Aerosol-forming device and method for detecting user inhalation

Abstract

An aerosol-forming device for forming aerosol from a substrate of an aerosol-forming article is described, which comprises a dielectric heater arrangement configured to heat, in a puff-on- demand heating operation, at least a part of a substrate of an aerosol-forming article by dielectric heating to form aerosol, and control circuitry configured to control the dielectric heater arrangement, wherein the control circuitry is further configured to detect a user inhalation at the aerosol-forming device based on determining one or more of a change in at least one operational parameter of the dielectric heater arrangement, and a change in a power consumption of the dielectric heater arrangement.

Description

[0001] P 17562

[0002] FTR4075 1 / 68

[0003] AEROSOL-FORMING DEVICE AND METHOD FOR DETECTING USER INHALATION The present disclosure generally relates to the field of aerosol-forming devices and systems for generating aerosol, also referred to as aerosol-generating devices and aerosol-generating systems. In particular, the present disclosure relates to an electronic aerosol-forming device and an electronic aerosol-forming system configured to generate or form aerosol, for example aerosol inhalable by a user in one or more user inhalations or puffs. Further, the present disclosure relates to a method of detecting a user inhalation at an aerosol-forming device or system.

[0004] Aerosol-forming or aerosol-generating devices are typically designed as handheld devices that can be used by a user for consuming or experiencing, for instance in one or more user inhalations or puffs, for example in a puff-on-demand operation or puff-on-demand heating operation, aerosol generated from an aerosol-forming substrate or an aerosol-forming article. Therein, aerosol is typically generated by heating at least a part of the substrate to a certain temperature sufficient to release aerosol from the substate, also referred to as volatilization or vaporization temperature. The aerosol-forming devices the present disclosure pertains to are, in particular, directed to the field of e-vapor devices, e-cigarettes, and vaporizers as well as heated tobacco products (HTP), heat-not-burn (HNB) devices, tobacco and tobacco-substitute products. The aerosol-forming devices according to aspects of the present disclosure may also pertain to other types of inhalers, dispensers, or atomizers, for example inhalers, dispensers, or atomizers for medical or pharmaceutical applications.

[0005] Typical aerosol-forming systems can be designed as one-part systems or devices including an aerosol-forming device that can be operated by a user to generate aerosol, for example from a removable or non-removable aerosol-forming article. Alternatively, aerosol-forming systems can be designed as two-part systems or devices comprising an aerosol-forming device and a companion device for storing and / or charging the aerosol-forming device. In either design or configuration, the aerosol-forming system or device can be used by a user for consuming or inhaling, for instance in one or more user inhalations or puffs, aerosol generated based on heating an aerosol-forming substrate of an aerosol-forming article couplable or fixedly attached to the aerosol-forming system. In the context of the present disclosure, an aerosol-forming device can refer to both a one-part device and a two-part device, unless explicitly specified otherwise.

[0006] The aerosol-forming article, also referred to as aerosol-generating article, can comprise an aerosol-generating or aerosol-forming substrate. Therein, the aerosol-forming substrate may include a liquid material, a solid material, or both liquid and solid material. Exemplary aerosolforming substrates can comprise solid substrate material with one or more ingredients, such as tobacco material, tobacco cast leaves (TCL) material or cannabis-based material. The substrate material can, for example, be assembled, often with other elements or components, to form a substantially stick, rod, cylinder, tab, or cuboid-shaped aerosol-forming substrate or article.P 17562

[0007] FTR4075 2 / 68

[0008] However, other designs and configurations are also possible. Other exemplary aerosol-forming substrates include a liquid with one or more ingredients that can be vaporized.

[0009] The liquid, solid or a mixed-form of solid and liquid aerosol-forming substrate may contain one or more ingredients, active ingredients or active agents, which may be vaporized during an inhalation, user inhalation or puff and inhaled by the user in one or more user inhalations. A user inhalation or inhalation is synonymously and interchangeably used herein with “puff” of the user. Exemplary ingredients of the aerosol-forming article or substrate include nicotine, nicotine-containing substances, water, aroma, sugar, moisturising agent, botanicals, preservative, flavouring, for example cocoa, liquorice, menthol and lactic acid or other additives or ingredients. Other exemplary ingredients of the aerosol-forming substrate include one or more pharmaceutical agents, one or more drugs, one or more adjuvants or other active agents. Accordingly, the aerosol formed from a corresponding substrate may contain one or more of these ingredients, active ingredients or active agents and / or may be inhalable by the user in one or more user inhalations. In addition, the aerosol-forming substrate can include an aerosol former, for example but not limited to propylene glycol, polypropylene glycol (PG), vegetable glycerin (VG), polyethylene glycol (PEG), glycerol esters, triacetin, or other aerosol former.

[0010] The aerosol-forming article may be configured in shape and size to be inserted at least partially into the aerosol-forming device or system. In conventional systems or devices, the aerosol-forming article can be at least partly inserted into a heating volume, heating cavity, receiving space, or heating chamber of the aerosol-forming device for aerosol consumption. Alternatively or additionally, aerosol-forming substrates can comprise one or more liquids and / or solids, which can, for example, be supplied to the aerosol-forming device in the form of a cartridge, capsule, pod, reservoir, or container. Corresponding exemplary aerosol-forming articles can comprise a cartridge having a reservoir containing or being fillable with the liquid and / or solid substrate, which can be vaporized during aerosol consumption by the user based on heating the substrate and / or liquid. Usually, such cartridge or container can be removably coupled to, attached to or at least partially inserted into the aerosol-forming device. Alternatively, the cartridge may be fixedly mounted to the aerosol-forming device and refilled by inserting liquid and / or solid into the cartridge.

[0011] For generating the aerosol during use or consumption, heat can be supplied by a heating element, heater device, heater arrangement or heat source to heat at least a portion or part of the aerosol-forming substrate. At least a part of the heater arrangement can be arranged in the handheld device or a handheld part of the aerosol-forming device. Alternatively or additionally, at least a part of or the heater arrangement can be fixedly associated with or arranged within an aerosol-forming article which can be attached to and / or powered by the handheld device or handheld part of the aerosol-forming device.P 17562

[0012] FTR4075 3 / 68

[0013] Dielectric heating arrangements have been proposed to heat and vaporize the one or more ingredients of the aerosol-forming substrate, by subjecting the substrate to an alternating electric field, taking advantage of dielectric properties of the aerosol-forming substrate.

[0014] Typically, aerosol-forming devices comprise an energy storage, for example a rechargeable energy storage, providing the electrical energy needed to operate the aerosol-forming device and especially for heating the aerosol-forming substrate and / or article, for example to generate aerosol using one or more aerosol-forming articles.

[0015] To actually store electrical energy, the energy storage may include one or more battery cells, one or more rechargeable battery cells, one or more accumulators, one or more capacitors, such as supercapacitors, or one or more other devices or components for storing electrical energy. Exemplary energy storages may include a plurality of rechargeable battery cells, such as for example between two and ten, preferably between two and four battery cells. Further, exemplary re-chargeable battery cells may be based on lithium-ion battery cells. For example, a cathode material may comprise lithium-cobalt-oxide (LCO), lithium-manganese-oxide (LMO), lithium-nickel-manganese-cobalt-oxide (NMC or NCM), lithium-iron-phosphate (LFP), and / or lithium-nickel-cobalt-aluminium-oxide (NCA). Alternatively or additionally, an anode material may comprise carbon (e.g. graphite), silicon and / or lithium-titanate-oxide (LTO).

[0016] The aerosol-forming device the present disclosure pertains to may, for example, refer to a handheld, battery-powered, lightweight and / or portable device. However, the present disclosure is not limited in this respect, but can be implemented in various forms and designs of aerosolforming devices and systems.

[0017] In the context of the present disclosure, the aerosol-forming device and / or the aerosolforming system may be a portable device and / or system. It may be battery powered. Particularly, the aerosol-forming device and / or the aerosol-forming system may be pocket-size, hand-held, suitable for one-hand use and / or may weigh less than 300 g, preferably less than 200 g. It may be shaped and / or sized to fit snugly into a user’s hand. It may be carried in jacket and / or trouser pockets. Particularly, the aerosol-forming device and / or the aerosol-forming system may be configured to provide aerosol for human inhalation and / or human consumption, particularly inhalation and / or consumption through the mouth.

[0018] For puff-on-demand operations, also referred to as puff-on-demand heating operations or response-to-draw operation, of aerosol-generating devices and systems, a puff triggering mechanism is usually required, for example by the user manually activating the puff or inhalation, or by a puff detection sensor that can detect when the user is taking a puff or inhalation. However, the use of manual activation is not favored by many users, as being imprecise with respect to the puff timing, and can lead to dry burning of liquid transfer elements or parts of the aerosol-forming substrate, for example when heat is generated during the moments where the user does not takeP 17562

[0019] FTR4075 4 / 68

[0020] a puff. With respect to automated detection, the puff detection sensor can become clogged or otherwise impeded to thereby cease proper operation. Also, it requires additional components for the aerosol forming device or system, that leads to additional costs and complexity.

[0021] Therefore, it may be desirable to provide for an improved aerosol-forming device, system and corresponding method, which at least partly mitigates or overcomes the aforementioned drawbacks of puff detection of conventional systems and devices. In particular, the aerosolforming device, system and method described herein may enable or allow for an improved control of the device, for example a control in accordance with an actual use or operation of the device by a user.

[0022] These advantages may be achieved by the features described herein.

[0023] Aspects of the present disclosure relate to an aerosol-forming device, an aerosol-forming system, and to a method of detecting a user inhalation at an aerosol-forming device or system. It is noted that any disclosure presented herein with reference to an or one aspect of the present disclosure, equally applies to any other aspect of the present disclosure, unless explicitly stated otherwise. In particular, it is emphasized that any disclosure presented herein with respect to an aerosol-forming device equally applies to an aerosol-forming system comprising such aerosolforming device and optionally a charger case or companion device.

[0024] According to an aspect, there is provided aerosol-forming device, also referred to herein as aerosol-generating device, for forming aerosol from a substrate of an aerosol-forming article. The aerosol-forming device comprises a dielectric heater arrangement configured to heat or dielectrically heat at least a part of a substrate of an aerosol-forming article by or based on dielectric heating to form aerosol. Therein, the dielectric heater arrangement may be configured to perform a puff-on-demand or response-to-draw heating operation. Alternatively, the dielectric heater arrangement and / or aerosol-forming device may be configured for session-based heating, for performing a session-based heating operation and / or for performing a session-based heating scheme. The aerosol-forming device further comprises a control circuitry configured to control the dielectric heater arrangement, wherein the control circuitry is configured to detect a user inhalation or puff at the aerosol-forming device based on determining one or more of a change in at least one operational parameter of the dielectric heater arrangement, and a change in a power consumption of the dielectric heater arrangement.

[0025] Accordingly, the detection of the user inhalation described herein can be implemented in an aerosol-forming device configured for puff-on-demand (or puff-based) heating and / or an aerosolforming device configured for session-based heating. In other words, the aerosol-forming device, control circuitry and / or dielectric heater arrangement can be configured for puff-based heating, puff-on-demand heating, and / or session-based heating.P 17562

[0026] FTR4075 5 / 68

[0027] Accordingly, the aerosol-forming device, respectively, the control circuitry thereof, can detect or determine the user inhalation based on one or more characteristics or parameters of the dielectric heater arrangement, for example without relying on manual activation of a puff triggering mechanism by a user and / or without necessarily relying on other components or sensors. Hence, an improved aerosol-forming device with improved detection means for detecting a user inhalation can be provided.

[0028] In some conventional aerosol-forming devices or systems, a dedicated puff sensor, for example a pressure sensor or flow sensor, is utilized to detect a user inhalation or puff at the aerosol-forming device. In the aerosol-forming device described herein, a reading or signal of such dedicated puff sensor can either be validated or checked for plausibility by additionally detecting the user inhalation based on one or more of the at least one operational parameter and the power consumption of the dielectric heater arrangement. Accordingly, the detection means to detect the user inhalation described herein can constitute a redundant puff detection means that supplements an existing puff sensor. This can, for example, allow improving reliability of the aerosol-forming device, and for example allow for operation of the device even in case the dedicated puff sensor fails. Alternatively, the aerosol-forming device may be configured to detect the user inhalation or puff solely based on the at least one operational parameter and / or the power consumption of the dielectric heater arrangement. Accordingly, a dedicated or separate puff sensor may not be required for detecting the user inhalation. As a consequence, space for the puff sensor in the aerosol-forming device may be saved, which may be of particular advantage when the aerosol-forming device is designed as handheld or battery-powered device. Also, an electrical power to operate the dedicated puff sensor may be saved, which can allow for energy efficient operation of the aerosol-forming device. This can be of particular advantage in case the aerosol-forming device is powered by a rechargeable or replaceable energy storage, for example including one or more battery cells.

[0029] Moreover, based on detecting the user inhalation based on determining a change in the at least one operational parameter and / or the power consumption of the dielectric heater arrangement, an operation or control of the device in accordance or correspondence with one or more user inhalations of the user may be enabled. For instance, control or operation of the dielectric heater arrangement may be synchronized with an inhalation pattern of the user based on determining the at least one operational parameter and the power consumption of the dielectric heater arrangement. In turn, this can enable an energy efficient operation of the device. Also, an improved aerosol quality or taste may be provided, for example across multiple user inhalations.

[0030] As used herein, detecting a user inhalation at the aerosol-forming device may refer to or include one or more of detecting an onset or start of the user inhalation, detecting that a user inhalation is being performed, detecting an occurrence of the user inhalation, detecting that theP 17562

[0031] FTR4075 6 / 68

[0032] user inhalation has been performed or has occurred, and detecting termination or an end of a user inhalation. In particular, the term “detecting the user inhalation” can include detecting one or more of an occurrence, an onset, a start, a duration, a termination or an end of the user inhalation.

[0033] In the context of the present disclosure, a "puff-on-demand" heating operation, also referred to as response-to-draw heating operation, can refer to a method of controlling the dielectric heater arrangement based on or in accordance with a user inhalation or puff being performed or occurring. For instance, the dielectric heater arrangement may be activated during or only during at least a part of or the user inhalation. Optionally, the dielectric heater arrangement may only be powered to a power level sufficient to generate aerosol during at least a part of the user inhalation. Puff-on-demand heating can be designed to optimize energy efficiency and, for example, enhance user experience by providing aerosol only when needed, thereby reducing unnecessary heating and potential degradation of the aerosol-forming substrate. A puff-on-demand heating operation of the aerosol-forming device, as used herein, may include or refer to operation of the aerosol-forming device, respectively, the dielectric heater arrangement, according to a puff-on-demand heating scheme.

[0034] As used herein, session-based heating, respectively, a session-based heating operation or session-based heating scheme can refer to an operation of the aerosol-forming device where the dielectric heater arrangement can maintain at least a part of an aerosol-forming substrate at an elevated temperature with respect to ambient temperature for a predetermined, for example continuous, period of time, which is also referred to as usage session. For example, the dielectric heater arrangement may be configured to continuously at least a part of an aerosol-forming substrate for a duration of the usage session. Accordingly, a usage session may have a fixed, predetermined and / or finite duration. Alternatively or additionally, a usage session may be associated with or defined by a maximum number of user inhalations. One or more aerosolforming articles may be experienced or used by the user in a single usage session.

[0035] Optionally, the aerosol-forming device and / or control circuitry may be configured to determine a number of user inhalations during one or more usage sessions based on determining one or more changes in one or more operational parameters and / or one or more changes in the power consumption.

[0036] As used herein, the dielectric heater arrangement may refer to a device configured to heat at least a part of the aerosol-forming substrate or article to generate aerosol through dielectric heating. Dielectric heating, generally, leverages electromagnetic or electric fields to induce heat in dielectric materials, which are typically non-conductive and can be polarized by an electric or magnetic field. This heating method exploits the ability of polar molecules within the substrate material to align with an alternating electric, magnetic or electromagnetic field. As the field alternates, these molecules continuously realign, causing molecular friction and dielectric loss,P 17562

[0037] FTR4075 7 / 68

[0038] which generates heat. This process is highly efficient for materials containing polar molecules, as is the case with aerosol-forming substrates.

[0039] The dielectric heater arrangement can operate according to different operation principles to dielectrically heat the aerosol-forming substrate. For example, the dielectric heater arrangement may include a resonant cavity, a transmission line, or both. The resonant cavity and / or transmission line may refer to a substantially closed and electrically conductive structure or chamber designed to contain and sustain electromagnetic waves, typically in the microwave frequency or radiofrequency range. The resonant cavity and / or transmission line may be shaped and configured to reflect electromagnetic waves, such that they may substantially remain confined within the resonant cavity and / or transmission line. The aerosol-forming substrate or article may be placed at least partly within this resonant cavity and / or transmission line and heated by the interaction of the electromagnetic waves with the substrate material.

[0040] Optionally, the dielectric heater arrangement may include an oscillator circuitry for generating and / or supplying electromagnetic waves to the resonant cavity and / or transmission line. In an exemplary configuration, the oscillator circuitry may comprise a wave generator, which may for example be coupled via an amplifier, coupler and / or impedance matching circuit to the resonant cavity and / or transmission line. The wave generator can also be referred to herein as radiofrequency generator.

[0041] Alternatively to a resonant cavity and / or transmission line, the dielectric heater arrangement may comprise a load capacitor with electrodes, for example one or more pairs of electrodes, between which at least a part of the aerosol-forming substrate can be placed or arranged. The electrodes can be operated, for example by the control circuitry and / or an oscillator circuitry, at a high-frequency or radiofrequency alternating current, such that a high-frequency or radiofrequency alternating electric or electromagnetic field can be generated between the electrodes to heat the substrate material by interaction with the alternating electric or electromagnetic field. It is emphasized that the present disclosure is not limited to a particular type of dielectric heater arrangement, but can be applied or used with any design or operation principle of the dielectric heater arrangement. Optionally, the dielectric heater arrangement may include an oscillator circuitry for generating the high-frequency or radiofrequency alternating electromagnetic field.

[0042] A frequency range of the electric or electromagnetic field in the load capacitor and / or a frequency range of the electromagnetic waves in the resonant cavity and / or transmission line may range from about 3 kHz to about 300 GHz. This frequency range may also be referred to as radiofrequency (RF) range. A sub-range of the RF range with frequencies of 3 MHz to about 30 MHz can be referred to herein as high-frequency (HF) range. Exemplary frequencies of the electromagnetic field I the resonant cavity may be about 2.45 GHz or 4.9 GHz.P 17562

[0043] FTR4075 8 / 68

[0044] The control circuitry, as used herein, may refer to a control means for controlling operation of the dielectric heater arrangement, and optionally one or more other functions of the aerosolforming device. The control circuitry may include one or more processors, for example a microcontroller unit (MCU), and / or one or more other processors. The control circuitry may generally be configured to execute programmed instructions, for example stored in a data storage or memory of the device, to manage the heating process of an aerosol-forming substrate or article based on controlling the dielectric heater arrangement, controlling power supply to the dielectric heater arrangement and / or controlling a power source or energy storage of the aerosol-forming device. The control circuitry may be implemented partly in software and partly in hardware. At least a part of the control circuitry and / or at least a part of its functionalities may be implemented as Application-Specific Integrated Circuit (ASIC), on a printed circuit board with one or more discrete components, as a microcontroller-based implementation, as Field-Programmable Gate Array (FPGA), or hybrid implementation using a combination thereof.

