Aerosol-generating device with dielectric heating unit

Abstract

The present invention provides an aerosol-generating device comprising an aerosol-generating unit configured to generate an aerosol, a dielectric heating unit comprising a radio frequency (RF) power source and a heating zone, and a flow path arranged to traverse the heating zone of the dielectric heating unit. The flow path comprises an upstream inlet configured to receive the aerosol from the aerosol-generating unit, and a downstream outlet configured to discharge the aerosol. The dielectric heating unit is configured to generate an alternating electric field in the heating zone to heat aerosol particulates of the aerosol through dipole rotation as the aerosol passes through the flow path.

Description

[0001] Aerosol-generating device with dielectric heating unit

[0002] The present invention relates to an aerosol-generating device, and specifically to an aerosol-generating device configured to generate and heat aerosol in a more efficient way. The present disclosure further relates to aerosol-generating systems comprising said aerosolgenerating device for heating an aerosol-forming substrate, such as substrates including an active ingredient, for example nicotine, or for inhaling a medical aerosol formed by mechanical aerosolgeneration method, the aerosol comprising one or more active ingredients dissolved or suspended in a liquid capable of being aerosolized.

[0003] Handheld, electrically operated aerosol-generating systems typically include an aerosolforming substrate and an aerosol-generating device that interacts with the substrate to generate an aerosol for a user to inhale. Typically, the process of aerosol generation varies depending on the application.

[0004] In electronic smoking devices, for example, such as an electronic cigarette (e-cigarette) or heated tobacco products (HTP), aerosol is typically generated by heating the substrate. Prior art aerosol-generating devices exist where a flow path from aerosol generation towards a mouthpiece outlet is relatively long causing undesired cooling of aerosol which may lead to condensation and humidity build-up and aerosol deposits along the flow path. Solutions have been proposed to address this problem by placing a tempering coil or other resistive heating element in the flow path downstream from aerosol generation. However, the time required to heat the aerosol is relatively long and requires a significant amount of energy. In addition, the heating energy that can be departed to the aerosol via heat convection is limited.

[0005] In other applications, for example in medical devices, such as Ventolin inhalers or other types of metered dose inhalers (MDI), compressed air is commonly used to create a fine mist from a liquid medication via a discharge nozzle. However, aerosol droplets exiting from these devices are often sized for lungs of adults, and less for relatively smaller living beings because their airways tend to have smaller geometries as compared to adults.

[0006] It would be desirable to provide a device and systems that overcome one or more of said drawbacks.

[0007] Aerosol-Generating Device

[0008] According to a first aspect of the present invention, there is provided an aerosol-generating device comprising an aerosol-generating unit configured to generate an aerosol, a dielectric heating unit comprising a radio frequency (RF) power source and a heating zone, and a flow path arranged to traverse the heating zone of the dielectric heating unit. The flow path comprising an upstream inlet configured to receive the aerosol from the aerosol-generating unit, and a downstream outlet configured to discharge the aerosol, for example for inhalation. The dielectric heating unit is configured to generate an alternating electric field in the heating zone to heat aerosol particulates of the aerosol through dipole rotation as the aerosol passes through the flow path.

[0009] The dielectric heating unit may enable for a more efficient heating of aerosols, because heating energy in the form of dipole rotation can be applied directly to aerosol particulates, e.g. droplets or particles of the aerosol, via the oscillating electric field, due to the relatively high relative permittivity of the particulates as compared to the surrounding gas or air. Thereby, heating energy is concentrated to the particulates rather than being applied to side walls that form the flow path or to a gas (e.g., air) surrounding the aerosol droplets or particles.

[0010] The dielectric heating unit may be controlled such that a temperature drop of the aerosol along the fluidic extension of the heating zone is avoided or reduced as compared to the absence of any dielectric heating by the dielectric heating unit.

[0011] The dielectric heating unit may be controlled to change a temperature gradient of the aerosol that is flowing or moving along the heating zone along the flow path so to have a slower cooling rate as compared to an unheated flow path. Hence, the temperature of the aerosol could still be lower than the temperature at the inlet, but having been subjected to less cooling as compared to an unheated flow path.

