensions can be used in the heater assembly 10. For example, it was found that an expansion member with a main surface area of 10.2 mm² exerts a tensile force of 5.1 N when dry, which is also sufficient to rupture the porous body 14.

[0151] Figure 1The heater assembly 10 further includes electrical contacts 18 electrically connected to the electrical heating element 12. The electrical contacts 18 are disposed on the same porous outer surface 14a as the electrical heating element 12 and are disposed at opposite sides of the porous outer surface 14a. The electrical heating element 12 extends between the electrical contacts 18 in a serpentine or undulating manner to increase the length of the electrical heating element 12 between the electrical contacts 18 and thereby increase the amount of heating of the porous outer surface 14 during operation of the heater assembly 10. In Figure 1 In an exemplary heater assembly 10, the electrical contacts include one or more of copper, zinc, or gold, but other suitable materials may also be used.

[0152] Figure 2A and Figure 2B are Figure 1 a schematic side view and a plan view, respectively, of the heater assembly. As described above, the electrical heating element 12 and the electrical contacts 18 are disposed on the first porous outer surface 14a of the porous body 14, which is shown as being at the top in Figure 2A . Thus, the first porous outer surface 14a represents the heating surface or the aerosolization surface of the heater assembly 10. The expansion member 16 is disposed inside the porous body 14 and extends vertically upward from the lower or second porous outer surface 14b by more than 50% of the height of the porous body 14, leaving only a portion X of the material of the porous body 14 above the expansion member 16. The second porous outer surface 14b receives the liquid aerosol-forming matrix from a reservoir or a liquid storage portion (not shown) and thus represents the liquid absorption surface of the heater assembly 10. Extending downward to the second porous outer surface 14b helps to ensure that the expansion member 16 is supplied with the liquid aerosol-forming matrix when the liquid aerosol-forming matrix is available, since the expansion member 16 will be in contact with the liquid aerosol-forming matrix. When the liquid aerosol-forming matrix is not supplied to the expansion member 16 such that the expansion member 16 expands, stress is concentrated in the portion X of the material of the porous body 14. The expansion member 16 can be disposed within the porous body 14 by molding the porous body 14 around the expansion member 16. Alternatively, slots can be formed in the second porous outer surface 14b and the expansion member 16 can be inserted into the slots in a compressed or wetted state.

[0153] As can be seen in Figure 2B , the expansion member 16 extends across more than 50% of the width of the porous body 14, leaving only a portion Y of the material of the porous body 14 on either side of the expansion member 16. When the liquid aerosol-forming matrix is not supplied to the expansion member 16 such that the expansion member 16 expands, stress is also concentrated in the portion Y of the material of the porous body 14.

[0154] Figure 3 is Figure 1Schematic perspective view of the heater assembly 10, in which the expansion member 16 has caused the porous body 14 to rupture. Figure 3 Shows the force applied by the expansion member 16 to rupture the porous body 14. The expansion member 16 has two major surfaces, namely, the surface of the expansion member 16 having the largest surface area. When the expansion member 16 expands, the major surface of the expansion member 16 applies pressure or force out of the plane of the expansion member 16 (i.e., in a direction orthogonal to the major surface of the expansion member 16), as shown in Figure 3 by arrow A. The pressure or force represented by arrow A is used to push apart the portions of the porous body 14 on either side of the expansion member 14 to rupture the porous body 14. The expansion member 16 also applies pressure or force within its own plane, as represented by arrow B. The pressure or force represented by arrow B acts on any material in its path and further contributes to rupturing the porous body 14.

[0155] As discussed above, the electric heating element 12 is deposited or printed onto Figure 1 the first porous outer surface 14a of the heater assembly 10. Such methods for forming the electric heating element result in a relatively weak mechanical strength of the electric heating element. As can be seen in Figure 2A the rupture of the porous body 14 has caused the electric heating element 12 to break. This breaks the circuit between the electrical contacts 18, such that the electric heating element 12 can no longer operate and the heater assembly 10 is irreversibly disabled.

[0156] Figures 4A to 4D Schematic diagram of a heater assembly according to another example of the present disclosure. Figures 4A to 4D The heater assemblies all have a configuration similar to that of the heater assembly of Figure 1 and the same reference numerals have been used to denote the same features.

