Aerosol-forming article and device of improved efficiency

Abstract

An aerosol-forming article (18) for use in an aerosol-forming system, comprising a liquid reservoir (19) configured to store a liquid aerosol-forming substrate (20), a liquid transfer element (21), comprising a liquid ingress surface (22) fluidically connected to the liquid reservoir (19), a vapor egress surface (23) fluidically connected to an aerosolization space (24), and a liquid transfer volume (25) between the liquid ingress surface (22) and the vapor egress surface (23) configured to transfer liquid from the liquid ingress surface (22) to the vapor egress surface (23), at least two electrodes (26) configured to establish an alternating electric field at a heating zone (28), the heating zone (28) encompassing at least a part of the vapor egress surface (23), wherein the at least two electrodes (26) are arranged at, on or at least partly embedded in the liquid transfer element (21) at, on, or under the vapor egress surface (23), such that vaporized liquid egressing from the vapor egress surface (23) flows between the at least two electrodes (26) to reach a downstream airflow path (34).

Description

[0001] AEROSOL-FORMING ARTICLE AND DEVICE OF IMPROVED EFFICIENCY

[0002] The present disclosure relates to an aerosol-forming article for use in an aerosol-forming device, an aerosol-forming device, particularly for use with the aerosol-forming article and a corresponding aerosol-forming system, and a method of heating a liquid aerosol-forming substrate in an aerosol-forming article and / or an aerosol-forming device.

[0003] 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 inhalations or puffs, aerosol generated from an aerosol-forming substrate or an aerosol-forming article, for example by heating. The aerosol-forming devices of the present disclosure are mainly directed to the field of tobacco and tobacco-substitute products, for example electronic cigarettes, e-vapor devices, and / or vaporisers. The aerosol-forming devices of the present disclosure may also pertain to other types of inhalers, dispensers, or atomizers, for example inhalers, dispensers, or atomizers for medical applications.

[0004] 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. Alternatively, aerosol-forming systems can be designed as two-part systems or devices comprising an aerosolforming 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 inhalations or puffs, aerosol generated based on heating an aerosol-forming article or substrate couplable 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.

[0005] The aerosol-forming article, also referred to as aerosol-generating article, cartridge, capsule, reservoir, or pod, can comprise an aerosol-generating or aerosol-forming substrate, for example a liquid aerosol-forming substrate, such as a tobacco or nicotine-containing substrate. 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 aerosolforming article is usually formed as a pod, cartridge, capsule, or reservoir, that can be at least partly inserted into a receiving space or receptacle or receptacle chamber of the aerosol-forming device for aerosol consumption.

[0006] Exemplary aerosol-forming substrates can comprise liquid substrate material, containing one or more active ingredients and one or more aerosol formers. The substrate material can, for example, be assembled, often with other elements or components, to form a substantially podshaped aerosol-forming article. Such aerosol-forming article can be configured in shape and size to be inserted at least partially into a receiving space of the aerosol-forming device. The aerosolforming device may comprise a heating element or heater device for heating the substrate of theaerosol-forming article to cause vaporization. The heating element or heater device may be part of the aerosol-forming article and / or the aerosol-forming device. 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 or container. Corresponding exemplary aerosol-forming articles can, for example, comprise a cartridge containing or 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 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. The aerosol generated from the aerosolforming substrate or article may comprise or include one or more of nicotine, aroma, sugar, moisturising agent, botanicals, preservative, flavouring, for example cocoa, liquorice, menthol and lactic acid or other additives. The aerosol generated from the aerosol-forming substrate or article may additionally or alternatively comprise one or more pharmaceutical agents or drugs and may include one or more adjuvants. In addition, the aerosol-forming substrate can further include one or more aerosol formers, for example but not limited to propylene glycol (PG), vegetable glycerin (VG), polyethylene glycol (PEG), glycerol esters, triacetin, or other.

[0007] For generating the aerosol during use or consumption, heat can be supplied by a heating element, heater device or heat source to heat at least a portion or part of the aerosol-forming substrate. The heating element, heater device or heat source 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 entire heating element or heater device or heat source can be fixedly associated with or arranged within an aerosol-forming article, for instance in the form of a cartridge, which can be attached to and / or powered by the handheld device or handheld part of the aerosolforming device.

[0008] Conventionally, resistive heating may be used to heat the liquid substrate. However, the present disclosure relates to dielectric or microwave heating achieved through an alternating electrical field using electrical energy supplied via, drawn from or stored in an energy storage or battery of the aerosol-forming device. As used herein, a battery of the aerosol-forming device can generally refer to an energy storage of the aerosol-forming device configured to store electrical energy. Accordingly, the term energy storage can include one or more batteries, one or more capacitors, one or more accumulators or other types of energy storage. Also, any reference to a battery herein can include a plurality of batteries.

[0009] Typically, aerosol-forming devices comprise an energy storage, for example a battery, 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 in one ormore usage sessions using one or more aerosol-forming articles. The battery may, for example, be a lithium-ion battery.

[0010] According to aspects of the present invention, aerosol-forming devices may form aerosol by heating a liquid aerosol-forming substrate, the constituents of which may be provided as a liquid from the start or which may at least partly be extracted from solid components included in the aerosol-forming article. Typically, the liquid is transported to the heating device by a liquid transfer element, for example a wicking element. The transport of liquid may be caused by capillary action due to small flow paths in the liquid transfer element, by gravity, or by other means, for example by pumping and / or an actuator. To achieve enough flow of the liquid aerosol-forming substrate to the heating device to be able to provide the user with the desired aerosol for consumption, liquid transfer elements of sufficient size are necessary, for example defined as a cross-sectional area of a flow.

[0011] With the background art devices using dielectric heating, it is possible that a portion of the volume of the liquid transfer element is heated at locations where it is soaked by the liquid aerosolforming substrate, leading to undesired volumetric heating of the liquid aerosol-forming substrate, and potentially creating vapor bubbles that can be trapped at undesired locations, causing ejection of liquid droplets from the vapor egress surface of a liquid transfer element.

[0012] In addition, devices using dielectric heating may heat other components of the aerosolforming article or device as well other than just the liquid aerosol-forming substrate. For example, separation walls, aerosol flow pathways, and device walls may be arranged juxtaposed to the electric fields caused by the dielectric heating or even at least partly in the heating zone. Heating these components also leads to a loss of energy and can potentially cause undesired substances.

[0013] It may therefore be desirable to provide for an improved aerosol-forming article and / or device in which heating and vaporization of liquid aerosol-forming substrate is achieved with more efficiency. In particular, unnecessary volumetric heating of the liquid transfer element and / or other components of the article and / or device can be avoided.

[0014] These advantages may be achieved by the features described herein.

[0015] According to an aspect of the present invention, there is provided an aerosol-forming article for use in an aerosol-forming device and / or an aerosol-forming system, comprising a liquid reservoir configured to store a liquid aerosol-forming substrate, a liquid transfer element, comprising a liquid ingress surface fluidically connected to the liquid reservoir, a vapor egress surface fluidically connected to an aerosolization space, and a liquid transfer volume between the liquid ingress surface and the vapor egress surface configured to transfer liquid from the liquid ingress surface to the vapor egress surface, at least two electrodes configured to establish an alternating electric field at a heating zone, the heating zone encompassing at least a part of the vapor egress surface or the entire vapor egress surface, wherein the at least two electrodes arearranged at, on or at least partly embedded in the liquid transfer element at, on, or under the vapor egress surface, such that vaporized liquid egressing from the vapor egress surface flows between the at least two electrodes to reach a downstream airflow path. The at least two electrodes may form the dielectric heating zone between them. The dielectric heating zone may be arranged closer to the vapor egress surface than the liquid ingress surface.

[0016] 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.

[0017] The liquid transfer element may also be referred to as wicking element. It may provide liquid transport from the liquid ingress surface towards the vapor egress surface by capillary action, by gravity, or by a combination of both. Alternatively or additionally, an actuator or a pump may be used to actively move the liquid aerosol-forming substrate from the liquid ingress surface towards the vapor egress surface. The liquid transfer element may be arranged at least partly in the heating zone, particularly with the vapor egress surface. The heating zone may be defined by the portion of the liquid transfer element that is exposed to the alternating electric field caused by the electrodes that is sufficiently strong to cause vaporization of the liquid aerosol-forming substrate. The electrodes may, for example, be arranged in proximity of, at, on, or in contact with the liquid transfer element so that the heating zone encompasses or substantially encompasses the vapor egress surface of the liquid transfer element. Thereby, the liquid aerosol-forming substrate can be reliably and completely or substantially completely vaporized in the heating zone, even if some of the liquid aerosol-forming substrate may exit the liquid transfer element, i.e. the vapor egress surface, in liquid form. In effect therefore, also in this case, vapor formed from the liquid aerosolforming substrate at the heating zone and thus at the vapor egress surface enters the aerosolization chamber from the heating zone. The liquid transfer element may be at least partly arranged between the at least two electrodes. Therefore, when the liquid is heated by the dielectric heating caused by the alternating electric field by the electrodes, the temperature of the liquid may increase until the vaporization temperature of the one or more components of the liquid is reached inside the liquid transfer element, more specifically at the vapor egress surface. At this point, at least a part of the liquid turns into vapor. For example, the liquid may have various components or constituents with different vaporization temperatures. For example, an aerosolformer and / or a carrier liquid may be vaporized and may carry out one or more active agents inthe vapor, so that an inhalable aerosol may be formed in the aerosolization chamber with the one or more active agents, e.g. for example nicotine. Generally, the liquid transfer element may be fully or partially soaked with liquid aerosol-forming substrate, for example all the way to the vapor egress surface. Once dielectric heating occurs, preferably with the strongest intensity of the RF electric field zone at the vapor egress surface, the liquid may be vaporized at or in close proximity to the vapor egress surface, such that the vaporized liquid will exit the liquid transfer element by the vapor egress surface. Preferably only very little or a strongly reduced creation of vapor bubbles inside the liquid transfer element away from the vapor egress surface is caused. Such bubbles could be trapped and cause ejection of non-vaporized liquid from the vapor egress surface, which should be avoided to prevent liquid from dripping from the device.

[0018] The at least two electrodes may be configured and / or arranged so that the maximum strength of the alternating electric field and therefore the highest heating power density is reached at and / or on the vapor egress surface. In other words, the at least two electrodes may be configured and / or arranged so that the electric field strength is focused on the vapor egress surface. This may ensure reliable vaporization of the liquid aerosol-forming substrate and may prevent significant vaporization inside the liquid transfer element, causing undesired volumetric heating and thereby creating bubble and / or liquid ejection. For example, the at least two electrodes may be configured and / or arranged so that the electric field is strong enough to vaporize the liquid aerosol-forming substrate or at least a part of the liquid aerosol-forming substrate only at the vapor egress surface or up to a maximum of 2 mm or up to a maximum of 1.5 mm or up to a maximum of 1 mm or up to a maximum of 0.5 mm or up to a maximum of 0.3 mm into the liquid transfer element, for example from the vapor egress surface.

[0019] In practice, the liquid aerosol-forming substrate may flow from the reservoir into the liquid transfer element, particularly through the liquid ingress surface. It may then flow through the liquid transfer volume toward the vapor egress surface. During this passage, the liquid is heated in the heating zone and may eventually be vaporized, for example close to or at the vapor egress surface. At the vapor egress surface, vapor or vaporized liquid egresses from the vapor egress surface and flows into the aerosolization space. For example, the vapor or vaporized liquid egresses from the vapor egress surface in a direction perpendicular or normal to the vapor egress surface. The vapor or vaporized liquid may then pass through or between the at least two electrodes and may then flow into a downstream airflow path. For example, the vapor or vaporized liquid may pass through or between the at least two electrodes in the same direction as the egress from the vapor egress surface. In other words, the vapor or vaporized liquid may pass through or between the at least two electrodes in or along the normal direction of the vapor egress surface or a direction perpendicular to the vapor egress surface. The downstream airflow path mayconnect the aerosolization chamber to an aerosol outlet of the aerosol-forming device, for example a mouthpiece.

[0020] The vapor exiting the heating zone and / or the vapor egress surface may be mixed with incoming air from an air inlet in the aerosolization chamber. For this, the aerosolization chamber may be fluidically connected to the outside environment through an air inlet and air flow path. When the user draws or puffs on the cartridge, i.e. the aerosol-forming article, that is in operative connection with the aerosol-forming device or on a mouthpiece fluidically connected to the aerosol-forming article downstream of the aerosolization chamber, outside air is drawn into the device and through the aerosolization chamber, where it is mixed with the vapor exiting the vapor egress surface. The vapor cools off and small droplets may be formed, ultimately leading to the forming or generation of aerosol from the mixture of vapor and air. The mixture of vapor, for example vaporized liquid, air and aerosol may then flow through or into an airflow path, for example a downstream airflow path. The aerosol may then flow though the downstream airflow path to the aerosol outlet of the aerosol-forming device, for example the mouthpiece. The aerosol exiting the aerosol outlet and / or the mouthpiece may then be consumed by the user through inhalation.

[0021] That the at least two electrodes are arranged on or at least partly embedded in the liquid transfer element may mean that the electrodes are in direct contact with the liquid transfer element, i.e. the material constituting the liquid transfer element. The at least two electrodes may be arranged at, on, or under the vapor egress surface. This may mean that the electrodes may be arranged in contact with or adjacent to the vapor egress surface. An arrangement under the vapor egress surface may describe an arrangement recessed or partly embedded in the liquid transfer element, particularly the vapor egress surface. As outlined later in more detail, this may be achieved by placing, depositing or moulding the liquid transfer element on the at least two electrodes during production, or the other way around. The at least two electrodes may be arranged on an outer surface of the liquid transfer element. The at least two electrodes may be at least partly embedded or inset or recessed into the body of the liquid transfer element, at the vapor egress surface. This may mean that the at least two electrodes may be form-fittingly engaged by the liquid transfer element, i.e. the material constituting the liquid transfer element, in at least three directions. In contrast, the at least two electrodes being arranged at least partly inside the liquid transfer element, without having contact to the material of the liquid transfer element, does not constitute being embedded according to aspects of the present disclosure. As outlined in more detail below, there may also be provided an interface layer between the electrodes and the liquid transfer element. In this case, the electrodes may be in direct contact with the interface layer and / or the liquid transfer element. The interface layer in turn may be, on one side, in direct contact with the liquid transfer element, and on the other side, for exampleopposing side, may be in direct contact with the electrodes. In embodiments with more than two electrodes, the same features may apply.

