Heater assembly with expansion member

Abstract

A heater assembly (10) for an aerosol generating system, the heater assembly (10) comprising an electric heating element (12) for heating a liquid aerosol-forming substrate to form an aerosol, and a porous body (14) for supplying the liquid aerosol-forming substrate to the electric heating element (12), the electric heating element (12) comprising a porous body (14) disposed on a porous outer surface (14a) of the porous body (14), and an expansion member (16) disposed within the porous body (14) such that the liquid aerosol-forming substrate can be supplied to the expansion member (16), the expansion member (16) being configured to expand when dry, thereby applying pressure to the interior of the porous body (14), such that if the liquid aerosol-forming substrate is not supplied to the expansion member (16), the expansion member (16) will rupture the porous body (14), rendering the heater assembly (10) irreversibly unusable.

Description

[Technical Field]

[0001] The present disclosure relates to a heater assembly for an aerosol generation system. In particular, but not exclusively, the present disclosure relates to a heater assembly for a handheld, electrically operated aerosol generation system for heating an aerosol-generating substrate to generate an aerosol and deliver the aerosol to the mouth of a user. The present disclosure further relates to a cartridge and an aerosol generation system including the heater assembly, as well as a method of manufacturing the heater assembly. [Background technology]

[0002] Aerosol generating systems that heat a liquid aerosol-forming substrate to generate an aerosol for delivery to a user are generally known in the art. These systems typically include an aerosol generator and a replaceable cartridge. The cartridge contains a liquid aerosol-forming substrate that can release a volatile compound when heated. The cartridge also typically includes a heater for heating the liquid aerosol-forming substrate. In known aerosol generating systems, the heater includes a resistive heating element wound around a wick that supplies the liquid aerosol-forming substrate to the heating element. The aerosol generator or cartridge also includes a mouthpiece. When a user holds the mouthpiece and draws, an electric current flows through the heating element, heating the heating element by resistive or Joule heating, which in turn heats the liquid aerosol-forming substrate supplied by the wick. This releases the volatile compound from the liquid aerosol-forming substrate, which then cools, forming an aerosol. The aerosol is then drawn into the user's mouth through the mouthpiece.

[0003] Such known aerosol generating systems have many drawbacks. For example, they are difficult to manufacture with consistent manufacturing tolerances, which can result in inconsistent vapor production and flavor generation. These manufacturing tolerances can also affect heat transfer from the heating element to the wick, reducing the energy efficiency of such devices. A further problem faced by such known aerosol generating systems is "dry heat" or "dry puffs," which occur when the heating element is heated without sufficient liquid aerosol-forming substrate being supplied to the heating element. This can occur, for example, when a user consumes all of the liquid aerosol-forming substrate in a cartridge, causing the cartridge to become depleted and require replacement. During operation, a supply of liquid aerosol-forming substrate to the heating element is preferably maintained to keep the heating element moist, helping to ensure satisfactory aerosol generation when a user puffs. Dry heat can result in overheating of the heating element and potentially thermal decomposition of the liquid aerosol-forming substrate, which can produce undesirable by-products and further result in unsatisfactory aerosol production. Allowing the aerosol generating system to continue to operate when no liquid aerosol-forming substrate is being supplied to the heating element can degrade the user experience.

[0004] It would be desirable to provide a more energy-efficient heater assembly that can produce a more consistent aerosol, that reduces the likelihood that a user will experience dry heat or dry puffs, and that prevents a user from being able to continue using an aerosol-generating system when no liquid aerosol-forming substrate is being supplied to the heating element. Summary of the Invention

[0005] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generation 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 inside the porous body so that the liquid aerosol-forming substrate can be supplied thereto. The expansion member may be configured to expand when dry, thereby applying pressure to the interior of the porous body, such that if the liquid aerosol-forming substrate is not supplied to the expansion member, the expansion member will rupture the porous body, irreversibly disabling the heater assembly. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic perspective view of a heater assembly according to one embodiment of the present disclosure. [Figure 2A] 2A and 2B are schematic side and top views, respectively, of the heater assembly of FIG. 1. [Figure 2B] 2A and 2B are schematic side and top views, respectively, of the heater assembly of FIG. 1. [Figure 3] 2 is a schematic perspective view of the heater assembly of FIG. 1 after the porous mass has ruptured, illustrating the force applied by the expansion member to rupture the porous mass; FIG. [Figure 4A] FIG. 10 is a schematic side view of a heater assembly according to a further embodiment of the present disclosure. [Figure 4B] FIG. 10 is a schematic side view of a heater assembly according to a further embodiment of the present disclosure. [Figure 4C] FIG. 10 is a schematic side view of a heater assembly according to a further embodiment of the present disclosure. [Figure 4D] FIG. 2 is a schematic plan view of a heater assembly according to another embodiment of the present disclosure. [Figure 5] 1 is a schematic cross-sectional view of an aerosol generation system according to one embodiment of the present disclosure. [Figure 6]1 is a flowchart of a method for manufacturing a heater assembly for an aerosol generation system, according to one embodiment of the present disclosure.

[0007] It will be understood that the figures in the present application are schematic and have been simplified for purposes of clarity, and as a result, some features may be omitted and features are not necessarily drawn to scale.

[0008] References to orientations such as vertical, horizontal, top, bottom, upper, lower, etc., when describing features of the present disclosure are not intended to imply any limitations on the orientation of those features, but are merely intended to indicate the relative spatial arrangement of the features, particularly with reference to the drawings or in normal use, It will be understood that features of the present disclosure may have different orientations when in use. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiment will now be further described with reference to the figures.

[0010] Referring to FIG. 1, a heater assembly 10 is shown comprising a heating element 12 for heating a liquid aerosol-forming substrate to form an aerosol, and a rectangular parallelepiped-shaped porous body 14 for supplying the liquid aerosol-forming substrate from a reservoir (not shown) to the electric heating element 12. The electric heating element 12 is disposed on a first porous outer surface 14a of the porous body 14. In the exemplary heater assembly 10 of FIG. 1, the electric heating element 12 is deposited on the first porous outer surface 14a of the porous body 14 by a suitable physical vapor deposition or gas phase deposition process or by a printing process. The electric heating element 12 comprises a nickel-chromium (NiCr) alloy, although it will be understood that other suitable electrically conductive materials suitable for resistive heating may be used. The porous body comprises a ceramic formed from silicon dioxide (SiO) or calcium silicate (CaSiO), although other suitable ceramics may be used.

[0011] A substantially planar expansion member 16 is disposed within the porous body 14. This arrangement means that when a liquid aerosol-forming substrate is available for the electric heating element 12, the liquid aerosol-forming substrate is also provided for the expansion member 16. Conversely, when a liquid aerosol-forming substrate is not available for the electric heating element 12, no liquid aerosol-forming substrate is provided for the expansion member 16. The expansion member 16 is made of hydrophobic cellulose, which exhibits dry swelling, i.e., it has a smaller size when wet and expands when dry. Therefore, hydrophobic cellulose is characterized by having a negative drying shrinkage coefficient. When no liquid aerosol-forming substrate is provided for the expansion member 16, for example, when dry heating occurs due to depletion of the liquid aerosol-forming substrate in the reservoir, i.e., the liquid storage portion, the expansion member 16 will expand. This applies pressure or force to the interior of the porous body 14, causing the expansion member 16 to intentionally rupture the porous body 14 and irreversibly disable the heater assembly 10 in a controlled manner.

[0012] 1, the expansion member 16 passes through more than 50 percent of the height and width of the porous body 14 in the vertical plane. As a result, less than 50 percent of the material making up the porous body 14 remains in the vertical plane where the expansion member 16 is located. Therefore, stresses in the porous body 14 due to the pressure or force applied by the expansion member 16 are concentrated in the remaining material of the porous body 14, thereby helping to fracture the porous body 14 in a controlled and specific manner, i.e., along the vertical plane where the expansion member 16 is located.

