Heater assembly with measurement contacts

Abstract

Provided is a heater assembly for an aerosol generation system, the heater assembly comprising: an electric heating element for heating a 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 along a porous outer surface of the porous body; a protective layer disposed to extend over at least a portion of the electric heating element to protect the electric heating element; and measurement contacts disposed to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element.

Description

[Technical Field]

[0001] The present disclosure relates to a heater assembly for an aerosol generation system. In particular, but not exclusively, the present invention relates to a heater assembly for a handheld, electrically operated aerosol generation system for heating an aerosol-forming substrate to generate an aerosol and delivering the aerosol to a user's mouth. The present disclosure further relates to a cartridge and an aerosol generation system including the heater assembly, as well as a method of operating 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 prior art. These systems typically include an aerosol generating device and a replaceable cartridge. The cartridge contains a liquid aerosol-forming substrate capable of releasing 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 generating device or cartridge also includes a mouthpiece. When negative pressure is applied to the mouthpiece, electrical 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 cools and forms an aerosol. The aerosol is then drawn into the user's mouth through the mouthpiece.

[0003] Such known aerosol generating systems have several drawbacks. For example, the aerosol generating systems described above can be difficult to manufacture with consistent manufacturing tolerances, which can result in inconsistent vapor and flavor generation. Inconsistent manufacturing tolerances can also affect the transfer of heat from the heating element to the wick, reducing the energy efficiency of such devices. Another problem encountered with such known aerosol generating systems is "dry heating" or "dry puffs," which occur when the heating element is heated with insufficient liquid aerosol-forming substrate supplied to the heating element. This can occur, for example, when a user consumes all the liquid aerosol-forming substrate in the cartridge, causing the cartridge to become depleted and require replacement. During operation, it is preferable to maintain a supply of liquid aerosol-forming substrate to the heating element so that the heating element remains moist, as this helps ensure satisfactory aerosol generation when negative pressure is applied to the mouthpiece. Dry heating can result in overheating of the heating element and potentially thermal decomposition of the liquid aerosol-forming substrate, which can result in undesirable by-products and unsatisfactory aerosol generation. If the liquid aerosol-forming substrate is not supplied to the heating element, the aerosol generating system may continue to operate, resulting in a poor user experience.

[0004] One known aerosol generating system has a ceramic body and a heating element to which power is supplied through electrical contacts. The ceramic body has a coating or protective layer on a single surface. Liquid is supplied to the heating element from a liquid reservoir through pores in the ceramic body. This known aerosol generating system may also experience a "dry heat" or "dry puff" situation and therefore have associated drawbacks, namely, undesirable by-products, unsatisfactory aerosol, and a poor user experience.

[0005] It would be desirable to provide a more energy-efficient heater assembly that can generate a more consistent aerosol. It is desirable to provide a heater assembly 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

[0006] According to an 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 heater assembly may include an electric heating element. The electric heating element may be disposed along a porous outer surface of the porous body. The porous outer surface on which the electric heating element is disposed may be substantially flat. The electric heating element may extend at least partially into pores of the porous outer surface. The heater assembly may include a protective layer. The protective layer may be disposed to extend over at least a portion of the electric heating element to protect the electric heating element. The heater assembly may include measurement contacts arranged to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element.

[0007] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generation system. The heater assembly includes an electric heating element for heating a liquid aerosol-forming substrate to form an aerosol. The heater assembly includes a porous body for supplying the liquid aerosol-forming substrate to the electric heating element. The heater assembly includes the electric heating element disposed along a porous outer surface of the porous body. The heater assembly includes a protective layer disposed to extend over at least a portion of the electric heating element to protect the electric heating element. The heater assembly includes measurement contacts disposed to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element.

[0008] This arrangement allows the presence, absence, or amount of liquid to be accurately determined despite the presence of a protective layer, thereby reducing the likelihood of a dry-heating event. When a protective layer is present, it is unexpectedly difficult to determine resistance changes in the electric heating element. An advantage of the claimed arrangement is that the resistance across the heating assembly can be accurately measured as the heating assembly is heated to detect the presence, absence, or amount of liquid and control the temperature of the electric heating element to avoid a dry-heating condition.

[0009] Advantageously, the heater assembly enables the aerosol generation system to detect and control the occurrence of an overheat or underheat condition. By using the measurement junctions to measure an electrical parameter, an overheat or underheat condition can be detected which, if prevented, can reduce the likelihood of undesirable by-products being produced and a poor user experience for the user. By using the measurement junctions to measure an electrical parameter, it can be determined when the liquid level falls below a predetermined value and, therefore, approaches an overheat or underheat condition.

[0010] As used herein, the term "aerosol-generating device" refers to a device that interacts with a liquid aerosol-forming substrate to generate an aerosol.

[0011] As used herein, the term "aerosol-generating cartridge" refers to a component that interacts with a liquid aerosol-forming device to generate an aerosol. The aerosol-generating cartridge contains or is configured to contain a liquid aerosol-generating substrate.

[0012] The term "aerosol-generating substrate" as used herein refers to a substrate capable of releasing volatile compounds capable of forming an aerosol. Such volatile compounds can be released by heating the aerosol-forming substrate.

[0013] As used herein, the term "electrical heating element" refers to a component that transfers thermal energy to a liquid aerosol-generating substrate. It is understood that the electrical heating element may be disposed directly on the porous body.

[0014] As used herein, the term "electrical parameter" refers to an electrical property, including, but not limited to, voltage or potential difference, current, or electrical resistance. An electrical parameter may be monitored by directly measuring the parameter, such as voltage, or may be determined indirectly from another electrical parameter(s). For example, electrical resistance may be determined using Ohm's Law by first determining the voltage across and current through a component and dividing the voltage by the current.

[0015] As used herein, the term "porous body" refers to a component having a plurality of pores, at least some of which are interconnected. The porous body is configured to contain a liquid within the plurality of pores.

[0016] As used herein, the term "protective layer" refers to a component configured to protect an electric heating element. Specifically, the protective layer is configured to extend the life of the electric heating element.

[0017] As used herein, the term "sufficient" as used in the phrase "sufficient amount of liquid aerosol-forming substrate" refers to an amount of aerosol-forming substrate that, when present in an electric heating element, prevents dry heating or a dry puff condition.