[0022] That the at least two electrodes are arranged at the liquid transfer element may mean that the electrodes are not in direct contact with the liquid transfer element, i.e. the material constituting the liquid transfer element. In other words, the at least two electrodes may be distanced from the liquid transfer element, for example from the vapor egress surface. For example, the electrodes may be distanced from the liquid transfer element by a maximum of 2 mm or by a maximum of 1 mm or by a maximum of 0.5 mm or by a maximum of 0.3 mm or by a maximum of 0.2 mm or by a maximum of 0.1 mm. However, the at least two electrodes may still be configured and / or arranged so that the maximum strength of the alternating electric field is reached at and / or on the vapor egress surface. This may be achieved by specific electrode designs which focus the electric field at the desired space. Such designs may be found by simulations targeting specific use cases and arrangements.

[0023] The liquid ingress surface may be defined by a surface area of the liquid transfer element directed towards the liquid reservoir or a liquid channel that is fed by liquid from the liquid reservoir. Therefore, the liquid ingress surface may be in direct contact with the liquid aerosolforming substrate stored in the liquid reservoir. The vapor egress surface may be defined as the surface areaof the liquid transfer element directed towards the aerosolization chamber. Therefore, the vapor egress surface may be in direct contact with the air, vapor and / or aerosol in the aerosolization chamber. As explained in more detail later, the liquid transfer element may be or may comprise a porous material or a material comprising capillaries or other small flow pathways, forming a plurality of contiguous liquid pathways from the liquid ingress surface to the vapor egress surface. It is also possible that the liquid transfer element is made from a solid body having a plurality of parallelly-arranged flow channels, for example flow channels having dimensions to cause a capillary flow, each leading from the liquid ingress surface to the vapor egress surface. Therefore, the liquid ingress surface and / or the vapor egress surface can be an uneven or rough surface. However, the liquid ingress surface and / or the vapor egress surface may be, for the purposes herein, be understood as a face end or face end surface of the liquid transfer element at the specific sides constituting the liquid ingress surface and / or the vapor egress surface. For example, the liquid ingress surface and / or the vapor egress surface may refer to an area and / or surface and / or plane defining or being defined by said end faces of the liquid transfer element. For example, the liquid ingress surface and / or the vapor egress surface may refer to an area and / or plane parallel to and / or located at and / or following the shape, particularly the macroscopic shape, of the respective end face of the liquid transfer element.

[0024] The aerosol-forming article and / or aerosol-forming device according to aspects of the present disclosure may be configured to be used with dielectric heating. The electrodes may bepart of a dielectric heating arrangement, for example including an oscillator which may provide a radio frequency, RF, voltage across the electrodes, to cause the generation of an RF electric field between the electrodes, as explained in more detail below. An alternating electric field may be established between at least two electrodes which together may form a capacitor or load capacitor. The heating zone may therefore be formed at least partly between the at least two electrodes. The heating zone may reach beyond the space between the electrodes, for example for up to several millimetres, for example for up to 3 mm or up to 2 mm or up to 1 mm. The electrodes may be part of and / or may be arranged in the aerosol-forming article. This means that the aerosol-forming device configured to be used with the aerosol-forming article according to aspects of the present disclosure may be free of the at least two electrodes, for example free of any electrodes configured for dielectric heating. The aerosol-forming device may comprise electrode connection elements or terminals, i.e. electrical connections, to electrically connect the electrodes of the removable aerosol-forming article to the aerosol-forming device, for interconnection with the oscillator, power system and / or power supply of the aerosol-forming device. Apart from the electrodes, the aerosol-forming article may also comprise other passive components of the feedback loop, for example one or more inductors. Alternatively, the feedback loop, for example the one or more inductors, are arranged in the aerosol-forming device, and the aerosol-forming article may exclusively comprise the electrodes and their electrical connections.

[0025] The liquid aerosol-forming substrate may be guided directly through the heating zone, i.e. into the area where the alternating electric field is caused by the at least two electrodes, entering the heating zone on one side and then exiting the heating zone as vapor. The heating zone may contain at least part of the liquid transfer element or liquid transfer volume. For example, the liquid aerosol-forming substrate may exit the liquid transfer element as vapor at the vapor egress surface. Alternatively or additionally, the liquid aerosol-forming substrate may be vaporized after exiting the liquid transfer element at the vapor egress surface as liquid. By performing heating only at the heating zone that is arranged substantially around the vapor egress surface, a constant, sufficient vaporization of liquid aerosol-forming substrate may be achieved through the heating zone, and the heat transfer to the liquid aerosol-forming substrate is efficient and has reduced losses, for example because only a little or no parts of the liquid transfer element need to be heated, thereby saving energy and increasing battery life.

[0026] For example, to further increase this efficiency, it may be provided that the components are arranged and / or designed so that the flow direction or effective flow direction of the liquid aerosolforming substrate and / or vapor does not change, i.e. stays the same, during the transport of the liquid and / or through the heating zone. In other words, it may be provided that an effective flow direction of liquid aerosol-forming substrate and / or vapor formed from the liquid aerosol-forming substrate through the heating zone is unidirectional, for example substantially orthogonal to amain direction of the strongest amplitudes of an alternating electrical field in the dielectric heating zone. The direction of the strongest amplitudes of the alternating electrical field in the dielectric heating zone may be from one electrode to the other, the field lines always beginning and ending perpendicular to the surface of the electrodes, even if the design of the electrodes also leads to curved field lines. The effective flow direction may be defined as the overall direction in which a fluid predominantly moves through a medium, in this case the liquid transfer element, when observed at a larger scale, averaging out small-scale variations in flow paths. In other words, the effective flow direction may be defined in a quantitative way as the direction in which liquid aerosol-forming substrate enters the heating zone and in which the vapor formed from the liquid aerosol-forming substrate exits the heating zone into the aerosolization chamber. While on a microscopic scale, the liquid and / or vapor may flow in different directions, for example in turbulent flow or variable directions of a capillary flow in a porous body, these flow directions may be averaged out in the effective flow direction, leaving only the direction of quantitative transport. The liquid aerosol-forming substrate and the vapor formed from the liquid aerosol-forming substrate may flow between and / or through the at least two electrodes, for example in a way that in a direction orthogonal to the flow direction, for example in a direction orthogonal to the effective flow direction, the liquid and / or vapor is always between the opposing electrodes. By providing a unidirectional flow, particularly through the heating zone, the liquid entering the heating zone may be efficiently pre-heated by the alternating electric field and then, downstream in the heating zone, may be vaporized, the vapor also being transported off in the same direction. In this way, no or only little heat is lost to other components of the device, for example to parts of the liquid transfer element outside, particularly upstream, of the heating zone, and / or to volumes of the liquid aerosol-forming substrate which are not about to undergo heating and vaporization in the heating zone. Therefore, in effect, no or comparatively little heating energy is lost and the overall efficiency of the aerosol-forming device as well as battery life is increased, leading to a more efficient use of the alternating electric field for the dielectric heating to cause sufficient volumetric heating power to cause rapid vaporization. Another advantage lies in the fact that the volumetric heating power of the liquid aerosol-forming substrate by dielectric heating will be the largest where the electric field amplitude is the highest, and therefore the liquid transfer element and electrodes can be designed that the strongest volumetric heating power is caused at the furthest downstream portions of the flow, particularly the flow through the liquid transfer element, right at the liquid egress surface. In this way, vaporization of liquid away from the vapor egress surface can be avoided, which might lead to ejection of still liquid substrate from the vapor egress surface by the expanding vapor. In this way, the amount of liquid substrate, which has not been vaporized, and which reaches the mouthpiece may be minimized.To avoid heating any more components or parts of components of the aerosol-forming device than absolutely necessary for the provision of the vapor and ultimately the aerosol, it may be provided that no other components other than the liquid transfer element or parts of the liquid transfer element, potentially at least a part of the aerosolization chamber, and potentially a housing component separating the liquid transfer element from the electrodes, for example a wall component or wall, are arranged inside of the heating zone, e.g. are exposed to a meaningfully strong alternating electric field. In other words, it may be provided that the heating zone is free of components other than the liquid transfer element or parts of the liquid transfer element, potentially at least a part of the aerosolization chamber, and potentially a housing component separating the liquid transfer element from the electrodes, for example a wall component or wall.

[0027] The dielectric heating zone may be defined by the arrangement and geometry of the at least two electrodes. Particularly, the dielectric heating zone may be defined as the volume in which an alternating electrical field of sufficient strength for pre-heating and / or heating and / or vaporization of the liquid aerosol-forming substrate is achieved. The dielectric heating zone may be arranged between the electrodes and may also reach beyond the volume or space between the electrodes, for example for a few millimetres, for example for up to 3 mm or up to 2.5 mm or for up to 2 mm or up to 1.5 mm or for up to 1 mm or up to 0.5 mm.

[0028] The vapor egress surface of the liquid transfer element may form an outer surface of the liquid transfer element towards the aerosolization chamber or space. The at least two electrodes may be arranged at, on or at least partly embedded in the vapor egress surface. The volume between the electrodes may comprise the vapor egress surface and / or may be arranged adjacent, for example directly adjacent, to the vapor egress surface. The volume between the electrodes may therefore be arranged next to the liquid transfer element, i.e. the vapor egress surface, but may be free of the material of the liquid transfer element or the liquid transfer volume. In this case, the volume between the electrodes may contain only an open space which may be fluidically connected to or be part of the aerosolization chamber. On the other hand, the liquid transfer element may be arranged in and / or protrude into the volume between the electrodes so that the vapor egress surface of the liquid transfer element is arranged in, i.e. inside, the heating zone. In this case, the volume between the electrodes may partly contain an open space which may be fluidically connected to or be part of the aerosolization chamber and may partly contain a part of the liquid transfer element, for example comprising the vapor egress surface. The volume between the electrodes may even be filled, for example completely filled, by the liquid transfer element. In this case, the volume between the electrodes may only contain a part of the liquid transfer element. For instance, the volume between the electrodes may end with the vapor egress surface of the liquid transfer element, which may be fluidically connected to the aerosolization chamber. These particular arrangements ensure efficient heating and prevent liquid from exitingthe heating zone at the vapor egress surface, thereby ensuring complete vaporization of the liquid aerosol-forming substrate.

[0029] The liquid transfer element may be made of or may comprise a wicking material, for example a porous or fibrous material or a material comprising channels or microchannels, for example a porous ceramic material, for example a porous silicon ceramic material. The liquid transfer element can also comprise a plurality of fluidically parallelly arranged flow channels, leading from liquid ingress surface to the vapor egress surface. The liquid transfer element and / or the wicking material may be configured to cause capillary flow of the liquid aerosol-forming substrate, particularly in the effective flow direction. The liquid transfer element can also be arranged to cause gravitational flow of the liquid to the heating zone, or a combination of gravitational and capillary flow. For example, the liquid transfer element may be made of or may comprise food and / or medical grade silicate-based or clay-based ceramic. Other suitable materials may include alumina oxide ceramics. As another example, a material used for the liquid transfer element can be glass-based. Glass is an inert material that does not degrade with repeated heating cycles and also has a low relative permittivity or dielectric constant, thereby absorbing substantially less dielectric energy than a liquid aerosol-forming substrate or e-liquid. For example, the material for the glass can be primarily vitreous silica or quartz glass. The liquid transfer element may have a porosity of from 50% to 70%, for example from 55% to 65%, for example of 60%. An average pore size or microchannel size may be from 10 pm to 50 pm, for example from 15 pm to 40 pm or from 20 pm to 30 pm. The liquid transfer element may also have a variable porosity, for example a higher porosity at the liquid ingress surface and a lower porosity at the vapor egress surface or a lower porosity at the liquid ingress surface and a higher porosity at the vapor egress surface. Analogously, the liquid transfer element can be made of a plurality of flow channels having a larger cross-sectional flow area at the vapor egress surface as compared to the liquid ingress surface or having a larger cross-sectional flow area at the liquid ingress surface as compared to the vapor egress surface. In other words, the porosity of the liquid transfer element may diminish or become smaller or increase or become bigger, either stepwise or continually, in a direction from the liquid ingress surface towards or to the vapor egress surface, for example in the direction of the effective flow direction as described herein. This change in porosity or overall cross-sectional flow surface allows to facilitate the evacuation of vapor of the liquid aerosol-forming substrate that expands relative to its liquid state. All of these features may be used to improve flow parameters.

[0030] As already mentioned, only a part of the liquid transfer volume or the liquid transfer element may be arranged in or inside the heating zone and / or the volume between the electrodes. For example, a maximum of 50% or a maximum of 40% or a maximum of 30% or a maximum of 20% or a maximum of 15% or a maximum of 10% of the liquid transfer volume or the liquid transferelement may be arranged in or inside the dielectric heating zone and / or the volume between the electrodes. In this way, heating or volumetric heating of a part of the liquid transfer volume or the liquid transfer element not necessary for preheating and vaporizing the liquid aerosol-forming substrate is avoided. In other words, in this way, only a small part of the liquid transfer volume or liquid transfer element is heated which is necessary for efficient preheating and vaporization of the liquid aerosol-forming substrate, whereas areas not contributing to vapor and ultimately the aerosol flow are not heated, saving energy and improving efficiency.

[0031] The heating zone may define a heating volume in which the liquid aerosol-forming substrate is preheated and vaporized while flowing through the heating zone. The heating volume may also be defined as the volume in which an alternating electrical field of sufficient strength for preheating and / or heating and / or vaporization of the liquid aerosol-forming substrate is achieved. The dimensions and features as previously described for the heating zone may also be applicable to the heating volume. Both the preheating and the vaporization of the liquid aerosol-forming substrate is implemented, for example exclusively implemented, inside of the heating volume. That the preheating and the vaporization of the liquid aerosol-forming substrate is exclusively implemented inside of the heating volume may mean that no active heating of liquid aerosolforming substrate may be implemented anywhere outside of the heating volume. While it may still be possible that heat is passively transported to liquid outside of the heating volume, for example by heat conduction, no active heating is implemented.

[0032] As mentioned, heating of the liquid aerosol-forming substrate in the heating zone may be implemented by dielectric heating, and may, for example, primarily depend on dielectric heating. However, to increase heating power in the heating zone, it may further be provided that the at least two electrodes are configured for resistive heating. Joule-type heating may also be achieved by Eddie currents due to the alternating currents of the oscillation circuit. In other words, it may be provided that the at least two electrodes are configured to have resistive heating properties, for example with a conductivity o of at least 1x106S / m at 20°C or at least 5x106S / m at 20°C or at least 1x107S / m at20°C or at least 5x107S / m at20°C. The at least two electrodes may therefore themselves heat up during heating. Because the heating zone between the electrodes may have a very small diameter or cross-section, the heat of the electrodes may be conducted to the liquid aerosol-forming substrate flowing through the heating zone, thereby contributing to preheating and / or vaporization of the liquid aerosol-forming substrate. Simultaneously, the conductivity o in the given range is high enough for effective dielectric heating by establishing the alternating electrical field in the range of radio frequencies.