[0012] The dielectric heating unit may be controlled to heat-up the aerosol that is flowing or moving along the heating zone, such that a temperature of the aerosol at the downstream outlet is equal to or higher than a temperature of the aerosol at the upstream inlet.

[0013] The dielectric heating unit may be controlled such that condensation of the aerosol may be prevented or reduced compared to a flow path in which no or ineffective heating is provided.

[0014] A temperature of the aerosol when dielectrically heated by the dielectric heating unit may be lower than a threshold temperature at which droplets of the aerosol evaporate or at which solid particles of the aerosol vaporize.

[0015] Alternatively, a temperature of the aerosol when dielectrically heated by the dielectric heating unit may be equal to or higher than the threshold temperature at which droplets of the aerosol evaporate, thereby causing a droplet size reduction.

[0016] Dielectric Heating unit i. Resonant cavity, Transmission line

[0017] The dielectric heating unit may comprise a resonant cavity, a transmission line, or both, and the RF power source may include an electromagnetic (EM) wave source configured to feed an EM wave to the resonant cavity, the transmission line, or both.

[0018] The EM wave source may be configured to generate and feed an electromagnetic wave via a coupler to the resonant cavity, the transmission line, or both at a frequency in a range from 800 MHz to 25 GHz, preferably between 1 Ghz to 5 GHz, preferably around 2.4 Ghz or 4.8 Ghz. ii. Electrodes

[0019] The dielectric heating unit may comprise at least two electrodes, and the RF power source includes an RF oscillation circuit configured to provide an RF voltage to the at least two electrodes.

[0020] The RF oscillation circuit may be configured to operate the at least two electrodes at a radio frequency in the ultra-high frequency range (UHF), or in a range from 100 MHz to 2 GHz, preferably from 300 MHz to 1 GHz.

[0021] The power source may be the RF voltage source.

[0022] The at least two electrodes may form a load capacitor that is part of the RF oscillation circuit.

[0023] The RF oscillation circuit may comprise an inverting switching unit with a feedback loop connected between the input and the output of the switching unit, wherein the load capacitor and an inductor is part of the feedback loop. Moreover, the RF oscillation circuit may comprise a delay element for setting a switching frequency of the inverting switching unit. The delay element may be configured to impede the switching speed of the switching unit. Specifically, the delay element may delay a switching signal received by the switching unit.

[0024] An oscillation circuit comprising a delay element is sometimes referred to as a delay-line oscillator. A delay-line oscillator is a form of electronic oscillator that uses a delay line, or delay element as its principal timing element. The delay-line oscillator may be set to oscillate by inverting the output of the delay line or delay element and feeding that signal back to the input of the delay line or delay element with appropriate amplification.

[0025] The delay element may be realized with a physical delay line (such as an LC network or a transmission line). In some examples, capacitances and inductances may be distributed across the length of the delay element. In some examples, the delay element comprises a cascade of logic gates for creating a gate delay. The timing of an oscillation circuit using a physical delay element may be much more accurate. It is also easier to get such an oscillation circuit to oscillate in the desired mode.

[0026] The at least two electrodes may be shaped as electrode plates opposed to each other, forming the flow path and the heating zone therebetween.

[0027] The at least two electrodes may comprise one or more pairs of interdigitated electrodes arranged as parallel strips along a longitudinal extension of a cylindrical, oval, or other tubular arrangement, to form a cylindrical, oval, or other tubular flow path therebetween.

[0028] The cylindrical flow path may include an inner obstruction, for example a tubular element, arranged at the cylindrical axis, such that the incoming aerosol is forced to pass in close proximity to the inner cylindrical surface that is adjacent to the interdigitated electrodes.

[0029] The inner obstruction may include an element having a cylindrical shape.

[0030] Flow Path The flow path may be a space at least in part arranged within the heating zone. In particular, the flow path may be a space between two electrodes of the dielectric heating unit.

[0031] An inner surface of the flow path may have hydrophobic properties, or has properties that disfavor an attachment of aerosol-particles thereto, such as low wettability, low surface roughness.