[0018] The liquid aerosol-forming substrate may be a liquid at room temperature. The liquid aerosol-forming substrate may contain both liquid and solid components. The liquid aerosol-forming substrate may contain nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may contain a plant-derived material. The liquid aerosol-forming substrate may contain tobacco. The liquid aerosol-forming substrate may contain a tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may contain a homogenised tobacco material. The liquid aerosol-forming substrate may contain a non-tobacco-containing material. The liquid aerosol-forming substrate may contain a homogenised plant-derived material.

[0019] The liquid aerosol-forming substrate may include one or more aerosol formers. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Examples of suitable aerosol formers include glycerin and propylene glycol. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate). The liquid aerosol-forming substrate may include water, solvents, ethanol, plant extracts, and natural or artificial flavors.

[0020] 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%.

[0021] The electrical parameter may be an electrical parameter of the protective layer. The measurement contacts may be disposed on the surface of the protective layer on opposite sides of the surface of the protective layer. The measurement contacts may be disposed on opposite sides of the surface of the protective layer such that the measurement contacts can measure the electrical parameter across the protective layer. The protective layer has a thickness, a width, and a length. The thickness may be smaller than the width or the length. The measurement contacts may be spaced apart from each other in a direction perpendicular to the thickness. This has the advantage of allowing the presence or absence of liquid in the protective layer to be accurately determined.

[0022] The electrical parameter may be an electrical parameter of the porous body. The measurement contacts may be located on opposing surfaces of the porous body. This is a particularly advantageous arrangement in which the likelihood of a dry-heating event is reduced. The heater assembly may be configured to move the liquid aerosol-forming substrate from the unheated surface of the porous body to the heated surface of the porous body. There may be cases in which the liquid aerosol-forming substrate is present on the heated surface of the porous body but not within the porous body. In such cases, measurement of the electrical parameter of the porous body may be used to identify and avoid a dry-heating event. By measuring the electrical parameter of the porous body, the likelihood of a dry-heating event is reduced.

[0023] The measurement contacts may be arranged on opposite surfaces of the porous body such that the measurement contacts can measure the electrical parameter across the porous body.The measurement contacts may be arranged on the surface of the porous body.The measurement contacts may be arranged on opposite sides of the surface of the porous body such that the measurement contacts can measure the electrical parameter across the porous body.

[0024] The measurement contacts may be spaced apart from one another in a direction aligned or parallel to the porous outer surface. The porous body may have a liquid absorption side and an aerosolization side. The measurement contacts may be disposed on the aerosolization side of the porous body.

[0025] The electrical parameter may be indicative of electrical resistance.

[0026] The electrical parameters can be used to determine whether the porous body or protective layer has been supplied with enough liquid aerosol-forming substrate. Values ​​for the electrical parameters can be stored in the memory of the aerosol-generating system. By comparing the electrical parameters with one or more values ​​stored in the memory, the aerosol-generating system can determine whether the electric heating element has been supplied with enough liquid aerosol-forming substrate.

[0027] The electric heating element may be electrically connected to the electrical contacts. The electric heating element may be configured to heat the liquid aerosol-forming substrate when a potential difference is applied to the electrical contacts. The electric heating element may have one or more of a curvilinear or serpentine shape. The electric heating element may include an electrically resistive heating element. The electric heating element may be made of any suitable electrically conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. An example of a suitable doped ceramic includes doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable alloys include stainless steel, constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timetal®, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. Electric heating elements may be made from stainless steel, for example, 300 series stainless steels such as AISI 304, 316, 304L, and 316L.

[0028] Additionally, the electric heating element may include a combination of the above materials. A combination of materials may be used to improve control of the resistance of the electric 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 and chemical parameters. Advantageously, high resistance heating allows for more efficient use of battery energy.

[0029] According to certain embodiments of the present disclosure, there is provided a cartridge for an aerosol generation system. The cartridge may include a heater assembly. 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.

[0030] According to one embodiment of the present disclosure, there is provided a cartridge for an aerosol generation system, the cartridge including a heater assembly, a liquid reservoir configured to hold a liquid aerosol-forming substrate, the liquid reservoir being disposed opposite a porous outer surface of the heater assembly.

[0031] According to certain embodiments of the present disclosure, an aerosol generation system is provided. The aerosol generation system may include a cartridge. The aerosol generation system may include a power source for supplying power to the electric heating element. The aerosol generation system may include a control circuit configured to control the supply of power from the power source to the electric heating element. The control circuit may be further configured to receive a signal from the measurement contact and determine, based on the signal, whether a liquid aerosol-forming substrate is supplied to the electric heating element.

[0032] According to one embodiment of the present disclosure, there is provided an aerosol generation system, the aerosol generation system comprising a cartridge, a power supply for supplying power to an electric heating element, and a control circuit configured to control the supply of power from the power supply to the electric heating element, the control circuit being further configured to receive a signal from the measurement contact and determine, based on the signal, whether a liquid aerosol-forming substrate is supplied to the electric heating element.

[0033] The electrical parameter may be greater than a maximum threshold or less than a minimum threshold, indicating that the amount of liquid aerosol-forming substrate supplied to the electric heating element is below a threshold amount. The maximum threshold may be a maximum threshold indicating resistance. The maximum threshold is 7×10 based on a distance between the glycerol aerosol-forming substrate and the measurement contacts of 7 mm. 7 This can be related to a maximum threshold resistance value in ohms. The maximum threshold is 7×10 based on a glycerol aerosol-forming substrate and a distance between the measurement contacts of 7 mm. 7 The maximum threshold resistance may be in ohms. The minimum threshold may be the minimum threshold value indicating conductance. The minimum threshold may be (1 / 7) x 10 -7 It can be related to the Siemens minimum threshold conductance value. The minimum threshold is (1 / 7) x 10 -7 It may be a minimum threshold conductance value in Siemens ohms.

[0034] The controller may be configured to prevent power from being supplied to the electric heating element if no liquid aerosol-forming substrate is supplied to the electric heating element or if the liquid aerosol-forming substrate in the electric heating element falls below a threshold amount.