[0033] For example, the at least two electrodes may include a metal material or metal alloy, for example a metal material or metal alloy causing heating by ohmic losses or Joule-type losses, i.e. resistive heating. In one embodiment, for example, the at least two electrodes may include anickel alloy, for example an alloy of nickel, chromium and iron. In another embodiment, for example, the at least two electrodes may include copper or aluminum or an alloy of copper and aluminum. It may also be provided that the at least two electrodes comprise a precious metal, for example gold and / or platinum. As the conductive layers forming the electrodes may be very thin, use of such materials may still be economical.

[0034] For example, the at least two electrodes may be provided and / or may be configured as layers or strips having a thickness of between 300 nm and 30 pm, for example of between 500 nm and 25 pm. The heating zone or heating zones may be at least partly established between the lateral face sides of the electrodes, i.e. the sides of the electrodes facing each other.

[0035] The properties of the electrodes may be balanced or optimized between ohmic losses, i.e. resistive heating, and dielectric heating. For the dielectric heating, higher conductivity is beneficial. It may therefore be provided that the at least two electrodes have a conductivity o of at least 1x107at 20°C. It has been found that electrodes of this conductivity work very well with the oscillation circuits employed by the invention.

[0036] The aerosol-forming article may comprise a protective film covering the at least two electrodes. For example, the protective film may comprise a low-dielectric material and / or may have a thickness of 0.1 mm or less. The protective film may protect the electrodes from contact with the liquid transfer element and / or the liquid aerosol-forming substrate and / or the vapor and / or aerosol.

[0037] According to aspects of the present disclosure, at least one heating zone is provided between the at least two electrodes. However, additional heating zones may be provided by adding more electrodes. For example, the aerosol-forming article may comprise at least one additional electrode, wherein at least one additional heating zone is formed between the at least one additional electrode and another electrode. In this embodiment, therefore, at least one electrode may be used twice, i.e. may be used to establish two heating zones. This may mean that, in use, at least one electrode is used to establish an alternating electric field with at least two other electrodes. Therefore, two heating zones may be established directly next to each other, separated only by the double-use electrode itself.

[0038] Additionally or alternatively, the aerosol-forming article may comprise at least two additional electrodes. An additional dielectric heating zone may be formed between the at least two additional electrodes. In this embodiment, the established additional heating zone may be arranged anywhere in the aerosol-forming article, for example distanced from the first heating zone. It may also be provided that two pairs of electrodes form at least three heating zones, for example wherein electrodes of opposite polarity are arranged neighbouring each other on opposite sides of the respective heating zones.In any of the described embodiments, a plurality of heating zones may be established, for example two or three or four or five or six or more than six heating zones. The heating zones may be arranged in a stacked or juxtaposed manner, such that the heating zones are all arranged in the same plane. Alternatively, the heating zones may be radially arranged with respect to each other. Other arrangements may also be possible. In the middle of the radially arranged heating zones, for example the liquid reservoir may be arranged. The heating zones may each comprise their own, separate liquid transfer element to supply the heating zones with liquid aerosol-forming substrate from the liquid reservoir. Alternatively, all the heating zones may be supplied by liquid aerosol-forming substrate by a single, common liquid transfer element. Each of the heating zones may be associated with and / or comprise and / or be arranged directly next to a separate vapor egress surface, irrespective of whether each heating zone has its own liquid transfer element or a common liquid transfer element is used. By establishing more than one heating zone, more aerosol may be produced per unit of time.

[0039] In case the aerosol-forming article and / or the aerosol-forming device comprises at least two heating zones, at least two of these heating zones may be separately and / or individually activated. For example, the electrodes establishing the respective heating zones may be separately and / or individually powered and / or connected to the feedback loop such that a controller may activate only one of the heating zones at a time or both heating zones simultaneously. The individually controllable heating zones may be associated with the same or different liquid transfer elements and liquid reservoirs. For example, each of the separately controllable heating zones may be associated with a separate liquid transfer element and / or a separate liquid reservoir. For example, in this way, different liquid aerosol-forming substrates may be used, each in their own liquid reservoir. These separate and different liquid aerosol-forming substrates may then be vaporized and aerosolized independently from each other, either one at a time, or simultaneously as a mixture. Different aerosols and / or aerosol mixtures may in this way be provided to the user with only one device.

[0040] The liquid transfer element may comprise at least two vapor egress surfaces, wherein at least two electrodes forming a dielectric heating zone may be arranged at, on or at least partly embedded in the liquid transfer element at each vapor egress surface. However, the liquid transfer element may comprise more than two vapor egress surfaces, for example a plurality of vapor egress surfaces, wherein each vapor egress surface may be associated with a different heating zone. For example, a plurality of electrodes of alternating polarities may be arranged on the liquid transfer element. For example, the plurality of electrodes may be arranged in a mesh or a grid, for example the electrodes of alternating polarity being arranged interdigitated with respect to each other. For example, the electrodes may be arranged in a matrix or checkerboard pattern, and the heating zones formed by these electrodes may be polarized and / or powered accordingto a checkerboard color arrangement, i.e. in alternating arrangement. In an embodiment, at least two pairs of electrodes or a plurality of electrodes of alternating polarity may be arranged in an interdigitated pattern, parallel stripes, or mesh at the associated liquid transfer element and / or vapor egress surface. In this way, a heating zone is established between every pair of neighbouring electrodes. Also, the outer surface of the liquid transfer element is separated in different vapor egress surfaces between the electrodes and / or in the respective heating zones.

[0041] It may be provided that the at least two electrodes, for example all electrodes, may be arranged following the shape of the associated liquid transfer element and / or vapor egress surface. In other words, the electrodes may be arranged next to each other at or on the outer surface of the liquid transfer element comprising the one or more vapor egress surfaces. For example, the liquid transfer element and / or the vapor egress surface or surfaces may be plane or planar. In this case, the electrodes may be arranged in a stacked manner and / or in a plane. The liquid transfer element and / or the vapor egress surface or surfaces may alternatively be rounded, for example cylindrical or spherical. In this case, the electrodes may be arranged along or similarly to the curve of the vapor egress surface. It may be provided that a distance between adjacent electrodes at the vapor egress surface is constant or substantially constant. In other words, the heating zone between the electrodes may have a constant thickness or width, particularly in the direction from one of the adjacent electrodes to the other and / or along the direction of the electric field in the heating zone. This may be applicable to both plane or planar as well as rounded vapor egress surfaces.

[0042] In the case of a rounded liquid transfer element and / or the vapor egress surface, but also in other cases, the at least two electrodes may be configured and / or arranged with respect to each other such that the volume between the at least two electrodes forms a constriction on a side facing the vapor egress surface. The at least two electrodes may be configured and / or arranged with respect to each other such that the distance between the at least two electrodes is smallest where the distance of the at least two electrodes to the vapor egress surface is smallest. In other words, a bottleneck between the electrodes is formed in close proximity or in the closest possible proximity to the vapor egress surface. I.e., the bottleneck may be directed towards the vapor egress surface. For example, when the electrodes have a rectangular cross-section, they may be tilted with respect to each other so that a bottleneck is formed between the closest corners of the rectangular cross-section. These corners may then be the ones directed towards the vapor egress surface. The strength of the electric field may be strongest where the distance between the electrodes is smallest. By arranging the electrodes in this way, the volume of space with the strongest electric field may be brought close to or may comprise the vapor egress surface, facilitating reliable vaporization of the liquid aerosol-forming substrate.The at least two electrodes may be configured and / or arranged following a curved line or plane. For example, the curved line or plane may be similar to the shape of the vapor egress surface and / or the liquid transfer element. The at least two electrodes may thus be configured and / or arranged following the shape of the vapor egress surface and / or the liquid transfer element. The concave side of the curved line or plane may be directed towards the vapor egress surface. In case the curved line or plane is similar to the shape of the vapor egress surface, this may be automatically so. By directing the concave side of the curved line or plane towards the vapor egress surface, bottlenecks or constrictions between the electrodes may be directed towards the vapor egress surface as well. As explained above, this may concentrate the alternating electric field and therefore the heating power at the concave side and the vapor egress surface and leads to reliable vaporization.

[0043] The liquid transfer element may have any suitable shape, for example a complex three-dimensional shape, which may provide both for an efficient transport of the liquid aerosol-forming substrate from the liquid reservoir to the heating zones and between the electrodes as well as for an arrangement of the at least two electrodes in a way providing energetically efficient and quantitatively sufficient vaporization of the liquid. To keep manufacturing costs low, simple and easy moldable shapes may be preferable. For example, the liquid transfer element may be shaped as a cylinder, for instance a hollow cylinder. The inner surface and / or the lateral surface of the hollow cylinder may then be used as the liquid egress surface and / or the vapor egress surface of the liquid transfer element. For example, when the liquid transfer element is at least partly arranged as a hollow cylinder, the liquid reservoir and / or the liquid ingress surface may be arranged on the inside surface of the hollow cylinder and the vapor egress surface may be arranged on the lateral surface of the hollow cylinder. In this case, the transfer of the liquid aerosol-forming substrate may be provided from the inside of the hollow cylinder to the outside, wherein the heating zones may be arranged around and / or along the lateral surface of the liquid transfer element. For example, a plurality of electrodes may be arranged around and / or along the lateral surface of the liquid transfer element, forming a plurality of heating zones between them. Alternatively, when the liquid transfer element is at least partly arranged as a hollow cylinder, the liquid reservoir and / or the liquid ingress surface may be arranged on the lateral surface of the hollow cylinder and the vapor egress surface may be arranged on the inside surface of the hollow cylinder. In this case, the transfer of the liquid aerosol-forming substrate may be provided from the outside of the hollow cylinder to the inside, wherein the heating zones and / or the electrodes may be arranged around and / or along the inner surface of the liquid transfer element. For example, a plurality of electrodes may be arranged around and / or along the inner surface of the liquid transfer element, forming a plurality of heating zones. In both cases, the electrodes themselves and therefore also the heating zones may be arranged in a cylindrical pattern. Thelongitudinal axis and / or direction of each electrode may be arranged parallel to the cylinder axis of the liquid transfer element.

[0044] The electrodes themselves may also have any suitable form or shape. For example, the electrodes or at least a part of the electrodes may have a polygonal cross-section, for example a rectangular cross-section. Such electrodes may have sharp corners or rounded corners. The corners may be used to optimize the strength and distribution of the electric field for a specific use case. For example, sharp corners may lead to peaks in the electric field strength, while rounded corners may avoid such peaks. Alternatively, the electrodes or at least a part of the electrodes may have a rounded cross-section, for example a circular or circular section or oval cross-section. The electrodes may all have the same shape or some electrodes may be differently shaped than others. The electrodes or at least a part of the electrodes may be configured as a rod, plate, strip, pin, tube, track, or film. The electrodes may be configured or provided with smooth edges and / or rounded corners, i.e. may be edge-finished, chamfered or deburred or may be manufactured with smooth edges and / or rounded corners. Sharp edges and protrusions of the electrodes might lead to local maxima of the electric field which could cause local hot spots and uncontrolled and / or premature vaporization.

[0045] As mentioned, the electrodes may be in direct contact with the liquid transfer element. However, it may also be provided that an interface layer is arranged between the electrodes and the liquid transfer element. In this case, the interface layer may be arranged in direct contact with the liquid transfer element, whereas the electrodes may be arranged in direct contact with the interface layer. The interface layer may be provided and / or configured as a protective layer avoiding direct contact between the liquid aerosol-forming substrate and the material of the electrodes. Additionally, the interface layer may be provided and / or configured to simplify manufacturing, for example by providing an improved bond between the electrode and the material of the liquid transfer element and / or by providing a smooth, non-porous surface. Therefore, the aerosol-forming article may further comprise an interface layer arranged between the at least two electrodes, for example between all electrodes, and the liquid transfer element. The interface layer may comprise a non-porous and / or non-conductive dielectric material, for example a glass material or a polymer. Other suitable materials may also be used. The interface layer may also be configured to prevent sharp edges or protrusions of the electrodes, for example extending into cavities or capillaries of the porous liquid transfer element. This may also prevent local maxima of the electric field.

[0046] The interface layer may be positioned and / or arranged with respect to the electrode and / or the liquid transfer element so that it does not lie in the volume between the electrodes. In other words, the interface layer may not be arranged between two electrodes forming a heating zone. For example, the interface layer may be arranged perpendicular to the effective flow rate of theliquid aerosol-forming substrate through the liquid transfer element, for example upstream of the heating zone. Additionally or alternatively, the heating zone between the at least two electrodes may be free of the interface layer or of material of the interface layer. By keeping the interface layer out of the heating zone, the distance between the electrodes forming the heating zone may still be kept very small for efficient heating. Also, the interface layer itself does not need to be overly heated, avoiding a waste of heating power.

[0047] Several possibilities exist for cost-effective manufacturing of the aerosol-forming article according to the present disclosure. For example, the at least two electrodes and / or the interface layer may be created and / or arranged on the respective substrate by thick film deposition or thin film deposition, for example chemical vapor deposition or physical vapor deposition. Layers or films of a thickness of from a few hundred nanometers up to for example 25 pm or 30 pm may be created, therefore requiring very little material. In this way, the at least two electrodes and / or the interface layer may be created and / or arranged on the liquid transfer element. Additionally or alternatively, the at least two electrodes may be created and / or arranged on the interface layer in this way. It may also be possible that the interface layer is created and / or arranged on the liquid transfer element differently and that only the at least two electrodes are created and / or arranged on the interface layer by thick film deposition or thin film deposition.

[0048] The liquid transfer element may be created and / or arranged on the interface layer and / or on the at least two electrodes by overmoulding, for example by low-pressure injection moulding. In other words, the interface layer, the at least two electrodes or both may first be provided. Then the liquid transfer element may be overmoulded onto the interface layer, the at least two electrodes or both. Using this technique, the at least two electrodes and / or the interface layer may be at least partly embedded in the material of the liquid transfer element. The overmoulded liquid transfer element and electrodes with interconnection pins can be pressed into a capsule-like shell, for example a housing, i.e. a plastic housing, that may form or comprise the reservoir, mouthpiece and air pipe to the outlet. The thus-produced aerosol-forming article may then be closed by plastic welding a bottom lid to the article, or by a press-fitted bottom lid having a seal ring or washer. By using thick or thin film deposition techniques as well as overmoulding, very close and characteristic bonds between the surfaces of the different elements may be achieved, which increase integrity of the aerosol-forming article and benefit small distances, for example between the electrodes for efficient heating.