[0032] The flow path may include a porous body to increase the heating energy exposure of the aerosol.

[0033] The flow path may include a membrane having a filtering function. The filtering function may be configured to filter out large aerosol particles.

[0034] Flow Direction-Changing Elements

[0035] The flow path may comprise flow direction-changing elements to lengthen the exposure of the aerosol to the alternating electric field, thereby exposing the aerosol to more heating energy.

[0036] The flow direction-changing elements may include baffles or walls.

[0037] Flow Path Shape

[0038] The flow path may be formed as a tube or channel defining the upstream inlet and the downstream outlet, with a middle section arranged in the heating zone.. The tube or channel may include an outer periphery so as to define a rigid structure.

[0039] The tube or channel may be made of a material having a low dielectric constant or relative permittivity, for example a polymeric material, a low dielectric ceramic material, or a glass material, for example guartz glass. As an example, PEEK and PEI could be used as the polymeric material .

[0040] The electrodes may be coated with a material that forms the walls of the tube or channel defining the flow path.

[0041] The tube or channel may be shaped as a meandering, spiraled, wavy structure to lengthen the exposure of the aerosol to the alternating electric field, thereby exposing the aerosol to more heating energy.

[0042] Aerosol-Generating Unit

[0043] The aerosol-generating unit may be further configured to cause and / or allow a discharge of the aerosol with a certain flow rate. i. Caused (i.e., Active) Discharge

[0044] The aerosol-generating unit may comprise a push aerosol type configuration configured to, upon activation, push out the aerosol via the downstream outlet, thereby causing a discharge of the aerosol with a certain flow rate

[0045] The aerosol-generating unit may comprise at least one of a pressurizing device, a mechanical aerosol generation such as vibrating membranes, and / or an aerosol spray, to cause a discharge of the aerosol with a certain flow rate. The certain flow rate may be predefined, preset or selectable. ii. Allowed (i.e., Passive) Discharge

[0046] The aerosol-generating unit may comprise a pull aerosol type configuration that, upon an airflow generated by a user inhalation or puff, allows the aerosol to be discharged through the downstream outlet at a flow rate corresponding to an inhaling or puffing power applied by the user. iii. Aerosol-Generating Unit Chamber including Heating Chamber to Receive an Aerosol- Forming Substrate

[0047] The aerosol-generating unit may comprise a heating chamber which is arranged to receive an aerosol-forming substrate. The heating chamber may comprise a heating element, which in operation heats the aerosol-forming substrate by one or more of dielectric heating, inductive heating, resistive / external heating, and / or radiative / infrared heating, and a nucleation or aerosolization chamber in fluidic communication with the heating chamber, thereby generating aerosol.

[0048] It is also possible that the aerosol-generating unit includes a coil-and-wick type heating element for heating a liguid aerosol-forming substrate, or another type of liguid atomizing unit, for example a porous body type liguid transfer element with resistive heating, for example a meshtype heater.

[0049] An inner surface of the aerosol-generating chamber may have a smallest width or diameter that is greater than a smallest width or diameter respectively of an inner surface of the flow path. a) Dielectric Heater

[0050] The heating element may comprise an dielectric heating element comprising at least two electrodes, a resonant cavity, and / or transmission line which in operation heats the aerosolforming substrate by dipole rotation when subjected to an alternating electric field inside the aerosol-generating chamber.

[0051] The at least two electrodes of the dielectric heating element of the aerosol-generating unit and the at least two electrodes of the dielectric heating unit may be independent and electrically isolated from each other, such as by an air gap, and / or differently controlled from each other.

[0052] The at least two electrodes of the dielectric heating element of the aerosol-generating unit and the at least two electrodes of the dielectric heating unit may be connected to each so as to form a contiguous single capacitor, wherein a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating element of the aerosol-generating unit and a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating unit are different, thereby causing different electrical field strengths within the heating chamber and the flow path, respectively. By having connected electrodes only one RF oscillator feeding an RF voltage to the connected electrodes may be required, thereby increasing overall efficiency.