[0035] According to an embodiment of the present disclosure, there is provided a method for controlling heating in an aerosol-generating system including a heater assembly. 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 along a porous outer surface of the porous body. A protective layer may be disposed to extend over at least a portion of the electric heating element to protect the electric heating element. The heater assembly may include measurement contacts disposed to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element. The method may include measuring an electrical parameter of the heater assembly between the measurement contacts to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element.

[0036] According to one embodiment of the present disclosure, there is provided a method for controlling heating in an aerosol-generating system including a heater assembly. The heater assembly includes an electric heating element for heating a liquid aerosol-forming substrate to form an aerosol. The heater assembly includes a porous body for supplying the liquid aerosol-forming substrate to the electric heating element. The electric heating element is disposed along a porous outer surface of the porous body. A protective layer is disposed to extend over at least a portion of the electric heating element to protect the electric heating element. The heater assembly includes measurement contacts disposed to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element. The method includes measuring the electrical parameter of the heater assembly between the measurement contacts to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element.

[0037] The sufficient amount of liquid aerosol-forming substrate may be an amount that provides an electrical connection between the measurement contacts. This electrical connection may be achieved without shorting, i.e., the aerosol-forming substrate may form a path for an electric current between the measurement contacts. The sufficient amount of liquid aerosol-forming substrate in the porous body may be an amount that generates enough aerosol to allow a user to inhale at least one time. The sufficient amount of liquid aerosol-forming substrate in the porous body is preferably an amount that generates enough aerosol to allow a user to inhale at least five times. The sufficient amount of liquid aerosol-forming substrate in the porous body may be 0.3 mg to 32.5 mg, preferably 1.5 mg to 32.5 mg. The sufficient amount of liquid aerosol-forming substrate in the porous body may be at least 20 mg, preferably at least 30 mg. The sufficient amount of liquid aerosol-forming substrate in the porous body may be 32.5 mg. The sufficient amount of liquid aerosol-forming substrate on the protective layer may be an amount that generates enough aerosol to allow a user to inhale once. The sufficient amount of liquid aerosol-forming substrate on the protective layer may be 0.3 mg to 15 mg, preferably 10 mg to 15 mg. The sufficient amount of liquid aerosol-forming substrate on the protective layer may be at least 1 mg, preferably at least 5 mg, more preferably at least 10 mg.

[0038] The method may include determining an indication of one or more of the absence of the liquid aerosol-forming substrate, the presence of the liquid aerosol-forming substrate, and the amount of the liquid aerosol-forming substrate based on the electrical parameter measurement.

[0039] The method can include preventing power from being supplied to the electric heating element upon determining a low amount of liquid aerosol-forming substrate within the porous body.

[0040] The method may include preventing power from being supplied to the electric heating element upon detecting the absence of the liquid aerosol-forming substrate within the porous body.

[0041] The porous body may have a very high electrical resistance when dry. The porous body may have a liquid absorption side and an aerosolization side. An electrical heating element may be disposed along the aerosolization side of the porous body. The porous body may be configured to supply a liquid aerosol-forming substrate from the liquid absorption side to the aerosolization side of the porous body. The porous body may be a ceramic body. The porous body may be an open-pore body, i.e., it may include a plurality of interconnected open pores. The porous body may define a series of capillaries. The porous body may be fabricated by sintering. The porous body may be fabricated by directly sintering ceramic powder to form a porous body with pores between interconnected powder particles. The porous body may be fabricated by using a sacrificial material within the ceramic powder, where the sacrificial material is used as a spacer to form the pores. The sacrificial material may be burned off during sintering.

[0042] The protective layer may have a very high electrical resistance when dry. The protective layer may include or consist of an inorganic material. The protective layer may be disposed so as to substantially cover the porous body. The protective layer may have a maximum electrical resistance of 1×10 per cm. -11 The protective layer may have an electrical conductivity of up to 1 x 10 per cm. -14 The protective layer may have an electrical conductivity of 1 x 10 per cm. -14 The protective layer may have an electrical conductivity of up to 1 x 10 per cm. -12 The protective layer may have an electrical conductivity of 1 x 10 per cm. -12 It may have Siemens electrical conductivity.

[0043] The aerosol generating system may be portable. The aerosol generating system may have a size comparable to that of a conventional cigar or cigarette.

[0044] The aerosol generating device may contain a control circuit. The control circuit 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 circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application-specific integrated chip (ASIC) or other electronic circuit capable of providing control. The control circuit may be configured to continuously power the electric heating element after activation of the device, or to provide power intermittently, such as after each puff. Power may be supplied to the electric heating element in the form of current pulses, for example, by pulse-width modulation (PWM). The control circuit may include additional electronic components. For example, in some embodiments, the control circuit may include a sensor element, a switch element, or a display element.

[0045] The aerosol generating device may contain a power source in the form of a battery. The battery may be rechargeable. 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 many cycles of charging and discharging. The power source may have a capacity that allows for sufficient energy storage for one or more user experiences with the aerosol generating system; for example, the power source may have a capacity sufficient to allow continuous generation of aerosol for approximately six minutes, corresponding to the typical time it takes to smoke one conventional cigarette, or a multiple of six minutes. In another example, the power source may have a capacity sufficient to allow for a predetermined number of puffs or discontinuous operation of the aerosol generating system.

[0046] The aerosol generating device may include a housing. The housing may be elongated. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is lightweight and not brittle.

[0047] The cartridge may be removably connectable to the aerosol generating device.

[0048] The cartridge of the aerosol generation system may have a connecting end. At the connecting end, the cartridge may be connected or connectable to an aerosol generation device. The connecting end of the cartridge may have electrical contacts that are electrically connectable to electrical contacts on the aerosol generation device. The cartridge may include one or more of a mouthpiece, a cartridge body, an external air inlet, an internal air passage, and an aerosol outlet.

[0049] The mouthpiece may be connected or connectable to the cartridge body. The mouthpiece may be connected or connectable to the cartridge body so as to define one or more external air inlets between the mouthpiece and the cartridge body. The mouthpiece may be disposed at an end of the cartridge body. The mouthpiece may be disposed at an end of the cartridge body opposite the connected end. The mouthpiece may include an aerosol outlet.

[0050] The cartridge body may include a heater assembly. The cartridge body may include a liquid reservoir. The heater assembly may be located adjacent to or at the connecting end. The liquid reservoir may be located between the heater assembly and the mouthpiece.