[0045] Further, as used herein, the at at least one operational parameter of the dielectric heater arrangement may generally refer to a parameter of the dielectric heater arrangement that is indicative of or related to an actual dielectric heating operation performed by the dielectric heater arrangement to heat a substrate. In particular, the at least one operational parameter may be indicative of a physical property or characteristic of one or more components of the dielectric heater arrangement, which one or more components can be involved in, directly involved in, or cause the heating of the substrate by dielectric heating.

[0046] The term power consumption of the dielectric heater arrangement may refer to the amount of electric energy consumed by the heater arrangement per unit time to heat the substrate material of the aerosol-forming article. Accordingly, the term power consumption can be synonymously or interchangeably used herein with energy consumption per time or unit time. The power consumption can, for example, be measured in watts and / or be representative or indicative of the rate at which electrical energy is converted into heat or thermal energy within the substrate material.

[0047] The aerosol-forming device may comprise one or more main air inlets or air inlets, through which a user can draw air into one or more air channels or airflow paths in the device. During user inhalation, the user may draw air from a surrounding or external environment of the aerosolforming device via the at least one main air inlet into the device. The drawn air may then be conveyed or guided via the one or more air channels, airflow path structures or airflow paths towards the dielectric heater arrangement. Therein, at least a part of the drawn air can flow past the dielectric heater arrangement. Alternatively or additionally, at least a part of the drawn air may flow through at least a part of the aerosol-forming article. For example, the aerosol-forming article may comprise an air inlet that can be coupled to one or more air channels of the device, such thatP 17562

[0048] FTR4075 9 / 68

[0049] air can enter the aerosol-forming article. The aerosol-forming article may further optionally comprise an air or aerosol outlet, where the drawn air, enriched with aerosol, can leave the aerosol-forming article towards the user’s mouth for inhalation.

[0050] The change in the at least one operational parameter and / or the change in the power consumption of the dielectric heater arrangement can be associated with or caused by a change in an airflow past or towards at least a part of the dielectric heater arrangement indicative of the user inhalation. This airflow that is induced by the user inhalation can lead to a cooling or decrease in temperature of at least a part of the dielectric heater arrangement, the aerosol-forming article or substrate. Further, when the user stops inhaling or the user inhalation terminates, the airflow may be reduced or may stop, which may cause a heating or increase in the temperature of at least a part of the of the dielectric heater arrangement, the aerosol-forming article or substrate. Due to these changes in temperature, specifically the decrease in temperature or increase in temperature that are induced by changes in the airflow, the at least one operational parameter and / or the power consumption of the dielectric heater arrangement can change or can be altered, which change can then be determined or detected by the control circuitry. Further, this change can act as indicator for the user inhalation, and thus can effectively be used by the control circuitry to detect the user inhalation, in particular one or more of start of the user inhalation, onset of the suer inhalation, occurrence of the user inhalation, termination of the user inhalation, end of the user inhalation and / or duration of the user inhalation.

[0051] The at least one operational parameter of the dielectric heater arrangement can include one or more of an impedance of a load of the dielectric heater arrangement, an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement, and a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the substrate of the aerosol-forming article. These operational parameters can be substantially influenced by temperature, which in turn allows for the detection of the user inhalation, for example due to the cooling caused by the user inhalation, as described in detail in the following.

[0052] In an exemplary configuration, the dielectric heater arrangement may include at least one of a resonant cavity and a transmission line. The resonant cavity and / or transmission line, for example together with the material contained or arranged therein, such as the aerosol-forming substrate, air and / or other material or medium, may form, constitute or define a “load” of the dielectric heater arrangement. Further optionally, also material or components of the aerosolforming device arranged in the vicinity of the dielectric heater arrangement, for example arranged in an influence area or volume of the alternating electromagnetic field, which may be referred to as dielectric heating zone, can contribute to or be part of the load of the dielectric heater arrangement. Accordingly, the load of the dielectric heater arrangement may refer to an electricalP 17562

[0053] FTR4075 10 / 68

[0054] load formed by at least one of the resonant cavity and the transmission line, optionally with material arranged in an influence area or volume of the alternating electromagnetic field.

[0055] Optionally, the dielectric heater arrangement may comprise an oscillator circuitry, for example comprising or being configured as a wave generator, which may for example be coupled via an amplifier, coupler and / or impedance matching circuit to the resonant cavity and / or transmission line. Accordingly, the oscillator circuitry may be configured to supply electromagnetic waves to the resonant cavity and / or transmission line, for example via a coupler and / or impedance matching circuit.

[0056] For example, when the aerosol-forming substrate or article is placed or situated at least partly in the resonant cavity and / or transmission line, the aerosol-forming substrate with the resonant cavity and / or transmission line can define the load of the dielectric heater arrangement. The load of the dielectric heater arrangement will change its impedance depending on the temperature of the load, for example upon cooling or heating, due to the temperature-induced change in the relative permittivity of the load, respectively, the material constituting the load. The change in the impedance of the load of the dielectric heater arrangement will cause a change of an oscillation frequency of the oscillator circuitry and / or wave generator thereof. Also, the change in the impedance of the load of the dielectric heater arrangement will cause a change in the power consumption. One or more of these changes in one or more operational parameters of the dielectric heater arrangement and / or the power consumption can be used by the control circuitry to detect the user inhalation at the aerosol-forming device, respectively, start, onset, duration, occurrence, termination and / or end thereof.

[0057] Specifically, the airflow from the puff or user inhalation can convey or transport air from the external environment of the aerosol-forming device, for example through a main air inlet towards or through a receiving space or heating chamber for removably receiving the aerosol-forming article. The substrate, for example a solid substrate or an e-liquid soaked into a liquid transfer element of a cartridge or pod that is exposed to a dielectric heating zone in the heating chamber or receiving space, can have an elevated temperature due to utilization of the device by the user and / or it can be pre-heated to a certain temperature above the room or ambient temperature, as will be described detail hereinbelow. In either case, also the walls of the device that form the receiving space or heating chamber, and the casing walls of the cartridge, pod or aerosol-forming article, can heat-up, for example due to their exposure to the radiofrequency electric or electromagnetic field of the dielectric heater arrangement, and hence have an elevated temperature compared to ambient temperature. Therefore, an airflow induced by the user’s inhalation will depart a certain degree of cooling to the components of the device and aerosolforming article, such as the casing walls of the aerosol-forming article, to the substrate via the casing wall of the cartridge, pod or aerosol-forming article, and to the walls that form the receivingP 17562

[0058] FTR4075 11 / 68

[0059] space or heating chamber. The wall or casing wall can be chosen to be very thin, even membrane like, to avoid having too much volume that can be dielectrically heated, which can allow for a certain cooling of the substrate, such as an e-liquid or solid substrate material. The cooling of these elements or components of the aerosol-forming device can lead to an effective change of the relative permittivity of material or components arranged in the vicinity of the dielectric heater arrangement, for example in the influence area or volume of the alternating electric or electromagnetic fields generated by the dielectric heater arrangement, which can include at least a part of the aerosol-forming article and / or substrate. Specifically, a decrease in temperature may lead to an increase in the relative permittivity. When the user stops inhaling, the airflow may be reduced or stopped, which may lead to a heating or increase in temperature of the dielectric heater arrangement as well as material and / or components arranged in the vicinity thereof. As a consequence, the relative permittivity of the load will change, in particular decrease with increasing temperature. These changes in the relative permittivity of the dielectric heater arrangement and / or of material or components surrounding or being arranged in the vicinity of the dielectric heater arrangement, which can include the aerosol-forming substrate and / or article, can lead to an effective change in at least one operational parameter and the power consumption of the dielectric heater arrangement, which can be detected to detect the user inhalations, for example, one or more of start, onset, termination or end thereof.

[0060] In an example, the aerosol-forming device may comprise an air channel, airflow path or duct fluidly coupled to an air inlet or main air inlet of the device, such that a user can draw air through the air inlet, into the airflow path and towards the dielectric heater arrangement. For instance, the airflow path may pass along a wall of the aerosol-forming article, for example a casing wall of a pod, cartridge or container. Accordingly, the wall may be arranged between the airflow path or air channel and at least a part of the dielectric heater arrangement and / or aerosol-forming article, such as a wicking element, liquid transfer element, reservoir and / or other components. When the user inhales, cool air having room or environmental temperature may be drawn through the airflow path or air channel and depart a cooling onto the wall as well as material or components arranged in the vicinity thereof, such as the wicking element, liquid transfer element, reservoir and / or other components of the aerosol-forming article and / or dielectric heater arrangement. Likewise, when the user stops inhaling, the temperature of these components or material may increase. Hence, via the airflow path or air channel, changes in temperature can be induced in the dielectric heater arrangement and / or aerosol-forming article or substrate in correspondence with the user inhalation, thereby enabling detection of the user inhalation, including its start, onset, occurrence, termination and end.

[0061] The wall between the airflow path or air channel and at least a part of the dielectric heater arrangement and / or aerosol-forming article may be arranged or configured to provide efficientP 17562

[0062] FTR4075 12 / 68

[0063] thermal coupling, thereby ensuring a fast response. Also, dielectric heating of the wall may be minimized. For example, the wall may be made of a low-dielectric, high-temperature, food grade microwave-safe material. As the wall may be in close range to dielectric heater arrangement and thus may be subjected to a high dielectric field strength, the wall may be made of a material that has a lower relative permittivity as the remaining parts.

[0064] For example, the wall can be made of or comprise a low dielectric material. Alternatively or additionally, a thickness of the wall may be small and / or the wall may be thin. For example, a thickness of the wall may range from about 2 mm to about 100 pm, in particular from about 1.5 mm to about 200 pm. Preferably, the thickness of the wall may be below about 1 mm, more preferably below about 500 pm. Accordingly, the wall may be thin, for example membrane-like, to ensure good thermal coupling.

[0065] Materials that can be used are for the wall can include, but are not limited to, Quartz glass, Polyether Ether Ketone (PEEK), Polyetherimide (PEI), hard plastic materials used for microwaveable food containers such as TritanTM (Bisphenol A (BPA)-free copolyester), BPA-free polycarbonates, high-density polyethylene (HDPE), siloxane, polysiloxane, polypropylene, Polyethylene, Terephthalate (PET, PETE).

[0066] For instance, in case the dielectric heater arrangement is configured with a load capacitor, the cooling of the walls, dielectric heater arrangement, aerosol-forming article and / or substrate can increase the relative permittivity of the substrate, which is located at least partly in the load capacitor for heating. Due to the increase in the relative permittivity, also the capacitance of the load capacitor increases or changes. This change or increase in the capacitance of the load capacitor can then be utilized or determined to detect the user inhalation, respectively, start, onset or occurrence thereof. Furthermore, the increase in capacitance of the load capacitor can lead to a decrease in an oscillation frequency of an oscillator circuitry and / or to an increase in the power consumption of the dielectric heater arrangement.

[0067] Similarly, in case the dielectric heater arrangement includes a resonant cavity and / or a transmission line that is configured to receive or hold at least a part of the substrate for heating and that is fed or supplied with HF or RF waves via an oscillator circuitry, an impedance of the load formed by the inserted substrate or article and the resonant cavity and / or transmission line can change due to the change in the relative permittivity of the substate material and other elements that are subjected to the airflow, which results from the decrease in temperate induced by the user inhalation. In particular an increase of the relative permittivity caused by the user inhalation and the associated cooling effect can lead to an increase in the impedance of the load. The change or increase in the impedance can then be utilized or determined to detect the user inhalation, respectively start, onset or occurrence thereof. Moreover, the dielectric heater arrangement can include an oscillator circuitry, optionally comprising a wave generator orP 17562

[0068] FTR4075 13 / 68

[0069] radiofrequency generator, for generating the radiofrequency electric or electromagnetic field. Due to the change or increase in the impedance of the load formed by the substrate and the resonant cavity and / or transmission line, also an oscillation frequency of the oscillator circuitry, wave generator or RF generator can change and / or a power consumption of the dielectric heater arrangement can change. Specifically, an increase in the impedance of the load may lead to a decrease in the oscillation frequency of the oscillator circuitry and / or an increase in the power consumption, which may be detected to determine start, onset and / or occurrence of the user inhalation. Also, this change or decrease in the oscillation frequency and / or the increase in the power consumption can be utilized or determined to detect the user inhalation, start or occurrence thereof.

[0070] Accordingly, the control circuitry can be configured to detect the user inhalation, start of the user inhalation and / or onset of the user inhalation based on determining one or more of an increase in an impedance of the load of the dielectric heater arrangement, a decrease of an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement, a decrease of an oscillation frequency of a wave generator of an oscillator circuitry of the dielectric heater arrangement, an increase in a capacitance of a load capacitor of the dielectric heater arrangement, and an increase in the power consumption of the dielectric heater arrangement. Also multiple of these parameters or characteristics may be utilized for puff detection or detecting start of a user inhalation, which may further increase precision and accuracy of the detection.

[0071] Generally, the term relative permittivity, also referred to as the dielectric constant, is a measure of how much a material can be polarized in an electric field compared to a vacuum, and in this sense how much energy the material can store. The relative permittivity is a dimensionless quantity that indicates the extent to which a material can concentrate electric flux and is defined as the ratio of the permittivity of the material to the permittivity of free space.

[0072] As used herein, the term “relative permittivity” may also be referred to as the real part of the complex, frequency-dependent relative permittivity, measured at a temperature of 20 degrees Celsius, in an alternating electric field at a very low frequency (VLF) of 1 Kilohertz or less, as defined in the international standard I EC 62631-2-1:2018. It will be appreciated that the frequency value of 1 Kilohertz is included here solely as a general reference and other definitions may use different frequencies.

[0073] The control circuitry can be configured to detect the user inhalation, an onset, a start and / or an end thereof based on determining a change of an impedance of the load of the dielectric heater arrangement, an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement, a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the aerosol-forming article, and the power consumption of the dielectric heater arrangement. As mentioned above, these parameters or characteristics of the dielectricP 17562

[0074] FTR4075 14 / 68

[0075] heater arrangement are substantially influenced by temperature or changes in temperature, and thus can reliably be used to detect the actual user inhalation at the aerosol-forming device.

[0076] The cooling effect caused by the airflow of the user inhalation towards or past at least a part of the dielectric heater arrangement can change or increase the relative permittivity of the substrate material that may be arranged at least partly in the dielectric heater arrangement, for example in a load capacitor, a resonant cavity and / or transmission line, and can also change the relative permittivity of some of the elements around the dielectric heating arrangement, for example the air or aerosol channels or ducts, an airflow path, casing or cartridge walls, or other elements in the vicinity of the dielectric heater arrangement. As a consequence, either the impedance of the load formed by the substrate and resonant cavity (and / or transmission line), or the capacitance of the load capacitor increases when the user starts inhaling. As the oscillation frequency of an oscillator circuitry, which for example comprises the load capacitor or resonant cavity and supplies it with an alternating electric or electromagnetic field, is indirectly proportional to the overall inductance and capacitance of the oscillator circuitry, also referred to as LC constant of the circuitry, the oscillation frequency of the oscillator circuitry decreases with increasing relative permittivity and / or decreasing temperature of the substrate and / or dielectric heater arrangement. With decreasing oscillation frequency, increasing capacitance and / or increasing impedance, also the resistive part of the oscillator circuitry or the entire dielectric heater arrangement, for example as seen from a DC side of the circuitry, increases, such that the power consumption of the dielectric heater arrangement increases due to the increase in the equivalent resistance of the circuitry or entire dielectric heater arrangement. The latter effect can allow to detect the user inhalation or start thereof based on determining a change, in particular an increase, in the power consumption of the dielectric heater arrangement, which can be caused by increasing heating losses occurring when the relative permittivity increases.

[0077] Accordingly, the control circuitry can be configured to detect the user inhalation at the aerosol-forming device, respectively its onset, duration, and / or start, based on determining one or more of an increase in an impedance of the load of the dielectric heater arrangement, a decrease of an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement, a decrease of an oscillation frequency of a wave generator of an oscillator circuitry of the dielectric heater arrangement, an increase in a capacitance of a load capacitor of the dielectric heater arrangement, and an increase in the power consumption of the dielectric heater arrangement. Also multiple of these parameters or characteristics may be utilized for puff detection or detecting start of a user inhalation, which may further increase precision and accuracy of the detection.

[0078] As noted above, the dielectric heater arrangement may comprise an oscillator circuitry, for example comprising or being configured as a wave generator, which may for example be coupled via a coupler and / or impedance matching circuit to the resonant cavity and / or transmissionP 17562

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[0080] line. The impedance matching circuit, can refer to a component configured to ensure that the maximum or optimal amount of power can be transferred from an oscillator circuitry or wave generator to the resonant cavity and / or transmission line, where the dielectric material can be heated. Based on the impedance matching circuit, reflections and losses in the transmission of an electromagnetic field, for example in the transmission line to the resonant cavity, can be minimized, thereby optimizing the efficiency of the heating process. If the impedance of the load of the dielectric heater arrangement changes due to a changing relative permittivity of the substrate caused by a change in temperature, the impedance matching circuit may adopt its impedance. Also this can be operatively controlled by the control circuitry, thereby enabling the control circuitry to detect the user inhalation based on determining the change in impedance of the load of the dielectric heater arrangement and / or the change in impedance of the impedance matching circuit. Accordingly, one or more of a change in impedance of the load and a change in impedance of the impedance matching circuit may be determined by the user inhalation to detect the user inhalation.

[0081] The control circuitry can be configured to determine the change in the at least one operational parameter and / or the power consumption of the dielectric heater arrangement based on two or more consecutive measurements of at least one operational parameter and / or the power consumption. Optionally, the control circuitry can be configured to perform the two or more measurements within a predetermined period of time or time window. Accordingly, two or more measurements may be performed at different times. For example, the control circuitry may be configured to perform two or more measurements of at least one operational parameter and / or the power consumption within a predetermined period of time of less than about 200 ms, for example less than about 100 ms, preferably less than about 50 ms, and even more preferably less than about 20 ms or even less than about 10 ms. This may allow for reliable and quick detection the start or onset of the user inhalation, as well as termination thereof. One or more predetermined periods of time may be stored in a data storage or memory of the device.

[0082] Further optionally, one or more threshold values for one or more changes in the at least one operational parameter and / or the power consumption of the dielectric heater arrangement may be utilized by the control circuitry to detect one or more user inhalations, in particular to detect one or more of a start or onset of the user inhalation, a duration of the user inhalation, a termination or end of the user inhalation, and an occurrence of the user inhalation. For example, the control circuitry may be configured to detect a user inhalation based on determining a change in the at least one operational parameter and / or the power consumption, which determined change reaches or exceeds one or more predefined threshold values for the change in the at least one operational parameter and / or power consumption, optionally within a predetermined period of time. Since changes in the at least one operational parameter and / or power consumptionP 17562

[0083] FTR4075 16 / 68

[0084] can include increases and decreases, either the same or different threshold values for an increase and decrease of the at least operational parameter and / or the power consumption can be utilized by the control circuitry, and for example stored in a data storage or memory thereof.