[0013] Hydrophobic cellulose expands to at least five times its size when dry compared to its size when saturated with the liquid aerosol-forming substrate. In the exemplary heater assembly 10 of FIG. 1, the porous body has dimensions of 9.2 mm x 4.1 mm x 4.6 mm. The expansion member 16 has dimensions of 3 mm x 3 mm x 1.5 mm when wet. When dry, the expansion member 16 was found to expand to 15 mm x 15 mm x 7.5 mm, i.e., the expansion member 16 was found to be five times larger in its dry state than in its wet state. The expansion of the expansion member 16 was found to apply a pressure of 0.5 Newtons per square millimeter or a tensile force of 4.5 Newtons, which is sufficient to rupture the porous body 14. Other sizes of expansion members can be used in the heater assembly 10. For example, an expansion member with a major surface having a surface area of ​​10.2 square millimeters has been found to exert a tensile force of 5.1 Newtons when dry, which is also sufficient to fracture the porous body 14.

[0014] The heater assembly 10 of Figure 1 further includes electrical contacts 18 electrically connected to the electric heating element 12. The electrical contacts 18 are disposed on the same porous outer surface 14a as the electric heating element 12, and also on the opposite side of the porous outer surface 14a. The electric heating element 12 extends in a serpentine or undulating manner between the electrical contacts 18, thereby increasing the length of the electric heating element 12 between the electrical contacts 18 and thus increasing the amount of heat generated by the porous outer surface 14 during operation of the heater assembly 10. In the exemplary heater assembly 10 of Figure 1, the electrical contacts comprise one or more of copper, zinc, or gold, although other suitable materials may be used.

[0015] 2A and 2B are schematic side and top views, respectively, of the heater assembly of FIG. 1. As noted above, the electric heating element 12 and electrical contacts 18 are disposed on the first porous outer surface 14a of the porous body 14, which is shown uppermost in FIG. 2A. The first porous outer surface 14a thus represents the heat-generating or aerosol-generating surface of the heater assembly 10. The expansion member 16 is disposed within the porous body 14 and extends vertically upward from the lower surface, i.e., from the second porous outer surface 14b, for more than 50 percent of the height of the porous body 14, thereby leaving only a portion X of the porous body 14 material above the expansion member 16. The second porous outer surface 14b receives liquid aerosol-forming substrate from a reservoir, i.e., liquid storage portion (not shown), and thus represents the liquid-absorbing surface of the heater assembly 10. Extending downward to the second porous outer surface 14b ensures that the expansion member 16 comes into contact with the liquid aerosol-forming substrate when it is available, thereby helping to ensure that the liquid aerosol-forming substrate is supplied to the expansion member 16. When no liquid aerosol-forming substrate is supplied to the expansion member 16 to expand it, stress is concentrated in the portion X of the material that makes up the porous body 14. The expansion member 16 may be disposed within the porous body 14 by molding the porous body 14 around the expansion member 16. Alternatively, a slot may be formed in the second porous outer surface 14b, and the expansion member 16 may be inserted into the slot in a compressed, i.e., wet, state.

[0016] 2B, the expansion member 16 extends across more than 50 percent of the width of the porous body 14, leaving only the portion Y of the material that makes up the porous body 14 on either side of the expansion member 16. When no liquid aerosol-forming substrate is supplied to the expansion member 16 to expand it, stresses are also concentrated in the portion Y of the material that makes up the porous body 14.

[0017] Figure 3 is a schematic perspective view of the heater assembly 10 of Figure 1 in which the porous mass 14 has been broken by the expansion member 16. Figure 3 illustrates the force applied by the expansion member 16 to break the porous mass 14. The expansion member 16 has two major surfaces, i.e., the two surfaces having the largest surface area of ​​the expansion member 16. As the expansion member 16 expands, the major surfaces of the expansion member 16 apply pressure or force outward from the plane of the expansion member 16, i.e., perpendicular to the major surfaces of the expansion member 16, as indicated by arrow A in Figure 3. The pressure or force indicated by arrow A acts to spread the portions of the porous mass 14 located on either side of the expansion member 14 apart, thereby breaking the porous mass 14. The expansion member 16 also applies pressure or force within its own plane, as indicated by arrow B. The pressure or force indicated by arrow B acts against any material located in its path, which further assists in rupturing the porous body 14 .

[0018] As mentioned above, the electric heating element 12 is deposited or printed on the first porous outer surface 14a of the heater assembly 10 of FIG. 1. This method for forming the electric heating element results in an electric heating element with relatively low mechanical strength. As can be seen from FIG. 2A, rupture of the porous body 14 results in rupture of the electric heating element 12. This interrupts the electrical circuit between the electrical contacts 18, so that the electric heating element 12 can no longer operate and the heater assembly 10 is irreversibly disabled.

[0019] Figures 4A-4D are schematic diagrams of heater assemblies according to further embodiments of the present disclosure. All heater assemblies in Figures 4A-4D have similar structures to those in Figure 1, and like reference numerals are used to refer to like features.

[0020] 4A shows a schematic side view of a heater assembly 11 including a porous body 14 having an electric heating element 12 and electrical contacts 18 disposed on a first porous outer surface 14a of the porous body 14. The heater assembly 11 of FIG. 4A differs from that of FIG. 1 in that an 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 traverses more than 50 percent of the length of the porous body 14 in a horizontal plane and more than 50 percent of the width (not shown) of the porous body 14 in a horizontal plane. As with the heater assembly 10 of FIG. 1, when liquid aerosol-forming substrate is not supplied to the expansion member, forces act both within and outside the plane in which the expansion member 17 lies, causing the porous body 14 to rupture.

[0021] FIG. 4B shows a schematic side view of a heater assembly 13 including a porous body 14 having an electric heating element 12 and electrical contacts 18 disposed on a first porous outer surface 14a of the porous body 14. The heater assembly 13 of FIG. 4B differs from that of FIG. 1 in that the porous body 14 has a line of weakness in the form of a notch 20 on the second porous outer surface 14b, shown at the bottom in FIG. 4B. Although not visible in FIG. 4B, 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 upward to the first porous outer surface 14a. 1, when no liquid aerosol-forming substrate is supplied to the expansion member, forces act both in and out of the plane of the expansion member 19, causing the porous body 14 to fracture. The presence of the notches 20 concentrates stresses in the area of ​​reduced material thickness above the notches 20, causing the porous body to fracture in a controlled manner along the line defined by the notches 20. By extending upward to the first porous outer surface 14a, the expansion member 19 may help lift the electric heating element 12 from the porous outer surface 14a so that it fractures.

[0022] Figure 4C shows a schematic side view of a heater assembly 15 including a porous body 14 having an electric heating element 12 and electrical contacts 18 disposed on a first porous outer surface 14a of the porous body 14. The heater assembly 13 of Figure 4C differs from that of Figure 1 in that the porous body 14 has multiple expansion members 21 disposed therein. As with the heater assembly 10 of Figure 1, when no liquid aerosol-forming substrate is supplied to the expansion members 21, forces act both in and out of the plane of both expansion members 21, causing the porous body 14 to rupture.

[0023] Figure 4D is a schematic plan view of a heater assembly 23 including a porous body 14 with an electric heating element 12 and electrical contacts 18 disposed on the porous body 14. The heater assembly 23 of Figure 4D differs from that of Figure 1 in that the expansion member 25 is asymmetrically disposed within the porous body 14. The expansion member 25 extends from one side or end 14c of the porous body and traverses more than 50 percent of the width of the porous body 14, leaving a portion Y of the porous body 14 material on the other side or end 14d of the porous body 14 to the 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., traverses the entire height of the porous body 14. When no liquid aerosol-forming substrate is supplied to the expansion member 16 to expand it, stress is concentrated at portion Y of the material that makes up the porous body 14, causing the porous body to fracture.