[0157] Figure 4A Shows a schematic side view of the heater assembly 11, which includes a porous body 14 having an electric heating element 12 and electrical contacts 18 disposed on the first porous outer surface 14a of the porous body 14. Figure 4A The heater assembly 11 of Figure 1 differs from the heater assembly of Figure 1 in that the expansion member 17 is disposed within the porous body 14 parallel to the first porous outer surface 14a at substantially the midpoint of the height of the porous body 14. The expansion member 17 extends through more than 50% of the length of the porous body 14 in a horizontal plane and also extends through more than 50% of the width of the porous body 14 (not shown) in a horizontal plane. Similar to Figure 1 the heater assembly 10, when the expansion member is not supplied with the liquid aerosol-forming matrix, forces act both within and out of the plane of the expansion member 17 to rupture the porous body 14.

[0158] Figure 4B A schematic side view showing the heater assembly 13, the heater assembly including a porous body 14 having an electric heating element 12 and an electrical contact 18 disposed on a first porous outer surface 14a of the porous body 14. Figure 4B The heater assembly 13 of Figure 1 differs from the heater assembly of Figure 4B in that the porous body 14 has a weakened line in the form of a notch 20 on a second porous outer surface 14b, the second porous outer surface being shown as being at the bottom in Figure 4B . Although not visible in Figure 1 , the notch 20 extends across the entire width of the porous body 14. The notch 20 provides a region of reduced material thickness above the notch 20. An expansion member 19 is located directly above the notch 20 and extends vertically to the first porous outer surface 14a. Similar to

[0159] Figure 4C A schematic side view showing the heater assembly 15, the heater assembly including a porous body 14 having an electric heating element 12 and an electrical contact 18 disposed on a first porous outer surface 14a of the porous body 14. Figure 4C The heater assembly 13 of Figure 1 differs from the heater assembly of Figure 1 in that the porous body 14 has a plurality of expansion members 21 disposed inside the porous body 14. Similar to

[0160] Figure 4D A schematic plan view of the heater assembly 23, the heater assembly including a porous body 14 having an electric heating element 12 and an electrical contact 18 disposed on the porous body 14. Figure 4D The heater assembly 23 of Figure 1The heater assembly is different in that the expansion member 25 is asymmetrically arranged within the porous body 14. The expansion member 25 extends from one side or edge 14c of the porous body and passes through more than 50% of the width of the porous body 14, leaving a portion Y of the material of the porous body 14 on the other side or edge 14d of the porous body 14 towards one side of the expansion member 25. The expansion member 25 also extends from the lower porous outer surface of the porous body to the upper porous outer surface, i.e., it passes through the entire height of the porous body 14. When the liquid aerosol forming matrix is not supplied to the expansion member 16 to cause the expansion member 16 to expand, stress is concentrated in the portion Y of the material of the porous body 14 to cause the porous body to rupture.

[0161] Figures 4A to 4D The expansion members 17, 19, 21, and 25 can be respectively arranged within the porous body 14 by molding the porous body 14 around the expansion member 16. Alternatively, Figure 4B and 4D The porous bodies 14 of the heater assemblies 13 and 23 can respectively have slots arranged in the porous outer surface or sides of the porous body 14, and the expansion members 19 and 25 can be inserted into the slots in a compressed or wet state.

[0162] Figure 5 FIG. 12 is a schematic cross-sectional view of an aerosol generating system 50 according to an example of the present disclosure. The aerosol generating system 50 includes two main components: a cartridge 100 and a body portion or aerosol generating device 200. The aerosol generating device 200 includes a recess 202 for receiving the connecting end 102 of the cartridge 100. By inserting the connecting end 102 of the cartridge 100 into the recess 202, the cartridge 100 is removably connected to the aerosol generating device 200. The connecting end 102 of the cartridge 100 and the recess 202 of the aerosol generating device 200 each have electrical contacts or connections (not shown), which are arranged to cooperate to provide an electrical connection between the cartridge 100 and the aerosol generating device 200. The aerosol generating device 200 includes a power source in the form of a battery 204 and a control circuitry 206, which in this example is a rechargeable lithium-ion battery. The aerosol generating system 50 is portable and has dimensions comparable to a conventional cigar or cigarette.