[0085] In an example, the control circuitry may be configured to determine or detect a start or onset of a user inhalation based on two or more consecutive measurements of one or more operational parameters and / or the power consumption of the dielectric heater arrangement, the two or more measurements being performed within a first period of time. Therein, the control circuitry may be configured to compute the difference between the two or more measured values of the at least one operational parameter and / or the power consumption, and for example compute one or more of an increase in the impedance, a decrease in the oscillation frequency, an increase in the capacitance of the load capacitor and an increase in the power consumption. Further, the control circuitry may be configured to compare the determined difference of one or more operational parameters and / or the power consumption to one or more first threshold values for the one or more operational parameters and / or the power consumption. Upon determining or confirming that the computed one or more differences reach or exceed the one or more threshold values, the control circuitry may determine or detect the user inhalation, respectively its start, onset or occurrence.

[0086] Further optionally, the control circuitry may be configured to determine or detect termination or the end of the user inhalation based on further two or more consecutive measurements of one or more operational parameters and / or the power consumption of the dielectric heater arrangement, the further two or more measurements being performed within a second period of time, which may be equal to or differ from the first period of time. Therein, the control circuitry may be configured to compute the difference between the two or more measured values of the at least one operational parameter and / or the power consumption, and for example compute one or more of a decrease in the impedance, an increase in the oscillation frequency, a decrease in the capacitance of the load capacitor and a decrease in the power consumption of the dielectric heater arrangement, and compare the difference to at least one second threshold value, which may be equal to or differ from the at least one first threshold value of the respective operational parameter and / or the power consumption. Upon determining or confirming that the computed one or more differences in one or more operational parameters and / or the power consumption reaches or exceeds the at least one threshold value, the control circuitry may determine or detect the user inhalation, respectively its termination or end. Further optionally, the control circuitry may compute a duration of the user inhalation based on time information associated with the determination of the increase and the decrease in the one or more operational parameters and / or the power consumption.FTR4075

[0087] 17 / 68

[0088] In an example, one or more relative threshold values for a relative change, decrease and / or increase in one or both the at least one operational parameter and the power consumption of the dielectric heater arrangement may be about 5% to about 50%, for example about 10% to about 30%, in particular about 15% to about 20%. In an example, the control circuitry can be configured to determine one or more of the change in said at least one operational parameter of the dielectric heater arrangement with respect to a reference value for said at least one operational parameter, and the change in the power consumption of the dielectric heater arrangement with respect to a reference value for the power consumption. One or more of such reference values may be stored in a data storage or memory of the aerosol-forming device. For example, one or more reference values for the at least one operational parameter and / or the power consumption may be experimentally determined in one or more calibration measurements at one or more predetermined temperatures. Accordingly, the reference values may map or associate the respective operational parameter or power consumption with an actual temperature of the dielectric heater arrangement or a substrate contained therein. Alternatively or additionally, a reference value may be provided by one of two or more measurements of said at least on operational parameter and / or the power consumption performed by the control circuitry to detect a change, respectively, a decrease or increase in the corresponding operational parameter and / or the power consumption, as described above.

[0089] Also, it is noted that the change in the at least one operational parameter and / or the power consumption can be determined by the control circuitry as a relative change, for example relative to the situation where no user inhalation occurs, such as at a time before or shortly before start of the user inhalation.. The value of the at least one operational parameter and / or the power consumption, for example when the device is pre-heated or ready for being used by the user and / or before the first user inhalation occurs, can be used as baseline or reference for detecting the actual change in the at least one operational parameter and / or the power consumption that occurs when the user performs a user inhalation. Accordingly, a change in the at least one operational parameter and / or a change in the power consumption can refer to a change of the respective operational parameter or power consumption occurring during the user inhalation with respect to or compared to the operational parameter or power consumption before start of the user inhalation, but preferably when the device is ready for being used in one or more user inhalations, for example when the device is pre-heated to a pre-heating temperature, as described in detail hereinbelow.

[0090] Accordingly, the one or more reference values for the at least one operational parameter and / or the power consumption can be determined or set by the control circuitry with the device being substantially at room temperature or being subject to the current local temperature and / or humidity conditions. This can allow to enhance the reliability of the detection of the change in theFTR4075

[0091] 18 / 68

[0092] at least one operational parameter and / or the user inhalation. Also, a detection reaction time that may be required to actually detect a user inhalation after its start can be consistent for different temperatures of the ambient air, respectively for different ambient conditions, including different air humidities, for example.

[0093] Further optionally, one or more threshold values for the change in the at least one operational parameter and / or the power consumption may be utilized by the control circuitry to detect the user inhalation. Hence, one or more relative threshold values for the change in the at least one operational parameter and / or the power consumption may be used. Based on or by determining that the change in the at least one operational parameter and / or the power consumption reaches or exceeds the one or more threshold values, the control circuitry may detect occurrence of the user inhalation. Alternatively or additionally, absolute threshold values for the at least one operational parameter and / or the power consumption may be used by the control circuitry to detect occurrence of the user inhalation at the aerosol-forming device.

[0094] In an example, the dielectric heater arrangement may comprise a resonant cavity and / or transmission line configured to receive at least a part of the aerosol-forming article or substrate, and optionally an oscillator circuitry configured to supply an electromagnetic field to the resonant cavity and / or transmission line to heat the aerosol-forming article or substrate. Therein, the control circuitry may be configured to detect the user inhalation at the aerosol-forming device based on determining a change in at least one of an impedance of a load of the dielectric heater arrangement, an oscillation frequency of the oscillator circuitry, and the power consumption of the dielectric heater arrangement. In particular, at least one of an increase of the impedance of the load, a decrease of the oscillation frequency, and an increase in the power consumption of the dielectric heater arrangement can be determined by the control circuitry to detect the start or onset of the user inhalation. Alternatively or additionally, one or more of a decrease of the impedance of the load, an increase of the oscillation frequency, and decrease in the power consumption of the dielectric heater arrangement can be determined by the control circuitry to detect the termination or end of the user inhalation.

[0095] In a further example, the dielectric heater arrangement may comprise a resonant cavity and / or transmission line configured to receive at least a part of the aerosol-forming article or substrate, and optionally an oscillator circuitry configured to supply an electromagnetic field to the resonant cavity and / or transmission line to heat the aerosol-forming article or substrate. Therein, the control circuitry may be configured to detect the user inhalation, for example start, onset, termination and / or end of the user inhalation, at the aerosol-forming device based on determining a change determining or detecting one or more of: a change of an impedance of the load formed by the resonant cavity and optionally the aerosol-forming article, a change of a Q-factor, a change of a resonance and / or anti-resonance frequency, a standing wave ratio (SWR), a change of SWR,FTR4075

[0096] 19 / 68

[0097] a reflection coefficient, a change in reflection coefficient, a frequency, an oscillation frequency, a change in a frequency, a change in an oscillation frequency, and a change in power consumption of the dielectric heater arrangement. Alternatively or additionally a change in any one or more operational parameters of the resonant cavity can be used to detect the user inhalation.

[0098] The control circuitry may be further configured to monitor specific electromagnetic characteristics or operational parameters of the dielectric heater arrangement. These parameters can provide high-precision indicators of the cooling effect induced by a user inhalation.

[0099] For example, the control circuitry may be configured to determine or detect a user inhalation by monitoring the reflection coefficient and / or the Standing Wave Ratio or Voltage Standing Wave Ratio (SWR), for example at an input of the resonant cavity. By way of example, an impedance matching circuit may be tuned to a baseline temperature for detecting a user inhalation. The cooling effect of the airflow induced by the user inhalation can increase the relative permittivity of the substrate, which can cause the impedance of the load to shift away from the matched state. This mismatch can result in an increase in the reflection coefficient and / or the SWR, as a larger portion of the supplied radiofrequency energy may be reflected back from the cavity. As the user stops inhaling, the temperature can increase, the impedance may return toward the matched baseline, and a corresponding decrease in the SWR or reflection coefficient can be determined by the control circuitry to detect termination of the user inhalation.

[0100] Alternatively or additionally, the control circuitry may monitor the Q-factor of the resonant cavity to detect user inhalation. The Q-factor, representing the ratio of energy stored to energy dissipated (e.g. per cycle), can be sensitive to the dielectric loss and relative permittivity of the material within the dielectric heater arrangement. The cooling induced by a user inhalation can alter or change the molecular friction and dielectric loss properties of the aerosol-forming substrate. A determined change in the Q-factor, for example a shift in the sharpness of the resonance peak, can serve as a trigger for the control circuitry to detect the start or end of a user inhalation.

[0101] Alternatively or additionally, the control circuitry may be configured to determine a change in the anti-resonance frequency (parallel resonance) of the dielectric heater arrangement. Similar to the resonance frequency or oscillation frequency, the anti-resonance frequency can be dependent on the effective capacitance and inductance of the load formed by the resonant cavity and optionally the substrate contained therein. The cooling-induced increase in relative permittivity can cause a downward shift in the anti-resonance frequency. The control circuitry can detect the onset of inhalation based on this decrease and detect the termination of inhalation based on a subsequent increase in the anti-resonance frequency as the system re-heats.

[0102] In another example, the dielectric heater arrangement may comprise an oscillator circuitry with a load capacitor, which may preferably be included in a feedback loop of the oscillatorP 17562

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[0104] circuitry and which may be configured to receive at least a part of the aerosol-forming article to heat the aerosol-forming substrate. Therein, the control circuitry may be configured to detect the user inhalation at the aerosol-forming device based on determining a change in one or more of an oscillation frequency of the oscillator circuitry, in a capacitance of the load capacitor and the power consumption of the dielectric heater arrangement. In particular, an increase in power consumption, an increase in the capacitance and / or a decrease in the oscillation frequency may be determined by the control circuitry in order to detect the start or onset of the user inhalation. Alternatively or additionally, one or more of a decrease in power consumption, a decrease in the capacitance and / or an increase in the oscillation frequency may be determined by the control circuitry in order to detect the termination or end of the user inhalation.

[0105] The control circuitry can further be configured to monitor or determine one or more of: an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency at a gate terminal of a transistor of the oscillator circuitry; an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency of a switching device of the oscillator circuitry; an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining an oscillation frequency of a wave generator of the oscillator circuitry; a frequency of an alternating magnetic or electric field in a load capacitor of the oscillator circuitry; an impedance of a load of the dielectric heater arrangement; an output voltage or current of a power supply of the aerosolforming device; and an input voltage or current supplied to the dielectric heater arrangement. Accordingly, a change in the oscillation frequency may, for example, be determined based on determining a change in a switching frequency at the gate terminal of a transistor of the oscillator circuitry, based on determining a change in a switching frequency of a switching device of the oscillator circuitry, based on determining a change in an oscillation frequency of a wave generator of the oscillator circuitry, and / or based on determining a change in the frequency of the alternating electric or magnetic field in the load capacitor. Further, the change in power consumption can be determined based on determining one or both a change in the voltage and a change in the current supplied to the dielectric heater arrangement.

[0106] The control circuitry may be configured to monitor or determine one or more of the aforementioned quantities or parameters continuously during use of the device for aerosol consumption, or repeatedly, for example with a comparatively high repetition frequency in the hertz to kilohertz or even Megahertz range. For instance, the repetition frequency may be at least 5 Hz to 10 Hz or more.

[0107] In an example, the control circuitry may be configured to monitor, determine, measure and / or sample, during at least a part of a user inhalation or one or more user inhalations, one or more of the at least one operational parameter of the dielectric heater arrangement, the powerP 17562

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[0109] consumption of the dielectric heater arrangement, the impedance of the load of the dielectric heater arrangement, the oscillation frequency of the oscillator circuitry of the dielectric heater arrangement, and the capacitance of a load capacitor of the dielectric heater arrangement. In this respect, the control circuitry together with the dielectric heater arrangement can perform sensing functions that would otherwise have to be performed by additional sensors, such as flow meters and pressure sensors. Optionally, also temperature values of the dielectric heater arrangement or other parameters correlating therewith may be monitored, determined, measured and / or sampled during at least a part of a user inhalation or one or more user inhalations. Optionally, corresponding data indicative of the timely evolution of the monitored or sampled one or more of the at least one operational parameter, the power consumption, the impedance of the load of the dielectric heater arrangement, the oscillation frequency of the oscillator circuitry of the dielectric heater arrangement, and the capacitance of a load capacitor of the dielectric heater arrangement may be recorded by the aerosol-forming device.

[0110] In a further optional implementation, the data indicative of the timely evolution of the monitored or sampled one or more of the at least one operational parameter, the power consumption, the impedance of the load of the dielectric heater arrangement, the oscillation frequency of the oscillator circuitry of the dielectric heater arrangement, and the capacitance of a load capacitor of the dielectric heater arrangement, for example recorded or sampled during at least a part of a user inhalation or one or more user inhalations, can be evaluated or analyzed by the control circuitry to determine one or more characteristics of one or more user. Such evaluation or analysis can optionally include spectral analysis of the sampled or measured values. For example, a first order derivative, a second order derivative and / or one or more higher orders of derivative with respect to time may be computed by the control circuitry to derive one or more characteristics of one or more user inhalations. By way of example, the control circuitry may be configured to determine one or more of a flow velocity, flow profile or speed of air drawn in one or more user inhalations, a duration of one or more user inhalations and / or usage sessions, a timing of one or more user inhalations, an air pressure during one or more user inhalations, an air volume drawn in one or more user inhalations and / or usage sessions, a puff duration, a puff rate, a puff frequency, or other parameters. Accordingly, a flow-sensor or other sensor may be implemented based on evaluating or analyzing data indicative of the timely evolution of the monitored or sampled one or more of the at least one operational parameter, the power consumption, the impedance of the load of the dielectric heater arrangement, the oscillation frequency of the oscillator circuitry of the dielectric heater arrangement, and the capacitance of a load capacitor of the dielectric heater arrangement, for example recorded or sampled during at least a part of a user inhalation or one or more user inhalations.P 17562

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[0112] The aerosol-forming substrate may be or comprise a liquid aerosol-forming substrate. Liquid substrates for aerosol-forming devices are also referred to as e-liquids. Exemplary liquid substrate materials can include Propylene Glycol or polypropylene glycol (PG) or Vegetable Glycerin (VG), polyethylene glycol (PEG), glycerol esters, triacetin, or other aerosol former which may optionally be used as carrier material in conjunction with a nicotine-containing solution, or other ingredients, such as flavorings or cannabinoid oils. It is emphasized, though, that the present disclosure is not limited to liquid substrate or substrate material, but can be applied to solid substrates or substrates containing solid substrate material in addition to liquid substrate material.

[0113] For liquid substrates, the aerosol-forming article can include a cartridge, pod or container, which can at least partly be filled with the liquid substrate, optionally with one or more further ingredients, including solid ingredients. The cartridge may, for example, include a reservoir or compartment configured to hold the liquid substrate. Further, the cartridge may include a wick or wicking element, also referred to a liquid transfer element, which can be configured or arranged for drawing the liquid from the reservoir to at least a part of the dielectric heater arrangement. Common materials used for the wicking element ca include organic cotton, silica, or ceramic. Generally, the wick or wicking element can ensure that the liquid substrate is consistently supplied to the dielectric heater arrangement for vaporization. Usually, a surface of the wicking element is exposed to or contacts the liquid substrate in the reservoir, such that substrate material can enter the wicking element, for example by capillary forces, diffusion, and / or osmotic forces. The surface exposed to or facing the liquid substrate is usually referred to as liquid ingress surface or area of the wicking element. A further surface or part of the wicking element, which is also referred to as vapor egress surface or area, can be arranged adjacent to, in contact with, or close to at least a part of the dielectric heater arrangement, such that the liquid substrate can be vaporized near or at the vapor egress surface and leave the cartridge or wicking element as vapor or aerosol to be inhaled by the user in one or more user inhalations.

[0114] The control circuitry can be configured to power the dielectric heater arrangement to a first power level for heating the substrate of the aerosol-forming article to a pre-heating temperature above ambient temperature and below a volatilization temperature of one or more ingredients of the substrate sufficient to release aerosol from the aerosol-forming article. Therein, the control circuitry may be configured to detect the user inhalation, in particular the start or onset of the user inhalation, during a time period where the dielectric heater arrangement is powered to the first power level. Alternatively or additionally, the control circuitry may be configured to power the dielectric heater arrangement at the first power level in order to detect the user inhalation, the start of the user inhalation and / or the onset of the user inhalation at the aerosol-forming device. For instance, the dielectric heater arrangement may be powered at the first power level while noP 17562

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[0116] puff or user inhalation occurs at the device, but optionally after start or activation of the device to be used for aerosol consumption by a user.

[0117] As used herein, “powering” the dielectric heater to the first power level may mean or include the provision of dielectric heating power at a first level. For example, power the dielectric heater to the first power level may include supplying electrical power to the dielectric heater arrangement at the first power level, such that the dielectric heater arrangement and / or at least a part of the substrate is heated to the pre-heating temperature, for example during a time where no puff is being taken. This can include one or more of supplying a voltage at a first power level and a current at a first level to the dielectric heater arrangement. Alternatively or additionally, this can involve adjusting a duty cycle of the dielectric heater arrangement, such that the dielectric heater arrangement and / or at least a part of the substrate is heated to the pre-heating temperature.

[0118] Further, powering the dielectric heater at a second power level may mean or include supplying electrical power to the dielectric heater arrangement at the second power level, such that the dielectric heater arrangement and / or at least a part of the substrate is heated to a target temperature, for example to at least the volatilization temperature or vaporization temperature. This can include one or more of supplying a voltage at a second power level and a current at a second level to the dielectric heater arrangement. Alternatively or additionally, this can involve adjusting a duty cycle of the dielectric heater arrangement, such that the dielectric heater arrangement and / or at least a part of the substrate is heated to the target temperature, for example to at least the volatilization temperature or vaporization temperature.

[0119] The volatilization temperature may also be referred to as vaporization temperature and may denote a temperature sufficient to vaporize one or more ingredients from the substrate. The preheating temperature may be selected such that the temperature of the dielectric heater arrangement is between an ambient temperature of the surrounding air and the volatilization temperature of the one or more ingredients of the substrate. Pre-heating above ambient or room temperature provides for the cooling effect or can ensure that a cooling effect can be departed by the user inhalation, which can then be detected by the control circuitry with high accuracy based on detecting a change in the at least one operational parameter and / or power consumption. Also, pre-heating below the volatilization temperature can ensure that no or no meaningful vaporization and / or degradation of the substrate material occurs at times where the user is not puffing or inhaling.

[0120] Moreover, pre-heating the dielectric heater arrangement for puff detection, respectively, for detecting the user inhalation, more specifically to detect a start of the inhalation or puff, can also allow having the aerosol-forming substrate at an elevated temperature above the room temperature before the puff or user inhalation, but still before any vaporization of the one or more ingredients of the substrate occurs. This can allow to shorten a response time for vaporizing theP 17562

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[0122] substance or substrate material, which can improve the user experience. In addition, a liquid substrate material can be brought into a less viscous state by the pre-heating, which can bring advantages for vaporization, liquid delivery and aerosol formation, for example on its way from the liquid ingress to the vapor egress surface of the wicking element or liquid transfer element.