[0024] Each expansion member 17, 19, 21, 25 in Figures 4A-4D may be disposed within the porous body 14 by molding the porous body 14 around the expansion member 16. Alternatively, the porous body 14 of each heater assembly 13, 23 in Figures 4B and 4D may have slots disposed in the porous outer surface or side of the porous body 14, and the expansion members 19, 25 may be inserted into the slots in a compressed or wetted state.

[0025] 5 is a schematic cross-sectional view of an aerosol generation system 50 according to one embodiment of the present disclosure. The aerosol generation system 50 includes two main components: a cartridge 100 and a main body part or aerosol generation device 200. The aerosol generation device 200 includes a recess 202 for receiving the connecting end 102 of the cartridge 100. The cartridge 100 is removably connectable to the aerosol generation device 200 by inserting the connecting end 102 of the cartridge 100 into the recess 202. The connecting end 102 of the cartridge 100 and the recess 202 of the aerosol generation device 200 each include cooperatively arranged electrical contacts or connectors (not shown) that provide electrical connection between the cartridge 100 and the aerosol generation device 200. The aerosol generation device 200 contains a power source, in the form of a battery 204, in this example a rechargeable lithium-ion battery, and control circuitry 206. The aerosol generating system 50 is portable and has a size comparable to that of a conventional cigar or cigarette.

[0026] The cartridge 100 includes a cartridge housing 104 and a mouthpiece 106. The cartridge housing 104 contains a reservoir or liquid storage portion 108 for holding a liquid aerosol-forming substrate 110. The liquid storage portion 108 has an opening at its lower end or base, and the heater assembly 10 is disposed within the opening. The heater assembly 10 corresponds to the heater assembly 10 of FIG. 1, but is inverted in the cartridge 100 of FIG. 5, so that the first porous outer surface 14a of the porous body 14, which includes the electric heating element (not shown), is located at the bottom in FIG. 5, and the second porous outer surface 14b of the porous body 14 is located at the top. As mentioned 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 provides the liquid aerosol-forming substrate 110 by transporting it through the thickness of the porous body 14 to the electric heating element, where, in use, the liquid aerosol-forming substrate is heated by the electric heating element to generate an aerosol. Thus, the first porous outer surface 14a represents the heat-generating or aerosol-generating surface of the heater assembly 10. The generated aerosol passes through an aerosol-generating cavity 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 connections (not shown) on the cartridge connecting end 102, enabling electrical power to be supplied to the heater assembly 10.

[0027] Each of the connection end 102 of the cartridge 100 and the recess 202 of the aerosol generating device 200 has an electrical contact or connection portion (not shown) that is arranged to cooperate with each other to provide an electrical connection between the cartridge 100 and the aerosol generating device 200.

[0028] An air inlet 114 is disposed at the interface between the mouthpiece 106 and the aerosol generation device 200. In the example of Figure 5, the air inlet 114 is shown as two separate openings. However, it will be understood that the air inlet may extend continuously around the periphery of the mouthpiece 106 at the interface between the mouthpiece 106 and the aerosol generation device 200. A first airflow path, i.e., an inlet airflow path 116, extends from the air inlet 114 into a recess 202 in the aerosol generation device 200 located between the inner wall of the recess 202 and the outer surface of the cartridge housing 104. Air from the first airflow path 116 then passes around the base of the cartridge body 104. The base of the cartridge housing 104 has an opening 118 that penetrates the cartridge housing 104 and communicates with the aerosol cavity 112. A second airflow path 119 passes through the opening 118 and impinges onto the first porous outer surface 14a, which includes an electric heating element (not shown). Air from the second airflow path passes across the first porous outer surface 14a of the heater assembly 10, entraining the aerosol generated by the heater assembly. A third or outlet airflow path 120 extends from the aerosol cavity 112 to an aerosol outlet 122 formed at the proximal end of the mouthpiece 106. The third airflow path flows through the liquid reservoir 108, between the inner wall of the cartridge housing 104 or mouthpiece 106 and the outer wall of the liquid reservoir 108. The airflow paths through the aerosol generation system 50 of FIG. 5 are indicated by dashed arrows.

[0029] The aerosol generation system 50 is configured so that a user can inhale or draw aerosol into their mouth through the aerosol outlet 122 by inhaling or sucking on the mouthpiece 106 of the cartridge 100. In operation, when a user inhales 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 through the third airflow path 120 to the aerosol outlet 122. A control circuit 206 controls the supply of power from the battery 204 to the cartridge 100 during system operation. The power supplied to the cartridge 100 controls the amount and nature of vapor generated by the heater assembly 10. The control circuit 206 may include an airflow sensor (not shown), and may supply power to the heater assembly 10 when the airflow sensor detects a user puff. Alternatively, a user may activate the aerosol generation system 50 by pressing a button (not shown). When a user draws on the mouthpiece 106 of the cartridge 100, the heater assembly 10 is activated, generating vapor that is entrained in the airflow passing through the heater assembly 10. The vapor cools within the aerosolization cavity 112 to form an aerosol that is drawn into the user's mouth via the third airflow pathway 120 and the aerosol outlet 122.

[0030] FIG. 6 is a flowchart of a method 300 for manufacturing a heater assembly for an aerosol generating system. The method 300 includes a step S1 of compressing an expansion member and maintaining the expansion member in a compressed state during manufacturing of the heater assembly. The expansion member may be mechanically compressed in a dry state, for example, in a press, and maintained in that state until insertion into the porous body of the heater assembly. The compressed expansion member can be maintained in a compressed state by impregnating it with a resin while it is in a compressed state. The resin can be soluble in the liquid aerosol-forming substrate, such that the resin dissolves upon contact with the liquid aerosol-forming substrate when the heater assembly is placed inside a liquid-filled cartridge, in which case the expansion member is maintained in a compressed state due to wetting. As a further alternative, the expansion member can be compressed by wetting and maintained in a compressed state by maintaining it in a wet state during manufacturing.

[0031] The method 300 includes a step S2 of disposing the compressed expansion member within the porous body of the heater assembly. The compressed expansion member may be disposed within the porous body by molding the porous body around the expansion member. For example, the compressed expansion member, maintained in a compressed state by impregnating it with a liquid-soluble resin, may be placed within a mold that forms the porous body. A liquid-soluble thermal protective coating may also be applied to the compressed expansion member to protect it during curing or firing of the ceramic porous body. Alternatively, slots may be formed in the porous outer surface of the porous body, and the expansion member may be inserted into the slot in a compressed or wet state.

[0032] The method 300 includes step S3 of providing an electric heating element on the porous outer surface of the porous body, i.e., on the heat-generating or aerosolizing surface of the porous body, for heating the liquid aerosol-forming substrate. As mentioned above, the electric heating element can be prepared by depositing an electrically conductive material on the porous outer surface using a physical or chemical vapor deposition process.

[0033] The numbering of the steps in method 300 is not intended to imply any particular order in which the method steps should be performed. Steps S1-S3 may be performed in any suitable order, and additional steps may be included before, after, or between steps S1-S3.

[0034] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generation 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 inside the porous body so that the liquid aerosol-forming substrate can be supplied thereto. The expansion member is configured to expand when dry, thereby applying pressure to the interior of the porous body. Therefore, if the liquid aerosol-forming substrate is not supplied to the expansion member, the expansion member will rupture the porous body, irreversibly disabling the heater assembly.

[0035] The term "porous" is used herein to refer to a member or material that is permeable to the liquid aerosol-forming substrate and allows the liquid aerosol-forming substrate to move through it.