[0163] The cartridge 100 includes a cartridge housing 104 and a mouthpiece 106. The cartridge housing 104 includes a reservoir or liquid storage portion 108 for holding a liquid aerosol forming matrix 110. The liquid storage portion 108 has an opening in its lower end or base, and a heater assembly 10 is arranged in the opening. The heater assembly 10 corresponds to the heater assembly 10 in Figure 1 but is inverted in the cartridge 100 of Figure 5 such that the first porous outer surface 14a of the porous body 14 including an electrical heating element (not shown) is in Figure 5is at the bottom and the second porous outer surface 14b of the porous body 14 is at the top. As discussed above, the second porous outer surface 14b receives the liquid aerosol-forming substrate 110 from the liquid storage portion 108 and represents the liquid-absorbing surface of the heater assembly 10. The porous body 14 supplies the liquid aerosol-forming substrate by transporting the liquid aerosol-forming substrate 110 through the thickness of the porous body 14 to the electrical heating element, where in use, the liquid aerosol-forming substrate is heated by the electrical heating element to generate an aerosol. Thus, the first porous outer surface 14a represents the heating surface or aerosolization surface of the heater assembly 10. The generated aerosol is transferred to the aerosolization chamber 112 between the first porous outer surface 14a of the heater assembly 10 and the inner surface of the base of the cartridge housing 104. Electrical contacts (not shown) on the first porous outer surface 14a of the heater assembly 10 are electrically connected to electrical connection portions (not shown) on the connection end 102 of the cartridge to permit power to be supplied to the heater assembly 10.

[0164] The connection end 102 of the cartridge 100 and the recess 202 of the aerosol generating device 200 each have electrical contacts or connection portions (not shown) that are arranged to cooperate to provide an electrical connection between the cartridge 100 and the aerosol generating device 200.

[0165] The air inlet 114 is disposed at the interface between the mouthpiece 106 and the aerosol generating device 200. In Figure 5 the example, the air inlet 114 is shown as two discrete openings. However, it should be understood that the air inlet may extend continuously around the perimeter of the mouthpiece 106 at the interface between the mouthpiece 106 and the aerosol generating device 200. The first air flow path or intake air flow path 116 extends from the air inlet 114 between the inner wall of the recess 202 and the outer surface of the cartridge housing 104 into the recess 202 of the aerosol generating device 200. Then, the air from the first air flow path 116 bypasses the base of the cartridge body 104. The base of the cartridge housing 104 has an aperture 118 that passes through the cartridge housing 104 into the aerosolization chamber 112. The second air flow path 119 passes through the aperture 118 and impinges on the first porous outer surface 14a including the electrical heating element (not shown). The air from the second air flow path passes over the first porous outer surface 14a of the heater assembly 10, entraining the aerosol generated by the heater assembly. The third air flow path or exhaust air flow path 120 extends from the aerosolization chamber 112 to the aerosol outlet 122 formed in the proximal end of the mouthpiece 106. The third air flow path flows through the liquid storage portion 108 between the inner wall of the cartridge housing 104 or the mouthpiece 106 and the outer wall of the liquid storage portion 108. In Figure 5 the air flow paths through the aerosol generating system 50 are represented by dashed arrows.

[0166] The aerosol-generating system 50 is configured such that a user can draw or puff on the mouthpiece 106 of the cartridge 100 to draw aerosol through the aerosol outlet 122 into their mouth. In operation, when the user draws on the mouthpiece 106, air is drawn from the air inlet 114 through the first airflow path 116 and the second airflow path 119, past the heater assembly 10, and via the third airflow path 120 to the aerosol outlet 122. When the system is activated, the control circuitry 206 controls the power supply from the battery 204 to the cartridge 100. The power supplied to the cartridge 100 controls the amount and characteristics of the vapor generated by the heater assembly 10. The control circuitry 206 may include an airflow sensor (not shown), and when a user draw is detected by the airflow sensor, the control circuitry 206 may supply power to the heater assembly 10. Alternatively, the user may activate the aerosol-generating system 50 by pressing a button (not shown). When the user draws on the mouthpiece 106 of the cartridge 100, the heater assembly 10 is activated and generates vapor, which is entrained in the airflow passing through the heater assembly 10. The vapor cools within the aerosolization chamber 112 to form an aerosol, which is then drawn through the third airflow path 120 and the aerosol outlet 122 into the user's mouth.

[0167] Figure 6 Flowchart of a method 300 for manufacturing a heater assembly for an aerosol-generating system. The method 300 includes step S1: compressing an expansion member and maintaining the expansion member in a compressed state during the manufacture of the heater assembly. The expansion member may be mechanically compressed in a dry state (e.g., within a press) and maintained in that state until inserted into the porous body of the heater assembly. The compressed expansion member may be maintained in the compressed state by impregnating it with a resin in the compressed state. The resin may be soluble in a liquid aerosol-forming matrix such that once the heater assembly is installed in a liquid-filled cartridge, the resin dissolves upon contact with the liquid aerosol-forming matrix, such that the expansion member is then maintained in the compressed state due to being wetted. As another alternative, the expansion member may be compressed by wetting it and maintained in the compressed state during manufacture by keeping it wet.