[0051] The liquid reservoir may be disposed on a first side of the heater assembly. The 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. The airflow path may extend through the electric heating element. The airflow path may be configured to transmit the aerosol. The cartridge body may be configured so that airflow passing through the heater assembly entrains vaporized aerosol-forming substrate. The cartridge may be configured so that air can flow from outside the system, through the external air inlet, and into the cartridge body. The cartridge may be configured so that the air can then flow toward the connecting end. At the connecting end, the air may be directed to turn back and flow through the center of the cartridge. In doing so, the airflow may pass through the heater assembly. At the heater assembly, the air may be combined with the aerosol. The cartridge may be configured so that, after being combined with the aerosol, the airflow passes through the center of the cartridge to the mouthpiece. The airflow may then pass out through the aerosol outlet opening.

[0052] The mouthpiece may include an internal baffle. The internal baffle may be integrally molded with the outer wall of the mouthpiece portion. The baffle may ensure that as air is drawn from the inlet to the aerosol outlet opening, it flows over a heater assembly on the cartridge where the aerosol-forming substrate is vaporized. As the air passes over the heater assembly, the vaporized substrate is entrained in the airflow and may cool before exiting the aerosol outlet opening, forming an aerosol.

[0053] Features described with respect to one of the above embodiments may equally be applied to other embodiments of the present disclosure. [Example]

[0054] The present invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0055] Example 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 a liquid aerosol-forming substrate to an electric heating element, the electric heating element being disposed along a porous outer surface of the porous body; a protective layer disposed to extend over at least a portion of the electric heating element to protect the electric heating element. Example 2: 10. The heater assembly of claim 1, further comprising a measurement contact arranged to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element. Example 3: 3. The heater assembly of any one of claims 1 to 2, wherein the protective layer comprises an inorganic material. Example 4: The protective layer is up to 1 x 10 per cm -11 The heater assembly of any of Examples 1-3 having an electrical conductivity of Siemens. Example 5: The protective layer is up to 1 x 10 per cm -12 The heater assembly of any of Examples 1-4, having an electrical conductivity of Siemens. Example 6: The heater assembly of any one of Examples 2 to 5, wherein the electrical parameters are electrical parameters of the protective layer. Example 7: 7. The heater assembly of any of Examples 2-6, wherein the measurement contacts are positioned on a surface of the protective layer on opposite sides of the surface of the protective layer such that the measurement contacts can measure an electrical parameter across the protective layer. Example 8: The heater assembly of any of Examples 2 to 7, wherein the electrical parameters are electrical parameters of the porous body. Example 9: The protective layer is up to 1 x 10 per cm -12 The heater assembly of any of Examples 1-8 having an electrical conductivity of Siemens. Example 10: The protective layer is up to 1 x 10 per cm -14 The heater assembly of any of Examples 1-9 having an electrical conductivity of Siemens. Example 11: The heater assembly of any one of Examples 1 to 10, wherein the porous body comprises a fired ceramic material. Example 12: 12. The heater assembly of any of Examples 2-11, wherein the measurement contacts are positioned on opposing surfaces of the porous body such that the measurement contacts can measure an electrical parameter across the porous body. Example 13: The heater assembly of any one of Examples 2 to 12, wherein the electrical parameter is electrical resistance. Example 14: 14. The heater assembly of any one of Examples 1-13, wherein the electric heating element is electrically connected to an electrical contact. Example 15: 15. The heater assembly of example 14, wherein the electrical heating element is configured to heat the liquid aerosol-forming substrate when an electrical potential difference is applied across the electrical contacts. Example 16: 1. A cartridge for an aerosol generation system, comprising: A heater assembly according to any one of Examples 1 to 15; a liquid reservoir configured to hold a liquid aerosol-forming substrate; The cartridge, wherein the liquid reservoir is disposed opposite the porous outer surface of the heater assembly. Example 17: 1. An aerosol generating system comprising: A cartridge according to Example 16, a power supply for supplying power to the electric heating element; An aerosol generation system comprising: a control circuit configured to control the supply of power from the power source to the electric heating element, the control circuit further configured to receive a signal from the measurement contact and determine, based on the signal, whether a liquid aerosol-forming substrate is being supplied to the electric heating element. Example 18: The aerosol-generating system of Example 17, wherein the electrical parameter is greater than a maximum threshold or less than a minimum threshold, indicating that less than a threshold amount of liquid aerosol-forming substrate is supplied to the electric heating element. Example 19: The maximum or minimum threshold is at least 1 x 10 per centimeter measured across the measurement contact. ~10 The aerosol generating system described in Example 18 associated with the Siemens minimum conductivity. Example 20: The maximum or minimum threshold is at least 1 x 10 per centimeter measured across the measurement contact. -9 The aerosol generating system described in Example 19, associated with the Siemens minimum conductivity. Example 21: The maximum or minimum threshold is at least 1 x 10 per cm measured across the measurement contact. -8 The aerosol generating system described in Example 20 associated with the Siemens minimum conductivity. Example 22: The maximum or minimum threshold is at least 1 x 10 per cm measured across the measurement contact. -7 The aerosol generating system described in Example 21 associated with the Siemens minimum conductivity. Example 23: 23. An aerosol generating system according to any one of Examples 17 to 22, wherein the controller is configured to prevent power from being supplied to the electric heating element when no liquid aerosol-forming substrate is supplied to the electric heating element. Example 24: 24. An aerosol-generating system according to any one of Examples 17 to 23, wherein the controller is configured to prevent power from being supplied to the electric heating element when the amount of liquid aerosol-forming substrate within the porous body is below a threshold amount. Example 25: 1. A method for controlling heating in an aerosol generating system comprising a heater assembly, comprising: The heater assembly an electric heating element for heating the liquid aerosol-forming substrate to form an aerosol; a porous body for supplying a liquid aerosol-forming substrate to an electric heating element, the electric heating element being disposed along a porous outer surface of the porous body; a protective layer disposed over at least a portion of the electric heating element to protect the electric heating element; a measurement contact arranged to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is being supplied to the electric heating element; The method is measuring an electrical parameter of the heater assembly between measurement contacts to detect whether a liquid aerosol-forming substrate is supplied to the electric heating element. Example 26: 26. The method of example 25, comprising determining an indication of one or more of the absence of the liquid aerosol-forming substrate, the presence of the liquid aerosol-forming substrate, and the amount of the liquid aerosol-forming substrate based on the electrical parameter measurements. Example 27: 27. The method of example 26, wherein determining one or more indications of the absence of the liquid aerosol-forming substrate, the presence of the liquid aerosol-forming substrate, or the amount of the liquid aerosol-forming substrate comprises comparing the measured electrical parameter with one or more predetermined reference parameters. Example 28: 28. The method of claim 26 or 27, wherein the one or more predetermined reference parameters are the absence of a liquid aerosol-forming substrate, the presence of a liquid aerosol-forming substrate, or a resistance or conductance value indicative of the amount of liquid aerosol-forming substrate. Example 29: A method according to any one of Examples 26 to 28, comprising preventing power from being supplied to the electric heating element upon determining that the amount of liquid aerosol-forming substrate in the porous body is small. Example 30: 30. The method of any one of Examples 26 to 29, comprising preventing power from being supplied to the electric heating element upon determining that the amount of liquid aerosol-forming substrate on the protective layer is low. Example 31: The small amount of liquid aerosol-forming substrate is 1 x 10 per cm across the measurement contact. -8 The method of example 30, as determined by measuring an electrical parameter indicative of an electrical conductivity of less than Siemens. Example 32: 32. The method of any of examples 26 to 31, comprising preventing power from being supplied to the electric heating element upon detecting the absence of the liquid aerosol-forming substrate within the porous body. Example 33: 33. The method of any of examples 26-32, comprising preventing power from being supplied to the electric heating element upon detecting the absence of the liquid aerosol-forming substrate on the protective layer. Example 34: In the absence of a liquid aerosol-forming substrate, the aerosol concentration is 1 x 10 per cm across the measurement contact. -11 The method of any of Examples 26 to 33, determined by a measurement showing an electrical conductivity of less than Siemens.