[0036] An advantage of providing an electric heating element on the porous outer surface of the porous body is that it helps alleviate manufacturing tolerance issues in heaters that include wicks and coils. This is because the electric heating element is fixed relative to and in contact with the porous body, which helps supply the liquid aerosol-forming substrate to the electric heating element. This also helps transfer heat from the electric heating element to the liquid aerosol-forming substrate, helping to improve energy efficiency. The size and placement of the electric heating element relative to the porous body are also fixed, which helps produce aerosol more consistently.

[0037] Advantageously, by providing an expansion element inside the porous body that expands when dry and applies pressure or force to the interior of the porous body when no liquid aerosol-forming substrate is supplied to the expansion element, the porous body can be intentionally fractured or split in a controlled manner when dry heating is encountered. The absence of a liquid aerosol-forming substrate supplied to the expansion element implies that no liquid aerosol-forming substrate is also supplied to the electric heating element, and dry heating occurs. The fracture or splitting of the porous body may also destroy or sever the heating element disposed along the porous outer surface of the porous body. Thus, fracture of the porous body irreversibly disables the heater assembly, rendering the aerosol generation system unusable until the cartridge containing the disabled heater assembly is replaced. Furthermore, the likelihood of the porous body failing uncontrollably and breaking into multiple pieces, as can occur due to extreme temperature cycling of the heating element during dry heating, can be reduced. This may help improve the safety of heater assemblies for aerosol generation systems. Additionally, a more reliable mechanical defeat means may be provided in the event of dry heat, compared to known systems which tend to use electronic monitoring and defeat.

[0038] The expansion member may comprise a material with a negative drying shrinkage coefficient. Typically, most materials decrease in size when dry and increase in size when wet. Such materials are said to exhibit drying shrinkage and are characterized by a positive drying shrinkage coefficient. However, some materials decrease in size when wet and increase in size when dry. Such materials are said to exhibit drying expansion and are characterized by a negative drying shrinkage coefficient. Advantageously, by using an expansion member made from a material with a negative drying shrinkage coefficient, the porous body can be broken by applying a force onto it when no liquid aerosol-forming substrate is supplied to the expansion member. Thus, such a material can provide a simple mechanical means for disabling the heater assembly in the event of dry heating.

[0039] The expansion member may comprise a hydrophobic material. The expansion member may comprise hydrophobic fibers. The expansion member may comprise a material having a contact angle greater than 150 degrees. The expansion member may comprise hydrophobic cellulose or superhydrophobic cellulose. As used herein, the term "hydrophobic cellulose" refers to a cellulosic material that has been subjected to a chemical or physical treatment to render the cellulosic surface hydrophobic so that it repels water. For example, this can be achieved by coating the fibers of the cellulosic material with a low surface energy material, such as a hydrocarbon or fluorine-containing compound. However, any suitable means for achieving hydrophobicity may be used.

[0040] Advantageously, the hydrophobic cellulose is a material that exhibits dry expansion and is characterized by a negative drying shrinkage coefficient. Surprisingly, it has been discovered that an expansion member comprising hydrophobic cellulose can exert sufficient pressure on the porous body when dry, causing the porous body to rupture and rendering the heater assembly unusable. That is, when no liquid aerosol-forming substrate is provided to the expansion member, the hydrophobic cellulose expands, causing the porous body to rupture. However, during normal operation or storage, the hydrophobic cellulose is maintained in a saturated, wet state by the liquid aerosol-forming substrate provided by the porous body. Because the expansion member has a significantly reduced size in the wet state, it does not exert pressure on the porous body and does not interfere with the operation of the heater assembly.

[0041] The expansion member may be substantially planar. Geometrically, the term "planar" is used to refer to an expansion member that extends along a surface in two dimensions rather than a third dimension. Advantageously, being substantially planar allows the expansion member to apply pressure both outward from and along the plane, which can assist in rupturing the porous body. This configuration may assist in rupturing the porous body in a controlled manner along the plane of the expansion member when no liquid aerosol-forming substrate is supplied to the expansion member.

[0042] The expansion member may pass through at least 50 percent of the dimensions of the porous mass in any plane. Preferably, the expansion member may pass through at least 60 percent of the dimensions of the porous mass in any plane. More preferably, the expansion member may pass through at least 70 percent of the dimensions of the porous mass in any plane. Even more preferably, the expansion member may pass through at least 80 percent of the dimensions of the porous mass in any plane.

[0043] The expansion element may pass through 50 to 80 percent of the dimensions of the porous mass in any plane. Preferably, the expansion element may pass through 60 to 80 percent of the dimensions of the porous mass in any plane. More preferably, the expansion element may pass through 70 to 80 percent of the dimensions of the porous mass in any plane. Even more preferably, the expansion element may pass through 75 to 80 percent of the dimensions of the porous mass in any plane. Advantageously, passing through at least 50 percent of the dimensions of the porous mass in any plane reduces the amount of remaining material to maintain the structural integrity of the porous mass in that plane. Tensile stresses due to pressure applied by the expansion element are concentrated within the reduced cross-sectional area to the point where they exceed the tensile strength of the porous mass material, causing the porous mass to fracture.

[0044] The expansion member may pass through the length of the porous body in any plane. The expansion member may pass through the width of the porous body in any plane. The expansion member may pass through the thickness of the porous body in any plane.

[0045] The expansion member may be configured to expand at least three times, preferably at least four times, and more preferably at least five times in size in its dry state compared to its saturated state. The terms "dry" or "dry state" are used herein to refer to an expansion member having a moisture content of less than 20 percent, based on the dry weight of the material from which the expansion member is made. Advantageously, expanding at least three times in size aids in rupturing the porous body by applying pressure or force to the expansion member on the porous body when no liquid aerosol-forming substrate is supplied to the expansion member.

[0046] The expansion member may be configured to apply a pressure of at least 0.3 Newtons per square millimeter, preferably at least 0.4 Newtons per square millimeter, and more preferably at least 0.5 Newtons per square millimeter, onto the porous body when the expansion member is in its expanded state. The expansion member may be configured to apply a pressure of about 0.3 Newtons per square millimeter to 0.8 Newtons per square millimeter, preferably about 0.4 Newtons per square millimeter to 0.7 Newtons per square millimeter, and more preferably about 0.5 Newtons per square millimeter to 0.6 Newtons per square millimeter, onto the porous body when the expansion member is in its expanded state. It will be understood that the expansion member is in its expanded state when it is in a dry state, i.e., when no liquid aerosol-forming substrate is supplied to the expansion member. These pressures have been found to be sufficient to rupture the porous body in accordance with the present disclosure.

[0047] The expansion member may have a first major surface. The expansion member may have a second major surface. The second major surface may be opposite the first major surface. The second major surface may be spaced apart from the first major surface by the thickness of the expansion member. The major surface of the expansion member may have a surface area of ​​between 6 square millimeters and 16 square millimeters, preferably between 7 square millimeters and 14 square millimeters, and more preferably between 8 square millimeters and 12 square millimeters. These surface areas have been found to be sufficient to fracture porous bodies in accordance with the present disclosure.

[0048] The expansion member may be disposed perpendicular to the porous outer surface on which the electric heating element is disposed. Optionally, the expansion member may be disposed parallel to the porous outer surface on which the electric heating element is disposed. Both of these configurations for the expansion member have been found to be sufficient to rupture the porous body in accordance with the present disclosure.

[0049] The porous outer surface on which the electric heating element is disposed may comprise a first porous outer surface of the porous body. The first porous outer surface thus comprises the heat-generating or aerosolization surface of the heater assembly. The porous body may have a second porous outer surface configured to receive the liquid aerosol-forming substrate. The second porous outer surface thus comprises the liquid-absorbing surface of the heater assembly. The second porous outer surface may be located opposite the first porous outer surface. The porous body is configured to deliver the liquid aerosol-forming substrate from the liquid-absorbing side to the aerosolization side of the porous body.