[0168] Method 300 includes step S2: disposing a compressed expansion member within the porous body of the heater assembly. The compressed expansion member can be disposed within the porous body by molding the porous body around the expansion member. For example, a compressed expansion member maintained in a compressed state by being impregnated with a liquid-soluble resin can be placed within a mold that forms the porous body. A liquid-soluble thermal protection coating can also be applied to the compressed expansion member to protect it when the ceramic porous body is cured or fired. Alternatively, slots can be formed in the porous outer surface of the porous body, and the expansion member can be inserted into the slots in a compressed or wet state.

[0169] Method 300 includes step S3: providing an electrical heating element on the porous outer surface of the porous body (i.e., the heating surface or aerosolization surface of the porous body) for heating a liquid aerosol-forming substrate. As discussed above, the electrical heating element can be provided by depositing a conductive material on the porous outer surface using a physical or chemical deposition process.

[0170] The numbering of the steps of method 300 is not intended to imply any particular order in which the steps of the method are to be performed. Steps S1 to S3 can be performed in any suitable order, and other steps can be included before, after, or between steps S1 to S3.

Claims

1. A heater assembly for an aerosol generating system, the heater assembly comprising: an electrically heated element for heating a liquid aerosol-forming substrate to form an aerosol; a porous body for supplying the liquid aerosol-forming substrate to the electrically heated element, the electrically heated element being disposed on a porous outer surface of the porous body; and an expansion member disposed inside the porous body such that the liquid aerosol-forming substrate can be supplied to the expansion member, wherein the expansion member is configured to expand when dry to apply pressure on the inside of the porous body such that, in the case where the expansion member is not supplied with the liquid aerosol-forming substrate, the expansion member causes the porous body to rupture and irreversibly disables the heater assembly.

2. The heater assembly according to claim 1, wherein the expansion member comprises a material having a negative dry shrinkage coefficient.

3. The heater assembly according to claim 2, wherein the expansion member comprises hydrophobic cellulose.

4. The heater assembly according to any one of claims 1 to 3, wherein the expansion member is substantially planar.

5. The heater assembly according to any one of claims 1 to 4, wherein the expansion member extends through at least 50% of the size of the porous body in any one plane.

6. The heater assembly according to any of the preceding claims, wherein the expansion member is configured to expand to at least 3 times its size, preferably at least 4 times its size, and more preferably at least 5 times its size in its dry state compared to its saturated state.

7. The heater assembly according to any of the preceding claims, wherein the expansion member is configured to apply a pressure of approximately 0.3 to 0.8 newtons per square millimeter on the porous body in its expanded state.

8. The heater assembly according to any of the preceding claims, wherein the main surface of the expansion member has a surface area between 6 square millimeters and 16 square millimeters.

9. The heater assembly according to any of the preceding claims, wherein the expansion member is disposed perpendicular to the porous outer surface.

10. The heater assembly according to any of claims 1 to 8, wherein the expansion member is disposed parallel to the porous outer surface.

11. The heater assembly according to any of the preceding claims, wherein the porous body comprises a weakening line, and the expansion member is arranged to cause the porous body to rupture along the weakening line.

12. The heater assembly according to any of the preceding claims, further comprising electrical contacts connected to the electrically heated element, each electrical contact being disposed at opposite sides of the porous outer surface such that the electrically heated element extends between and forms an electrical connection therebetween.

13. The heater assembly according to any of the preceding claims, wherein the heater assembly comprises a plurality of expansion members.

14. A cartridge for an aerosol generating system, the cartridge comprising: the heater assembly according to any one of claims 1 to 13; and A liquid storage portion configured to hold a liquid aerosol-forming substrate; wherein the liquid storage portion is disposed on a side of the heater assembly opposite the porous outer surface.

15. An aerosol-generating system comprising: a cartridge according to claim 14; and an aerosol-generating device including a power source for supplying power to the heater assembly and control circuitry for controlling the supply of power from the power source to the heater assembly; wherein the cartridge is removably coupled to the aerosol-generating device.

16. A method of manufacturing a heater assembly for an aerosol-generating system, the method comprising: compressing an expansion member and maintaining the expansion member in a compressed state during manufacture of the heater assembly; disposing the compressed expansion member within a porous body configured to supply a liquid aerosol-forming substrate to a porous outer surface of the porous body, the expansion member being disposed within the porous body such that the liquid aerosol-forming substrate can be supplied to the expansion member, the expansion member being configured to expand upon drying in use to apply pressure on an interior of the porous body; and providing an electrical heating element for heating the liquid aerosol-forming substrate, the electrical heating element being provided on the porous outer surface.

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