[0056] The embodiments will now be further described with reference to the figures. [Brief explanation of the drawings]

[0057] [Figure 1] FIG. 1 is a schematic diagram of a heater assembly according to an embodiment of the present disclosure, in which measurement contacts are disposed on a protective layer. [Figure 2] FIG. 2 is a schematic diagram of a heater assembly according to an embodiment of the present disclosure, in which the measurement contacts are disposed on the porous body. [Figure 3] FIG. 3 is a schematic diagram of a cartridge having a heater assembly according to one embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic diagram of an aerosol generation system according to one embodiment of the present disclosure. [Figure 5] FIG. 5 is a flow chart illustrating a method for controlling heating in an aerosol generating system according to one embodiment of the present disclosure. [Figure 6] FIG. 6 is an electrical circuit illustrating the conversion of electrical resistance measurements into electrical signals. DETAILED DESCRIPTION OF THE INVENTION

[0058] The above and other features and advantages of the exemplary embodiments will become more apparent from the detailed description of the exemplary embodiments with reference to the accompanying drawings. However, the specific structural and functional details disclosed herein are merely representative for the purpose of describing the exemplary embodiments. However, the exemplary embodiments may be embodied in many alternative forms and should not be construed as being limited to only the embodiments set forth herein.

[0059] Thus, while exemplary embodiments are susceptible to various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that there is no intention to limit the exemplary embodiments to the particular forms disclosed, but on the contrary, the exemplary embodiments are intended to cover all modifications, equivalents, and alternatives falling within the scope of the exemplary embodiments. Like numerals refer to like elements throughout the description of the figures.

[0060] Spatial relationship terms (e.g., "below") may be used herein for ease of description to describe the relationship between one element or feature and another element or feature as shown in the figures. It should be understood that the spatial relationship terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures were turned upside down, an element described as "below" another element or feature would then be oriented "above" the other element or feature. Thus, the term "below" may encompass both an above and below orientation. The device may be oriented otherwise (rotated 90 degrees or at other orientations), and the spatial relationship descriptors used herein will be interpreted accordingly.

[0061] When an element or layer is referred to as "disposed on" another element or layer, it should be understood that the element or layer may be directly on, directly connected to, directly bonded to, or directly covering the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as "disposed directly on" another element or layer, there are no intervening elements or layers present.

[0062] The terminology used herein is for the purpose of describing various embodiments only and is not intended to limit example embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be further understood that the terms "includes," "including," "comprises," and "comprising," when used herein, specify the presence of stated features, integers, steps, operations, or elements, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, or groups thereof.

[0063] The exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the exemplary embodiments. As such, variations from the illustrated shapes, resulting, for example, from manufacturing techniques or tolerances, are expected. Thus, the exemplary embodiments should not be construed as limiting the shapes of regions illustrated herein and include deviations in shape that result, for example, from manufacturing. Accordingly, the regions illustrated in the figures are schematic in nature, and their shapes are not intended to represent the actual shape of a region of a device and are not intended to limit the scope of the exemplary embodiments. Like reference numerals refer to like elements throughout the figures. The accompanying drawings should not be considered to be drawn to scale unless expressly noted. It is understood that the drawings in the present application are schematic, and that some features have been omitted for clarity.

[0064] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the exemplary embodiments belong. It will be further understood that terms (including terms defined in commonly used dictionaries), unless expressly so defined herein, should be interpreted to have a meaning consistent with the meaning of those terms in the context of the relevant art, and not in an idealized or overly formal sense.

[0065] The accompanying drawings are intended to illustrate exemplary embodiments and are not to be construed as limiting the scope of the intended claims.

[0066] 1, a schematic diagram of a heater assembly 100 for an inductively heated aerosol generation system according to one embodiment of the present disclosure is shown. The heater assembly 100 comprises an electric heating element 120, a porous body 110, a protective layer 140, and measurement junctions 150, an electrical circuit 160, an electrical parameter measuring device 170, and a control circuit (not shown for clarity).

[0067] Porous body 110 is configured to supply the liquid aerosol-forming substrate to electric heating element 120. Specifically, porous body 110 is configured to transfer the liquid aerosol-forming substrate from a liquid reservoir (not shown in FIG. 1 for clarity) to electric heating element 120. Porous body 110 is configured to store a portion of the liquid aerosol-forming substrate until it is aerosolized by electric heating element 120.