[0050] The porous body may comprise a heat resistant material. The porous body may comprise a material having a pyrolysis temperature of at least 250 degrees Celsius.

[0051] The porous body may be formed from 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 from a material that has a tensile strength, for a given cross-sectional area, that is less than the pressure or force that can be applied by an expansion member. However, it will be understood that brittle materials, such as ceramics, will typically fail at tensile stresses below their theoretical tensile strength due to inherent weaknesses or defects in their structure.

[0052] The porous body may comprise a ceramic. The porous body may comprise any suitable inert or biocompatible ceramic. Examples of suitable ceramics include ceramics comprising aluminum oxide, zirconium oxide, silicon oxide, calcium silicate, and calcium phosphates, including hydroxyapatite. The porous body may comprise a ceramic comprising one or more of Al2O3, ZrO2, SiO2, and Ca2SiO3. In a preferred example, the porous body comprises a ceramic containing one or both of SiO2 and Ca2SiO3. An advantage of using ceramic materials is that they are thermally stable at temperatures at which heater assemblies typically operate, and generally have a thermal decomposition temperature significantly higher than that of conventional wicks. This may help reduce the risk of undesirable by-products being generated during dry heating.

[0053] The porous body may comprise a plurality of interconnected open cell voids.

[0054] The porous body may comprise a capillary material that transports liquid through the material by capillary action. The porous body may have a fibrous or porous structure. The porous body may comprise a bundle of capillaries. For example, the porous body may comprise a plurality of fibers or threads or other microscopic tubes. The porous body may comprise fibers or threads made of cotton or treated cotton, such as 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.

[0055] The porous body may include a slot for receiving the expansion member. The slot may be disposed in a porous outer surface of the porous body. The slot may be disposed in a second porous outer surface of the porous body. The second porous outer surface may be located opposite the first porous outer surface. The slot may be disposed in a porous side of the porous body. The slot may extend into the interior of the porous body.

[0056] The porous mass may include lines of weakness, fault lines, or points of weakness. The lines of weakness, fault lines, or points of weakness may comprise features that cause the porous mass to fracture or fail at stress or force levels that are below the expected or theoretical tensile strength of the material comprising the porous mass. The expansion member may be positioned to fracture the porous mass along the lines of weakness. The lines of weakness, fault lines, or points of weakness may comprise areas of reduced cross-sectional area, such that when the expansion member applies a force onto the porous mass, stress is concentrated in the areas of reduced cross-sectional area. The expansion member may be aligned with the lines of weakness, fault lines, or points of weakness. The lines of weakness, fault lines, or points of weakness may comprise notches. Advantageously, the lines of weakness, fault lines, or points of weakness help reduce the tensile stress at which the material comprising the porous mass fails. This means that when no liquid aerosol-forming substrate is supplied to the expansion member, the expansion member must apply less pressure or force to rupture the porous body.

[0057] The electric heating element may comprise discrete, solid, pre-formed components. The electric heating element may have any suitable shape or form. Examples of suitable shapes and forms include, but are not limited to, a strip, a strip, a filament, a wire, a mesh, a flat spiral coil, a fiber, or a fabric. The heating element may be fluid permeable.

[0058] In some examples, the electric heating element may be at least partially embedded within 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 improve heating of the liquid aerosol-forming substrate and delivery of the aerosol by securing the electric heating element relative to the porous body and by increasing contact between the electric heating element and the porous body.

[0059] In some preferred examples, the heating element is planar. A planar heating element may extend substantially in a plane.

[0060] In some preferred examples, the heating element comprises a mesh. The heating element may comprise an array of filaments forming a mesh. As used herein, the term "mesh" encompasses lattices and arrays of filaments with spaces between them. The term mesh also includes woven and nonwoven fabrics.

[0061] The filaments may be formed by etching a sheet material such as foil. This may be particularly advantageous when the heater assembly comprises an array of parallel filaments. If the heating element comprises a mesh or weave of filaments, the filaments may be individually formed or woven together.

[0062] The heating element may comprise an electrically resistive heating element. The heating element may be made from any suitable electrically conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, electrically "conductive" ceramics (e.g., molybdenum disilicide, etc.), carbon, graphite, metals, metal alloys, and composites made from ceramic and metallic materials. Such composites may comprise doped or undoped ceramics. An example of a suitable doped ceramic includes 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, iron-containing alloys, nickel-based superalloys, iron-based superalloys, cobalt-based superalloys, stainless steel-based superalloys, Timetal®, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The heating element may be made of stainless steel, such as 300 series stainless steels, e.g., AISI 304, 316, 304L, 316L, etc. In a preferred example, the electric heating element may comprise one or more of NiCr and TiZr.

[0063] Additionally, the heating element may comprise a combination of the above materials. Using a combination of materials may improve control over 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 if one of the materials is more advantageous from another perspective, such as price, machinability, or other physical or chemical parameters. Advantageously, heating at a high resistance allows for more efficient use of the battery energy.

[0064] The electric heating element may be formed from an electrically conductive material deposited on a porous outer surface. As used herein, the term "electrically conductive material" means a material having a 1x10 -2 It refers to a material having a resistivity of Ω-m or less. As used herein, the term "deposited" means applied by a physical or chemical process, for example in liquid, plasma, or vapor form, as a layer or coating that is subsequently condensed or aggregated to form the electric heating element, rather than simply laid down onto or fixed to the porous body as a solid, preformed element.

[0065] The electric heating element may be deposited directly 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.

[0066] In some examples, the electrically conductive material of the electric heating element may be at least partially diffused into the porous outer surface of the porous body. As used herein, the term "diffusing into the porous outer surface" means that the electrically conductive material penetrates into the material of the porous outer surface at the interface between the electrically conductive material and the porous body, for example, by extending into the pores of the porous outer surface. This arrangement may help to improve heating of the liquid aerosol-forming substrate and aerosol delivery by securing the electric heating element to the porous body and further increasing contact between the electric heating element and the porous body.

[0067] The electrically conductive material forming the electric heating element may be deposited onto the porous outer surface in any suitable manner, for example, the electrically conductive material may 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.

[0068] In some examples, at least one heating element comprises a printable conductive material printed onto the porous outer surface of the porous body. In such embodiments, any suitable known printing technique may be used, such as one or more of screen printing, gravure printing, flexographic printing, and inkjet printing. Such printing processes may be particularly applicable in connection with high speed manufacturing processes.

[0069] Alternatively, the electrically conductive material forming the electric heating element may be deposited onto the porous outer surface of the porous body by one or more vacuum deposition processes such as vapor deposition and sputtering.

[0070] The at least one heating element may be formed from any suitable electrically conductive material, and in certain preferred embodiments, the electrically conductive material comprises one or more of a metal, a conductive polymer, and a conductive ceramic.

[0071] Suitable conductive metals include, but are not limited to, aluminum, silver, nickel, gold, platinum, copper, tungsten, and alloys thereof. In some embodiments, the conductive material comprises a metal powder suspended in an adhesive, such as an epoxy resin. In one embodiment, the conductive material comprises a silver-loaded epoxy.

[0072] Suitable conductive polymers include PEDOT (poly(3,4-ethylenedioxythiophene)), PSS (poly(p-phenylene sulfide)), PEDOT:PSS (a blend of PEDOT and PSS), PANI (polyaniline), PPY (poly(pyrrole)), PPV (poly(p-phenylene vinylene)), or combinations thereof.

[0073] Suitable conductive ceramics include ITO (indium tin oxide), SLT (lanthanum doped strontium titanate), SYT (yttrium doped strontium titanate), or combinations thereof.