[0049] To increase the heating power to reach sufficient volumetric dielectric heating power densities required for vaporization, it may be provided that the distance between the electrodes is made small. For example, the heating zone may be made small so that higher heating temperatures may be reached by the same voltage used for the dielectric heating. The liquid ingress surface may be larger than the vapor egress surface, for example because parts of theliquid transfer element on the side of the vapor egress surface may be covered by the electrodes. In general, the at least two electrodes may be arranged in parallel to each other. In this way, the electric field strength is approximately uniform throughout the heating zone except for fringe effects, and heating is also uniform. The at least two electrodes may be arranged such that a distance between them, for example the smallest distance between them, particularly at the vapor egress surface or on a side oriented towards the vapor egress surface, is at most 2 mm or at most 1.75 mm or at most 1.5 mm or at most 1.25 mm or at most 1 mm, or at most 0.75 mm, or at most 0.5 mm. Particularly, an extension of the vapor egress surface between the at least two electrodes may be at most 2 mm or at most 1.75 mm or at most 1.5 mm or at most 1.25 mm or at most 1 mm, or at most 0.75 mm, or at most 0.5 mm. Using these dimensions, a high heating power may be achieved with minimal energy consumption.

[0050] In use, the aerosol-forming article is inserted into the receptacle chamber of the aerosolforming device. For heating in the heating zones, the electrodes of the aerosol-forming article need to be connected to the parts of the oscillator circuit arranged in the device and a power supply of the aerosol-forming device. For this purpose, the aerosol-forming article may further comprise at least two electrode connection terminals in electrical connection with the at least two electrodes. The at least two electrode connection terminals may be connectable to at least two electrode connection elements of the aerosol-forming device when the aerosol-forming article is removably inserted into or coupled to the aerosol-forming device for use. When the aerosolforming article is inserted into the aerosol-forming device, the electrode connection terminals electrically contact the electrode connection elements so the power from the aerosol-forming device may be used for dielectric and / or resistive heating by the at least two electrodes.

[0051] For the dielectric heating, it may be preferred that the polarization of the electrodes is changed in radio frequency, e.g. an alternating RF voltage is applied across at least one pair of electrodes to cause the RF electric field. The at least two electrode connection terminals and / or the at least two electrode connection elements may be configured and / or shaped such that they have a longer extension in an insertion direction of the aerosol-forming article into the aerosolforming device than in a direction perpendicular to the insertion direction. For example, the at least two electrode connection terminals and / or the at least two electrode connection elements may be configured and / or shaped as pins, rods or cylinders. Specifically, the at least two electrode connection terminals and / or the at least two electrode connection elements may be free of pads or other shapes which might add a capacitance into the circuit with the oscillator. Keeping the circuit, particularly the radio frequency feedback loop oscillation circuit free from parasitic capacitance increases its energy efficiency and avoids alterations of the oscillation frequency and the impedance or gain achieved by the feedback loop.As mentioned, the at least two electrodes may form opposing electrodes of a capacitor, specifically a load capacitor, of a feedback loop of an oscillator circuit, thereby providing the dielectric heating effect in the heating zone. The feedback loop may be used to provide the oscillating current which in turn provides the oscillating electrical field in the heating zone. The feedback loop may include at least one inductor, such as a coil, a choke, or a reactor. The aerosolforming article may include the feedback loop and the at least two electrodes may be fixedly connected to the feedback loop. In this case, therefore, the feedback loop or at least part of the feedback loop comprising the at least one inductor may be part of the aerosol-forming article. Alternatively, the feedback loop may be part of the aerosol-forming device. In this case, the aerosol-forming article may be free of the feedback loop, for instance free of inductors of the feedback loop, and the at least two electrodes may be removably connectable to the feedback loop arranged in the aerosol-forming device. The more elements of the oscillation circuit may be arranged on the aerosol-forming device and not in the aerosol-forming article, the more cost-effective and environmentally sustainable the aerosol-forming article may be.

[0052] The aerosol-forming article may further comprise an aerosolization chamber arranged in fluid connection to the vapor egress surface and / or the heating zone. The aerosolization chamber may, for example, be formed by a part of the housing of the aerosol-forming article. It may be configured to receive vapor from the vapor egress surface and / or the heating zone. Further, the aerosolization chamber may be in fluid connection to at least one air inlet and to a mouthpiece outlet or mouthpiece for delivering the aerosol to a user. When a user draws of puffs on the mouthpiece, fresh air or ambient air or air from the outside environment may be drawn into the aerosol-forming device and into the aerosol-forming article. The air may enter the aerosolization chamber through the at least one air inlet. There, the air may mix with and cool the vapor coming from the heating zone. Droplets may form so that ultimately, an aerosol is formed which may then be consumed by the user by inhaling through the mouthpiece.

[0053] The aerosol-forming article and / or the at least two electrodes, for example all electrodes, may comprise a protective coating covering and / or arranged on the electrodes. The protective coating may be configured to provide electrical insulation, mechanical protection and / or chemical resistance. The protective coating may comprise and / or be made from a food-grade, microwaveable and / or biocompatible material. It may be or may comprise a low-dielectric, thermally and mechanically stable, non-toxic material. For example, the protective coating may comprise and / or be made from one or more of polyether ether ketone, PEEK, polyetherimide, PEI, and a polymer comprising units derived from substituted or unsubstituted para-xylylene monomer units, for example Parylene N. The protective coating may be arranged between the electrodes and the liquid transfer element. For example, the protective coating may constitute an interface between the electrodes and the liquid transfer element and / or between the electrodesand the vapor formed from the aerosol-forming substrate. It may protect the electrodes from direct contact with the aerosol-forming substrate and / or the vapor or aerosol. In this way, corrosion of the electrodes may be prevented. Additionally, contamination of the aerosol with metal, particularly metal ions, is prevented as well.

[0054] As an example, a thickness of the protective coating, for example a thickness of a layer or lining provided by the protective coating, may be at least 0.01 pm or at least 0.05 pm or at least 0.1 pm, and / or up to 100 pm, for example up to 75 pm or up to 50 pm, or up to 25 pm, or up to 20 pm, or up to 15 pm, or up to 10 pm, or up to 5 pm or up to 2 pm or up to 1 pm or up to 0.5 pm, or up to 0.1 pm, for example 15 pm.

[0055] According to another aspect of the present invention, there is provided an aerosol-forming device, specifically an e-vapor type aerosol forming device, which may comprise the aerosolforming article according to aspects of the present disclosure. The aerosol-forming device may comprise at least two electrode connection elements configured to electrically connect to the at least two electrodes of an aerosol-forming article, for example the aerosol-forming article according to aspects of the present disclosure, when the aerosol-forming article is inserted into the aerosol-forming device for use. The aerosol-forming device may further comprise a receptacle chamber configured to receive the aerosol-forming article according to aspects of the present disclosure. The aerosol forming device may be configured to form or generate aerosol using the aerosol-forming article, for example from the liquid aerosol-forming substrate comprised in the aerosol-forming article. All of the features, effects and advantages of the aerosol-forming article according to the present disclosure are also applicable to the aerosol-forming device and vice versa.

[0056] The aerosol-forming device may comprise an oscillator circuit electrically connected to the at least two electrode connection elements to provide an alternating electrical field to establish a dielectric heating zone, for example an electric field alternating directions with a radio frequency. In other words, the oscillator circuit may be configured to drive the dielectric heating between the electrodes. The oscillator circuit may comprise a feedback loop. For example, the feedback loop may include at least one inductor. Possible implementations of the oscillator circuit will be described in more detail below.

[0057] According to another aspect of the present invention, there is provided an aerosol-forming system, comprising the aerosol-forming article according to the present disclosure and an aerosol-forming device, for example the aerosol-forming device according to the present disclosure. The aerosol forming device may be configured to form or generate aerosol using the aerosol-forming article. All of the features, effects and advantages of the aerosol-forming article and / or the aerosol-forming device according to the present disclosure are also applicable to the aerosol-forming system and vice versa.According to another aspect of the present invention, there is provided a method of heating a liquid aerosol-forming substrate in an aerosol-forming article, for example an aerosol-forming article according to the present disclosure, and / or an aerosol-forming device, for example an aerosol-forming device according to the present disclosure, comprising: establishing a an alternating electric field between two electrodes to create a heating zone; guiding the liquid aerosol-forming substrate from a liquid reservoir through a liquid ingress surface into a liquid transfer element and through the dielectric heating zone to a vapor egress surface of the liquid transfer element; and dielectric heating and vaporizing of the liquid aerosol-forming substrate in the dielectric heating zone; wherein the dielectric heating zone encompasses at least a part of the vapor egress surface. An effective flow direction of liquid aerosol-forming substrate and / or vapor formed from the liquid aerosol-forming substrate through the heating zone may be unidirectional, for example orthogonal to a direction of a main direction of the alternating electrical field in the heating zone. All of the features, effects and advantages of the aerosol-forming article and / or the aerosol-forming device and / or the aerosol-forming system according to the present disclosure are also applicable to the method and vice versa.

[0058] 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.

[0059] Example 1. An aerosol-forming article for use in an aerosol-forming device and / or an aerosol-forming system, comprising

[0060] a liquid reservoir configured to store a liquid aerosol-forming substrate,

[0061] a liquid transfer element, comprising a liquid ingress surface fluidically connected to the liquid reservoir, a vapor egress surface fluidically connected to an aerosolization space, and a liquid transfer volume between the liquid ingress surface and the vapor egress surface configured to transfer liquid from the liquid ingress surface to the vapor egress surface,

[0062] at least two electrodes configured to establish an alternating electric field at a heating zone, the heating zone encompassing at least a part of the vapor egress surface,

[0063] wherein the at least two electrodes are arranged at, on or at least partly embedded in the liquid transfer element, for example at, on, or under the vapor egress surface,

[0064] for example such that vaporized liquid egressing from the vapor egress surface flows between the at least two electrodes to reach or into a downstream airflow path.

[0065] Example 2. The aerosol-forming article according to Example 1,

[0066] wherein the vapor egress surface forms an outer surface of the liquid transfer element towards the aerosolization space, and wherein the at least two electrodes are arranged at, on or at least partly embedded in the vapor egress surface.

[0067] Example 3. The aerosol-forming article according to any one of the previous Examples,wherein the liquid transfer element is made of or comprises one or more of a material comprising channels or microchannels, for example a plurality of channels or microchannels, and

[0068] a wicking material, for example a porous material, for example a glass-based material, for example a material comprising or primarily comprising vitreous silica or quartz glass, or a porous ceramic material, for example a porous silicon ceramic material,

[0069] for example wherein the liquid transfer element is configured to cause capillary flow of the liquid aerosol-forming substrate or wherein the liquid transfer element is configured to facilitate flow of the liquid aerosol-forming substrate by gravity.

[0070] Example 4. The aerosol-forming article according to any one of the previous Examples, wherein only a part of the liquid transfer volume is arranged in the heating zone, for example a maximum of 50% or a maximum of 40% or a maximum of 30% or a maximum of 20% or a maximum of 15% or a maximum of 10%.

[0071] Example 5. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes are configured to have resistive heating properties, for example with a conductivity o of at least 1x106 S / m at 20°C or at least 5x106 S / m at 20°C or at least 1x107 S / m at 20°C or at least 5x107 S / m at 20°C.

[0072] Example 6. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes include a metal material or metal alloy causing heating by ohmic losses and / or

[0073] wherein the at least two electrodes include a nickel alloy, for example an alloy of nickel, chromium and iron, or

[0074] wherein the at least two electrodes include copper or aluminum or an alloy of copper and aluminum.

[0075] Example 7. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes have a conductivity o of at least 1x107 at 20°C.

[0076] Example 8. The aerosol-forming article according to any one of the previous Examples, further comprising at least one additional electrode, wherein at least one additional heating zone is formed between the at least one additional electrode and another electrode.

[0077] Example 9. The aerosol-forming article according to any one of the previous Examples, further comprising at least two additional electrodes, wherein an additional heating zone is formed between the at least two additional electrodes.

[0078] Example 10. The aerosol-forming article according to any one of the previous Examples, wherein two pairs of electrodes form at least three heating zones, for example wherein electrodes of opposite polarity are arranged neighbouring each other on opposite sides of the respective heating zones.Example 11. The aerosol-forming article according to any one of the previous Examples, wherein the liquid transfer element comprises at least two vapor egress surfaces, wherein at least two electrodes forming a dielectric heating zone between them are arranged at, on or at least partly embedded in the liquid transfer element at each vapor egress surface.

[0079] Example 12. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes, for example all electrodes, are arranged following the shape of the associated liquid transfer element and / or vapor egress surface.

[0080] Example 13. The aerosol-forming article according to any one of the previous Examples, wherein at least two pairs of electrodes or a plurality of electrodes of alternating polarity are arranged in an interdigitated pattern, parallel stripes, or mesh at the associated liquid transfer element and / or vapor egress surface.

[0081] Example 14. The aerosol-forming article according to any one of the previous Examples, wherein the vapor egress surface is planar.

[0082] Example 15. The aerosol-forming article according to any one of the previous Examples, wherein the vapor egress surface is rounded, for example cylindrical or spherical, for example wherein a distance between adjacent electrodes at the vapor egress surface is constant or substantially constant.

[0083] Example 16. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes are configured and / or arranged with respect to each other such that the volume between the at least two electrodes forms a constriction on a side facing the vapor egress surface.

[0084] Example 17. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes are configured and / or arranged following a curved line or plane, wherein the concave side of the curved line or plane is directed towards the vapor egress surface.

[0085] Example 18. The aerosol-forming article according to any one of the previous Examples, wherein the liquid transfer element is at least partly arranged as a hollow cylinder, wherein the liquid reservoir and / or the liquid ingress surface is arranged on the inside surface of the hollow cylinder and the vapor egress surface is arranged on the lateral surface of the hollow cylinder, or wherein the liquid transfer element is at least partly arranged as a hollow cylinder, wherein the liquid reservoir and / or the liquid ingress surface is arranged on the lateral surface of the hollow cylinder and the vapor egress surface is arranged on the inside surface of the hollow cylinder.

[0086] Example 19. The aerosol-forming article according to any one of the previous Examples, wherein the electrodes have a polygonal cross-section, for example a rectangular crosssection, orwherein the electrodes have a rounded cross-section, for example a circular or circular section cross-section.

[0087] Example 20. The aerosol-forming article according to any one of the previous Examples, further comprising an interface layer arranged between the at least two electrodes, for example between all electrodes, and the liquid transfer element, for example wherein the interface layer comprises a non-porous and / or non-conductive dielectric material, for example a glass material or a polymer.

[0088] Example 21. The aerosol-forming article according to the previous Example, wherein the interface layer is arranged perpendicular to an effective flow rate of the liquid aerosol-forming substrate through the liquid transfer element, and / or

[0089] wherein the heating zone between the at least two electrodes is free of the interface layer or of material of the interface layer.