[0068] The porous body 110 is a rectangular block. The porous body 110 includes a plurality of open pores. The plurality of open pores are interconnected to provide a fluid path for the aerosol-generating liquid through the porous body 110. The porous body 110 includes a material that does not chemically interact with the liquid aerosol-forming substrate. The porous body 110 includes a ceramic. The porous body 110 includes Ca2SiO3 or SiO2 (or Ca2SiO3 and SiO2). It will be understood that the porous body 110 may have different shapes or include different materials.

[0069] The electric heating element 120 is configured to heat the liquid aerosol-forming substrate to form an aerosol. The electric heating element 120 is configured to convert electrical energy into thermal energy and then into electrical current, via the material resistance of the electric heating element 120.

[0070] The electric heating element 120 is elongated. The electric heating element 120 comprises NiCr or TiZr (or NiCr and TiZr). It will be appreciated that the electric heating element 120 may have a different shape or may comprise a different material.

[0071] The electric heating element 120 is disposed along the porous outer surface of the porous body 110. The electric heating element 120 is in direct contact with the porous body 110. The electric heating element 120 is disposed on a single surface of the porous body 110.

[0072] The electric heating element 120 is electrically connected to the electrical contacts 130. The electric heating element 120 is configured to heat the liquid aerosol-forming substrate as an electric potential difference is applied to the electrical contacts 130. The electrical contacts 130 are disposed at each end of the elongated electric heating element 120. The electrical contacts 130 are disposed directly on the same surface of the porous body 110 as the electric heating element 120. The electrical contacts 130 comprise CuZnAu. The electrical contacts 130 are disposed on opposite edges of the porous outer surface of the porous body 110. The electrical contacts 130 are aligned with opposite edges of the porous outer surface of the porous body 110.

[0073] The protective layer 140 is disposed to extend over at least a portion of the electric heating element 120 to protect the electric heating element 120. The protective layer 140 is configured to protect the electric heating element 120 to extend the life of the electric heating element 120. The protective layer 140 is configured to prevent the electric heating element 120 from oxidizing.

[0074] The protective layer 140 is planar. The protective layer 140 has a size and shape configured to cover the electric heating element 120. The protective layer 140 is configured to completely cover the surface of the electric heating element 120. The protective layer 140 is configured to substantially cover the porous body 110 below the electric heating element 120. The protective layer 140 comprises an inorganic material such as Al2O3, SiO2, MgO, BaO, CaO, ZrO2, or ZnO. It will be understood that the protective layer 140 may have a different shape or may comprise a different material.

[0075] The protective layer 140 is disposed along the electric heating element 120. The protective layer 140 is in direct contact with the electric heating element 120. The protective layer 140, the electric heating element 120, and the porous body 110 are disposed such that the electric heating element 120 is between the protective layer 140 and the porous body 110.

[0076] The measurement contacts 150 are disposed directly on the surface of the protective layer 140 on opposite sides of the surface of the protective layer 140 such that the measurement contacts 150 can measure an electrical parameter across the protective layer 140. The measurement contacts 150 are arranged to enable measurement of an electrical parameter of the heater assembly 100 to detect whether a sufficient amount of liquid aerosol-forming substrate is supplied to the electric heating element 120.

[0077] Two measurement contacts 150 are provided. The measurement contacts 150 are identical to one another in terms of material, shape and size. The measurement contacts 150 are attached to the protective layer 140. The measurement contacts 150 extend from the inorganic protective layer 140.

[0078] An electrical circuit 160 is provided to interconnect the measurement contacts 150 via an electrical parameter measuring device 170, which in this example is a device configured to measure the electrical resistance between the measurement contacts 150. The electrical circuit 160 is configured to measure electrical resistance up to 0.1×10 7 It can measure down to ohms.

[0079] In this example, the electrical parameter measured across the measurement contact 150 is an electrical parameter of the protective layer 140. In this example, the electrical parameter represents the electrical resistance across the protective layer 140. The protective layer 140 is configured to have a very low electrical conductivity, so that the resistance measurement across the measurement contact 150 in the absence of liquid is high, corresponding to an open circuit measurement. As mentioned above, the porous body 110 may comprise SiO2, which has a porosity of 1×10 -12 When a liquid film is present on the protective layer, the resistance measurement across the measurement contact 150 will measurably decrease due to the high conductivity of the liquid. The liquid may have an electrical conductivity of, for example, 0.1×10 -6 The liquid may include propylene glycol, which may have an electrical conductivity of 0.06×10 -6The protective layer 140 may include glycerol, which may have an electrical conductivity of 0.05%. Thus, the electrical resistance measured across the protective layer 140 indicates whether liquid is present on, at, or within the protective layer 140. The electrical resistance measured across the protective layer 140 may decrease as the amount of liquid on, at, or within the protective layer increases.

[0080] The control circuitry (not shown in FIG. 1 for clarity) is configured to only allow power to the electric heating element 120 if the resistance measurement indicates that liquid is present on, at, or within the inorganic protective layer 140. This has the advantage of reducing the likelihood that a user will experience dry heating or a dry puff when using the aerosol generating device.

[0081] 2, there is shown a heater assembly 100 for an aerosol generating system according to a second embodiment of the present disclosure. The heater assembly 100 comprises an electric heating element 120, a porous body 110, a protective layer 140, and measurement contacts 150, an electric circuit 160, an electric parameter measuring device 170, and a control circuit (not shown for clarity).

[0082] The electric heating element 120, porous body 110, and protective layer 140 are as described in connection with the embodiment shown in FIG.

[0083] The measurement contacts 150 of the second embodiment are positioned directly on opposing surfaces of the porous body 110 such that the measurement contacts 150 can measure electrical parameters across the porous body 110 .

[0084] Two measurement contacts 150 are provided. The measurement contacts 150 are identical to one another in terms of material, shape and size. The measurement contacts 150 are attached to the porous body 110. Each measurement contact 150 extends along the side of the porous body 110 on which it is located.

[0085] An electrical circuit 160 is provided to interconnect the measurement contacts 150 via an electrical parameter measuring device 170, which in this embodiment is a device configured to measure the electrical resistance between the measurement contacts 150.