[0074] The conductive material may further comprise one or more additives selected from the group consisting of solvents, curing agents, adhesion promoters, surfactants, viscosity reducers, and agglomeration inhibitors. Such additives may be used, for example, to aid in the deposition of the conductive material onto the porous outer surface of the porous body, to increase the amount of diffusion of the conductive material into the porous outer surface of the porous body, to reduce the time it takes for the conductive material to harden, to increase the degree of adhesion between the conductive material and the porous body, or to reduce the amount of agglomeration of suspended particles, such as metal particles or powders, within the conductive material prior to application of the conductive material onto the porous outer surface of the porous body.

[0075] The heater assembly may further include a first electrical contact and a second electrical contact connected to the electrical heating element. The electrical contacts may be located on 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 between the electrical contacts.

[0076] 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.

[0077] In one example, the first electrical contact and the second electrical contact may be formed from a conductive material deposited directly onto the porous outer surface of the porous body.

[0078] The electrical heating element may extend in a wavy or serpentine manner between the electrical contacts, which helps to increase the length of the heating element between the electrical contacts that contact the porous outer surface, thereby helping to improve heating of the liquid aerosol-forming substrate.

[0079] The heater assembly may comprise a plurality of expansion members which may advantageously assist in increasing the amount of pressure or force applied onto the porous body when no liquid aerosol-forming substrate is supplied to the expansion members, which may assist in rupturing the porous body.

[0080] According to another embodiment of the present disclosure, there is provided a cartridge for an aerosol generation system. The cartridge may include any of the heater assemblies described above. The cartridge may also include a liquid reservoir configured to hold a liquid aerosol-forming substrate. The liquid reservoir may be disposed on the opposite side of the heater assembly from the porous outer surface.

[0081] According to another embodiment of the present disclosure, there is provided a cartridge for an aerosol generating system, the cartridge comprising any of the heater assemblies described above and a liquid reservoir configured to hold a liquid aerosol-forming substrate, the liquid reservoir being disposed opposite the porous outer surface of the heater assembly.

[0082] 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 liquid aerosol-forming substrate.

[0083] The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may comprise both liquid and solid components. The liquid aerosol-forming substrate may comprise nicotine. The liquid aerosol-forming substrate containing nicotine may be a nicotine salt matrix. The liquid aerosol-forming substrate may comprise a plant-derived material. The liquid aerosol-forming substrate may comprise tobacco. The liquid aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate when heated. The liquid aerosol-forming substrate may comprise a homogenised tobacco material. The liquid aerosol-forming substrate may comprise a non-tobacco-containing material. The liquid aerosol-forming substrate may comprise a homogenised plant-derived material.

[0084] The liquid aerosol-forming substrate may comprise one or more aerosol formers. An aerosol former is any suitable, well-known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperatures 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 such as triethylene glycol, 1,3-butanediol, and glycerin; esters of polyhydric alcohols such as glycerol monoacetate, glycol diacetate, or glycol triacetate; and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. The liquid aerosol-forming substrate may comprise water, solvents, ethanol, plant extracts, and natural or artificial flavors.

[0085] 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%.

[0086] The liquid reservoir may be disposed on a first side of the heater assembly. An airflow channel may be disposed on a side opposite the first side of the heater assembly. The airflow channel may be adjacent to the electric heating element. An airflow path may extend through the electric heating element. The airflow path may be configured to transport the aerosol. The cartridge body may be configured such that airflow passing through the heater assembly entrains vaporized aerosol-forming substrate.

[0087] The porous outer surface may comprise a first porous outer surface or aerosolization surface of the porous body. The porous body may comprise a second porous outer surface or liquid-absorbing surface. The second porous outer surface or liquid-absorbing surface may be located opposite the first porous outer surface. The liquid reservoir may be disposed on the same side of the heater assembly as the second porous outer surface or liquid-absorbing surface.

[0088] An aerosolization cavity may be disposed on the same side of the heater assembly as the first porous exterior surface or aerosolization surface. The aerosolization cavity may be in fluid communication with the first porous exterior surface or aerosolization surface to receive the aerosol from the heater assembly. The aerosolization cavity may be in fluid communication with the airflow path to entrain the aerosol in the airflow.

[0089] The cartridge may have a mouthpiece disposed at a mouth end of the cartridge, the mouthpiece may have an aerosol outlet through which the generated aerosol may be inhaled by a user, and the cartridge may have a connecting end configured to connect the cartridge to an aerosol generating device.

[0090] The cartridge may include an air inlet. The cartridge may include an enclosed airflow passage from the air inlet to the aerosol outlet. The enclosed airflow passage may extend from the air inlet, through the heater assembly, and to the aerosol outlet. The enclosed airflow passage may pass around the outer surface of the liquid reservoir. Alternatively, the enclosed airflow passage may pass through the liquid reservoir. For example, the liquid reservoir may have an annular cross-section defining an interior passage, and the airflow passage may extend through the interior passage of the liquid reservoir.

[0091] The cartridge may include a first airflow path extending in a first direction from the air inlet toward the heater assembly. The cartridge may include a second airflow path extending past the electric heating element and configured to entrain the aerosol. The cartridge may include a third airflow path extending in a second direction from the heater assembly to the aerosol outlet. The second direction may be opposite to the first direction. The second airflow path may provide a fluid connection between the first airflow path and the third airflow path.

[0092] The cartridge may include a cartridge housing. The cartridge housing may be formed from a durable material. The cartridge housing may be formed from a liquid-impermeable material. The cartridge housing may be formed from a moldable plastic material, such as polypropylene (PP) or polyethylene terephthalate (PET). The cartridge housing of the cartridge may define a liquid reservoir or a portion of the reservoir. The cartridge housing may define the liquid reservoir. The cartridge housing and the liquid reservoir may be integrally formed. Alternatively, the liquid reservoir may be formed separately from the cartridge housing or disposed within the cartridge housing.

[0093] According to another embodiment of the present disclosure, there is provided an aerosol generation system. The aerosol generation system may include any of the cartridges described above. The aerosol generation system may include an aerosol generation device. The aerosol generation device may include a power supply for supplying power to the heater assembly. The aerosol generation device may include control circuitry for controlling the supply of power from the power supply to the heater assembly. The cartridge may be removably connectable to the aerosol generation device.

[0094] According to another embodiment of the present disclosure, there is provided an aerosol generation system including any of the cartridges described above and an aerosol generation device, the aerosol generation device including a power supply for supplying power to the heater assembly, and a control circuit for controlling the supply of power from the power supply to the heater assembly, the cartridge being removably connectable to the aerosol generation device.

[0095] The aerosol generating device may include a housing. The housing may be elongated. The housing may comprise any suitable material or combination of such 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), polyethylene, etc. The material is preferably lightweight and non-brittle.

[0096] The housing of the aerosol generating device may define a recess or cavity for receiving a portion of the cartridge. The aerosol generating device may have a connecting end configured to removably couple the aerosol generating device to the cartridge. The connecting end may include a recess or cavity for receiving the cartridge.

[0097] The aerosol generating device may have a distal end opposite the connecting end, which 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.

[0098] The aerosol generation system may include an air inlet. The air inlet may be disposed at the interface between the cartridge and the aerosol generation device. The aerosol generation system may include an enclosed airflow path from the air inlet to the aerosol outlet. The enclosed airflow path may extend from the air inlet, through the heater assembly, and to the aerosol outlet.

[0099] The aerosol generation system may include a first airflow path extending in a first direction from the air inlet toward the heater assembly. The aerosol generation system may include a second airflow path extending past the electric heating element and configured to entrain the aerosol. The aerosol generation system may include a third airflow path extending in a second direction from the heater assembly to the aerosol outlet. The second direction may be opposite to the first direction. The second airflow path may provide a fluid connection between the first airflow path and the third airflow path.