[0123] Generally, the higher the pre-heating temperature of at least a part of the dielectric heater arrangement and / or substrate is relative to the environmental, ambient or room temperature, the better or faster may be the detection response for detecting the user inhalation or start thereof, because the cooling effect caused by the user inhalation increases with higher temperature difference or gradient between the incoming airflow drawn by the user and the dielectric heater arrangement or substrate. On the other hand, the lower the temperature difference or gradient is, the less energy may be required for the pre-heating. Accordingly, the pre-heating temperature should preferably be chosen to balance these effects.

[0124] The state of the aerosol-forming device, where the dielectric heater arrangement is preheated to the pre-heating temperature may also be referred to herein as “puff observation mode”, where the control circuitry can reliably and quickly detect occurrence of a user inhalation based on the change in at least one of the at least one operational parameter and the power consumption. Accordingly, the control circuitry may be configured to determine the change in at least one of the at least one operational parameter and the power consumption caused by or due to the user inhalation relative to or with respect to a value of the at least one operational parameter and / or the power consumption in the puff observation mode, respectively, when the dielectric heater arrangement is pre-heated to the pre-heating temperature, and for example no user inhalation occurred.

[0125] Pre-heating the aerosol-forming substrate or article to the pre-heating temperature, for example by powering the dielectric heater arrangement to the first power level, can significantly differ from a heat-up phase that may take place in aerosol-forming devices or systems that are configured to perform a continuous heating during a usage session, as is for example the case in many heat-not-burn aerosol-forming devices. In these devices, the aerosol-forming substrate is heated in a heat-up phase after start or activation of the device to a temperature above the volatilization temperature and is kept at a temperature above the volatilization temperature during the usage session. In contrast thereto, the aerosol-forming device described herein may be configured for puff-on-demand heating operation, session-based heating, or session-based heating operation, wherein the substrate and / or dielectric heater arrangement may be pre-heated to the pre-heating temperature, for example upon activation of the device, and operated to generate aerosol only during at least a part of the user inhalation. When heated to the pre-heating temperature no or no meaningful depletion of the substrate may occur, which may mean that noP 17562

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[0127] or substantially no aerosol is released from the substrate, because the pre-heating temperature is below the volatilization temperature.

[0128] By way of example, the pre-heating temperature may be above about 25°C, above about 30°C, preferably above about 40°C, more preferably above about 50°C, and even more preferably above about 60°C. Such temperatures may allow for an accurate detection of the user inhalation within a short period of time.

[0129] Alternatively or additionally, the pre-heating temperature may be below about 120°C, below about 100°C, preferably below about 90°C, more preferably below about 80°C, and even more preferably below about 70°C. Such temperatures may avoid degradation or vaporization of substrate material, such that substantially no or no meaningful depletion of the substrate occurs during the pre-heating or pre-heating time. Exemplary ranges for the pre-heating temperature may be about 50°C to about 100°C, preferably about 60°C to about 80°C, more preferably about 60°C and about 70°C.

[0130] Optionally, the control circuitry may be configured to determine the ambient temperature and adjust the pre-heating temperature in accordance with the ambient temperature. For instance, in cool areas or locations, a lower pre-heating temperature may be used compared to areas or locations with higher temperature.

[0131] The control circuitry may be configured to monitor or determine one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when the dielectric heater arrangement is powered to the first power level, alternatively or additionally, when the dielectric heater arrangement and / or substrate has reached the pre-heating temperature. For instance, the control circuitry may be configured to monitor or determine one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement upon powering the dielectric heater arrangement to the first power level and / or upon reaching the pre-heating temperature.

[0132] The control circuitry may be configured to power the dielectric heater arrangement to the first power level in response to one or more of:

[0133] a sensor signal of at least one sensor of the aerosol-forming device;

[0134] insertion of an aerosol-forming article at least partly into the aerosol-forming device; coupling of an aerosol-forming article to the aerosol-forming device;

[0135] mechanical decoupling of the aerosol-forming device from a companion device; and a control signal from one or more user interfaces triggered by a user of the aerosol-forming device. Such events or actions may reliably indicate the user’s intention to use the aerosol-forming device for aerosol consumption, and hence may constitute reliable triggers for the control circuitry to power the dielectric heater arrangement to the first power level.P 17562

[0136] FTR4075 26 / 68

[0137] In an example, one or more sensors configured to provide a sensor signal indicative of a potential imminent use of the aerosol-forming device for aerosol-consumption may be used to trigger powering the dielectric heater arrangement at the first power level. Such potential imminent use of the device may be indicative of a potential imminent user inhalation or puff taken by the user. Non-limiting examples of sensors that could be used for this purpose include, accelerometers, motion detection sensors, inertial sensors, gyroscopes, presence detection sensors, proximity detection sensors, near field sensors, touch sensors, capacitive sensors, temperature sensors such as surface temperature sensors, and others.

[0138] For example, the control circuitry can be configured to configure the device in a potential use mode, upon or in response to detecting one or more of the aforementioned events or actions. Therein, configuring the device into the potential use mode, or another mode of the device described herein, can include or refer to switching the device, by the control circuitry, into the respective mode. Optionally, this can comprise loading or setting one or more settings of the device.

[0139] Simultaneously or subsequently to configuring the aerosol-forming device in the potential use mode, the control circuitry can power the dielectric heater arrangement to the first power level to heat up at least a part of the dielectric heater arrangement to the pre-heating temperature. Further optionally, upon reaching the pre-heating temperature, the control circuitry may configure the device into the puff observation mode. One or more of entering the potential use mode and entering the puff observation mode may also be indicated to the user, for example via a user interface in the form of one or more of a visual, an acoustic, or a haptic signal.

[0140] In an example, the at least one sensor, based on which the control circuitry may power the dielectric heater arrangement to the first power level, can include one or more of a motion sensor, an accelerometer, for example but not limited to an inertial measurement unit (IMU), a gyroscope, an image sensor, a pyrometer, a presence sensor, a touch sensor or any other sensor or sensing means that allows to detect that the user intends using or moving the device for aerosol consumption and / or before starting aerosol consumption.

[0141] By way of example, the control circuitry can configure the device in the potential use mode in response to the user manually pressing a button, by automatic detection of use of the device based on a motion detector, such as an accelerometer, gyroscope, or camera with analysis of motion, or other type of motion detector such as pyrometer motion detector, detecting that the user has picked-up the device, presence detection of the user, touch detection, or proximity sensing to detect that the user has taken the device into his or her hands and / or is holding the device. It is also possible that the insertion of an aerosol-forming article triggers the potential use mode, or some other engagement of the aerosol-forming article with the receiving space, heating chamber or dielectric heater arrangement.P 17562

[0142] FTR4075 27 / 68

[0143] The control circuitry may further be configured to power the dielectric heater arrangement to the first power level based on supplying a first DC voltage to the dielectric heater arrangement that is smaller than a second DC voltage supplied by the control circuitry to the dielectric heater arrangement to heat the aerosol-forming article to form aerosol. Alternatively or additionally, the control circuitry may be configured to power the dielectric heater arrangement to the first power level based operating the dielectric heater arrangement at a first duty ratio that is smaller than a second duty ratio supplied by the control circuitry to the dielectric heater arrangement when powering the dielectric heater arrangement at a second power level, for example to heat the aerosol-forming article to form aerosol. The second power level may particularly refer to a power level, at which the dielectric heater arrangement can generate sufficient heat to release aerosol from the substrate. As the first power level is below the second power level, less energy may be consumed for the actual puff detection or detection of the user inhalation compared to energy consumption during a puff or user inhalation, where the dielectric heater arrangement is powered at the second power level. Further, less power or energy may be consumed by the device compared to powering the device always at the second power level that is also sufficient to generate aerosol. Overall, the device may be operated in an energy efficient manner. Hence, for example in case the device is battery-powered, more user inhalations may be granted to the user per fully charged battery or energy storage. In addition, degradation of the aerosol-forming article or substrate at times where no user inhalation occurs may be avoided, which can be beneficial in terms of taste and user experience.

[0144] The control circuitry may further be configured to, in response to detecting the user inhalation at the aerosol-forming device and / or start of the user inhalation, power the dielectric heater arrangement to a second power level for heating the aerosol-forming article to a volatilization temperature sufficient to release aerosol from the aerosol-forming article. In other words, as soon as or upon detecting, based on detecting the change in at least one of the at least one operational parameter and the power consumption of the dielectric heater arrangement, that a user inhalation occurs or starts, the control circuitry may supply an amount of electrical energy to the dielectric heater arrangement that is sufficient to heat at least a part of the heater arrangement and / or the substrate to the volatilization temperature, such that aerosol is released from the substrate and can be inhaled by the user.

[0145] In particular, the control circuitry may be configured to increase the heating power, power level, or energy supplied to the dielectric heater arrangement immediately upon detecting the occurrence or start of the user inhalation, for example to generate vapor and thereafter aerosol. The increase in the heating power from the first power level to the second power level can be implemented or provided in various ways. For example, a DC supply voltage to the dielectric heater arrangement may be increased by means of a DC-DC converter. Another way would beP 17562

[0146] FTR4075 28 / 68

[0147] to increase the duty cycle, for example by an immediate increase of the on time during periodic heating intervals. Other implementations, however, are possible and envisaged by the present disclosure.

[0148] For example, when powering the dielectric heater arrangement at the second power level, the temperature of the substrate can increase about 100°C within about 0.05 to 0.5 seconds, for example about 100°C within 0.2 seconds, preferably about 100°C within about 0.1 seconds.

[0149] In an example, the first power level can be below about 80%, below about 70%, below about 60%, below about 50%, below about 40%, below about 30%, below about 20%, below about 10%, below about 5%, or below about 2% of the second power level. Accordingly, powering the dielectric heater arrangement at the first power level to detect the user inhalation, may only require a fraction of the energy or power required to power the dielectric heater arrangement at the second power level during a puff to generate aerosol. Hence, a significant amount of electrical energy can be saved by this approach.

[0150] The control circuitry may further be configured to control a power supplied to the dielectric heater arrangement in response to detecting the user inhalation at the aerosol-forming device, such that the dielectric heater arrangement is maintained at the second power level and / or maintained at a temperature equal to or above the volatilization temperature. This can ensure that immediately after the user inhalation starts, inhalable aerosol is generated throughout the rest of the user inhalation. Hence, user experience and taste may be improved.

[0151] The control circuitry may further be configured to activate a further heater of the aerosolforming device to heat the aerosol-forming article in response to detecting the user inhalation at the aerosol-forming device. For example, a downstream convective heater may be arranged in the aerosol-forming device, which downstream convective heater may heat an airflow of air, for example drawn by the user during the user inhalation, towards the dielectric heater arrangement. Alternatively or additionally, one or more further heaters or heating devices may be arranged at the receiving space or heating chamber to provide supplementary heating for the dielectric heater arrangement or substrate.

[0152] The control circuitry may further be configured to determine whether the user inhalation has ended based on determining a further change in at least one of said at least one operational parameter of the dielectric heater arrangement and the power consumption of the dielectric heater. For example, the control circuitry may determine or monitor the at least one operational parameter and the power consumption during or throughout the user inhalation, and determine whether a further of change of the at least one operational parameter and / or the power consumption occurs, which can signal or indicate termination of the user inhalation. Therein, the changes in the at least one operational parameter and the power consumption that occur whenP 17562

[0153] FTR4075 29 / 68

[0154] the user starts inhaling may be changes in opposite direction as the changes in the at least one operational parameter and power consumption that occur when the user stops inhaling.

[0155] For example, one or more relative threshold values for the change in the at least one operational parameter and / or the power consumption can be utilized by the control circuitry to detect the end or termination of the user inhalation. Alternatively or additionally, one or more absolute threshold values for the at least one operational parameter and / or the power consumption can be utilized by the control circuitry to detect the end or termination of the user inhalation. In particular, the control circuitry may be configured to monitor or determine the at least one operational parameter and / or the power consumption during the user inhalation, and upon determining that the at least one operational parameter, the power consumption and / or the respective change in one or more of these quantities reaches or exceeds the respective one or more threshold values, the control circuitry may detect the end or termination of the user inhalation.

[0156] Alternatively or additionally, the control circuitry can be configured to determine termination or end of the user inhalation by determining the change in the at least one operational parameter and / or the power consumption of the dielectric heater arrangement based on two or more consecutive measurements of at least one operational parameter and / or the power consumption. Optionally, the control circuitry can be configured to perform the two or more measurements within a predetermined period of time or time window. Accordingly, two or more measurements may be performed at different times. As described above with respect to detecting start or onset of the user inhalation, for example, the control circuitry may be configured to perform two or more measurements of at least one operational parameter and / or the power consumption within a predetermined period of time of less than about 200 ms, in particular less than about 100 ms, preferably less than about 50 ms, and even more preferably less than about 20 ms or even less than about 10 ms. This may allow to reliably and quickly detect the start or onset of the user inhalation, as well as termination thereof. One or more predetermined periods of time may be stored in a data storage or memory of the device.

[0157] The detection of the termination or end of the user inhalation may rely on the same principle as described above with reference to detecting the user inhalation, respectively occurrence or the start thereof. However, the change in the at least one operational parameter and / or the power consumption to detect the start or occurrence of the user inhalation may be a change in opposite direction compared to the change in the at least one operational parameter and / or the power consumption to detect the end or termination of the user inhalation.

[0158] Specifically, as soon as the user inhalation stops, the cooling effect of the airflow departed on the substrate and / or dielectric heater arrangement stops, which can lead to a decrease in the relative permittivity of the substrate material. Due to the decrease in relative permittivity, theP 17562

[0159] FTR4075 30 / 68

[0160] impedance of the load of the dielectric heater arrangement decreases, which can be detected by the control circuitry to indicate termination of the user inhalation. Alternatively or additionally, the decrease in relative permittivity can cause a decrease in the capacitance of the load capacitor and / or an increase in the oscillation frequency of the oscillator circuitry. One or more of these changes in the operational parameters can be determined by the control circuitry to detect the end or termination of the user inhalation. Alternatively or additionally, the decrease in relative permittivity can cause a decrease in the power consumption of the dielectric heater arrangement, which can be determined by the control circuitry to detect the end or termination of the user inhalation.

[0161] Accordingly, the control circuitry can be configured to detect termination or an end of the user inhalation based on one or more of detecting a decrease in the impedance of the load of the dielectric heater arrangement, detecting a decrease in the capacitance of the load capacitor, detecting an increase in the oscillation frequency of the oscillator circuitry, and detecting a decrease in the power consumption of the dielectric heater arrangement. One or more threshold values for respective increases or decreases can be used by the control circuitry to detect the end or termination of the user inhalation.

[0162] Alternatively or additionally, the control circuitry can be configured to detect one or more of the user inhalation, start of the user inhalation, onset of the user inhalation, occurrence of the user inhalation and / or a duration of the user inhalation based on one or more of detecting an increase in the impedance of the load of the dielectric heater arrangement, detecting an increase in the capacitance of the load capacitor, detecting a decrease in the oscillation frequency of the oscillator circuitry, and detecting an increase in the power consumption of the dielectric heater arrangement. One or more threshold values for respective increases or decreases can be used by the control circuitry to detect the start or onset of the user inhalation.

[0163] The control circuitry can further be configured to decrease the power supplied to the dielectric heater arrangement from a second power level to a first power level below the second power level, or cut the power supplied to the dielectric heater arrangement completely, in response to determining that the user inhalation has ended. Alternatively or additionally, the control circuitry can be configured to interrupt or stop a supply of power to the dielectric heater arrangement in response to determining that the user inhalation has ended.

[0164] After one or more user inhalations have been taken by the user, at least a part of the device may have a temperature well above the room or ambient temperature. In particular, a temperature of the dielectric heater arrangement can be above or at least similar to the pre-heating temperature. This effect can enable the control circuitry to detect a subsequent user inhalation during the same aerosol experience without requiring to power the dielectric heater arrangement at the first power level after the first one or first few or a few user inhalations have been performed.P 17562

[0165] FTR4075 31 / 68

[0166] Alternatively, however, the dielectric heater arrangement may be powered at the first power level after each user inhalation, thereby ensuring that a subsequent user inhalation can be quickly and accurately determined.

[0167] Optionally, the control circuitry can be configured to deactivate a further heater of the aerosol-forming device to heat the aerosol-forming article in response to detecting that the user inhalation has ended. Also this may allow for energy efficient operation of the device.

[0168] The control circuitry can be configured to determine a depletion level of the aerosol-forming article based on determining the change in one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement. Also depletion of the substrate may change the overall relative permittivity of the load. In particular, the relative permittivity may decrease with increasing depletion, for example because less liquid with high permittivity or other ingredients may be present in the substrate. Similarly, for liquid substrate material, a flow of liquid through the liquid transfer element may be reduced with increasing depletion level, such that also the relative permittivity of the liquid transfer element or another part of the cartridge near a dielectric heating zone of the dielectric heater arrangement can decrease with increasing depletion. This decrease in relative permittivity can be detected by the control circuitry as it affects or changes the at least one operational parameter and / or the power consumption. Hence, the change in one or more of the at least one operational parameter and the power consumption of the dielectric heater arrangement can be used by the control circuitry to compute or estimate the depletion level of the aerosol-forming article.

[0169] In particular, the control circuitry can be configured to determine the depletion of the aerosolforming substrate or article based on one or more of determining a decrease in the impedance of a load of the dielectric heater arrangement, determining a decrease in the capacitance, determining an increase in the oscillation frequency, and determining a decrease in the power consumption. One or more threshold values for respective increases or decreases can be used by the control circuitry to determine the depletion or depletion level.

[0170] The control circuitry can further be configured to determine at least one reference or calibration value of one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when a power supply of the dielectric heater arrangement is interrupted. In particular, one or more reference or calibration values for the at least one operational parameter and / or the power consumption may be determined when the aerosol-forming device and / or its dielectric heater arrangement is substantially at room or ambient temperature. Determining one or more reference values at predetermined or well-defined conditions can allow to reliably and accurately detect user inhalations at the aerosol-forming device, respectively, occurrence, a start and / or an end of one or more user inhalations.P 17562

[0171] FTR4075 32 / 68

[0172] According to a further aspect of the present disclosure, there is provided an aerosol-forming system comprising an aerosol-forming device, as described hereinabove and hereinbelow. The aerosol-forming system comprises one or both an aerosol-forming article for generating aerosol, and a companion device for charging and / or storing the aerosol-forming device.

[0173] As mentioned above, any disclosure herein related to the aerosol-forming device equally applies to the aerosol-forming system, and vice versa.

[0174] The companion device may also be referred to as charger case. The aerosol-forming device may be mechanically couplable to the companion device in order to store the aerosol-forming device and / or in order to charge an energy storage of the aerosol-forming device via the companion device.