[0090] Example 22. The aerosol-forming article according to any one of Examples 20-21 , wherein the interface layer is arranged on the liquid transfer element and / or the at least two electrodes are arranged on the interface layer by thick film deposition or thin film deposition, for example chemical vapor deposition or physical vapor deposition, and / or

[0091] wherein the liquid transfer element is arranged on the interface layer by overmoulding. Example 23. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes are arranged on the liquid transfer element by thick film deposition or thin film deposition, for example chemical vapor deposition or physical vapor deposition.

[0092] Example 24. The aerosol-forming article according to any one of the previous Examples, wherein the liquid transfer element is arranged on the at least two electrodes by overmoulding.

[0093] Example 25. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes are arranged such that a distance between them, for example the smallest distance between them, is at most 2 mm or at most 1.75 mm or at most 1.5 mm or at most 1.25 mm or at most 1 mm or at most 0.75 mm or at most 0.5 mm.

[0094] Example 26. The aerosol-forming article according to any one of the previous Examples, wherein an extension of the vapor egress surface between the at least two electrodes is at most 2 mm or at most 1.75 mm or at most 1.5 mm or at most 1.25 mm or at most 1 mm or at most 0.75 mm or at most 0.5 mm.

[0095] Example 27. The aerosol-forming article according to any one of the previous Examples, further comprising at least two electrode connection terminals in electrical connection with the at least two electrodes, wherein the at least two electrode connection terminals areconnectable to at least two electrode connection elements of the aerosol-forming device when the aerosol-forming article is inserted into or coupled to the aerosol-forming device for use.

[0096] Example 28. The aerosol-forming article according to the previous Example, wherein the at least two electrode connection terminals and / or the at least two electrode connection elements are configured and / or shaped such that they have a longer extension in an insertion direction of the aerosol-forming article into the aerosol-forming device than in a direction perpendicular to the insertion direction, for example wherein the at least two electrode connection terminals and / or the at least two electrode connection elements are configured and / or shaped as pins, rods or cylinders.

[0097] Example 29. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes form opposing electrodes of a capacitor of a feedback loop of an oscillator circuit.

[0098] Example 30. The aerosol-forming article according to the previous Example, wherein the aerosol-forming article includes the feedback loop and the at least two electrodes are fixedly connected to the feedback loop or

[0099] wherein the aerosol-forming article is free of the feedback loop and the at least two electrodes are removably connectable to the feedback loop arranged in the aerosol-forming device.

[0100] Example 31. The aerosol-forming article according to any one of the previous Examples 29-30,

[0101] wherein the feedback loop includes at least one inductor.

[0102] Example 32. The aerosol-forming article according to any one of the previous Examples, further comprising an aerosolization chamber arranged in fluid connection to the vapor egress surface and / or the heating zone and configured to receive vapor from the vapor egress surface and / or the heating zone, the aerosolization chamber being in fluid connection to at least one air inlet and to a mouthpiece outlet for delivering the aerosol to a user.

[0103] Example 32a. The aerosol-forming article according to any one of the previous Examples, wherein the at least two electrodes, for example all electrodes, comprise a protective coating covering and / or arranged on the electrodes,

[0104] for example wherein the protective coating is configured to provide electrical insulation, mechanical protection and / or chemical resistance,

[0105] for example wherein the protective coating comprises and / or is made from one or more of polyether ether ketone, PEEK, polyetherimide, PEI, and a polymer comprising units derived from substituted or unsubstituted para-xylylene monomer units, for example Parylene N.

[0106] Example 32b. The aerosol-forming article according to the previous Example,wherein a thickness of the protective coating is at least 0.01 pm or at least 0.05 pm or at least 0.1 pm, and / or up to 100 pm, for example up to 75 pm or up to 50 pm, or up to 25 pm, or up to 20 pm, or up to 15 pm, or up to 10 pm, or up to 5 pm or up to 2 pm or up to 1 pm or up to 0.5 pm, or up to 0.1 pm, for example 15 pm.

[0107] Example 33. An aerosol-forming device, comprising

[0108] at least two electrode connection elements configured to electrically connect to the at least two electrodes of an aerosol-forming article, for example an aerosol-forming article according to any one of the previous Examples, when the aerosol-forming article is inserted into or coupled to the aerosol-forming device for use,

[0109] further comprising an oscillator circuit electrically connected to the at least two electrode connection elements to provide an alternating electrical field to establish a heating zone.

[0110] Example 34. The aerosol-forming device according to the previous Example, wherein the oscillator circuit comprises a feedback loop, for example wherein the feedback loop includes at least one inductor.

[0111] Example 35. An aerosol-forming system, comprising

[0112] the aerosol-forming article according to any one of Examples 1-32, and

[0113] an aerosol-forming device, for example the aerosol-forming device according to any one of Examples 33-34.

[0114] Example 36. A method of heating a liquid aerosol-forming substrate in an aerosolforming article, for example an aerosol-forming article according to any one of Examples 1-32, and / or an aerosol-forming device, for example an aerosol-forming device according to any one of Examples 33-34, and / or an aerosol-forming system, for example an aerosol-forming system according to the previous Example, comprising:

[0115] establishing an alternating electric field between two electrodes to create a heating zone; guiding the liquid aerosol-forming substrate from a liquid reservoir through a liquid ingress surface into a liquid transfer element and through the dielectric heating zone to a vapor egress surface of the liquid transfer element; and

[0116] dielectric heating and vaporizing of the liquid aerosol-forming substrate in the dielectric heating zone;

[0117] wherein the dielectric heating zone encompasses at least a part of the vapor egress surface. Examples will now be further described with reference to the figures in which:

[0118] Figure 1 shows an aerosol-forming system;

[0119] Figure 2 shows a schematic illustration of an oscillation circuit for use in an aerosolgenerating system;

[0120] Figure 3a shows a schematic illustration of an oscillation circuit;

[0121] Figure 3b shows a schematic illustration of another oscillation circuit;Figure 4 shows an oscillation circuit diagram;

[0122] Figure 5 shows a longitudinal section view of an aerosol-forming article;

[0123] Figure 6 shows an aerosol-forming article in cross-section through the fluid transfer element;

[0124] Figure 7 shows another aerosol-forming article in cross-section through the fluid transfer element;

[0125] Figure 8 shows a front view of a plurality of interdigitated electrodes on and / or embedded in the fluid transfer element;

[0126] Figure 9 shows another front view of a plurality of interdigitated electrodes on and / or embedded in the fluid transfer element;

[0127] Figure 10 shows another aerosol-forming article in cross-section through the fluid transfer element;

[0128] Figure 11 shows another aerosol-forming article in cross-section through the fluid transfer element;

[0129] Figure 12 shows another aerosol-forming article in cross-section through the fluid transfer element;

[0130] Figure 13 shows another aerosol-forming article in cross-section through the fluid transfer element;

[0131] Figure 14 shows a longitudinal section view of another aerosol-forming article;

[0132] Figure 15 shows a front view of electrodes on and / or embedded in a cylindrical fluid transfer element;

[0133] Figure 16 shows a front view of electrodes on and / or embedded in a spherical fluid transfer element;

[0134] Figure 17 shows a front view of electrodes on and / or embedded a fluid transfer element with air inlets;

[0135] Figure 18 shows a section through a liquid transfer element with electrodes and an interface layer at least partly embedded in the liquid transfer element;

[0136] Figure 19 shows a section through a liquid transfer element with electrodes and an interface layer, both electrodes and interface layer being at least partly embedded in the liquid transfer element;

[0137] Figure 20 shows a two-part system with an aerosol-forming article removably couplable to the aerosol-forming device;

[0138] Figure 21 shows a one-part system with an aerosol-forming article fixedly coupled to the aerosol-forming device; and

[0139] Figure 22 shows a flowchart of the method.

[0140] The figures are schematic only and not to scale.Figure 1 shows an aerosol-forming or aerosol-generating system 1 for forming or generating aerosol, for example for consumption or inhalation by a user in one or more usage sessions. The system 1 may comprise at least one of an aerosol-forming device 2 for generating aerosol and a companion device 3 for at least partially receiving the aerosol-forming device 2. The aerosolforming device 2 may also be referred to as a cartridge holder, a holder or a holder device. The companion device 3 may be a charging device for charging the aerosol-forming device 2 and / or an energy storage 15 or battery thereof.

[0141] The aerosol-forming device 2 may comprise a receiving space or receptable chamber 29 for at least partially inserting or receiving an aerosol-forming article 18. The aerosol-forming article 18 may comprise a reservoir that is filled with a liquid aerosol-forming substrate, such as a nicotine containing substrate, for example a liquid that can be vaporized and thereafter aerosolized for inhalation, the article 18 being in the form of a cartridge, pod, capsule, or container. The aerosolforming article 18 may at least partly protrude from the aerosol-forming device 2 when it is inserted into the aerosol-forming device 2, for example into the receptacle chamber 29 of the aerosolforming device 2. For example, the aerosol-forming article 18 may comprise a mouthpiece 4, through which a user may inhale aerosol provided by the aerosol-forming device 2 for consumption during a usage session. The mouthpiece 4 may be a part of the aerosol-forming article 18 protruding from the aerosol-forming device 2. Another part of the aerosol-forming article 18 may be arranged inside the aerosol-forming device 2 and is therefore not visible in Figure 1. It is also possible that the aerosol-forming article is fully inserted into the aerosol-forming device 2, with the mouthpiece 4 being part of the aerosol-forming device 2.

[0142] The aerosol-forming device 2 may further include processing circuitry or control circuitry with at least one controller 5 and one or more processors 6. For generating the aerosol during the inhalation or puff by the user, the aerosol-forming device 2 and article 18 may comprise a dielectric heating arrangement 7 to apply an alternating electric field to the liquid aerosol-forming substrate, to cause dielectric heating and vaporization. The processing circuitry and / or the controller 5 and / or the processor 6 may be configured to control actuation, activation and / or deactivation of the dielectric heating arrangement 7, for example using a puff sensing mechanism. Particularly, the dielectric heating arrangement 7 may comprise an oscillation circuit or at least parts of an oscillation circuit including a switching device used for dielectric heating, for example in conjunction with electrodes that are located in the aerosol-forming article 18, as explained in more detail below. The dielectric heating arrangement 7 may therefore not itself be heated, but be used to heat the liquid aerosol-forming substrate of the aerosol-forming article 18.

[0143] A puff sensor 39 may be arranged in the aerosol-forming device 2. The puff sensor 39 may be in fluid connection with an air flow path through the aerosol-forming device 2 and the aerosolforming article 18. For example, the puff sensor 39 may be or may comprise a pressure ordifferential pressure sensor or flow sensor and may detect when the user draws or puffs on the aerosol-forming device 2. The detected puff may then be used by the controller 5 to activate the dielectric heating arrangement 7. Heating of the aerosol-forming substrate may therefore be implemented on-demand, for example as puff-on-demand and / or response to draw. The puff can also be detected, indicated or triggered by the user via a user interface or input device 8. Thus, heating of the aerosol-forming substrate may be implemented to be user activated by the user performing an action, for example, for example button-activated by the user pressing a button or performing some other action triggering a control signal.

[0144] For powering the at least one dielectric heating arrangement 7 with electrical power, the aerosol-forming device 2 may further comprise the at least one energy storage 15, for example in the form of a battery, for storing electrical energy or power. In Figure 1 , both the aerosol-forming device 2 and the companion device 3 each comprise an energy storage 15 and the energy storage 15 is electrically coupled to the respective device 2, 3. In particular, energy storage 15 may be removably couplable to the aerosol-forming device 2 and / or the companion device 3. In other words, energy storage 15 may be a replaceable energy storage or battery. The connection between the energy storage 15 and the devices 2, 3 may be configured so that the devices 2, 3 may be run by electrical energy provided by the energy storage 15. Additionally, the connection between the energy storage 15 and the aerosol-forming device 2 and / or the companion device 3 may be configured so that data may be transmitted between the processing circuitries of the aerosol-forming device 2 and / or the companion device 3 and the energy storage 15.

[0145] The aerosol-forming device 2 may further comprise at least one electrical connector 12 for coupling to a corresponding at least one electrical connector 13 of the companion device 3 and / or an electrical connector of an external power supply (not shown), e.g., a USB charger. For example, when the aerosol-forming device 2 is at least partially inserted into the opening 14 of the companion device 3, the one or more electrical connectors 12 of the aerosol-forming device 2 may be coupled with the one or more electrical connectors 13 of the companion device 3 to charge the at least one energy storage 15 of the aerosol-forming device 2.

[0146] The aerosol-forming device 2 may further comprise a communications arrangement 9 or communication circuitry 9 with one or more communications interfaces 10 for communicatively coupling the aerosol-forming device 2 with the companion device 3 or other devices, 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, 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.The aerosol-forming device 2 may further comprise a data storage 11 or memory for storing information, program code or data. Data storage 11 may also store collected values of sensors and / or one or more mathematical functions or formulas, software and computer instructions that can be executed by the processing circuitry, particularly controller 5 and / or processor 6. One or more sensors 16 may be arranged on, at or in the aerosol-forming device 2 or the companion device 3 to collect data. One or more of the sensors 16 may for example be temperature sensors, strain sensors, puff sensors, accelerometers or any other suitable sensors.

[0147] The aerosol-forming device 2 may further comprise user interface components, for example comprising an input element or input device 8, for example in the form of a push button or a capacitive button. The input device 8 may be used as a power button to activate or deactivate the dielectric heating arrangement 7 for vaporization, thereby to activate or deactivate the aerosolforming device 2. Also, a puff sensor 39 can be arranged to detect a user inhalation or puff, to active the dielectric heating arrangement 7 during the puff. Upon activation of the aerosol-forming device 2, the dielectric heating arrangement 7 may be activated to rapidly vaporize the liquid aerosol-forming substrate of the aerosol-forming article 18, such that vapor and aerosol can be generated for consumption or inhalation by the user. The aerosol-forming device 2 and / or the companion device 3 may each comprise one or more output elements, such as a display device 17 and / or one or more LEDs, for outputting a signal and / or displaying information to a user, for example a user interface such as a GUI, or haptic and acoustic data output devices. The display device 17 may be, for example, a touchscreen and may therefore be configured as both an output and an input element.