[0100] The power source may be any suitable power source. Preferably, the power source is 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 multiple charge-discharge cycles. The power source may have a capacity that allows it to store sufficient energy for one or more user experiences with the aerosol generation system. For example, the power source may have a capacity sufficient to enable continuous generation of aerosol for approximately six minutes, corresponding to the typical time required to smoke a conventional cigarette, or for a multiple of six minutes. In another embodiment, the power source may have a capacity sufficient to enable a predetermined number of puffs or to enable intermittent activation of the aerosol generation system.

[0101] The control circuitry may include any suitable controller or electrical component. The controller may include a memory. Information for implementing the above-described methods may be stored in the memory. The control circuitry may include a microprocessor. The microprocessor may be a programmable microprocessor, microcontroller, or application specific integrated chip (ASIC), or other electronic circuitry capable of providing control. The control circuitry may be configured to provide power to the heating element continuously after activation of the device, or may be configured to provide power intermittently, such as between puffs. Power may be provided to the heating element in the form of current pulses, for example by pulse width modulation (PWM).

[0102] The control circuitry may include additional electronic components, for example, in some embodiments the control circuitry may include sensors, switches, or display elements.

[0103] The aerosol generation system may include a puff detector. The puff detector may be configured to detect when a user inhales on the aerosol generation system. The puff detector may be any suitable sensor capable of detecting when a user inhales on the aerosol generation device. For example, the puff detector may be an airflow sensor. The control circuit may be configured to provide power to the heating element when the puff detector detects a user inhaling on the aerosol generation system.

[0104] According to another embodiment of the present disclosure, there is provided a method for manufacturing a heater assembly for an aerosol generation system. The method may include compressing an expansion member. The method may include maintaining the expansion member in a compressed state during manufacturing of the heater assembly. The method may include disposing the compressed expansion member inside a porous body. The porous body may be configured to supply a liquid aerosol-forming substrate against a porous outer surface of the porous body. The expansion member may be disposed inside 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, in use. The expansion member may be configured to apply pressure onto the interior of the porous body when dry, in use. The method may include providing an electric heating element for heating the liquid aerosol-forming substrate. The electric heating element may be provided on the porous outer surface.

[0105] According to another embodiment of the present disclosure, there is provided a method for manufacturing a heater assembly for an aerosol generation system, the method including, during manufacturing the heater assembly, compressing an expansion member and maintaining the expansion member in a compressed state, disposing the compressed expansion member inside a porous body configured to supply a liquid aerosol-forming substrate against a porous outer surface of the porous body, the expansion member disposed inside the porous body such that the liquid aerosol-forming substrate can be supplied to the expansion member, the expansion member configured, in use, to expand when dry to apply pressure onto the interior of the porous body, and providing an electric heating element for heating the liquid aerosol-forming substrate and providing the electric heating element on the porous outer surface.

[0106] 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 using 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 being impregnated with a resin while in a compressed state, so that the expansion member remains in a compressed state after the resin hardens. The resin may be soluble in the liquid aerosol-forming substrate. The resin may be configured to dissolve upon contact with the liquid aerosol-forming substrate after the heater assembly is installed inside the liquid-filled cartridge.

[0107] The expansion member may be compressed by wetting the expansion member. The expansion member may be maintained in a compressed state by maintaining the expansion member in a wet state during manufacture.

[0108] 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 liquid soluble thermal protective coating to protect the expansion member during curing or firing of the ceramic porous body. Alternatively, the expansion member may be inserted wet into the slots of the porous body.

[0109] The step of providing an electric heating element on the porous outer surface of the porous body for heating the liquid aerosol-forming substrate may comprise depositing an electrically conductive material on the porous outer surface using any suitable physical or chemical vapor deposition process.

[0110] Features described in connection with one of the above embodiments may equally be applied to other embodiments of the present disclosure. [Example]

[0111] The present invention is defined in the claims. However, the following provides a non-exhaustive list of non-limiting examples. 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.