[0175] A mechanical coupling of the aerosol-forming device and the companion device may, in the context of the present disclosure, include a contact between a part or surface of the companion device and a part or surface of the aerosol-forming device. For instance, when coupling the aerosol-forming device with the companion device, a part of a housing or outer surface of the aerosol-forming device may be in contact or direct contact with a part of a housing, compartment or surface of the companion device. Accordingly, a mechanical coupling of the aerosol-forming device and the companion device can include a mechanical or physical contact between the aerosol-forming device and the companion device.

[0176] For example, the aerosol-forming device may be mechanically couplable to the companion device based on at least partly inserting the aerosol-forming device into the companion device, for example into a cavity, compartment or recess of the companion device. Alternatively or additionally, the companion device may be mechanically couplable with the aerosol-forming device based on at least partly receiving the aerosol-forming device in the companion device.

[0177] In an exemplary configuration, the companion device may comprise a compartment, cavity or recess for at least partly receiving the aerosol-forming device, for example, such that the aerosol-forming device is at least partly encompassed in or surrounded by the companion device.

[0178] Alternatively or additionally, the aerosol-forming device may be mechanically couplable to the companion device based on attaching a housing of the aerosol-forming device to the companion device. To attach the housing to the companion device, the companion device may, for example, comprise engagement means configured to engage with the housing of the aerosolforming device or corresponding engagement elements formed at or by the housing of the aerosol-forming device.

[0179] The control circuitry of the aerosol-forming device or a dedicated charging circuitry of the aerosol-forming device may be configured to charge the energy storage of the aerosol-forming device upon, based on or in response to mechanically coupling the aerosol-forming device with the companion device.P 17562

[0180] FTR4075 33 / 68

[0181] According to a further aspect of the present disclosure, there is provided a method of detecting a user inhalation at an aerosol-forming device or aerosol-forming system. The aerosolforming device comprises a dielectric heater arrangement to dielectrically heat a substrate of an aerosol-forming article or substrate in a puff-on-demand heating scheme and / or operation. Alternatively, the dielectric heater arrangement may be configured for session-based heating, for example to dielectrically heat a substrate of an aerosol-forming article in a usage session. The method comprises:

[0182] - supplying electrical power or energy to the dielectric heater arrangement to cause dielectric heating of the substrate; and

[0183] - detecting a user inhalation at the aerosol-forming device based on determining one or more of a change in at least one operational parameter of the dielectric heater arrangement and a change in a power consumption of the dielectric heater arrangement.

[0184] The aerosol-forming device may comprise the elements, functions and characteristics, as described hereinabove and hereinbelow. Accordingly, any disclosure herein related to the aerosol-forming device or system equally applies to method, and vice versa.

[0185] Supplying electrical power to the dielectric heater arrangement may include one or more of powering the dielectric heater arrangement, switching the heater arrangement on, activating the heater arrangement, and heating at least a part of the dielectric heater arrangement.

[0186] Detecting the user inhalation at the aerosol-forming device may include determining a change in one or more of:

[0187] an impedance of a load of the dielectric heater arrangement;

[0188] an oscillation frequency of an oscillator circuitry or wave generator of the dielectric heater arrangement;

[0189] a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the aerosol-forming article; and

[0190] the power consumption of the dielectric heater arrangement, for example a change in current or a change in voltage.

[0191] For example, detecting the user inhalation, for instance a start, onset, occurrence or duration of the user inhalation, at the aerosol-forming device can include determining one or more of:

[0192] an increase in an impedance of a load of the dielectric heater arrangement;

[0193] a decrease of an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement;

[0194] an increase in a capacitance of a load capacitor of the dielectric heater arrangement; and

[0195] an increase in the power consumption of the dielectric heater arrangement.P 17562

[0196] FTR4075 34 / 68

[0197] Alternatively or additionally, detecting the user inhalation, for instance termination, stop or end of the user inhalation, at the aerosol-forming device can include determining one or more of:

[0198] a decrease in an impedance of a load of the dielectric heater arrangement;

[0199] an increase of an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement;

[0200] a decrease in a capacitance of a load capacitor of the dielectric heater arrangement; and

[0201] a decrease in the power consumption of the dielectric heater arrangement.

[0202] As discussed in detail hereinabove with respect to the device, when the user inhales, air may be drawn into the device from an external environment, and an airflow towards or past at least a part of the dielectric heater arrangement, and optionally the substrate, can be generated. This leads to a temperature decrease and increase in the relative permittivity of the substrate, which in turn leads to one or more of the aforementioned changes in one or more operational parameters and the power consumption of the dielectric heater arrangement. This effect can allow for an accurate detection of a user inhalation, in particular occurrence or start thereof, but also termination of the user inhalation, where the effect is reversed.

[0203] Detecting the user inhalation can, for example, comprise monitoring and / or determining one or more of:

[0204] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency at a gate terminal of a transistor of the oscillator circuitry;

[0205] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency of a switching device of the oscillator circuitry, the switching device being configured for inverting operation;

[0206] a frequency of an alternating magnetic or electric field in a load capacitor of the oscillator circuitry;

[0207] an impedance of the load of the dielectric heater arrangement;

[0208] an output voltage or current of a power supply of the aerosol-forming device; and an input voltage or current supplied to the dielectric heater arrangement.

[0209] Supplying electrical power to the dielectric heater arrangement may comprise powering the dielectric heater arrangement at a first power level to heat the aerosol-forming article to a preheating temperature above ambient or room temperature and below a volatilization or vaporization temperature sufficient to release one or more active ingredients from the aerosolforming article and / or at least vapor from the substrate. As discussed in detail hereinabove, preheating may allow to reduce a response time for detecting the user inhalation, which may refer toP 17562

[0210] FTR4075 35 / 68

[0211] the time between actual start of the user inhalation and the actual detection by the control circuitry. Also, pre-heating can be advantageous, as the viscosity of a liquid substrate may be reduced.

[0212] Powering the dielectric heater arrangement at the first power level may be performed in response to one or more of:

[0213] receiving a sensor signal of at least one sensor of the aerosol-forming device; receiving a signal indicative of an insertion of an aerosol-forming article at least partly into the aerosol-forming device;

[0214] receiving a signal indicative of a coupling of an aerosol-forming article to the aerosolforming device;

[0215] receiving a signal indicative of a mechanical decoupling of the aerosol-forming device from a companion device; and

[0216] receiving a control signal from one or more user interfaces triggered by a user of the aerosol-forming device.

[0217] One or more of the events or actions may configure the device into a potential usage mode, where the control circuitry powers the dielectric heater arrangement to heat up itself and / or the substrate to the pre-heating temperature. Upon reaching the pre-heating temperature, the device may be ready for detecting user inhalations, and may be configured into a puff observation mode. Upon detecting a puff or user inhalation, the electrical power to the dielectric heater arrangement may be immediately increased to the second power level, which may be a maximum power level suppliable by the device or its energy storage, in order to quickly heat the substrate to the volatilization or vaporization temperature. This state or configuration of the device may also be referred to herein as puff power mode. For example, when powering the dielectric heater arrangement at the second power level, the temperature of the substrate can increase about 100°C within about 0.05 to 0.5 seconds, for example about 100°C within 0.2 seconds, preferably about 100°C within about 0.1 seconds.

[0218] The method may further comprise, upon detecting of the user inhalation, increasing a power supplied to the dielectric heater arrangement to heat the substrate to a volatilization temperature to cause vaporization of one or more active ingredients of the substrate. Alternatively or additionally, the method may comprise powering the dielectric heater arrangement to a second power level for heating the aerosol-forming article or substrate to a volatilization temperature sufficient to release one or more active ingredients from the substrate of the aerosol-forming article in response to detecting the user inhalation at the aerosol-forming device.

[0219] The method may further comprise determining termination of the user inhalation based on determining a further change in at least one of said at least one operational parameter of the dielectric heater arrangement and the power consumption of the dielectric heater; and optionally decreasing the power supplied to the dielectric heater arrangement in response to determiningP 17562

[0220] FTR4075 36 / 68

[0221] termination of the user inhalation. Accordingly, the same physical effect or correlation between the relative permittivity of the substrate and its temperature can be used to reliably detect termination of the user inhalation. Upon detecting termination, the power supply to the dielectric heater arrangement may be reduced or stopped completely, and the device may be switched or configured into the puff observation mode again and wit for the next user inhalation to increase the power level again to the second power level. Hence, an energy efficient synchronization of the inhalation patterns with the heating of the dielectric heater arrangement can be provided.

[0222] In an example, the method may further comprise determining a depletion level of the aerosol-forming article based on determining the change in one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement. As noted above, also depletion of the article or substrate leads to a change in the relative permittivity, which can be detected based on determining the change in at least one operational parameter and / or the power consumption.

[0223] The method may further comprise determining at least one reference or calibration value of one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when a power supply of the dielectric heater arrangement is interrupted. For instance, the at least one reference value may be determined at a fixed ambient temperature and when the dielectric heater arrangement is in thermal equilibrium with the ambient air.

[0224] The invention is defined in the claims. However, below there 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 another example, embodiment, or aspect described herein.

[0225] Example 1: An aerosol-forming device for forming aerosol from a substrate of an aerosol-forming article, comprising: a dielectric heater arrangement configured to (dielectrically) heat, for example in a puff-on-demand heating operation or in a session-based heating operation, at least a part of a substrate of an aerosol-forming article by dielectric heating to form aerosol, and” “control circuitry configured to control the dielectric heater arrangement, wherein the control circuitry is further configured to detect a user inhalation at the aerosol-forming device based on determining one or more of:

[0226] a change in at least one operational parameter of the dielectric heater arrangement, and a change in a power consumption of the dielectric heater arrangement.

[0227] Example 2: The aerosol-forming device according to the preceding example, wherein the change in said at least one operational parameter and / or the change in the power consumption of the dielectric heater arrangement is associated with or caused by a change in an air flow past at least a part of the dielectric heater arrangement indicative of the user inhalation.P 17562

[0228] FTR4075 37 / 68

[0229] Example 3: The aerosol-forming device according to any one of the preceding examples, wherein the at least one operational parameter of the dielectric heater arrangement includes at least one of:

[0230] an impedance of a load of the dielectric heater arrangement, the load optionally including or being formed by a resonant cavity and / or transmission line of the dielectric heater arrangement, and further optionally by at least a part of the aerosol-forming substrate and / or article,

[0231] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement, a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the substrate of the aerosol-forming article;

[0232] a Q-factor of the dielectric heater arrangement, resonant cavity and / or transmission line; a reflection coefficient of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0233] a standing wave ratio (SWR) of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0234] a resonance frequency of the dielectric heater arrangement, resonant cavity and / or transmission line; and

[0235] an oscillation frequency of the dielectric heater arrangement, resonant cavity and / or transmission line.

[0236] Example 4: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to detect the user inhalation at the aerosolforming device based on determining a change in one or more of:

[0237] an impedance of a load of the dielectric heater arrangement;

[0238] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement; a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the aerosol-forming article;

[0239] the power consumption of the dielectric heater arrangement;

[0240] a Q-factor of the dielectric heater arrangement, resonant cavity and / or transmission line; a reflection coefficient of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0241] a standing wave ratio (SWR) of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0242] a resonance frequency of the dielectric heater arrangement, resonant cavity and / or transmission line; and

[0243] an oscillation frequency of the dielectric heater arrangement, resonant cavity and / or transmission line.P 17562

[0244] FTR4075 38 / 68

[0245] Example 5: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to detect the user inhalation, start of the user inhalation and / or onset of the user inhalation at the aerosol-forming device based on determining one or more of:

[0246] an increase in an impedance of a load of the dielectric heater arrangement;

[0247] an increase in a capacitance of a load capacitor of the dielectric heater arrangement; a decrease in the oscillation frequency of an oscillator circuitry; and

[0248] an increase in the power consumption of the dielectric heater arrangement.

[0249] Example 6: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to determine one or more of the change in said at least one operational parameter of the dielectric heater arrangement with respect to a reference value for said at least one operational parameter, and the change in the power consumption of the dielectric heater arrangement with respect to a reference value for the power consumption.

[0250] Example 7: The aerosol-forming device according to any one of the preceding examples, wherein the dielectric heater arrangement comprises a resonant cavity and / or transmission line configured to receive at least a part of the aerosol-forming article, wherein the resonant cavity and / or transmission line, optionally together with the aerosol-forming substrate and / or article, form a load of the dielectric heater arrangement; and

[0251] wherein the control circuitry is configured to detect the user inhalation at the aerosol-forming device based on determining a change in at least one of an impedance of the load of the dielectric heater arrangement and the power consumption of the dielectric heater arrangement.

[0252] Example 7b: The aerosol-forming device according to any one of the preceding examples, wherein the at least one operational parameter of the dielectric heater arrangement includes at least one of:

[0253] a Q-factor of the dielectric heater arrangement, resonant cavity and / or transmission line; a reflection coefficient of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0254] a standing wave ratio (SWR) of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0255] a resonance frequency of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0256] an oscillation frequency of the dielectric heater arrangement, resonant cavity and / or transmission line; and

[0257] an anti-resonance frequency of the dielectric heater arrangement, resonant cavity and / or transmission line.P 17562

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[0259] Example 7c: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to detect an onset or start of the user inhalation based on determining one or more of:

[0260] an increase in the reflection coefficient of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0261] an increase in the standing wave ratio of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0262] a decrease in the anti-resonance frequency of the dielectric heater arrangement, resonant cavity and / or transmission line; and

[0263] a change in the Q-factor of the dielectric heater arrangement, resonant cavity and / or transmission line, for example shift away from a baseline value of the Q-factor.

[0264] Example 7d: The aerosol-forming device according to any one of the preceding examples, wherein the increase in the reflection coefficient or the standing wave ratio is associated with an impedance mismatch caused by an increase in a relative permittivity of the aerosol-forming substrate due to the user inhalation.

[0265] Example 7e: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to detect termination or an end of the user inhalation based on determining one or more of:

[0266] a decrease in the reflection coefficient of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0267] a decrease in the standing wave ratio of the dielectric heater arrangement, resonant cavity and / or transmission line;

[0268] an increase in the anti-resonance frequency of the dielectric heater arrangement, resonant cavity and / or transmission line; and

[0269] a return of the Q-factor of the dielectric heater arrangement, resonant cavity and / or transmission line toward a baseline value.

[0270] Example 7f: The aerosol-forming device according to any one of the preceding examples, wherein the dielectric heater arrangement comprises a resonant cavity or a transmission line, and wherein the at least one operational parameter is monitored via, based on or using an impedance matching circuit operatively coupled to the control circuitry.

[0271] Example 8: The aerosol-forming device according to any one of examples 1 to 7f, wherein the dielectric heater arrangement comprises an oscillator circuitry with a load capacitor, preferably included in a feedback loop of the oscillator circuitry and configured to receive at least a part of the aerosol-forming article to heat the aerosol-forming substrate, andP 17562

[0272] FTR4075 40 / 68

[0273] wherein the control circuitry is configured to detect the user inhalation at the aerosol-forming device based on determining a change in one or more of an oscillation frequency of the oscillator circuitry and the power consumption of the dielectric heater arrangement.

[0274] Example 9: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to monitor or determine one or more of: an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency at a gate terminal of a transistor of the oscillator circuitry;

[0275] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency of a switching device of the oscillator circuitry, the switching device being configured for inverting operation;

[0276] a frequency of an alternating magnetic or electric field in a load capacitor of the oscillator circuitry;

[0277] an impedance of a load of the dielectric heater arrangement;

[0278] an output voltage or current of a power supply of the aerosol-forming device; and an input voltage or current supplied to the dielectric heater arrangement.

[0279] Example 10: The aerosol-forming device according to any one of the preceding examples, wherein the aerosol-forming substrate is a liquid aerosol-forming substrate.

[0280] Example 11: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to power the dielectric heater arrangement to a first power level for heating the substrate of the aerosol-forming article to a pre-heating temperature above ambient temperature and below a volatilization temperature of one or mor ingredients of the substrate sufficient to release aerosol from the aerosol-forming article, and wherein the control circuitry is configured to detect the user inhalation during a time period where the dielectric heater arrangement is powered to the first power level.

[0281] Example 12: The aerosol-forming device according to the preceding example, wherein the pre-heating temperature is above about 25°C, above about 30°C, preferably above about 40°C, more preferably above about 50°C, and even more preferably above about 60°C; and / or wherein the pre-heating temperature is below about 120°C, below about 100°C, preferably below about 90°C, more preferably below about 80°C, and even more preferably below about 70°C.

[0282] Example 13: The aerosol-forming device according to any one of examples 11 and 12, wherein the control circuitry is configured to monitor or determine one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when the dielectric heater arrangement is powered to the first power level.P 17562

[0283] FTR4075 41 / 68

[0284] Example 14: The aerosol-forming device according to any one of examples 11 to 13, wherein the control circuitry is configured to power the dielectric heater arrangement to the first power level in response to one or more of:

[0285] a sensor signal of at least one sensor of the aerosol-forming device;

[0286] insertion of an aerosol-forming article at least partly into the aerosol-forming device; coupling of an aerosol-forming article to the aerosol-forming device;

[0287] mechanical decoupling of the aerosol-forming device from a companion device; and a control signal from one or more user interfaces triggered by a user of the aerosol-forming device.

[0288] Example 15: The aerosol-forming device according to the preceding example, wherein the at least one sensor includes one or more of a motion sensor, an accelerometer, a gyroscope, an image sensor, a pyrometer, a presence sensor, a touch sensor.

[0289] Example 16: The aerosol-forming device according to any one of examples 11 to 15, wherein the control circuitry is configured to power the dielectric heater arrangement to the first power level based on supplying a first DC voltage to the dielectric heater arrangement that is smaller than a second DC voltage supplied by the control circuitry to the dielectric heater arrangement to heat the aerosol-forming article to form aerosol.

[0290] Example 17: The aerosol-forming device according to any one of examples 11 to 16, wherein the control circuitry is configured to, in response to detecting the user inhalation at the aerosol-forming device and / or start thereof, power the dielectric heater arrangement to a second power level for heating the aerosol-forming article to a volatilization temperature sufficient to release aerosol from the aerosol-forming article.

[0291] Example 18: The aerosol-forming device according to the preceding example, wherein the first power level is below about 80%, below about 70%, below about 60%, below about 50%, below about 40%, below about 30%, below about 20%, below about 10%, below about 5%, or below about 2% of the second power level.

[0292] Example 19: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to control a power supplied to the dielectric heater arrangement in response to detecting the user inhalation at the aerosol-forming device, such that a temperature of the aerosol-forming article is substantially maintained or kept substantially constant during the user inhalation.

[0293] Example 20: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to activate a further heater of the aerosolforming device to heat the aerosol-forming article in response to detecting the user inhalation at the aerosol-forming device.P 17562

[0294] FTR4075 42 / 68

[0295] Example 21: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to determine whether the user inhalation has ended based on determining a further change in at least one of said at least one operational parameter of the dielectric heater arrangement and the power consumption of the dielectric heater.

[0296] Example 22: The aerosol-forming device according to the preceding example, wherein the control circuitry is configured to decrease the power supplied to the dielectric heater arrangement from a second power level to a first power level below the second power level, or cut the power supplied to the dielectric heater arrangement, in response to determining that the user inhalation has ended and / or upon detecting termination or end of the user inhalation; and / or wherein the control circuitry is configured to interrupt or stop a supply of power to the dielectric heater arrangement in response to determining that the user inhalation has ended.