[0148] Figure 2 is a schematic illustration of an exemplary oscillation circuit 250 that can be used as or for the dielectric heating arrangement 7 for aerosol-forming system 1 or aerosol-forming device 2. Oscillation circuit 250 may comprise a switching unit 260 interconnected with a resonator feedback loop 270 to provide for a self-oscillating signal to the switching unit 260. The switching unit 260 may comprise a single transistor, such as a bipolar junction transistor (BJT) or a field effect transistor (FET). The oscillation circuit described herein is exemplary only, and other types of oscillation circuits can be used, for example other types of resonant oscillator circuits where the load capacitor for causing the dielectric heating is part of the resonant feedback loop, or signal oscillators that are connected to an amplifier and an impedance matching circuit to apply an RF voltage to the electrodes for causing the alternating electric field for dielectric heating. Forced oscillators or forced oscillation circuits may also be used. The given embodiments of the oscillation circuits 250 and 355 (Figure 4) are therefore merely exemplary and not intended to limit any aspect of the invention.

[0149] The oscillation circuit 250 may further comprise a choke 280 that acts on an input to the feedback loop 270 to provide for a stimulation signal, for example a stimulation voltage. Theoscillation circuit may also comprise a biasing unit 290 acting on the feedback loop 270 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 unit 260 may be coupled to the feedback loop 270 providing a feedback switching signal in the form of a voltage U|Nto the switching unit 260. The configuration of the feedback loop 270 may be such that the output signal, e.g. the voltage UOUT of the switching unit 260, can undergo a phase change and arrives inverted at the input U|Nof the switching unit 260 for resonant oscillation. In other configurations, a current could be used as the feedback signal with a switching unit 260 comprising a BJT.

[0150] The feedback loop 270 may be configured to be self-oscillating and may oscillate at or close to a given resonance frequency determined by the values of the passive components of the feedback loop 270. Feedback loop 270 may be configured to provide a 180° phase shift from the output UQUT to input U|Nof switching unit 260 for oscillation, and, in addition, a transistor T (Figure 4) may be configured for inverting operation.

[0151] As shown in Figures 3a and 3b, feedback loop 270 may include a resonant circuit 272 comprising a load capacitor CLproviding for a first 90 degrees phase shift or quarter wave shift to the feedback signal. The heating zone according to the present disclosure may be arranged or may be provided inside the load capacitor CL. Feedback loop 270 may further include a capacitive element 274 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 unit 260 may be inverted and phase-shifted by 180 degrees. Switching unit 260 may itself be configured for inverted switching operation to provide a 180 degree phase shift between the input U|Nand the output UQUT of the switching unit 260.

[0152] Resonant circuit 272 may comprise first and second electrodes 130, 135 (which may both be referred to as electrodes 26), together forming a load capacitor CL(see Figure 4). When an aerosol-forming substrate, in the present case the liquid aerosol-forming substrate 20 that is brought into the heating zone by a liquid transfer element, is situated between the first and second electrodes 130, 135, it may form part of the load capacitor CL. In this non-limiting example of the oscillator, the load capacitor CLmay be formed in the feedback loop 270, and not at a separate output or part of a separate circuitry that is connected to the switching unit 260. This may enable a high-frequency oscillating voltage to be created across the electrodes 130, 135 of load capacitor CL, which is needed for sufficient and efficient dielectric heating of the aerosol-forming substrate 20, without having an additional output or circuit to the already resonating feedback loop 270. This may avoid unnecessary losses and circuit complexity. The resonant circuit 272 may comprise a series resonator circuit or a parallel resonator circuit.Figure 4 illustrates an oscillation circuit 355 according to a non-limiting, exemplary embodiment of the present disclosure. Oscillation circuit 355 may comprise a switching unit 260 in the form of a transistor T having an intrinsic capacitance Ci. Moreover, transistor T may be configured for inverting operation, for example as an inverting common source FET, MOSFET, more specifically a LDMOS, or a common emitter BJT. The source terminal of transistor T may be coupled to a DC power supply via a choke 280. Between the gate and source terminals of transistor T a feedback loop 270 may extend. The feedback loop 270 may comprise a resonant circuit 272 including a load capacitor CLhaving a first and second electrode 130, 135 separated by an aerosol-forming substrate 20 supplied from the aerosol-forming article 18. In the variant shown, the resonant circuit 272 may also be connected to ground via a delay line DL and a capacitor C2connected in series to the delay line DL. The circuit 355 may further comprise a biasing unit 290 coupled to the gate terminal of the transistor T via the delay line DL. As shown in Figure 4, the biasing unit 290 may be electrically connected between the delay line DL and the capacitor C2, so that the biasing unit 290 may be somewhat isolated from the high oscillation frequency of the feedback loop 270.

[0153] The delay line DL may be a time delay element, for example an element that has inductive behavior, for slowing down the arriving voltage wave from the feedback loop 270 during a period of the oscillation. This may allow to tune the resonant circuit 272 to a desired switching and oscillation frequency, to move the oscillation frequency away from the natural resonant frequency given by the resonant circuit 272. This may ensure that oscillation circuit 355 remains in a predefined frequency operating range to provide for the requisite inverted or 90° phase shifted feedback and also to make sure that the feedback loop has a low impedance to provide for a high gain.

[0154] The oscillation circuit 355 is shown with electrical contacts 160, 165 that may be arranged on each side of the load capacitor CL. The first and second electrodes 130, 135 are part of the removable aerosol-forming article 18 and are therefore removable from the rest of the oscillation circuit 355. Electrical contacts 160, 165 provide a removable electrical connection between the first and second electrode 130, 135 and the feedback loop 270. As exemplarily shown in the Figure, electrical contacts 160, 165 may be arranged at different positions in the oscillator circuit 355, resulting in different components being arranged on the aerosol-forming article 18 side or the aerosol-forming device 2 side. For example, electrical contacts 160, 165 may be arranged between the load capacitor CL, i.e. the electrodes 26, 130, 135, and the inductors LT and L2. In this case, only the electrodes 26, 130, 135 may be arranged on and removable with the aerosolforming article 18. As another example, the electrical contacts 160, 165 may be arranged between the inductors LT and L2and the load capacitor CL, i.e. the electrodes 26, 130, 135, on the one hand, and the rest of the oscillation circuit 355 on the other. In this case, the electrodes 26, 130,135 and the inductors LT and L2may be arranged on and removable with the aerosol-forming article 18. In embodiments where the load capacitor CLis fixed within the feedback loop 270, e.g. a non-removable cartridge as the aerosol-forming article 18, for example, electrical contacts 160, 165 provide electrical connections from the first and second electrodes to the next components in the feedback loop 270, e.g. inductors LT and L2or other components. Although two inductors LT and L2are shown, the oscillation circuit 355 may also only comprise one single inductor.

[0155] With respect to the power supply voltage, a DC power supply voltage may be provided, that is preferably in a range that is suitable for battery operation with one or more standard battery cells. Preferably, the DC power supply voltage is below 14V. For example, it is possible to operate the oscillation circuit 355 on a single battery cell, for example an 18650 battery cell (Li-Ion), or a similar battery cell, that provides for 3.2V to 3.9V. However, more preferably, a voltage of one battery cell of an exemplary 3.5V to 7V for power supply can be boosted, for example by a DC-DC converter (e.g. a boost circuit), or a voltage doubler. Alternatively or in addition, two or more battery cells can be used in series, or other configurations or arrangements that allow to increase a voltage from one or more battery cell can be used. It is also possible to have a controllable output voltage (e.g. DC-DC converter, voltage regulator), to control the temperature of heating by a change to the DC supply voltage, or to boost the voltage (for example to 10-12V) for maximum power at the preheating stage, to speed up the preheating stage with the goal to reach the aerosolization temperature quickly. Control of the DC supply voltage is one way that makes it possible to rapidly change heating power despite the oscillation circuit 355 freely oscillating.

[0156] A capacitor C-, may be arranged in parallel to the transistor T and therefore in parallel with the intrinsic capacitor of the transistor T (e.g. a field effect transistor). This may facilitate a less voltage-dependent oscillation and frequency, stabilize the oscillation, and also improve the overall dielectric heating efficiency. Capacitance of capacitor C-j may be chosen to be larger than the maximal intrinsic capacitor Ci of transistor T at the operating conditions, so that the variation of the intrinsic transistor based on frequency, temperature, etc. has much less or negligible influence on the feedback loop 270. For example, in a non-limiting embodiment, the value may be in a range between 2pF to 100pF, more preferably in a range between 5pF and 50pF.

[0157] Capacitive element 274 may comprise a capacitor C2arranged at the output or end of the resonant circuit 272. In one embodiment, capacitive element 274 may comprise more than one capacitor. As described above, capacitive element 274 may have the function of providing a 90° phase shift to the feedback voltage of feedback loop 270 with minimized losses or other undesired effects, and it therefore needs to have a high-quality factor or Q factor, preferably above 1000 at 100MHz. The capacitance value for capacitor C2of the capacitive element 274 may be relatively high as compared to capacitor C-j, for example in a range between 500pF to 100nF, more preferably between 1 nF and 50nF, which may lead to a low impedance of capacitive element 274.In one embodiment, the capacitive element 274 may be implemented as an RC network to provide for the 90° phase shift, for example using two single-resistor-capacitor networks, having two capacitors in the feedback loop, each capacitor connected to ground via a resistor.

[0158] Resonant circuit 272, together with capacitive element 274, may provide for a 180° phase shift and a voltage gain from the output UOUT to the input U|N, and transistor T (for example a FET) may be configured for inverting operation, thereby also providing for another 180° phase shift. This may result in a resonant or close-to resonant oscillation and an amplified voltage across the electrodes 130 and 135 of the load capacitor CL, as compared to the DC supply voltage. When operating close to resonance, the resonant circuit 272 circuit may behave inductively, having a high Q factor. Furthermore, the feedback loop 270 may be impedance-matched with the transistor T, to provide for a high gain, leading to an increased voltage across the load capacitor CL.

[0159] The combination of capacitor C-, , the feedback loop with resonant circuit 272 and capacitive element 274 may also be described as a bandpass filter or Pi or TT network that generates a 180° phase shift. In the illustrated embodiment, the resonant circuit 272 of the feedback loop 270 may not be connected to ground, but may be suspended with ends at each capacitor C-, and C2, thereby not having a direct ground connection at either end of resonant circuit 272, reducing stray elements and ground influences for more predictable operation.

[0160] At the operating frequency, the resonant circuit 272 including load capacitor CLmay act as an inductive load providing a first 90° phase shift, also referred to as a quarter-wave phase shift, and capacitive element 274, which may exemplarily include a high quality factor capacitor C2 connected to ground, may provide for the second 90° phase shift or quarter-wave phase shift.

[0161] In some embodiments, oscillation circuit 355 may be based on other resonant feedback loop oscillation circuit configurations, for example, but not limited to, the use of a Colpitts or Hartley type oscillator, using an inverting transistor T.

[0162] Figure 5 shows a sectional view through an aerosol-forming article 18 that can be removably connected to an aerosol-forming device 2 or holder. The section is in the longitudinal direction, for example parallel to the insertion direction of the aerosol-forming article 18 into the aerosolforming device 2. The aerosol-forming article 18 may comprise an article housing 31 and an outer shell 36. The article housing 31 may form separation walls and compartments of the aerosolforming article 18, for example for the liquid reservoir 19 and / or the aerosolization chamber 24. The outer shell 36 may form the outer contour and the outer shape or form of the aerosol-forming article 18. For example, the outer shell 36 may form a mouthpiece 4, which may, for example, have a tapered shape, and which may protrude from the aerosol-forming device 2 when the lower part of the aerosol-forming article 18 has been inserted into the aerosol-forming device 2. The mouthpiece 4 may be directly used by a user to inhale aerosol provided by the aerosol-formingdevice 2. The shape or outer shape of the aerosol-forming article 18 may be oblong and / or elongated, for example in the insertion direction, and may comprise rounded or angled corners.

[0163] The aerosol-forming device 18 may further comprise a liquid reservoir 19 containing a liquid aerosol-forming substrate 20, for example a vaping liquid or e-liquid. The liquid aerosol-forming substrate 20 may be in contact with a liquid transfer element 21 , which may comprise capillaries or a porous material, or a plurality of liquid transport channels, and which may therefore transport the liquid aerosol-forming substrate 20 from a liquid ingress surface 22 through the liquid transfer volume 25 of the liquid transfer element 21 into the heating zone 28. The heating zone 28 may be established by the electrodes 26 and may comprise a volume in which the electric field is strong enough for preheating and vaporizing the liquid aerosol-forming substrate 20. The liquid transport may be achieved through capillary action by virtue of small flow pathways inside the liquid transfer element 21, or by gravity, or by a combination of both. The heating zone 28 may be a dielectric heating zone, which may be defined and / or established between a pair of electrodes 26, at least one of which may lie above or below the plane of Figure 5 and which is therefore not shown. The heating zone 28 may be filled with the liquid transfer element 21 and / or may comprise an open space in fluidic connection with the aerosolization chamber 24. In the heating zone 28, for example during the transport of the liquid aerosol-forming substrate 20 through the liquid transfer element 21 , the liquid aerosol-forming substrate 20 may be heated, for example pre-heated, and then vaporized. The vaporized substrate 20 may then exit the heating zone 28 and / or the liquid transfer element 21 through the vapor egress surface 23 of the liquid transfer element 21. The vapor egress surface 23 of the liquid transfer element 21 may be fluidically connected to, i.e. the liquid transfer element 21 may end in, the aerosolization chamber 24, which may be part of an air flow path 34 through the aerosol-forming device 2. Fresh air or outside air or environmental air drawn from the outside of the aerosol-forming device 2 may enter the aerosolization chamber 24 through an air inlet 32. The air may then mix with the vapor flowing from the vapor egress surface 23 and / or the heating zone 28, resulting in the formation of droplets and thereby the formation of an aerosol. By the draw or puff of the user, the aerosol may then flow through the air flow path 34 into the mouthpiece 4 to be inhaled by the user.

[0164] The electrodes 26 of the aerosol-forming article 18 may be electrically connected to an electrode connection terminal 30. For example, there may be provided two electrode connection terminals 30 (as with electrodes 26, the two electrode connection terminals 30 are arranged one above the other in Figure 5, which is why only one can be seen), each electrode connection terminal 30 being connected to one or more electrodes 26. The electrode connection terminals 30 may be connectable to electrode connection elements 35 of the aerosol-forming device 2 (see Figure 1), and therefore to parts of the oscillation circuit 250, 355 on the aerosol-forming device 2 side. Both the electrode connection terminals 30 and the electrode connection elements 35 maybe of slim elongated shape, for example oriented parallel to the direction of insertion of the aerosol-forming article 18 into the aerosol-forming device 2, to avoid parasitic capacitance in the installation circuitry 250, 355, particularly the feedback loop 270. The electrode connection terminals 30 may be configured to electrically connect to the electrode connection elements 35 when the aerosol-forming article 18 is inserted into the aerosol-forming device 2. For example, the electrode connection terminals 30 may correspond to or may be the electrical contacts 160, 165.