[0112] Example 1: A heater assembly for an aerosol generating system, comprising: an electric 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 electric heating element. Example 2: 10. The heater assembly of example 1, wherein the electric heating element is disposed on the porous outer surface of the porous body. Example 3: The heater assembly of Example 1 or Example 2, further comprising an expansion member disposed inside the porous body so that a liquid aerosol-forming substrate can be supplied, the expansion member being configured to expand when dry, thereby applying pressure onto the inside of the porous body, such that if the liquid aerosol-forming substrate is not supplied to the expansion member, the expansion member will rupture the porous body, thereby rendering the heater assembly irreversibly unusable. Example 4: 4. The heater assembly of example example 3, wherein the expansion member comprises a material having a negative drying shrinkage coefficient. Example 5: The heater assembly of example 3 or example 4, wherein the expansion member comprises a hydrophobic material. Example 6: The heater assembly of example 4 or example 5, wherein the expansion member comprises a hydrophobic cellulose. Example 7: The heater assembly of any one of Examples 3 to 6, wherein the expansion member is substantially planar. Example 8: The heater assembly of any one of Examples 3-7, wherein the expansion member passes through at least 50 percent of the dimension of the porous body in any plane. Example 9: 9. The heater assembly of example 8, wherein the expansion member passes through at least 60 percent of the dimension of the porous body in any plane. Example 10: 10. The heater assembly of example example 9, wherein the expansion member passes through at least 70 percent of the dimension of the porous body in any plane. Example 11: 11. The heater assembly of example embodiment 10, wherein the expansion member passes through at least 80 percent of the dimension of the porous body in any plane. Example 12: The heater assembly of any one of Examples 3 to 7, wherein the expansion member passes through 50 to 80 percent of the dimension of the porous body in any plane. Example 13: 13. The heater assembly of claim 12, wherein the expansion element passes through 60 to 80 percent of the dimension of the porous body in any plane. Example 14: 14. The heater assembly of claim 13, wherein the expansion element passes through 70 to 80 percent of the dimension of the porous body in any plane. Example 15: 14. The heater assembly of claim 13, wherein the expansion element passes through 75 to 80 percent of the dimension of the porous body in any plane. Example 16: The heater assembly of any of Examples 3-15, wherein the expansion member is configured to expand to at least three times its size in its dry state compared to its saturated state. Example 17: 17. The heater assembly of example example 16, wherein the expansion member is configured to expand to at least four times its size in its dry state compared to its saturated state. Example 18: 17. The heater assembly of example example 16, wherein the expansion member is configured to expand to at least five times its size in its dry state compared to its saturated state. Example 19: The heater assembly of any of Examples 3 to 18, wherein the expansion member is configured to apply a pressure of at least 0.3 Newtons per square millimeter onto the porous body when the expansion member is in its expanded state. Example 20: 20. The heater assembly of example example 19, wherein the expansion member is configured to apply a pressure of at least 0.4 Newtons per square millimeter onto the porous body when the expansion member is in its expanded state. Example 21: 21. The heater assembly of example embodiment 20, wherein the expansion member is configured to apply a pressure of at least 0.5 Newtons per square millimeter onto the porous body when the expansion member is in its expanded state. Example 22: The heater assembly of any of Examples 3 to 21, wherein the expansion member, in its expanded state, is configured to apply a pressure of about 0.3 Newtons per square millimeter to about 0.8 Newtons per square millimeter onto the porous body. Example 23: 23. The heater assembly of example example 22, wherein the expansion member, in its expanded state, is configured to apply a pressure of about 0.4 Newtons per square millimeter to about 0.7 Newtons per square millimeter onto the porous body. Example 24: 23. The heater assembly of example embodiment 22, wherein the expansion member, in its expanded state, is configured to apply a pressure of about 0.5 Newtons per square millimeter to about 0.6 Newtons per square millimeter onto the porous body. Example 25: The heater assembly of any one of Examples 3 to 24, wherein the major surface of the expansion member has a surface area of ​​between 6 square millimeters and 16 square millimeters. Example 26: 26. The heater assembly of example embodiment 25, wherein a major surface of the expansion member has a surface area of ​​between 7 square millimeters and 14 square millimeters. Example 27: 27. The heater assembly of example embodiment 26, wherein a major surface of the expansion member has a surface area of ​​between 8 square millimeters and 12 square millimeters. Example 28: The heater assembly of any one of Examples 3 to 27, wherein the expansion member is disposed perpendicular to the porous outer surface. Example 29: The heater assembly of any one of Examples 3 to 27, wherein the expansion member is disposed parallel to the porous outer surface. Example 30: The heater assembly of any of Examples 1-29, wherein the porous body comprises a material having a pyrolysis temperature of at least 250 degrees Celsius. Example 31: The heater assembly of any one of Examples 1 to 30, wherein the porous body comprises ceramic. Example 32: 32. The heater assembly of example embodiment 31, wherein the porous body comprises a ceramic containing one or both of SiO2 and Ca2SiO3. Example 33: The heater assembly of any one of Examples 1 to 32, wherein the porous body includes a slot for receiving an expansion member. Example 34: 34. The heater assembly of example example 33, wherein the slot is disposed within the porous outer surface of the porous body. Example 35: 34. A heater assembly as described in Example 33, wherein the porous outer surface comprises a first porous outer surface, the slot being disposed within a second porous outer surface of the porous body, the second porous outer surface being located opposite the first porous outer surface. Example 36: 34. The heater assembly of example example 33, wherein the slot is disposed within the porous side of the porous body. Example 37: A heater assembly described in any one of Examples 3 to 36, wherein the porous body has a line of weakness and the expansion member is arranged to break the porous body along the line of weakness. Example 38: 38. The heater assembly of Example 37, wherein the line of weakness comprises a notch. Example 39: The heater assembly of any of Examples 1-38, wherein the electric heating element is formed from an electrically conductive material deposited on the porous outer surface. Example 40: A heater assembly as described in any of Examples 1 to 38, further comprising electrical contacts connected to the electric heating element, each electrical contact being located on opposite sides of the porous outer surface, whereby the electric heating element extends between the electrical contacts and forms an electrical connection between the electrical contacts. Example 41: 41. The heater assembly of example embodiment 40, wherein the electric heating element extends between the electrical contacts in a wave-like or serpentine manner. Example 42: The heater assembly of any one of Examples 3 to 42, wherein the heater assembly includes a plurality of expansion members. Example 43: A cartridge for an aerosol generating system, comprising: a heater assembly according to any one of Examples 1 to 42; and a liquid storage portion configured to hold a liquid aerosol-forming substrate, the liquid storage portion being disposed on the opposite side of the heater assembly from the porous outer surface. Example 44: An aerosol generating system comprising: a cartridge as described in Example 43; and an aerosol generating device having a power supply for supplying power to the heater assembly and further having a control circuit for controlling the supply of power from the power supply to the heater assembly, wherein the cartridge is removably connectable to the aerosol generating device. Example 45: An aerosol generation system as described in Example 44, further comprising an air intake. Example 46: 46. ​​The aerosol generation system of Example 45, wherein the air inlet is located at the interface between the cartridge and the aerosol generation device. Example 47: An aerosol generation system as described in Example 45 or Example 46, comprising: a first airflow path extending in a first direction from the air intake toward the heater assembly; a second airflow path extending through the electric heating element and configured to entrain the aerosol; and a third airflow path extending in a second direction from the heater assembly to the aerosol outlet, the second direction being opposite to the first direction, wherein the second airflow path provides a fluid connection between the first airflow path and the third airflow path. Example 48: A method for manufacturing a heater assembly for an aerosol generation system, the method comprising: compressing an expansion member and maintaining the expansion member in a compressed state during manufacturing of the heater assembly; disposing the compressed expansion member inside a porous body configured to supply a liquid aerosol-forming substrate against a porous outer surface of the porous body, the expansion member being disposed inside the porous body such that the liquid aerosol-forming substrate can be supplied to the expansion member, the expansion member being configured, in use, to expand when dry to apply pressure onto the interior of the porous body; and providing an electric heating element for heating the liquid aerosol-forming substrate, and providing the electric heating element on the porous outer surface. Example 49: 49. The method of example 48, wherein the expansion member is compressed in a dry state. Example 50: 50. The method of example 49, wherein the compressed expansion element is maintained in a compressed state by impregnating the element with resin while in a compressed state. Example 51: The method of example 50, wherein the resin is soluble in the liquid aerosol-forming substrate. Example 52: 49. The method of example 48, wherein the expansion member is compressed by wetting the expansion member.

Claims

1. 1. A heater assembly for an aerosol generating system, comprising: an electric heating element for heating the liquid aerosol-forming substrate to form an aerosol; a porous body for supplying the liquid aerosol-forming substrate to the electric heating element, the electric heating element being disposed on a porous outer surface of the porous body; an expansion member disposed inside the porous body so that the liquid aerosol-forming substrate can be supplied, the expansion member being configured to expand when dry, thereby applying pressure onto the interior of the porous body, such that if the liquid aerosol-forming substrate is not supplied to the expansion member, the expansion member will rupture the porous body, thereby rendering the heater assembly irreversibly unusable.

2. 10. The heater assembly of claim 1, wherein the expansion member comprises a material having a negative drying shrinkage coefficient.

3. The heater assembly of claim 2 , wherein the expansion member comprises a hydrophobic cellulose.

4. The heater assembly of any preceding claim, wherein the expansion member is substantially planar.

5. 5. The heater assembly of claim 1, wherein the expansion member passes through at least 50 percent of the dimension of the porous body in any plane.

6. 6. A heater assembly according to any one of claims 1 to 5, wherein the expansion member is configured to expand at least three times, preferably at least four times, more preferably at least five times in size in its dry state compared to its saturated state.

7. 7. The heater assembly of claim 1, wherein the expansion member, in its expanded state, is configured to apply a pressure onto the porous mass of between about 0.3 Newtons per square millimeter and 0.8 Newtons per square millimeter.

8. A heater assembly according to any preceding claim, wherein the major surfaces of the expansion member have a surface area of ​​between 6 square millimetres and 16 square millimetres.

9. The heater assembly of any one of claims 1 to 8, wherein the expansion member is disposed perpendicular to the porous outer surface.

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

11. 11. A heater assembly as described in any one of claims 1 to 10, wherein the porous body has a line of weakness, and the expansion member is arranged to fracture the porous body along the line of weakness.

12. 12. The heater assembly of any one of claims 1 to 11, further comprising electrical contacts connected to the electric heating element, each electrical contact being located on opposite sides of the porous outer surface, whereby the electric heating element extends between and forms an electrical connection between the electrical contacts.

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

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

15. 1. An aerosol generating system comprising: A cartridge according to claim 14; an aerosol generating device comprising a power supply for supplying power to the heater assembly, and further comprising a control circuit for controlling the supply of power from the power supply to the heater assembly; An aerosol generating system, wherein the cartridge is removably connectable to the aerosol generating device.

16. 1. A method for manufacturing a heater assembly for an aerosol generating system, comprising: compressing an expansion member and maintaining the expansion member in a compressed state during manufacturing of the heater assembly; the compressed expansion member is disposed inside a porous body, the porous body is configured to supply a liquid aerosol-forming substrate to the porous outer surface of the porous body, the expansion member is disposed inside the porous body so that the liquid aerosol-forming substrate can be supplied to the expansion member, and the expansion member is configured to apply pressure onto the inside of the porous body by expanding when dried during use; providing an electric heating element for heating the liquid aerosol-forming substrate, and providing the electric heating element on the porous outer surface.

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