[0297] Example 23: The aerosol-forming device according to example 21 or 22, wherein the control circuitry is configured to deactivate a further heater of the aerosol-forming device to heat the aerosol-forming article in response to detecting that the user inhalation has ended.

[0298] Example 24: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to determine a depletion level of the aerosolforming article based on determining the change in one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement.

[0299] Example 25: The aerosol-forming device according to any one of the preceding examples, wherein the control circuitry is configured to determine at least one reference value of one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when a power supply of the dielectric heater arrangement is interrupted.

[0300] Example 26: An aerosol-forming system comprising an aerosol-forming device according to any one of the preceding examples and one or more of: an aerosol-forming article for generating aerosol; and a companion device for one or more of storing the aerosol-forming device and charging the aerosol-forming device.

[0301] Example 27: A method of detecting a user inhalation at an aerosol-forming device comprising a dielectric heater arrangement to dielectrically heat a substrate of an aerosol-forming article in a puff-on-demand heating scheme or a session-based heating scheme, the method comprising: supplying electrical power to the dielectric heater arrangement to cause dielectric heating of the substrate; and detecting a user inhalation at the aerosol-forming device based on determining one or more of a change in at least one operational parameter of the dielectric heater arrangement and a change in a power consumption of the dielectric heater arrangement.P 17562

[0302] FTR4075 43 / 68

[0303] Example 28: The method according to the preceding example, wherein detecting the user inhalation at the aerosol-forming device includes determining a change in one or more of:

[0304] an impedance of a load of the dielectric heater arrangement;

[0305] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement; an oscillation frequency of an oscillator circuitry;

[0306] a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the aerosol-forming article; and

[0307] the power consumption of the dielectric heater arrangement.

[0308] Example 29: The method according to example 27 or 28, wherein detecting the user inhalation, start of the user inhalation and / or onset of the user inhalation at the aerosol-forming device includes determining one or more of:

[0309] an increase in an impedance of a load of of the dielectric heater arrangement;

[0310] a decrease of an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement;

[0311] an increase in a capacitance of a load capacitor of the dielectric heater arrangement; and an increase in the power consumption of the dielectric heater arrangement.

[0312] Example 30: The method according to any one of examples 27 to 29, wherein detecting the user inhalation comprises monitoring or determining one or more of:

[0313] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency at a gate terminal of a transistor of the oscillator circuitry;

[0314] an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency of a switching device of the oscillator circuitry, the switching device being configured for inverting operation;

[0315] a frequency of an alternating magnetic or electric field in a load capacitor of the oscillator circuitry;

[0316] an impedance of a load of the dielectric heater arrangement;

[0317] an output voltage or current of a power supply of the aerosol-forming device; and an input voltage or current supplied to the dielectric heater arrangement.

[0318] Example 31 : The method according to any one of examples 27 to 30, wherein supplying electrical power to the dielectric heater arrangement comprises:

[0319] powering the dielectric heater arrangement at a first power level to heat the aerosol-forming article to a pre-heating temperature above ambient temperature and below a volatilization temperature sufficient to release one or more active ingredients from the aerosol-forming article.

[0320] Example 32: The method according to the previous example, wherein the dielectric heater arrangement is powered at the first power level in response to one or more of:

[0321] receiving a sensor signal of at least one sensor of the aerosol-forming device;P 17562

[0322] FTR4075 44 / 68

[0323] receiving a signal indicative of an insertion of an aerosol-forming article at least partly into the aerosol-forming device;

[0324] receiving a signal indicative of a coupling of an aerosol-forming article to the aerosol-forming device;

[0325] receiving a signal indicative of a mechanical decoupling of the aerosol-forming device from a companion device; and

[0326] receiving a control signal from one or more user interfaces triggered by a user of the aerosol-forming device.

[0327] Example 33: The method according to any one of examples 27 to 32, further comprising: upon detecting of the user inhalation, increasing a power supplied to the dielectric heater arrangement to heat the substrate to a volatilization temperature to cause vaporization of one or more active ingredients of the substrate.

[0328] Example 34: The method according to any one of examples 27 to 33, further comprising: powering the dielectric heater arrangement to a second power level for heating the aerosolforming article to a volatilization temperature sufficient to release one or more active ingredients from the substrate of the aerosol-forming article in response to detecting the user inhalation at the aerosol-forming device.

[0329] Example 35: The method according to any one of examples 27 to 34 further comprising: activating a further heater of the aerosol-forming device to heat the aerosol-forming article in response to detecting the user inhalation at the aerosol-forming device.

[0330] Example 36: The method according to any one of examples 27 to 35, further comprising: determining termination of the user inhalation based on determining a further change in at least one of said at least one operational parameter of the dielectric heater arrangement and the power consumption of the dielectric heater; and

[0331] optionally decreasing the power supplied to the dielectric heater arrangement in response to determining termination of the user inhalation.

[0332] Example 37: The method according to any one of examples 27 to 36, further comprising: determining a depletion level of the aerosol-forming article based on determining the change in one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement.

[0333] Example 38: The method according to any one of examples 27 to 37, further comprising: determining at least one reference value of one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when a power supply of the dielectric heater arrangement is interrupted.

[0334] Examples will now be further described with reference to the figures in which:

[0335] Figure 1 schematically shows an exemplary aerosol-forming system;P 17562

[0336] FTR4075 45 / 68

[0337] Figure 2A schematically shows a cross-sectional view of an exemplary aerosol-forming system along a longitudinal axis;

[0338] Figure 2B schematically shows a cross-sectional view of an exemplary aerosol-forming system along a transverse axis;

[0339] Figure 3 schematically illustrates an oscillator circuitry for an aerosol-forming system. Figures 4A and 4B each schematically illustrate an example of a resonant circuit for an aerosol-forming system;

[0340] Figure 5 illustrates a method of operating an aerosol-forming device or system; and Figure 6 shows a flow-chart illustrating a method of detecting a user inhalation at an aerosolforming device.

[0341] The figures are schematic only and not to scale.

[0342] Figure 1 shows an exemplary aerosol-forming or aerosol-generating system 500 for forming or generating aerosol, for example for consumption or inhalation by a user in one or more user inhalations or puffs. The system 500 comprises an aerosol-forming device 100 and optionally a companion device 300 for storing the aerosol-forming device 100. The companion device 300 may be a charging device or charger case for charging the aerosol-forming device 100 and / or an energy storage 190 or power supply 190 thereof.

[0343] The aerosol-forming device 100 may comprise an insertion opening 101 for at least partially or completely inserting an aerosol-forming article 200. The aerosol-forming article 200 may comprise an aerosol-forming substrate 210, which may, for example, include solid substrate material, such as a tobacco material. The aerosol-forming article 200 may be stick-like shaped, shaped, as rectangular parallelepiped, or shaped differently. In another example, the aerosolforming article 200, may include or be shaped as a cartridge 200, container 200, capsule 200, or pod 200 comprising a liquid substrate 210, for example a liquid that can be aerosolized for inhalation, as shown in greater detail in Figures 2A and 2B. Generally, the aerosol-forming substrate 210 may comprise tobacco-based or non-tobacco based materials having an aerosol forming material therein and optionally one or more active agents or ingredients, such as nicotine, pharmaceutical, botanicals, flavorants, liquid substrates with one or more active agents or ingredients, or a combination thereof.

[0344] Optionally, the aerosol-forming device 100 may comprise a mouthpiece (not shown), through which a user may inhale aerosol provided by the aerosol-forming device 100 for consumption. The aerosol may be provided from an aerosol-forming article 200 or substrate 210 provided inside or contained within the aerosol-forming device 100.

[0345] The exemplary aerosol-forming device 100 of Figure 1 further includes a dielectric heater arrangement 110 configured to dielectrically heat the aerosol-forming article 200 or substrate 210. In the example of Figure 1 , the dielectric heater arrangement 110 comprises a load capacitor 112P 17562

[0346] FTR4075 46 / 68

[0347] with a first electrode 114 and a second electrode 116, which are arranged opposite to each other and are spaced-apart from each other in a direction orthogonal or transverse to an insertion direction or axis 103 for inserting the aerosol-forming article 200. The insertion direction or axis 103 may define or be parallel to a longitudinal direction or axis of the device 100. The two opposing and spaced-apart electrodes 114, 116 form or define a receiving space 120 configured to at least partly receive the aerosol-forming article 200 or substrate 210 therebetween. The receiving space 120 may also be referred to herein as heating chamber 120.

[0348] The receiving space 120 and the aerosol-forming article 200 can be sized such that the aerosol-forming substrate 210 is in contact or in close proximity to both the first electrode 114 and the second electrode 116 of the load capacitor 112 when received within the receiving space 120. Moreover, the load capacitor 112 with the first electrode 114 and the second electrode 116 can form part of a feedback loop 133 (see Figure 3) of an oscillator circuitry 130, also referred to herein as oscillation circuit 130, via a first and second electrical contact 132, 134. It should be noted that the load capacitor 112 can comprise more than one electrode pair, in particular, the load capacitor 112 can comprise two, three, four, or even more pairs of interdigitated electrodes 114, 116. Also, it should be noted that the embodiment with load capacitor 112 is exemplary only. Alternatively, the dielectric heater arrangement 110 may comprise a resonant cavity (see Figure 4B) configured to receive the substrate 210 for dielectric heating thereof.

[0349] In other examples, the first electrode 114 and the second electrode 116 may form part of the aerosol-forming article 200 comprising the aerosol-forming substrate 210. In such embodiments, the receiving space 120 or a corresponding cavity between the first and second electrical contacts 132, 134 can be sized such that, when the aerosol-forming article 200 is placed or located within the receiving space 120, an electrical connection is established between the first electrode 114 and the first electrical contact 132, and the second electrode 116 and the second electrical contact 134.

[0350] In some embodiments, the width of the aerosol-forming article 200 comprising the aerosolforming substrate 210 can be slightly greater than the spacing between the first electrode 114 and the second electrode 116, such that the distal end of the aerosol-forming substrate 210 can be slightly compressed between the first electrode 114 and the second electrode 116. In some embodiments, the article 200, in an initial, uncompressed form may have a width between 5-30% larger than the distance between the first electrode 114 and the second electrode 116 in transverse direction. This may reduce or prevent the build-up of air between the first electrode 114 and the second electrode 116 when the aerosol-forming article 200 is received in the receiving space 120, Also, this may decrease a distance between first and second electrodes 114, 116 for dielectric heating, thereby improving dielectric properties of the load capacitor 112 and the accuracy of any measurements or determinations of the dielectric properties of theP 17562

[0351] FTR4075 47 / 68

[0352] aerosol-forming substrate 210 and / or load capacitor 112 performed by the aerosol-forming device 100.

[0353] The aerosol-forming device 100 further comprises a power supply 190, power source 190 or energy source 190, and a control circuitry 140 electrically, communicatively and / or operatively coupled to the dielectric heater arrangement 110 and / or the oscillator circuit 130. In this embodiment, the power supply 190 can be a rechargeable lithium ion battery, for example with one or more lithium ion battery cells. Hence, the aerosol-forming device 100 can be portable, battery-powered and handheld.

[0354] The control circuitry 140 can be configured to control the energy source 190 and / or the dielectric heater arrangement 110. In particular, the control circuitry 140 can be configured to control a supply of electrical power from the energy source 190 to the dielectric heater arrangement 110, thereby controlling the heating, a heating operation, activation and / or deactivation of the dielectric heater arrangement 110.

[0355] The control circuitry 140 can include one or more controllers, microcontrollers or processors 142 for data processing.

[0356] The energy source 190 may be charged based on connecting terminals of the device 100 with a main power supply, e.g., a USB charger. Alternatively, the energy storage 190 may be charged based on mechanically coupling the aerosol-forming device 100 with the companion device 300. In Figure 1, both the aerosol-forming device 100 and the companion device 300 comprise an energy storage 190, 310. In an example, energy storage 190 of the aerosol-forming device may be charged based on coupling the device 100 to the companion device, for example based on at least partly inserting the device 100 into a compartment or recess of the companion device 300. Upon mechanically coupling the device 100, 300, an electrical connection between terminals or electrical connections of the aerosol-forming device 100 and the companion device 300 can be established to charge the energy storage 190 of the aerosol-forming device 100 via the energy storage 310 of the companion device 300. The energy storage 310 of the companion device 300 can, for example, be re-charged via connection to a main power supply, e.g., a USB charger. Alternatively or additionally, one or both the energy storage 190 of the aerosol-forming device 100 and the energy storage 310 of the companion device 300 may be removable and / or replaceable. In other words, energy storages 190, 310 may be replaceable energy storages or batteries.

[0357] The aerosol-forming device 100 may further comprise a communications arrangement 150 or interface 150 for communicatively coupling the aerosol-forming device 100 with the companion device 300 or other devices, such as a smart phone or server, for example, via an Internet connection, a wireless LAN connection, a WiFi connection, a Bluetooth connection, a mobile phone network, a mobile data connection for example but not limited to a 3G / 4G / 5G connection,P 17562

[0358] FTR4075 48 / 68

[0359] an edge connection, an LTE connection, a BUS connection, a wireless connection, a wired connection, an optical data connection such as but not limited to IrDa, a radio connection, a near field connection, and / or an loT connection.

[0360] The aerosol-forming device 100 may further comprise a data storage 152 or memory for storing information, program code or data. Data storage 152 may also store collected values of sensors and / or one or more mathematical functions or formulas, software and / or computer instructions that can be executed by the control circuitry 140, particularly by the controller 142 and / or processor 142.

[0361] One or more sensors 154 may be arranged on, at or in the aerosol-forming device 100 to collect data. One or more of the sensors 154 may for example be a motion sensor, an accelerometer, a gyroscope, an image sensor, a pyrometer, a presence sensor, a touch sensor, a temperature sensor, a strain sensor, a pressure sensor, a flow sensor or any other suitable sensor.

[0362] The aerosol-forming device 100 may further comprise one or more user interface components 156 or user interfaces 156, for example comprising an input and / or output element, for example in the form of a pushbutton, a capacitive button, a touch display, one or more LEDs, an acoustic interface or the like. The one or more interface components 156 may be used or function as a power button to activate or deactivate the dielectric heater arrangement 110 thereby to activate or deactivate the aerosol-forming device 100. Upon activation of the aerosol-forming device 100, the dielectric heater arrangement 110 may be activated and heat may be applied to at least a part of the aerosol-forming article 200 or substrate 210, such that aerosol can be generated for consumption or inhalation by the user, for example in one or more user inhalations or puffs. The one or more user interface components 156 can be arranged on an outer surface of the device 100 or can be integrated in a housing of the device 100.

[0363] In use, power or electrical energy can be provide from the energy storage 190 to the dielectric heater arrangement 110, for example when a user activates the device 100. For example, the device 100 can be activated by one or more of a sensor signal of at least one sensor 154 of the aerosol-forming device, insertion of an aerosol-forming article 200 at least partly into the aerosol-forming device 100, coupling of an aerosol-forming article 200 to the aerosol-forming device 100, mechanical decoupling of the aerosol-forming device 100 from the companion device 300, and a control signal from the one or more user interfaces 156 triggered by the user of the aerosol-forming device 100. As noted above, sensor 154 can include one or more of a motion sensor, an accelerometer, a gyroscope, an image sensor, a pyrometer, a presence sensor, and a touch sensor, such that the device 100 can be activated for example by moving it, by touching it or by the mere presence of the user in the vicinity of the device 100.P 17562

[0364] FTR4075 49 / 68

[0365] As will be described in more detail hereinbelow, once activated, the device 100 may be configured by the control circuitry 140 in a potential use mode, where the dielectric heater arrangement 110 and / or the oscillator circuitry 130 can be powered to a first power level to heat up the at least a part of the dielectric heater arrangement 110 and / or substrate 210 to a preheating temperature above ambient temperature and below a volatilization or vaporization temperature sufficient to release aerosol from the substrate 210. Specifically, when powered, an alternating electric field is generated between the electrodes 114, 116 of the load capacitor 112, which dielectrically heats the substrate 210.

[0366] When heated to the pre-heating temperature, the device 100 or control circuitry 140 can be configured in a puff observation mode, where one or more operational parameters of the dielectric heater arrangement 110 and / or the power consumption of the dielectric heater arrangement 110 can be monitored to determine when a user inhalation takes place, respectively, to detect a user inhalation. It should be noted that the puff observation mode can be activated or configured as soon as the device 100 is activated, or with some delay after the activation to allow for heating at least a part of the dielectric heater arrangement 110 to or close to the pre-heating temperature.

[0367] When a user initiates a user inhalation or puff, air at ambient temperature can be drawn from an external environment of the device 100 via an air channel or airflow path 160 towards the dielectric heater arrangement 110. The air drawn by the user has a lower temperature than the dielectric heater arrangement 110 and substrate 210 that is pre-heated to the pre-heating temperature. Hence, the drawn air departs a cooling effect onto the dielectric heater arrangement 110 and substrate 210, which leads to a decrease in temperature and hence to an increase in relative permittivity of the substate 210. As a consequence, the capacitance of the load capacitor 112 increases, and an oscillation frequency of the oscillator circuitry 130 decreases due to the increasing capacitance, and hence increasing LC constant of the oscillator circuitry 130. Since also resistive losses will increase with increasing relative permittivity, the power consumption of the dielectric heater arrangement 110 will increase. One or more of these effects, respectively one or more of these changes in the capacitance of the load capacitor 112, the oscillation frequency of the oscillator circuitry 130 and the power consumption can be determined or monitored by the control circuitry 140 in order to detect an onset, a start and / or occurrence of the user inhalation.

[0368] Upon detecting the user inhalation, control circuitry 140 can increase the power provided to the dielectric heater arrangement 110 and power it at a second power level, where the dielectric heater arrangement 110 and / or substrate 210 can be heated to the volatilization or vaporization temperature to generate inhalable aerosol. Therein, upon detection of the user inhalation, the temperature of the dielectric heater arrangement 110 and / or substrate 210 may be increased at a rate of about 100°C within 0.2 seconds, within 0.1 seconds or even higher rate. Accordingly,P 17562

[0369] FTR4075 50 / 68

[0370] the power to the dielectric heater arrangement 110 can be immediately increased upon detecting a user inhalation to allow for aerosol generation and inhalation by the user. Hence, energy can be efficiently used during user inhalation and saved at other times. Also depletion of the substrate 210 can be avoided at times when the user does not inhale.

[0371] The opposite effect can be used by the control circuitry 140 to detect an end or termination of the user inhalation. Specifically, as soon as the user stops inhaling, the airflow stops and the dielectric heater 110 and substrate 210 will heat further up. This increase in temperature can decrease the relative permittivity of the substrate 210, and hence decrease the capacitance of the load capacitor 112, increase the oscillation frequency of the oscillator circuitry 130, and decrease the power consumption of the dielectric heater arrangement 110. One or more of these changes can be determined or detected by the control circuitry 140, thereby detecting termination of the user inhalation.