[0165] Figure 6 shows a cross-section through an aerosol-forming article 18, for example at the location of line A as shown in Figure 5. The Figure shows the different compartments of the aerosol-forming article 18 formed by the article housing 31. Particularly, the liquid reservoir 19 may be separated from the aerosolization chamber 24 by the liquid transfer element 21. Liquid aerosol-forming substrate 20 may enter the liquid transfer element 21 through the liquid ingress surface 22, which may be in direct contact with the liquid reservoir 19. The liquid aerosol-forming substrate 20 may then be transported through the liquid transfer volume 25 of the liquid transfer element 21 towards the vapor egress surface 23, which may be arranged on the opposite side of the liquid transfer element 21 with regard to the liquid ingress surface 22. At, on or near the vapor egress surface 23, at least two or a plurality of electrodes 26 may be arranged. The electrodes 26 may be arranged at, on or may be at least partly embedded in the material of the liquid transfer element 21. In the exemplary embodiment shown in Figure 6, the electrodes 26 may be partly embedded in the liquid transfer element 21. This may mean that part of the electrodes 26 are submerged in the material of the liquid transfer element 21. Simultaneously, a part of the electrodes 26 may protrude from the material of the liquid transfer element 21, for example into the aerosolization chamber 24. The parts of the liquid transfer element 21 which are in contact, particularly in direct contact, with the open space of the aerosolization chamber 24, may be regarded as the vapor egress surface 23 of the liquid transfer element 21.

[0166] The at least two electrodes 26 may be of different and alternating polarity. Accordingly, in the plurality of electrodes 26, neighboring electrodes 26 may be of different and altering polarity. In this way, an alternating electrical field may be provided in and around the volume between the electrodes 26, which may define at least one or a plurality of heating zones 28. The heating zones 28 may therefore, as a result of the positioning of the electrodes 26, at least partly comprise an open space of the aerosolization chamber 24 and / or may at least partly comprise parts of the liquid transfer element 21. As will be shown in other embodiments below, the heating zones 28 may also be completely filled by either open space of the aerosolization chamber 24 or parts of the liquid transfer element 21. The heating zones 28 may therefore be arranged directly at the vapor egress surface 23 of the liquid transfer element 21 and may even comprise the vapor egress surface 23. In the heating zones 28, the liquid aerosol-forming substrate 20 may thereforebe heated and vaporized directly at the vapor egress surface 23, for example still in the liquid transfer element 21 and / or directly after exiting the vapor egress surface 23, which may, in this case, be exited by liquid aerosol-forming substrate 20 in liquid form. Volumetric heating of the liquid transfer element 21 and / or the liquid aerosol-forming substrate 20 may in this way be avoided. Only a very small part of the liquid transfer element 21 and only the liquid aerosol-forming substrate 20 entering the heating zones 28 at the vapor egress surface 23 may be heated. Heating may therefore be efficient and avoid unnecessary losses.

[0167] Figure 7 shows another embodiment of an aerosol-forming article 18 in a cross-section corresponding to the one of Figure 6. In this embodiment, the aerosol-forming article 18 may comprise two liquid transfer elements 21, which may both be in contact with or connected to the same liquid reservoir 19. In essence, all of the features described herein for the previous embodiment are applicable for each one of the liquid transfer elements 21 of Figure 7. Each liquid transfer element 21 may have its own liquid ingress surface 22 and vapor egress surfaces 23 between its own at least two electrodes 26 or plurality of electrodes 26. Also, the aerosol-forming article 18 may comprise two aerosolization chambers 24, or one single aerosolization chamber 24 may be arranged so that both liquid transfer elements 21 are in contact with the aerosolization chamber 24 through their respective vapor egress surfaces 23.

[0168] Figure 7 shows an embodiment in which the electrodes 26 may be embedded, for example fully embedded, in the liquid transfer element 21. The heating zones 28 may be completely filled by material of the liquid transfer element 21. Particularly, the electrodes 26 may be embedded in the liquid transfer element 21 such that the side of the electrodes 26 oriented towards the aerosolization chamber 24 may lie in the same plane as the vapor egress surfaces 23. In other words, the side of the electrodes 26 oriented towards the aerosolization chamber 24 may be arranged flush with the vapor egress surfaces 23. However, also in this embodiment, the heating zones 28 may be arranged directly at the vapor egress surfaces 23, i.e. the exit of the heating zone 28 may coincide with the vapor egress surface 23.

[0169] In Figures 8 and 9, front views of electrodes 26 arranged on the liquid transfer element 21 are shown. In both examples, a total of six electrodes 26 are shown, however, more or less electrodes 26 may be used. In Figure 8, the electrodes 26 are arranged orthogonally or perpendicularly to the direction of insertion of the aerosol-forming article 18 into the receptacle chamber 29 of the aerosol-forming device 2. This may mean that the longitudinal direction of the electrodes 26 is arranged orthogonally or perpendicularly to the direction of insertion of the aerosol-forming article 18 into the receptacle chamber 29 of the aerosol-forming device 2. In contrast, in Figure 9, the electrodes 26 are arranged parallelly to the direction of insertion of the aerosol-forming article 18 into the receptacle chamber 29 of the aerosol-forming device 2. This may mean that the longitudinal direction of the electrodes 26 is arranged parallelly to the directionof insertion of the aerosol-forming article 18 into the receptacle chamber 29 of the aerosol-forming device 2. Other orientations of the electrodes 26 may however also be possible.

[0170] The electrodes 26 may be arranged in an interdigitated pattern or mesh. Neighboring electrodes 26 may be of different polarization induced by the oscillation circuit 250, 355, with which the electrodes 26 are electrically connected through electrode connection terminals 30 and electrical leads 27. In this way, heating zones 28 are established at the vapor egress surfaces 23 by the electrodes 26 of alternating, but different, polarization. The distance between neighboring electrodes 26 may be constant so that the heating zones 28 may have a constant width parallel to the electrodes 26, i.e. the longitudinal direction of the electrodes 26. The liquid aerosol-forming substrate 20 is therefore evenly heated in the heating zones 28. The electrode connection terminals 30 may be arranged on the article housing 31 so that they may be electrically connected to the electrode connection elements 35 in the receptacle chamber 29 of the aerosol-forming device 2 when the aerosol-forming article 18 is inserted into the aerosol-forming device 2. The article housing 31 and the electrode connection terminals 30 may therefore be provided with a complementary shape to the receptacle chamber 29 to provide for an easy fit.

[0171] Figure 10 shows another embodiment of an aerosol-forming article 18 in a cross-section. In this embodiment, the liquid transfer element 21 may be provided as a hollow cylinder. In other words, the liquid transfer element 21 may be in the shape of a hollow cylinder. As shown in Figure 10, at least part of the liquid reservoir 19 may be arranged inside the hollow cylinder. The aerosolization chamber 24 may be arranged outside of the hollow cylinder. Therefore, the inner surface of the hollow cylinder may also represent the liquid ingress surface 22 of the liquid transfer element 21. From there, the liquid aerosol-forming substrate 20 may be transported through the liquid transfer element 21 towards the vapor egress surfaces 23, which may be located on the lateral surface of the hollow cylinder, fluidically connected to the aerosolization chamber 24. Therefore, in this embodiment, the effective flow direction of the liquid aerosol-forming substrate 20 and / or the vapor formed from the liquid, may be the radial direction with respect to the cylinder axis of the hollow cylinder, from the inside of the hollow cylinder to the outside. In turn, the electrodes 26 may be arranged at, on and / or at least partly embedded in the liquid transfer element 21 at the vapor egress surfaces 23, i.e. at the lateral surface of the hollow cylinder. In the embodiment shown in Figure 10, the electrodes 26 may not be embedded in the liquid transfer element 21, but may be arranged on the lateral surface of the liquid transfer element 21 shaped as a hollow cylinder. The electrodes 26 may be arranged in a pattern or mesh, for example an interdigitated pattern or mesh, around the lateral surface of the hollow cylinder so that the electrodes 26 and the heating zones 28 between neighboring electrodes 26 may also form the shape of a hollow cylinder, following the shape of the lateral surface of the liquid transfer element 21, i.e. the vapor egress surfaces 23. In other words, the at least two electrodes 26 may beconfigured and / or arranged with respect to each other such that the volume between the at least two electrodes 26 forms a constriction on a side facing the vapor egress surface 23. The electrodes 26 may be closer together near the vapor egress surface 23 and may have an increased distance to each other in the effective flow direction through the electrodes 26 and / or the heating zone 28. With this circular or arcuate arrangement of the electrodes 26, the alternating electric field generated by adjacent electrodes 26 will concentrate inside the cylinder defined by the circular or arcuate arrangement of the electrodes 26, with a negligible part of the electric field generated outside the circular or arcuate arrangement. This arrangement is also shown in Figure 13, 14, 15 and 16, arranged on a cylindrical segment or a half-sphere, respectively. With the arrangement of the liquid transfer element 21 inside the space created by the curvature of the circle, arc, or other curved shape, this allows to better concentrate the electric field towards the vapor egress surface 23, improving efficiency and vaporization.

[0172] In Figure 11, another embodiment of an aerosol-forming article 18 with a liquid transfer element 21 shaped as a hollow cylinder is shown. In this embodiment, the relative positioning of the liquid reservoir 19 and the aerosolization chamber 24 are switched. The liquid reservoir 19 may be arranged on the outside of the liquid transfer element 21 shaped as a hollow cylinder, whereas the aerosolization chamber 24 may be arranged inside the hollow cylinder. The lateral surface of the hollow cylinder, which may be in contact with the liquid aerosol-forming substrate 20, may therefore represent the liquid ingress surface 22. Liquid aerosol-forming substrate 20 may therefore be transported from the lateral side of the hollow cylinder to the inside of the hollow cylinder, where the vapor egress surfaces 23 may be arranged between the electrodes 26. Also in this embodiment, the electrodes 26 may be arranged on and / or at least partly embedded in the liquid transfer element 21 at the vapor egress surfaces 23, i.e. at the inner surface of the hollow cylinder. The electrodes 26 may be arranged in a pattern or mesh, for example an interdigitated pattern or mesh, around the inner surface of the hollow cylinder so that the electrodes 26 and the heating zones 28 between neighboring electrodes 26 may also form the shape of a hollow cylinder, following the shape of the inner surface of the liquid transfer element 21, i.e. the vapor egress surfaces 23.

[0173] Figure 12 shows another variant, which may largely be similar to the embodiment of Figure 11. In contrast to Figure 11, the electrodes 26 may not be plane or planar. Instead, electrodes 26 may be rounded or round. Also, the electrodes 26 may be completely embedded in the material of the liquid transfer element 21 , as shown. For example, the electrodes 26 may be embedded in the liquid transfer element 21 such that the electrodes 26 and the vapor egress surfaces 23 are flush with each other and form one smooth surface. Although rounded electrodes 26 are shown in the specific example of Figure 12, any of the shown embodiments may also be provided with rounded electrodes 26. Also, rounded electrodes 26 may also be used only partly or not at allembedded in the material of the liquid transfer element 21. In general, the electrodes 26 may be plane or planar, for example in the form of plates, films and / or strips, as shown in Figures 6, 7, 10, and 11. Alternatively, the electrodes 26 may be rounded, as shown in Figure 12, using electrode poles, pins or rods. In the case of rounded electrodes 26 which are not fully oval or circular, for example electrodes in the shape of a circle section, the heating zone 28 may be arranged on the convex side of the electrodes 26. By choosing the specific shape of the electrodes 26, i.e. plane or rounded, the electric field in the heating zone 28 and therefore the parameters of heating the liquid aerosol-forming substrate 20 in the heating zone 28 may be tailored to the specific necessities of each use case. For example, different properties of different liquid substrates and / or individual preferences of users may be considered.

[0174] Figure 13 shows another cross-section of a variant of an aerosol-forming article 18. The embodiment of Figure 13 is very similar to the one of Figure 10, and the explanations pertaining to Figure 10 also apply to the embodiment of Figure 13. A difference between the embodiments is that according to Figure 13, the electrodes 26 may be arranged at the vapor egress surface 23 in the sense that the electrodes 26 may not be in direct contact with the vapor egress surface 23. Instead, the electrodes 26 may be distanced from the vapor egress surface 23. For example, the the electrodes 26 may be distanced from the vapor egress surface 23 by a maximum of 1 mm or by a maximum of 0.5 mm or by a maximum of 0.3 mm or by a maximum of 0.1 mm. In this way, the vapor egress surface 23 may be unobstructed by the electrodes 36 and may therefore have a bigger surface area than in other embodiments. The electrodes 26 may, for example, be held by connection elements at the top or the bottom of the aerosol-forming article 18 (and therefore not shown in the Figure). Additionally or alternatively, the electrodes 26 may be held by dielectric spacer elements 41, which in turn may be held by connection elements at the top or the bottom of the aerosol-forming article 18. The dielectric spacer elements 41 may be arranged outside the volume between the electrodes 26 to avoid unnecessary heating. Spacer elements 41 may comprise or may be made of a dielectric material, for example a low-dielectric and / or electrically non-conducting or insulating material. The spacer elements 41 may be arranged between the electrodes 26 and the vapor egress surface 23, for example between the electrodes 26 and the liquid transfer element 21. The spacer elements 41 may be at least partly arranged inside the liquid transfer element 21 and may protrude beyond the liquid transfer element 21 and / or the vapor egress surface 23. For example, the spacer elements 41 may be arranged to extend to the electrodes 26 in a radial pattern, for instance in relation to a middle axis, for example a longitudinal middle axis, of the aerosol-forming article 18. There may be one or more spacer elements 41 per electrode.

[0175] Figure 14 shows a longitudinal section through another possible embodiment of an aerosolforming article 18. The main difference to previous embodiments may lie in a differently shapedliquid transfer element 21. Specifically, the liquid transfer element 21 may be shaped such that liquid aerosol-forming substrate 20 may enter the liquid transfer element 21 through the liquid ingress surface 22 in the direction of insertion of the aerosol-forming article 18 into the aerosolforming device 2. The liquid may first be guided through the liquid transfer element 21 in the direction of insertion, and then make a turn towards the center of the aerosol-forming article 18. From there, the liquid aerosol-forming substrate 20 may then be guided against the direction of insertion of the aerosol-forming article 18 into the aerosol-forming device 2 to the vapor egress surfaces 23 and the electrodes 26, which may be arranged at and / or on and / or along and / or may be at least partly embedded in a convex end of the liquid transfer element. In other words, the vapor egress surface 23 of the liquid transfer element 21 may have a convex shape, for example may at least partly have a cylindrical or a spherical shape. In this way, the surface area of the end of the liquid transfer element 21, where the electrodes 26 and the vapor egress surfaces 23 are arranged, can be increased. Keeping the same distance between the electrodes 26, more electrodes 26 and therefore more heating zones 28 may thus be arranged at this side of the liquid transfer element 21, which may increase vapor and ultimately aerosol production. The convexshaped end of the liquid transfer element 21 may be in direct contact with and / or arranged in the aerosolization chamber 24. At least one air inlet 32, for example more than one air inlet 32, may be arranged in the liquid transfer element 21 , for example by providing one or more air channels through the liquid transfer element 21. Outside air may therefore enter the aerosolization chamber 24 through the air inlet 32 in the liquid transfer element 21, may mix with and cool the vapor coming from the vapor egress surfaces 23, thereby forming aerosol, which may then be transported through the downstream airflow path 34 to the mouthpiece 4 for consumption by the user. As also shown in Figure 14, the electrical leads 27 and / or the electrode connection terminal 30 may at least partly be provided inside the liquid transfer element 21. In other words, the electrical leads 27 and / or the electrode connection terminal 30 may extend through the liquid transfer element 21, particularly the liquid transfer volume 25, for electrically connecting the electrodes 26 to the circuitry of the aerosol-forming device 2.