[0086] In this example, the electrical parameter measured across the measurement contacts 150 is an electrical parameter of the porous body 110. In this example, the electrical parameter is indicative of the electrical resistance across the porous body 110. The electrical resistance across the porous body 110 is indicative of whether liquid is present on or within the porous body 110. If liquid is present on or within the porous body 110, the electrical resistance measured across the porous body 110 will be significantly lower than if no liquid is present. The electrical resistance measured across the porous body 110 may decrease as the amount of liquid within the porous body 110 increases.

[0087] 3 and 4, there is shown a schematic diagram of an exemplary aerosol generation cartridge 400 and a schematic diagram of an exemplary aerosol generation system 600. The aerosol generation system 600 comprises two main components: the cartridge 400 and the main body or aerosol generation device 500.

[0088] The aerosol-generating cartridge 400 includes a heater assembly 100 and liquid reservoirs 430, 435 configured to hold a liquid aerosol-forming substrate, the liquid reservoirs 430, 435 being disposed opposite the porous outer surface of the heater assembly.

[0089] The aerosol-generating system 600 comprises the cartridge 400, a power supply 510 for supplying power to the heating element, and a control circuit 520 configured to control the supply of power from the power supply 510 to the heating element, the control circuit 520 being further configured to receive a signal from the measurement contact and determine, based on the signal, whether a liquid aerosol-forming substrate is being supplied to the porous body, the electrical parameter measured by the measurement contact being greater than a maximum threshold or less than a minimum threshold, indicating that less than a threshold amount of liquid aerosol-forming substrate is being supplied to the porous body.

[0090] The connecting end 415 of the cartridge 400 is removably connected to a corresponding connecting end 505 of the aerosol generation device 500. The connecting end 415 of the cartridge 400 and the connecting end 505 of the aerosol generation device 500 each have cooperatively arranged electrical contacts or connections (not shown) to provide an electrical connection between the cartridge 400 and the aerosol generation device 500. The aerosol generation device 500 includes a power source in the form of a battery 510, which in this embodiment is a rechargeable lithium-ion battery, and a control circuit 520. The aerosol generation system is portable and has a size comparable to that of a conventional cigar or cigarette. A mouthpiece 425 is disposed at the end of the cartridge 400 opposite the connecting end 415.

[0091] The cartridge 400 comprises a housing 405 containing the heater assembly 100 of FIG. 1 or 2 and a liquid storage compartment or portion having a first storage portion 430 and a second storage portion 435. A liquid aerosol-forming substrate is held in the liquid storage compartment. Although not shown in FIG. 3 or 4, the first storage portion 430 of the liquid storage compartment is connected to the second storage portion 435 of the liquid storage compartment such that liquid in the first storage portion 430 can transfer to the second storage portion 435. The heater assembly 100 receives liquid from the second storage portion 435 of the liquid storage compartment. At least a portion of the porous body of the heater assembly 100 extends into the second storage portion 435 of the liquid storage compartment and contacts the liquid aerosol-forming substrate therein.

[0092] Airflow passages 440, 445 extend through the cartridge 400 from an air inlet 450 formed in the side of the housing 405, past the electric heating element of the heater assembly 100, and from the heater assembly 100 to a mouthpiece opening 410 formed in the housing 405 at the end of the cartridge 400 opposite the connecting end 415.

[0093] The components of the cartridge 400 are arranged so that the first storage portion 430 of the liquid storage compartment is between the heater assembly 100 and the mouthpiece opening 410, and the second storage portion 435 of the liquid storage compartment is positioned opposite the mouthpiece opening 410 of the heater assembly 100. In other words, the heater assembly 100 is positioned between the two portions 430, 435 of the liquid storage compartment and receives liquid from the second storage portion 435. The first storage portion 430 of the liquid storage compartment is closer to the mouthpiece opening 410 than the second storage portion 435 of the liquid storage compartment. Airflow passages 440, 445 extend past the electric heating element of the heater assembly 100 and between the first storage portion 430 and the second storage portion 435 of the liquid storage compartment.

[0094] The aerosol generation system is configured so that negative pressure can be applied at the mouthpiece 425 of the cartridge, drawing aerosol out through the mouthpiece opening 410. In operation, when negative pressure is applied at the mouthpiece 425, air is drawn from the air inlet 450 through the airflow passages 440, 445, past the heater assembly 100, and into the mouthpiece opening 410. A control circuit 520 controls the supply of power from the battery 510 to the cartridge 400 when the system is activated. This, in turn, controls the amount and characteristics of vapor produced by the heater assembly 100. The control circuit 520 may include an airflow sensor (not shown), and may supply power to the heater assembly 100 when a puff by the user is detected by the airflow sensor. This type of controller is well established in aerosol generation systems such as inhalers and e-cigarettes. When negative pressure is applied to the mouthpiece opening 410 of the cartridge 400, the heater assembly 100 is activated and generates vapor that is entrained in the airflow passing through the airflow passage 440. The vapor cools within the airflow in the passage 445, forming an aerosol that is then drawn through the mouthpiece opening 410 and into the user's mouth.

[0095] In operation, the mouthpiece opening 410 is typically the highest point in the system. The structure of the cartridge 400, and in particular the placement of the heater assembly 100 between the first storage portion 430 and the second storage portion 435 of the liquid storage compartment, is advantageous because it uses gravity to ensure that liquid substrate is delivered to the heater assembly 100 even as the liquid storage compartment begins to empty, but prevents oversupply of liquid to the heater assembly 100, which could lead to leakage of liquid into the airflow passage 440.

[0096] A method for controlling heating in an aerosol generating system is shown in the flow chart of Figure 5. The heater assembly controlled by this method comprises: an electric heating element for heating the liquid aerosol-forming substrate to form an aerosol; a porous body for supplying a liquid aerosol-forming substrate to an electric heating element, the electric heating element being disposed along a porous outer surface of the porous body; a protective layer disposed over at least a portion of the electric heating element to protect the electric heating element; and measurement contacts arranged to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is being supplied to the electric heating element.

[0097] In a first step 61, the method involves measuring an electrical parameter of the heater assembly between measurement junctions to detect whether a liquid aerosol-forming substrate is supplied to the electrical heating element.

[0098] In a second step 62, the method includes determining an indication of one or more of the absence of liquid aerosol-forming substrate, the presence of liquid aerosol-forming substrate, and the amount of liquid aerosol-forming substrate based on the electrical parameter measurement.