[0372] Upon detecting termination of the user inhalation, the control circuitry 140 may cut the power supply to the dielectric heater arrangement 110, and the next or subsequent user inhalation can be determined or detected, as the dielectric heater arrangement 110 and substrate 210 may still have an elevated temperature above room or ambient temperature. Optionally, however, the control circuitry 140 may power the dielectric heater arrangement at the first power level in response to detecting termination of the user inhalation, to ensure that the dielectric heater arrangement 110 and substrate 210 have at least the pre-heating temperature, in order to allow for cooling by air drawn by the user in the subsequent user inhalation, which can then be detected again by the control circuitry 140 as further change in one or more operational parameters and / or the power consumption.

[0373] Accordingly, a reliable, efficient and robust mechanism for detecting puffs or user inhalations can be implemented or provided, in particular without requiring dedicated hardware, such as a dedicated puff sensor for detecting when a puff occurs. This can also save space in the device 100 for other components or parts, or can allow to increase a size of the energy storage 190, for example.

[0374] Optionally, the control circuitry 140 may be configured to detect or determine depletion or a depletion level of the aerosol-forming article 200. With increasing depletion, the relative permittivity of the substrate 210 should decrease, and hence the capacitance of the load capacitor 112 should decrease, the oscillation frequency of the oscillator circuitry 130 should increase, and the power consumption of the dielectric heater arrangement 110 should decrease. One or more of these changes can be determined or detected by the control circuitry 140, thereby enabling determination of the depletion or depletion level of the article 200.

[0375] Figures 2A and 2B each show a cross-sectional view of an aerosol-forming system 500. Therein, Figure 2A shows a cross-section along a longitudinal axis or plane of the aerosol-formingP 17562

[0376] FTR4075 51 / 68

[0377] device 100, and Figure 2B shows a cross-section along the transverse axis or plane 20 shown in Figure 2A.

[0378] Unless stated otherwise, the aerosol-forming system 500 of Figures 2A and 2B comprises the same features, functions and elements as the aerosol-forming device 100 and system 500 described with reference to Figure 1. The exemplary system 500 of Figures 2A and 2B is specifically designed for vaporizing liquid substrate material 210.

[0379] The aerosol-forming article 200 of the device 100 is formed as cartridge 200, container 200 or pod 200, that can be inserted along a longitudinal axis of the device into a body 170 and / or receiving space 120 of the device 100. The cartridge 200 includes a reservoir 205 that is at least partly filled with the liquid substrate 210, which is also referred to as e-liquid 210. In particular, a bottom part 212 or end 212 of the cartridge 200 may be inserted into a receiving space 120 of the device 100. At an opposite end 214 of the aerosol-forming article 200, an aerosol outlet 215 can be formed, via which the user can draw air and inhalable aerosol.

[0380] The receiving space 120 is defined by two semi-circular, half cylindrical, or arc-like shaped electrodes 114, 116 of a dielectric heater arrangement 110 of the device 100. Also more than two electrodes 114, 116 or electrode pairs may be utilized. For example, a plurality of two, three or more electrode pairs of interdigitated electrodes may be arranged around at least a part of a circumference or perimeter of the cartridge 200.

[0381] The at least two electrodes 114, 116 are part of a load capacitor 112 of the dielectric heater arrangement 110 configured to dielectrically heat the liquid substrate material 210. The length of the electrodes 114, 116, measured parallel to an insertion direction of the cartridge 200 or longitudinal axis of the device 100, defines a dielectric heating zone 222, in which substrate material can be dielectrically heated and vaporized.

[0382] In order to vaporize the substrate 210 in a controlled manner, the cartridge 200 comprises a wicking element 220 or liquid transfer element 220, which includes a porous material that can be soaked with the substrate 210, for example via capillary forces, diffusion, or osmotic forces. The wicking or liquid transfer element 220 can be configured to draw the liquid substrate 210 from the reservoir 205 to at least a part of the dielectric heater arrangement 110, in particular towards the electrodes 114, 116. Common materials used for the wicking element ca include organic cotton, silica, or ceramic.

[0383] In the example shown in Figures 2A and 2B, the cartridge 200 includes two liquid transfer elements 220 arranged opposite to each other. Specifically, the two electrodes 114, 116 are spaced apart from each other along the circumferential direction of the device 100 or cartridge 200, such that two gaps 115, 117 are formed in circumferential direction of the device 100 or cartridge 200. In each gap 115, 117, one of the liquid transfer elements 220 is arranged, as canP 17562

[0384] FTR4075 52 / 68

[0385] best be seen in FIG. 2B. Also, each of the gaps 115, 117 forms or defines a load capacitor 112, which functions similar or analogue to the load capacitor 112 of Figure 1.

[0386] As also mentioned above, the electrodes 114, 116 can be part of the cartridge 200 and contacted to respective electrical contacts of the device 100. Alternatively, the electrodes 114, 116 can be part of the device 100.

[0387] To ensure a homogenous supply of substrate 210 from the reservoir 205 to the liquid transfer elements 220, the cartridge 200 comprises a feeding structure 230, which can for example, be a hollow cylindrical structure in the centre of the cartridge 200 at the bottom end 212, which is placed inside the receiving space 120 or heating zone 222. There can also be individual liquid feeding structures for each liquid transfer element 220.

[0388] A surface 240 of each of the liquid transfer elements 220 that faces the feeding structure 230 acts as liquid ingress area or surface (LIS), via which liquid substrate 210 is drawn by the liquid transfer elements 220. As the liquid transfer elements 220 are arranged in the gaps 115, 117 formed between the electrodes 114, 116 in circumferential direction, an electrical field strength between the electrodes 114, 116 can be very high at or near the liquid transfer elements 220, such that the substrate 210 can be vaporized within the liquid transfer elements 220. Vaporized substrate material can then exit or leave the liquid transfer elements 220 via so-called vapor egress areas or surfaces (VES) 242 of the wicking elements 220, which are arranged opposite to the liquid ingress surfaces 240 in radial direction of the device 100 or cartridge 200.

[0389] As can best be seen in Figure 2B, the liquid transfer elements 220 can be dome-like shape, have a trapezoidal cross-section, or be curved towards the inside of the cartridge 200, such that the respective vapor egress surface 242 is larger than the liquid ingress surface 240 of each liquid transfer element 220.

[0390] Between the cartridge 200 and the body 170 of the aerosol-forming device 100, an air channel 160 or airflow path 160 is formed. The airflow path 160 can have multiple sections that may be fluidly coupled or connected. In particular, an air inlet 161 can be formed as a gap between the cartridge 200 and the body 170, for example at or close to the end 214 of the cartridge 200 where the aerosol outlet 215 is formed. The gap or air inlet 161 may span the entire or only a part of the circumference of the device 100. Accordingly, the gap or air inlet 161 can be ring-like or annular formed.

[0391] The air inlet 161 connects to lateral sections 162 of the airflow path 160, which lateral sections 162 extend in longitudinal direction of the device 100 between the electrodes 114, 116 and the liquid transfer elements 220 on two opposite sides of the receiving space 120 along each of the vapor egress surfaces 242 towards the end 212 of the cartridge 200. The lateral sections 162 can also be formed as tubular or cylindrical sections that surround at least a part of the receiving space 120 and dielectric heater arrangement 110 along its circumference.P 17562

[0392] FTR4075 53 / 68

[0393] Near or close to the bottom part or end 212 of the cartridge 200, the airflow path 160, respectively, the lateral sections 161 thereof are connected via inlets or openings 164 at the bottom of the receiving space 120 to an interior volume 260 or interior channel 260 of the cartridge 200 that is fluidly coupled to the aerosol outlet 215, such that air can be drawn via the openings 162 towards the air outlet 215 of the cartridge 200 through the interior volume 260. The interior channel or volume 260 of the cartridge 200 may also serve as aerosolization chamber, as indicated by the circular arrow in Figure 2A. It should be noted that various designs and configurations of the airflow path 160 are possible. For example, on two opposing sides of the vapor egress surface 242 of each liquid transfer element 220, a lateral airflow channel may be formed.

[0394] Similar to the functionality of the device 100 of Figure 1, upon activation of the device 100 of Figures 2A and 2B, the control circuitry 140 may power the dielectric heater arrangement 110 to a first power level to heat up the at least a part of the dielectric heater arrangement 110 and / or substrate 210 in the heating zone 222 to a pre-heating temperature above ambient temperature and below a volatilization or vaporization temperature sufficient to release aerosol from the substrate 210. When heated to the pre-heating temperature, the device 100 or control circuitry 140 can monitor or determine one or more operational parameters of the dielectric heater arrangement 110 and / or the power consumption of the dielectric heater arrangement 110, in order to determine when a user inhalation takes place, respectively, to detect a user inhalation.

[0395] When a user initiates a user inhalation or puff, air at ambient temperature can be drawn from an external environment of the device 100 via the air inlets 161 of the airflow path into the lateral sections 162. The lateral sections 162 of the airflow path 160 pass by the vapor egress surfaces 242 of the liquid transfer elements 220 and pass by the electrodes 114, 116, as shown by the arrows in Figure 2A, such that the drawn air cools the dielectric heater arrangement 110 aerosol-forming article 200 and / or substrate 210 in the heating zone 222. This leads to a decrease in temperature and hence to an increase in relative permittivity of the substate 210. As a consequence, the capacitance of load capacitors 112 defined or formed by the gaps 115, 117 arranged between the electrodes 114, 117 in circumferential direction increases, and an oscillation frequency of the oscillator circuitry 130 decreases due to the increasing capacitances, and hence increasing LC constant of the oscillator circuitry 130. In addition, the power consumption of the dielectric heater arrangement 110 increases. One or more of these effects, respectively one or more of these changes in the capacitance of the load capacitors 112, the oscillation frequency of the oscillator circuitry 130 and the power consumption can be determined or monitored by the control circuitry 140 in order to detect the onset, start and / or occurrence of the user inhalation.P 17562

[0396] FTR4075 54 / 68

[0397] To allow for a fast and reliable detection of a start, occurrence, end or termination of a user inhalation, a good thermal coupling between the airflow path 160 or section 162 thereof with the aerosol-forming article 200, substrate 210 and / or at least a part of the dielectric heater arrangement 110, a wall 270 or casing wall 270 of the aerosol-forming article 200 may be appropriately chosen, along which the airflow path 160 or section 162 may be arranged.

[0398] In the example shown in Figures 2A and 2B, the wall 270 of the article 200 constitutes or defines at least a part of a wall of the airflow path 160 and / or the lateral sections 162 thereof. Accordingly, the wall 270 may be arranged in radial direction of the device 100 between one of the electrodes 114, 116 and the adjacent liquid transfer element 220. Thus, air drawn by the user from the surrounding may be in contact with the wall 270, thereby leading to a cooling or heating of the wall 270 as well as material or components in the vicinity of the wall 270 in correspondence with the occurrence of user inhalations or an airflow through the airflow path 160. Therefore, the temperature of the material or components in vicinity or close to the wall 270, which may be arranged in the heating zone 222, can change with changing temperature of the air in the airflow path 160 and / or the lateral sections 162 thereof. The materials or components that will undergo a temperature change can include, for example, the wicking elements 220, at least a part of the electrodes 114, 116, at least a part of the substrate 210, other parts of the dielectric heater arrangement 110 and / or other parts of the aerosol-forming article 200.

[0399] When the user inhales, cool air may be drawn through the airflow path 160 or air channel 160 and depart a cooling onto the wall 270 as well as material or components arranged in the vicinity thereof and / or arranged in the heating zone 222, such as the wicking elements 242, reservoir and / or other components of the aerosol-forming article 200, substrate 210 and / or dielectric heater arrangement 110. Likewise, when the user stops inhaling, the temperature of these components or material may increase. Hence, via the airflow path 160 or air channel 160, changes in temperature, and thus relative permittivity, can be induced in the dielectric heater arrangement 110, aerosol-forming article 200 and / or substrate 210 in correspondence with the user inhalation, thereby enabling detection of the user inhalation, including its start, onset, occurrence, termination and end.

[0400] The wall 270 between the airflow path 160 and at least a part of the dielectric heater arrangement 110 and / or aerosol-forming article 210 may be arranged or configured to provide efficient thermal coupling, thereby ensuring a fast response. Also, dielectric heating of the wall 270 may be minimized. For example, the wall 270 may be made of a low-dielectric, high-temperature, food grade microwave-safe material. As the wall 270 may be in close range to dielectric heater arrangement 110 or electrodes 114, 116 and thus may be subjected to a high dielectric field strength, the wall 270 may be made of a material that has a lower relative permittivity as the remaining parts in the heating zone 222.P 17562

[0401] FTR4075 55 / 68

[0402] For example, the wall 270 can be made of or comprise a low dielectric material. Alternatively or additionally, a thickness of the wall 270 may be small and / or the wall 270 may be thin. For example, a thickness of the wall 270 may range from about 2 mm to about 100 pm, in particular from about 1.5 mm to about 200 pm. Preferably, the thickness of the wall 270 may be below about 1 mm, more preferably below about 500 pm. Accordingly, the wall 270 may be thin, for example membrane-like, to ensure good thermal coupling.

[0403] Materials that can be used are for the wall 270 can include, but are not limited to, Quartz glass, Polyether Ether Ketone (PEEK), Polyetherimide (PEI), hard plastic materials used for microwaveable food containers such as TritanTM (Bisphenol A (BPA)-free copolyester), BPA-free polycarbonates, high-density polyethylene (HDPE), siloxane, polysiloxane, polypropylene, Polyethylene, Terephthalate (PET, PETE).

[0404] Upon detecting the user inhalation, control circuitry 140 can increase the power provided to the dielectric heater arrangement 110 and power it at the second power level, where the dielectric heater arrangement 110 and / or substrate 210 can be heated to the volatilization or vaporization temperature to generate inhalable aerosol. Air drawn through the inlets 161 and lateral sections 162 of the airflow path 160 flows past the vapor egress surfaces 242 of the liquid transfer elements 220, where vapor is released into the airflow. The airflow, enriched with vapor, then flows towards the central interior volume or interior channel 260 of the cartridge 200 via the openings 164, where aerosol can be formed, for example in an aerosolization chamber. The air, enriched with aerosol, can then be drawn into the user’s mouth via the aerosol outlet 215 of the cartridge 200.

[0405] As described with reference to Figure 1 , as soon as the user stops inhaling, the temperature of the dielectric heater arrangement 110 and substrate 210 increases, which leads to a decrease in the relative permittivity of the substrate 210. As a consequence, the capacitances of the load capacitors 112 decrease, the oscillation frequency of the oscillator circuitry 130 increases, and the power consumption of the dielectric heater arrangement 110 decreases. One or more of these changes can be determined or detected by the control circuitry 140, thereby detecting termination of the user inhalation.

[0406] Upon detecting termination of the user inhalation, the control circuitry 140 may cut the power supply to the dielectric heater arrangement 110, and the next or subsequent user inhalation can be determined or detected, as the dielectric heater arrangement 110 and substrate 210 may still have a temperature well above room or ambient temperature. Optionally, however, the control circuitry 140 may power the dielectric heater arrangement 110 at the first power level to ensure that the dielectric heater arrangement 110 and substrate 210 have at least the pre-heating temperature, in order to allow for cooling by air drawn by the user in the subsequent user inhalation, which can then be detected again by the control circuitry 140.FTR4075

[0407] 56 / 68

[0408] Figure 3 is a schematic illustration of an oscillator circuitry 130 for use in the aerosol-forming system 100 of Figures 1 to 2B, respectively in a dielectric heater arrangement 110 thereof. Oscillator circuitry 130 comprises a switching unit 131 or switching device 131 interconnected with a resonator feedback loop 133 or feedback loop 133 to provide for a self-oscillating signal to the switching device 131. The switching device 131 comprises a single transistor, such as a bipolar junction transistor (BJT) or a field effect transistor (FET). The oscillator circuitry 130 can further comprise a choke 135 that acts on an input to the feedback loop 133 to provide for a stimulation signal, for example a stimulation voltage.

[0409] The oscillator circuitry 130 also comprise a biasing unit 136 acting on the feedback loop 133 for providing a variable or controllable biasing signal, for example a biasing voltage for setting the operating conditions. In the variant shown, the feedback signal can be described as a voltage. The output voltage UOUT of the switching device 131 is coupled to the feedback loop 133 providing a feedback switching signal in the form of a voltage U|Nto the switching device 260. The configuration of the feedback loop 133 is such that the output signal, e.g. the voltage UOUT of the switching device 131 can undergo a phase change and arrives inverted at the input U|Nof the switching device 131 for resonant oscillation. In other configurations, a current could be used as the feedback signal with a switching device 131 comprising a BJT.

[0410] Feedback loop 133 is configured to provide a 180° phase shift from the output UOUT to input U|Nof switching device 131 for oscillation, and in addition, a transistor can be configured for inverting operation.

[0411] As shown in Figure 4A, feedback loop 133 includes a resonant circuit 137 comprising the load capacitor 112 providing fora first 90 degrees phase shift or quarter wave shift to the feedback signal. Feedback loop 133 further includes a capacitive element 138 providing for a second 90 degrees phase shift or quarter wave shift to the feedback signal, such that the feedback signal reaching the input of the switching device 131 is inverted and phase-shifted by 180 degrees. Switching device 131 is itself configured for inverted switching operation to provide a 180 degree phase shift between the input U|Nand the output UOUT of the switching device 131.

[0412] Resonant circuit 137 comprises the first and second electrodes 114, 116 of the dielectric heater arrangement 110, together forming the load capacitor 112. When an aerosol-forming substrate 210 is arranged between the first and second electrodes 114, 116, it forms part of the load capacitor 112. Importantly, the load capacitor 112 is formed in the feedback loop 133, and not at a separate output or part of a separate circuitry that is connected to the switching device 131. This enables a high-frequency oscillating voltage to be created across the electrodes 114, 116 of load capacitor 112, which is needed for sufficient and efficient dielectric heating of the aerosol-forming substrate 210, without having an additional output or circuit to the alreadyFTR4075

[0413] 57 / 68

[0414] resonating feedback loop 133, which would create unnecessary losses and circuit complexity. The resonant circuit 137 may comprise a series resonator circuit or a parallel resonator circuit.

[0415] The feedback loop 133 is configured to be self-oscillating and will oscillate at or close to a given resonance or oscillation frequency determined by the values of the passive components of the feedback loop 133. Since oscillator circuitry 130 is operatively coupled to the control circuitry 140, the control circuitry 140 can determine the oscillation frequency of the oscillator circuitry 130. This enables the control circuitry 140 to determine a change in the oscillation frequency which can be caused by the cooling effect of air drawn by the user in a user inhalation, thereby detecting the user inhalation. Hence, the dielectric heater arrangement 110 can act as puff sensor allowing to detect the user inhalation without requiring a dedicated or separate sensor.

[0416] Further, the switching device 131 can be coupled to one of the electrodes 114, 116 via a transistor 139, which can be configured for inverting operation, for example as an inverting common source Field Effect Transistor (FET), Metal Oxide Field Effect Transistor (MOSFET), or a common emitter Bipolar Junction Transistor (BJT).