[0176] Figure 15 schematically shows a top view of the electrodes 26 arranged on a cylinder segment that forms the end surface and vapor egress surface 23 of the liquid transfer element 21, for example in the embodiment of Figure 14. As can be seen, the electrodes 26 may, also in this case, be arranged such that their distance from each other in neighboring electrodes 26 may be kept constant. The electrodes 26 may also have the same dimensions, but may appear narrower at the side due to the perspective on the cylinder surface in Figure 15. In this way, the width of the heating zones 28 may be kept constant. The same applies to electrodes 26 arranged in an at least partly spherical shape over the end surface of the liquid transfer element 21, which is schematically shown in Figure 16. Also in this case, the distance between neighboringelectrodes 26 and therefore the width of the heating zones 28 may be constant or substantially constant.

[0177] Figure 17 schematically shows a top view of the liquid transfer element 21 having an at least partly cylindrical shape, as may for example be used in the embodiment of Figure 14. The electrodes 26 forming the heating zones 28 are also shown. Figure 16 also illustrates that a plurality of air inlets 32 may be formed and / or provided through the liquid transfer element 21. The amount and shape and / or size of the air inlets 32 may be tailored to user preference and / or the type of aerosol-forming substrate 20 used. For example, the amount and shape and / or the size of the air inlets 32 may be paramount for the resistance to draw of the aerosol-forming device 2, which is a major factor for user comfort and experience.

[0178] In Figure 18 and 19, another feature of the present disclosure is shown. Specifically, both Figures show a section through the liquid transfer element 21 and at least one electrode 26 arranged on the liquid transfer element 21. The section of Figure 18 is parallel to the longitudinal extension of the electrode 26, whereas the section of Figure 19 is perpendicular to the longitudinal extension of the electrodes 26, thereby showing more than one electrode 26. The main difference to previous embodiments is that the electrodes 26 may not be arranged directly on or in direct contact with the liquid transfer element 21. Instead, an interface layer 33 may be arranged between the electrodes 26 and the liquid transfer element 21, the interface layer 33 separating the electrodes 26 from the liquid transfer element 21. Specifically, the interface layer 33 may be arranged upstream of the electrodes 26 in the flow direction or effective flow direction of the liquid aerosol-forming substrate 20. The interface layer 33 may therefore be arranged outside of the heating zone 28 or in a fringe region of the heating zone 28, thereby avoiding the interface layer 33 being overly heated and wasting energy. The interface layer 33 may be made from and / or comprise a dielectric material, for example glass, ceramic or plastic material. The interface layer 33 may have a smooth surface and may be used as a substrate for depositing the material of the electrodes 26, avoiding having to deposit the electrodes 26 directly on the porous or rough surface of the liquid transfer element 21.

[0179] As also shown in Figure 18 and 19, the interface layer 33 may be embedded in the liquid transfer element 21. Particularly, the interface layer 33 may be fully embedded in the liquid transfer element 21 so that the interface layer 33 ends flush with the outer surface of the liquid transfer element 21, as shown in Figure 18. Particularly, the interface layer 33 may not protrude from the liquid transfer element 21. The interface layer 33 may also be embedded so far into the liquid transfer element 21 that the electrodes 26 arranged on the interface layer 33 may also be at least partly or fully embedded in the material of the liquid transfer element 21, as explained above and as for example shown in Figure 19.As already mentioned, the aerosol-forming system 1 according to aspects of the disclosure may comprise a removable aerosol-forming article 18 or may comprise an aerosol-forming article 18 as a fixedly connected component of the aerosol-forming device 2. An aerosol-forming system 1 comprising a removable aerosol-forming article 18 is shown in Figure 20. The aerosol-forming article 18 may comprise electrodes 26, 130, 135 forming the load capacitor CL. The aerosolforming article 18 may further comprise an article part 42 of the oscillation circuit 250, 355. The aerosol-forming device 2 may comprise the holder part 37 of the oscillation circuit 250, 355. The holder part 37 and the article part 42 may together form the oscillation circuit 250, 355. The aerosol-forming article 18 may comprise electrode connection terminals 30 for electrically connecting the electrodes 26, 130, 135 and the article part 42 to the holder part 37 via electrode connection elements 35 of the aerosol-forming device 2. An electrical connection between the electrode connection terminals 30 and the electrode connection elements 35 may be established when the aerosol-forming article 18 is inserted into the receptacle chamber 29 of the aerosolforming device 2. The article part 42 of the oscillation circuit 250, 355 may simply comprise electrical leads 27 connecting the electrodes 26, 130, 135 to the electrode connection terminals 30. Alternatively, the article part 42 of the oscillation circuit 250, 355 may comprise additional components of the oscillation circuit 250, 355, for example inductor LT and / or inductor L2. As also shown in Figure 20, the oscillation circuit 250, 355 may be supplied with electrical power from the energy storage 15 of the aerosol-forming device 2 via a DC / DC-converter 38 and the holder part 37.

[0180] An aerosol-forming system 1 comprising a fixedly connected aerosol-forming article 18 is shown in Figure 21. In contrast to the embodiment of Figure 20, the aerosol-forming article 18 may form a permanent part or component of the aerosol-forming device 2, for example having a refillable reservoir 40 for the liquid aerosol-forming substrate 20 with a refill opening or valve (not shown). Therefore, the electrodes 26, 130, 135 and the article part 42 may be permanently electrically connected to the holder part 37. The oscillation circuit 250, 355 may therefore permanently be completed. In this case, the aerosol-forming system 1 may comprise a refillable reservoir 40 for liquid aerosol-forming substrate 20. A user may therefore refill the refillable reservoir 40 whenever the liquid aerosol-forming substrate 20 is depleted or partially depleted.

[0181] Figure 22 shows a flowchart of the method 60 of heating a liquid aerosol-forming substrate 20 in an aerosol-forming article 18 and / or an aerosol-forming device 2. The method may begin in step 61 by establishing a dielectric heating zone 28 by creating an alternating electric field between at least two electrodes 26. For this purpose, an oscillator circuit 250, 355 as explained herein may be used. In step 62, liquid aerosol-forming substrate 20 from a liquid reservoir 19 may be guided through the dielectric heating zone 28, for example by capillary action and / or gravity and / or pumping action and / or an actuator in a liquid transfer element 21. The liquid may be guidedthrough the liquid transfer element 21 and particularly through the heating zone 28 unidirectionally, as explained herein. This may mean that an effective flow direction of the liquid aerosol-forming substrate 20 and / or vapor formed from the liquid aerosol-forming substrate 20 through the dielectric heating zone 28 is unidirectional, for example orthogonal to a direction of an alternating electrical field in the dielectric heating zone 28. Method 60 may further comprise step 63 of dielectric heating and vaporization of the liquid aerosol-forming substrate 20 in the dielectric heating zone 28, wherein the dielectric heating zone 28 encompasses at least a part of the vapor egress surface 23. The dielectric heating zone 28 may be arranged closer to the vapor egress surface 23 than the liquid ingress surface 22. For example, as explained herein, the at least two electrodes 26 establishing and / or forming the heating zone 28 may be arranged at, on or at least partly embedded in the liquid transfer element 21 such that the dielectric heating zone 28 is arranged closer to the vapor egress surface 23 than the liquid ingress surface 22. The vapor may then be mixed with outside or environmental air to generate, produce or form an aerosol for consumption by a user by inhalation. All of the other features of the present disclosure as explained herein are also applicable to the method 60 and are not repeated.

[0182] In summary, the present disclosure provides for an aerosol-forming device 2 using dielectric heating with high efficiency with reduced losses. Using the invention, a reliable flow of high quality aerosol during each puff of the user can be ensured while simultaneously, the lifetime of the energy supply, for example the battery, of the aerosol-forming device 2 is increased.

[0183] The terms “upstream” and “downstream” as used in the present disclosure may pertain to a flow direction, for example the effective flow direction, of the liquid aerosol-forming substrate from the liquid reservoir to the aerosolization chamber, for example inside the liquid transfer element. An element arranged upstream of another element is located closer to the liquid reservoir and / or the liquid ingress surface than the other element. In turn, an element arranged downstream of another element is located closer to the aerosolization chamber and / or the vapor egress surface than the other element. These terms therefore signify the relative positioning of the respective elements along the flow direction, for example the effective flow direction, of the liquid aerosol-forming substrate from the liquid reservoir to the aerosolization chamber.

[0184] 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, maydeviate 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, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. CLAIMS1. An aerosol-forming article for use in an aerosol-forming system, comprisinga liquid reservoir configured to store a liquid aerosol-forming substrate,a liquid transfer element, comprising a liquid ingress surface fluidically connected to the liquid reservoir, a vapor egress surface fluidically connected to an aerosolization space, and a liquid transfer volume between the liquid ingress surface and the vapor egress surface configured to transfer liquid from the liquid ingress surface to the vapor egress surface,at least two electrodes configured to establish an alternating electric field at a heating zone, the heating zone encompassing at least a part of the vapor egress surface,wherein the at least two electrodes are arranged at, on or at least partly embedded in the liquid transfer element at, on, or under the vapor egress surface,such that vaporized liquid egressing from the vapor egress surface flows between the at least two electrodes to reach a downstream airflow path.

2. The aerosol-forming article according to any one of the previous claims,wherein the liquid transfer element is made of or comprises one or more ofa material comprising channels or microchannels, for example a plurality of channels or microchannels, anda wicking material, for example a porous material, for example a porous ceramic material, for example a porous silicon ceramic material,for example wherein the liquid transfer element is configured to cause capillary flow of the liquid aerosol-forming substrate or wherein the liquid transfer element is configured to facilitate flow of the liquid aerosol-forming substrate by gravity,and / or wherein only a part of the liquid transfer volume is arranged in the heating zone, for example a maximum of 50% or a maximum of 40% or a maximum of 30% or a maximum of 20% or a maximum of 15% or a maximum of 10%.

3. The aerosol-forming article according to any one of the previous claims,wherein the at least two electrodes are configured to have resistive heating properties, for example with a conductivity o of at least 1x106S / m at 20°C or at least 5x106S / m at 20°C or at least 1x107S / m at 20°C or at least 5x107S / m at 20°C.

4. The aerosol-forming article according to any one of the previous claims,further comprising at least one additional electrode, wherein at least one additional heating zone is formed between the at least one additional electrode and another electrode.48 / 505. The aerosol-forming article according to any one of the previous claims,wherein the at least two electrodes, for example all electrodes, are arranged following the shape of the associated liquid transfer element and / or vapor egress surface.

6. The aerosol-forming article according to any one of the previous claims,wherein at least two pairs of electrodes or a plurality of electrodes of alternating polarity are arranged in an interdigitated pattern, parallel stripes, or mesh at the associated liquid transfer element and / or vapor egress surface.

7. The aerosol-forming article according to any one of the previous claims,wherein the at least two electrodes are configured and / or arranged with respect to each other such that the volume between the at least two electrodes forms a constriction on a side facing the vapor egress surface.

8. The aerosol-forming article according to any one of the previous claims,wherein the at least two electrodes are configured and / or arranged following a curved line or plane, wherein the concave side of the curved line or plane is directed towards the vapor egress surface.

9. The aerosol-forming article according to any one of the previous claims,further comprising an interface layer arranged between the at least two electrodes, for example between all electrodes, and the liquid transfer element, for example wherein the interface layer comprises a non-porous and / or non-conductive dielectric material, for example a glass material or a polymer.

10. The aerosol-forming article according to the previous claim,wherein the interface layer is arranged perpendicular to an effective flow rate of the liquid aerosol-forming substrate through the liquid transfer element, and / orwherein the heating zone between the at least two electrodes is free of the interface layer or of material of the interface layer.

11. The aerosol-forming article according to any one of the previous claims,wherein the at least two electrodes are arranged such that a distance between them, for example the smallest distance between them, is at most 2 mm or at most 1.75 mm or at most 1.5 mm or at most 1.25 mm or at most 1 mm or at most 0.75 mm or at most 0.5 mm.49 / 5012. The aerosol-forming article according to any one of the previous claims,wherein the at least two electrodes form opposing electrodes of a capacitor of a feedback loop of an oscillator circuit, and / orwherein the aerosol-forming article includes the feedback loop and the at least two electrodes are fixedly connected to the feedback loop orwherein the aerosol-forming article is free of the feedback loop and the at least two electrodes are removably connectable to the feedback loop arranged in the aerosol-forming device.

13. An aerosol-forming device, comprisingat least two electrode connection elements configured to electrically connect to the at least two electrodes of an aerosol-forming article, for example an aerosol-forming article according to any one of the previous claims, when the aerosol-forming article is inserted into or coupled to the aerosol-forming device for use,further comprising an oscillator circuit electrically connected to the at least two electrode connection elements to provide an alternating electrical field to establish a heating zone.

14. An aerosol-forming system, comprisingthe aerosol-forming article according to any one of claims 1-12, andan aerosol-forming device, for example the aerosol-forming device according to the previous claim.

15. A method of heating a liquid aerosol-forming substrate in an aerosol-forming article, for example an aerosol-forming article according to anyone of claims 1-12, and / or an aerosol-forming device, for example an aerosol-forming device according to claim 13, and / or an aerosol-forming system, for example an aerosol-forming system according to the previous claim, comprising: establishing an alternating electric field between two electrodes to create a heating zone; guiding the liquid aerosol-forming substrate from a liquid reservoir through a liquid ingress surface into a liquid transfer element and through the dielectric heating zone to a vapor egress surface of the liquid transfer element; anddielectric heating and vaporizing of the liquid aerosol-forming substrate in the dielectric heating zone;wherein the dielectric heating zone encompasses at least a part of the vapor egress surface.

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