[0099] In a third step 63, the method includes preventing power from being supplied to the electric heating element upon determining that there is a small amount of liquid aerosol-forming substrate within the porous body.

[0100] In a fourth step 64, the method includes preventing power from being supplied to the electric heating element upon detecting the absence of a liquid aerosol-forming substrate within the porous body.

[0101] The third step 63 may be performed without the fourth step 64. Likewise, the fourth step 64 may be performed without the third step 63. It will be understood that the method need not be performed in the order of the steps shown in FIG.

[0102] Figure 6 shows in more detail a schematic circuit diagram of a portion of the control circuit 520 of the aerosol generation system of Figure 4. The circuit 200 of Figure 6 is used to determine one or more electrical parameters of the heater assembly.

[0103] The circuit 200 includes a resistance R corresponding to or equivalent to the resistance of the protective layer or porous body between two measurement contacts 210, 211, which is connected to a power supply via a connection 202. Z The power supply provides a voltage Vin. An additional resistor R of known value is connected to the heater R Z Resistor R Z and a known resistor R form a voltage divider. Z and an additional resistor R, a voltage V is applied to point Z of the circuit 200. Z There exists a voltage V Z is midway between ground and voltage Vin.

[0104] The circuit 200 includes a resistor R Z In this example, the electrical parameters are the resistance R Z An analog input 204 on the microcontroller MCU is used to monitor the voltage Vin provided by connection 202. An analog input 206 on the microcontroller MCU is used to monitor the voltage Vin at point Z. Z The analog input 206 is connected to the analog-to-digital converter (ADC) input of the microcontroller MCU. Z To measure the resistance of Z current through and resistance R Z The voltage across the resistor R is then determined using Ohm's law. Z Determine.

[0105] Resistance R Z The voltage across the Z and the resistance R Z The current through the resistor R is I. Z The resistance of can be determined by Equation 1: R Z =V Z / I (1)

[0106] The current through a known resistor R is Zis the same as the current through resistor R because the resistors are connected in series. Z The current through is current I. As mentioned above, resistor R has a known value. The voltage across resistor R is Vin - V Z By applying Ohm's Law, the current through resistor R can be determined by Equation 2: I=Vin-V Z / R (2)

[0107] So, combining (1) and (2), we get: R Z =(V Z / (Vin-V Z ))xR (3)

[0108] Therefore, when the aerosol generating system is in use, the microprocessor MCU can measure Vin and Vz and, knowing the value of resistor R, calculate the resistance R Z The resistance of the

[0109] The microprocessor MCU is configured to prevent power from being supplied to the electric heating element if no liquid aerosol-forming substrate is supplied to the porous body or if the amount of liquid aerosol-forming substrate in the porous body is below a threshold amount.

[0110] The microprocessor calculates the measured resistance R H By determining the inverse of , the electrical conductance can be determined.

[0111] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± ten percent (10%) of A. Within this context, the number A may be considered to include a numerical value that is within the typical standard error for measurement of the property that it modifies. In some instances, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

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 along a porous outer surface of the porous body; a protective layer disposed over at least a portion of the electric heating element to protect the electric heating element; and measurement contacts arranged to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is being supplied to the electric heating element.

2. The heater assembly of claim 1 , wherein the electrical parameter is an electrical parameter of the protective layer.

3. 3. The heater assembly of claim 1 or claim 2, wherein the measurement contacts are positioned on opposite sides of a surface of the protective layer such that the measurement contacts can measure the electrical parameter across the protective layer.

4. The heater assembly of claim 1 , wherein the electrical parameter is an electrical parameter of the porous body.

5. 5. The heater assembly of claim 1 or claim 4, wherein the measurement contacts are positioned on opposing surfaces of the porous body such that the measurement contacts can measure the electrical parameter across the porous body.

6. The heater assembly of any one of claims 1 to 5, wherein the electrical parameter indicates electrical resistance.

7. 7. The heater assembly of claim 1, wherein the electric heating element is electrically connected to electrical contacts, the electric heating element being configured to heat the liquid aerosol-forming substrate when a potential difference is applied to the electrical contacts.

8. 1. A cartridge for an aerosol generation system, comprising: A heater assembly according to any one of claims 1 to 7; 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.

9. 1. An aerosol generating system comprising: A cartridge according to claim 8, and An aerosol generating device, comprising: a power source for supplying power to the electric heating element; an aerosol generating system comprising an aerosol generating device, the aerosol generating device comprising: a control circuit configured to control the supply of power from the power source to the electric heating element, the control circuit further configured to receive a signal from the measurement contact and determine, based on the signal, whether a liquid aerosol-forming substrate is being supplied to the electric heating element.

10. 10. The aerosol generating system of claim 9, wherein the electrical parameter is greater than a maximum threshold or less than a minimum threshold, indicating that less than a threshold amount of liquid aerosol-forming substrate is supplied to the porous body.

11. 11. The aerosol generating system of claim 9 or claim 10, wherein the controller is configured to prevent power from being supplied to the electric heating element when no liquid aerosol-forming substrate is supplied to the porous body or when the amount of liquid aerosol-forming substrate in the porous body is below a threshold amount.

12. 1. A method for controlling heating in an aerosol generating system comprising a heater assembly, comprising: the heater assembly: 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 along a porous outer surface of the porous body; a protective layer disposed over at least a portion of the electric heating element to protect the electric heating element; and a measurement contact arranged to enable measurement of an electrical parameter of the heater assembly to detect whether a sufficient amount of liquid aerosol-forming substrate is being supplied to the electric heating element; The method comprises: measuring the electrical parameter of the heater assembly between the measurement contacts to detect whether a liquid aerosol-forming substrate is being supplied to the electric heating element.

13. 13. The method of claim 12, comprising determining an indication of one or more of the absence of a liquid aerosol-forming substrate, the presence of a liquid aerosol-forming substrate, and an amount of a liquid aerosol-forming substrate based on the electrical parameter measurements.

14. 14. The method of claim 13, comprising preventing power from being supplied to the electric heating element upon determining that there is a small amount of liquid aerosol-forming substrate within the porous body.

15. 15. A method according to claim 13 or claim 14, comprising preventing power from being supplied to the electric heating element upon detecting the absence of a liquid aerosol-forming substrate within the porous body.

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