[0417] The control circuitry 140 can, for example, be configured to determine the switching frequency of the switching device 131 and / or the switching frequency at a gate terminal of the transistor 139 in order to determine the change in the oscillation frequency of the oscillator circuitry 130, which is indicative of a change in the relative permittivity of the substrate 210 in the load capacitor 112 caused by the change in temperature, as described in detail herein. Alternatively or additionally, the control circuitry 140 can determine a frequency of the alternating electric field in the load capacitor 112 in order to determine the change in the oscillation frequency of the oscillator circuity 130 that is caused by the change in the relative permittivity of the substrate 210 in the load capacitor 112. Hence, the dielectric heater arrangement 110 can act as puff sensor allowing to detect the user inhalation without requiring a further sensor.

[0418] In an alternative embodiment, resonant circuit 137, respectively, the oscillator circuitry 130, may include a resonant cavity 141, as schematically illustrated in Figure 4B. The resonant circuit 137 including resonant cavity 141 may have an interior volume configured to receive an aerosolforming substrate 210, for example having an opening for inserting an aerosol-forming substrate 210. In an example, the resonant circuit 137 including resonant cavity 141 can be configured as a A / 4 resonator. The resonant circuit 137 including resonant cavity 141 may be configured to behave like an RLC circuit. The inductor L and the capacitor C are arranged in parallel to each other, to have a parallel resonance or a frequency close to the parallel resonance that can be stimulated by the switching device 131. Resonant circuit 137 including cavity 141 may be coupled to the feedback loop 133 using one or more of a capacitive coupling, an inductive antenna coupling (magnetic coupling), a direct electric coupling, or a window coupling (e.g. coupling with a loop).FTR4075

[0419] 58 / 68

[0420] The resonant circuit 137 including resonant cavity 141 can have any shape, but preferably has a cylindrical shape or a rectangular parallelepiped shape. In one embodiment, the resonant cavity 141 can be configured as a split-ring resonator. Alternatively to or in addition to the resonant cavity 141, the resonant circuit 137 may include a transmission line.

[0421] The oscillator circuitry 130 and / or resonant circuit 137 can include an impedance matching circuit 142 configured to supply electromagnetic waves to the resonant cavity 141. The impedance matching circuit 142 can be configured to adapt or change an impedance in accordance with an impedance of a load of the dielectric heater arrangement, which load may be constituted by the resonant cavity 141 and / or transmission line, optionally with the substrate 210. Hence, if the impedance of the load of the dielectric heater arrangement 110 changes due to a changing relative permittivity of the substrate caused by a change in temperature, the impedance matching circuit 142 adopts its impedance. Also this can be operatively controlled by the control circuitry 140, thereby enabling the control circuitry 140 to detect the user inhalation based on determining the impedance of the load of the dielectric heater arrangement 110 and / or the impedance of the impedance matching circuit 142. Hence, the dielectric heater arrangement 110 can act as puff sensor allowing to detect the user inhalation without requiring a further sensor.

[0422] Figure 5 illustrates operation of the aerosol-forming device 100 or system 500, for example an aerosol-forming device 100 of any of the previous Figures. Likewise, Figure 5 illustrates a method of detecting a user inhalation at an aerosol-forming device 100.

[0423] By way of example, the method includes the following steps, which are also referred to as dedicated modes of the aerosol-forming device 100, since the device 100 can for example be switched into particular configurations in each step.

[0424] The aerosol-forming device 100 can be configured into an idle mode, where the aerosolforming device 100 is turned on but not performing any heating. Further, the device 100 includes a potential use mode that can be triggered by a signal from one or more sensors 154, aerosolforming article insertion, or user instructions, for example. Further, the device 100 includes a puff observation mode that is configured once the potential use mode is established or detected, and a puff power mode, where the vaporization and aerosolization is performed. Moreover, the device 100 may include a calibration mode to adapt the sensing to environmental changes, which is optional. In the following, the exemplary configurations or modes of the device 100 or system 500, respectively, steps of the method are summarized.

[0425] The device 100 may start in idle mode. No dielectric heating is performed, but the control circuitry 140 or controller142 may be running or in interrupt mode to detect any status changes.

[0426] The potential usage or use mode can be instructed or started, for example, by the user actuating the user interface 156, for example manually pressing a button, or automatically by means of a sensor 154, such as a motion detector, accelerometer, gyroscope, camera withP 17562

[0427] FTR4075 59 / 68

[0428] analysis of motion, or other type of motion detector such as pyrometer motion detector, which can detect that the user has picked-up the device 100, for example. Accordingly, presence, touch, or proximity sensing can be used to detect that the user has taken the device 100 into his or her hands and / or is holding the device 100, or the like. It is also possible that the insertion of article 200 triggers the potential usage mode, or some other engagement of the cartridge 200 or article 200 with the receiving space 120.

[0429] Upon detecting or having instructed the potential usage mode, the control circuitry 140 activates the oscillator circuitry 130 and dielectric heater arrangement 110 by supplying electrical power at a first power level to the dielectric heater arrangement 110. The first power level can refer to a low power setting in the puff observation mode, for example by feeding it with a DC voltage and / or current that is substantially lower than a DC voltage and / or current for the full heating operation, which may be referred to herein as second power level. Preferably, the low power mode does not heat the aerosol-forming substrate 210 above a certain threshold temperature, but only to a pre-heating temperature, to avoid any aerosolization. The pre-heating temperature should, for example, be below 100°C, more preferably below 70°C, but a temperature that is higher than the environmental, ambient or room temperature, preferably above 30°C, more preferably above 40°C, even more preferably above 50°C, even more preferably above 60°C.

[0430] The puff observation mode can also have the function of pre-heating the aerosol-forming substrate 210 before the puff is taken, for example the e-liquid 210 in a cartridge 200. Thereby, the puff-observation mode can have the function of allowing for puff detection, and liquid preheating pre-puff. Pre-puff, the preheating allows to increase e-liquid viscosity, which can improve transport of the substrate to the wicking elements 220 and allows to reduce a time necessary to move the substrate temperature to vaporization, e.g. about 180°C-240°C, to provide for a more satisfying experience. The pre-heating temperature can be made such that it is just below the vaporization temperature of water, e.g. 100°C, or below the vaporization temperature of the aerosol former.

[0431] During or in the puff observation mode, the control circuitry 140 can monitor the oscillation frequency of the oscillator circuitry 130 and / or the power consumption of the dielectric heater arrangement 110. For example, the frequency at the gate of the transistor 139 of the oscillator circuitry 130 can be measured, or the frequency of the magnetic or electric field in the load capacitor 112, as described above. With respect to the power consumption, the voltage of the output of a DC-DC converter or an input to the oscillator circuitry 130 can be measured, as well as the current, for example by measuring the voltage drop over a shunt resistor. It is also possible that the temperature inside the receiving space 120 is measured, with an additional sensor.P 17562

[0432] FTR4075 60 / 68

[0433] When the device 100 is configured in the puff observation mode and no puff or user inhalation occurs, the control circuitry 140 can implement one or more mechanisms to configure the device 100 back into the idle mode. For example, the control circuitry 140 may determine a time expired since start of the puff observation mode or since the last user inhalation, and switch the device 100 back into the idle mode upon determining that the time expired reaches or exceeds a predetermined time period. For example, the device 100 may be configured from the puff observation mode into the idle mode upon determining that for at least 5 seconds, preferably at least 10 seconds, more preferably at least 15 seconds or 20 seconds, no user inhalation or puff occurred or was detected. Hence, the puff observation mode may be exited if no puff happens for a predetermined period of time.

[0434] Alternatively or additionally, one or more sensors may be utilized to determine whether or the device 100 is intended for being used for aerosol consumption. For example, one or more motion sensors, gyroscopes, accelerometers, inertial sensors, touch sensors, proximity sensors, image sensors or other sensors may be used to determine whether the device 100 is still used for aerosol consumption, when configured in the puff observation mode. For example, a motion pattern of the device 100 may be determined by the control circuitry 140. Upon detecting a change in the motion pattern or upon detecting a corresponding predefined motion pattern, the control circuitry 140 can configure the device 100 back into the idle mode. For example, when the user places the device 100 on a table, it may remain at a static position that can be detected by the control circuitry 140. Alternatively or additionally, when the user puts the device 100 into its pocket or transports it, a corresponding motion pattern may be detected by the control circuitry 140, thereby determining that the device 100 is not used anymore for aerosol consumption, and the device 100 may be configured back into the idle mode.

[0435] Upon taking a puff or user inhalation, while the device 100 is in the puff observation mode, for example for a puff-on-demand vaping operation or session-based heating, the airflow can pass by the electrodes 114, 116 of the dielectric heater arrangement 110, but will also pass through air channel 160 or airflow path 160, as shown in Figures 1, 2A and 2B. In the example shown in Figures 2A and 2B, the airflow path 160 can for example be located adjacent to the liquid transfer elements 220, such that e-liquid or substrate 210 in the liquid transfer elements 220, which are currently being heated at the pre-heating temperature, but also the liquid transfer elements 220 themselves can be cooled by the user inhalation. Likewise, in the example of Figure 1, the electrodes 114, 116 and / or load capacitor 112 with substrate 210 are cooled. This cooling effect will impact the overall relative permittivity that is seen by the electrodes 114, 116 of the dielectric heater arrangements 110, and therefore change the capacitance value of the load capacitors 112 shown in any of the foregoing Figures. In the example illustrated in Figures 2A and 2B, cooling air will pass by the vapor egress surfaces 242 to cause cooling.P 17562

[0436] FTR4075 61 / 68

[0437] Generally, the cooling effect leads to an increase of the relative permittivity of the substrate 210, and a consequential increase of the capacitance of the load capacitor 112. This in turn leads to a reduction of the switching or oscillation frequency of the oscillator circuitry 130. In addition, this also leads to an increase in the power consumption of the dielectric heater arrangement 110. Any of these changes can be determined by the control circuitry 140 to detect the user inhalation This determination can also be supported by values from a temperature sensor, e.g. a thermistor or NTC or PTC wire to detect the temperature of the receiving space 120.

[0438] During the puff observation mode, the control circuitry 140 can monitor the power consumption and / or frequency change in the oscillation frequency at a high repetition frequency, to determine if a user inhalation is being taken. Monitoring can include determining with predefined repetition rate, for example with a frequency in Hertz to Kilohertz or even Megahertz range. Upon determination that a user inhalation is being taken, the control circuitry 140 can exit the puff observation mode to increase the heating power to the second power level, for example according to a puff-on-demand heating profile or a session-based heating profile, in order to configure the device 100 in the puff power mode.

[0439] During the puff power mode, the control circuitry 140 can continue to monitor the switching or oscillation frequency of the oscillator circuitry 130 and / or the power consumption of the dielectric heater arrangement 110, to determine if the user inhalation has ended. This can be detected by observing a shift of the oscillation frequency, and a consequential shift of power consumption.

[0440] Upon detection of the ending of the user inhalation, the puff power mode can be exited, and the control circuitry 140 can revert back to the puff observation mode, or back to the idle mode where no puff is taken. This can be done based on data from the potential use mode, e.g. if there is still movement departed to the device, if there is still a user holding the device, or if the user still has not manually turned off the potential use mode, as indicated by the dashed line or arrow in Figure 5.

[0441] The device 100 may further comprise a calibration mode. For calibration purposes, during the non-use, for example at regular testing intervals, measurements can be performed to set a baseline for the power consumption and / or the oscillation frequency of the oscillator circuitry 130. As temperature and humidity of the environment may change, it is thereby possible to calibrate the measurement for puff detection.

[0442] If the dielectric heater arrangement 110 is used for a Heat-not-Burn type aerosol-forming substrate 210, it is also possible to detect a puff or user inhalation based on the same principles of the puff observation mode, but optionally during a full power step, e.g. during the puff power mode. During a heating, where the heater 110 is aerosolizing substances, the taking of the puff departs a cooling effect to the substrate material, for example cool air will flow through the heatedFTR4075

[0443] 62 / 68

[0444] substrate material. With or without temperature control, this cooling will depart a change of overall relative permittivity of the substrate material that is being heated and also departs a depletion effect and this will result in a change of the oscillation frequency of the oscillator circuitry 130 that can be detected by the control circuitry 140.

[0445] Figure 6 shows a flow chart illustrating steps of a method of detecting a user inhalation at an aerosol-forming device 100 or system 500, in particular an aerosol-forming device 100 or system 500 as described with reference to the foregoing figures.

[0446] At step S1, the method comprises supplying electrical power to the dielectric heater arrangement 110 to cause dielectric heating of the substrate 210. For example, the dielectric heater arrangement 110 may be powered at the first power level to pre-heat the substrate 210.

[0447] At step S2, the method comprises detecting a user inhalation at the aerosol-forming device 100 based on determining one or more of a change in at least one operational parameter of the dielectric heater arrangement 110 and a change in a power consumption of the dielectric heater arrangement 110.

[0448] For instance, detecting the user inhalation at the aerosol-forming device 100 at step S2 can include determining a change in an impedance of a load of the dielectric heater arrangement 110. Alternatively or additionally, detecting the user inhalation at the aerosol-forming device 100 at step S2 can include determining a change an oscillation frequency of an oscillator circuitry 130 of the dielectric heater arrangement 110. Alternatively or additionally, detecting the user inhalation at the aerosol-forming device 100 at step S2 can include determining a change in a capacitance of a load capacitor 112 of the dielectric heater arrangement 110 configured to receive at least a part of the aerosol-forming article 200. Alternatively or additionally, detecting the user inhalation at the aerosol-forming device 100 at step S2 can include determining a change in the power consumption of the dielectric heater arrangement 110. Alternatively or additionally, detecting the user inhalation at the aerosol-forming device 100 at step S2 can include determining a change an impedance of a load of the dielectric heater arrangement 110.

[0449] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, allFTR4075

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[0451] ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

[0452] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0453] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

FTR407564 / 68CLAIMS1. An aerosol-forming device for forming aerosol from a substrate of an aerosol-forming article, comprising:a dielectric heater arrangement configured to heat, in a puff-on-demand heating operation, at least a part of a substrate of an aerosol-forming article by dielectric heating to form aerosol, andcontrol circuitry configured to control the dielectric heater arrangement, wherein the control circuitry is further configured to detect a user inhalation at the aerosol-forming device based on determining one or more of:a change in at least one operational parameter of the dielectric heater arrangement, anda change in a power consumption of the dielectric heater arrangement.

2. The aerosol-forming device according to the preceding claim, wherein the change in said at least one operational parameter and / or the change in the power consumption of the dielectric heater arrangement is associated with or caused by a change in an air flow past at least a part of the dielectric heater arrangement indicative of the user inhalation.

3. The aerosol-forming device according to any one of the preceding claims, wherein the at least one operational parameter of the dielectric heater arrangement includes at least one of: an impedance of a load of the dielectric heater arrangement,an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement, and a capacitance of a load capacitor of the dielectric heater arrangement configured to receive at least a part of the substrate of the aerosol-forming article.

4. The aerosol-forming device according to any one of the preceding claims, wherein the control circuitry is configured to detect the user inhalation and / or start of the user inhalation at the aerosol-forming device based on determining one or more of:an increase in an impedance of a load of the dielectric heater arrangement;a decrease of an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement;an increase in a capacitance of a load capacitor of the dielectric heater arrangement; and an increase in the power consumption of the dielectric heater arrangement.P 17562FTR4075 65 / 685. The aerosol-forming device according to any one of the preceding claims, wherein the dielectric heater arrangement comprises a resonant cavity and / or transmission line configured to receive at least a part of the aerosol-forming article, wherein the resonant cavity and / or transmission line together with the substrate form a load of the dielectric heater arrangement; and wherein the control circuitry is configured to detect the user inhalation at the aerosolforming device based on determining a change in at least one of an impedance of a load of the dielectric heater arrangement and the power consumption of the dielectric heater arrangement.

6. The aerosol-forming device according to any one of the preceding claims, wherein the dielectric heater arrangement comprises an oscillator circuitry with a load capacitor, preferably included in a feedback loop of the oscillator circuitry and configured to receive at least a part of the aerosol-forming article to heat the aerosol-forming substrate, andwherein the control circuitry is configured to detect the user inhalation at the aerosolforming device based on determining a change in one or more of an oscillation frequency of the oscillator circuitry and the power consumption of the dielectric heater arrangement.

7. The aerosol-forming device according to any one of the preceding claims, wherein the control circuitry is configured to monitor or determine one or more of:an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency at a gate terminal of a transistor of the oscillator circuitry;an oscillation frequency of an oscillator circuitry of the dielectric heater arrangement based on determining a switching frequency of a switching device of the oscillator circuitry, the switching device being configured for inverting operation;a frequency of an alternating magnetic or electric field in a load capacitor of the oscillator circuitry;an impedance of a load of the dielectric heater arrangement;an output voltage or current of a power supply of the aerosol-forming device; and an input voltage or current supplied to the dielectric heater arrangement.

8. The aerosol-forming device according to any one of the preceding claims, wherein the aerosol-forming substrate is a liquid aerosol-forming substrate.

9. The aerosol-forming device according to any one of the preceding claims, wherein the control circuitry is configured to power the dielectric heater arrangement to a first power level for heating the substrate of the aerosol-forming article to a pre-heating temperature above ambientP 17562FTR4075 66 / 68temperature and below a volatilization temperature of one or more ingredients of the substrate sufficient to release aerosol from the aerosol-forming article, andwherein the control circuitry is configured to detect the user inhalation and / or start of the user inhalation during a time period where the dielectric heater arrangement is powered to the first power level.

10. The aerosol-forming device according to the preceding claim, wherein the pre-heating temperature is above about 25°C, above about 30°C, preferably above about 40°C, more preferably above about 50°C, and even more preferably above about 60°C; and / or wherein the pre-heating temperature is below about 120°C, below about 100°C, preferably below about 90°C, more preferably below about 80°C, and even more preferably below about 70°C.

11. The aerosol-forming device according to any one of claims 9 and 10, wherein the control circuitry is configured to monitor or determine one or more of said at least one operational parameter and the power consumption of the dielectric heater arrangement, when the dielectric heater arrangement is powered to the first power level.

12. The aerosol-forming device according to any one of claims 9 to 11, wherein the control circuitry is configured to, in response to detecting the user inhalation at the aerosol-forming device, power the dielectric heater arrangement to a second power level for heating the aerosolforming article to a volatilization temperature sufficient to release aerosol from the aerosol-forming article.

13. The aerosol-forming device according to the preceding claim, wherein the first power level is below about 80%, below about 70%, below about 60%, below about 50%, below about 40%, below about 30%, below about 20%, below about 10%, below about 5%, or below about 2% of the second power level.

14. The aerosol-forming device according to any one of the preceding claims, wherein the control circuitry is configured to determine whether the user inhalation has ended based on determining a further change in at least one of said at least one operational parameter of the dielectric heater arrangement and the power consumption of the dielectric heater.

15. An aerosol-forming system comprising an aerosol-forming device according to any one of the preceding claims and one or more of:P 17562FTR4075 67 / 68an aerosol-forming article for generating aerosol; anda companion device for one or more of storing the aerosol-forming device and charging the aerosol-forming device.

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