[0053] A width of the at least two electrodes of the dielectric heating unit may be narrower / wider in a direction perpendicular to a flow of the aerosol as compared to the two electrodes of the dielectric element of the aerosol-generating unit.

[0054] An opening may be provided at the connection portion serving as an air inlet.

[0055] A distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating element of the aerosol-generating unit may be from 10 times to 1.5 times, preferably from 5 times to 1 .5 times, in particular from 3 times to 2 times smaller or greater than a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating unit so as to cause different electrical field strengths between the respective electrode pairs.

[0056] As used herein, the term “electrodes pair” refers to an arrangement having a positive electrode and a negative electrode in distance to each other. b) Resistive Heater

[0057] The heating element of the aerosol-generating unit may comprise an aerosol-generating resistive or Joule heating element arranged within the aerosol-generating chamber, which in operation heats the aerosol-forming substrate by convective heating from the exterior. c) Inductive Heater

[0058] The heating element of the aerosol-generating unit may comprise an aerosol-generating inductive heating element comprising one or more coils, which in operation heats one or more susceptors arranged or received inside the aerosol-generating chamber, to be arranged inside, in contact, or in close proximity to the aerosol-forming substrate. d) Combination of Allowed (i.e., Passive) and Caused (i.e., Active) Discharges

[0059] The aerosol-generating unit may comprise a medical nebulizer spray or a metered dose inhaler (MDI), such as a ventolin inhaler, that, upon activation, causes a dose of the aerosol to be pushed out via the downstream outlet while an inhalation is performed by a user that can have some pulling effect.

[0060] Temperature Control

[0061] The aerosol-generating device may further comprise a temperature sensor arranged to measure a temperature of the aerosol, preferably arranged at or close to the downstream outlet of the flow path, and a controller configured to control the aerosol temperature of the flow of aerosol exiting the heating unit based on a signal from the temperature sensor, preferably in a closed-loop temperature control configuration, by changing one or more of: a heating power of the dielectric heating unit and / or a flow rate of the flow of aerosol generated by the aerosolgenerating unit. The heating power of the heating unit may be changed by increasing the power supply voltage to the RF power source, or by increasing a frequency of the RF power source, or both.

[0062] The flow rate of the aerosol-generating unit may be changed by opening up a flow path cross-section of a nozzle of the aerosol-generating unit.

[0063] The temperature sensor may be a resistance temperature detector.

[0064] The resistance temperature detector may comprise a resistive track made of a material with a positive temperature coefficient (PTC) or a negative temperature coefficient (NTC).

[0065] Mouthpiece Outlet and Nucleation Chamber

[0066] The heating element of the aerosol-generating unit may comprise a mouthpiece outlet and a mouthpiece channel in flow connection with the downstream outlet of the flow path and the mouthpiece outlet. The dielectric heating unit may be controlled such that a temperature drop of the aerosol between aerosol generation at the aerosol-generating unit and the mouthpiece outlet is avoided or reduced as compared to the absence of any dielectric heating by the dielectric heating unit.

[0067] The dielectric heating unit may be controlled such that condensation of the aerosol is prevented or reduced within the mouthpiece channel.

[0068] The dielectric heating unit may be controlled such that a temperature at the mouthpiece outlet is equal to or higher than a temperature of the aerosol when generated at the aerosolgenerating unit.

[0069] The heating element of the aerosol-generating unit may comprise a nucleation chamber with one or more air inlets. The nucleation chamber may be positioned between the mouthpiece channel and the dielectric heating unit. The nucleation chamber may be configured to receive the aerosol flow from the downstream outlet and to discharge the aerosol flow by infusing it with airflow from the air inlets, forming a combined aerosol to be inhaled by a consumer through the mouthpiece outlet.

[0070] The dielectric heating unit may be controlled such as to avoid that the aerosol temperature drops below a threshold temperature at which the aerosol condensates before reaching the nucleation chamber and / or the mouthpiece outlet.

[0071] The dielectric heating unit may be controlled such as to heat up the aerosol in a manner that the aerosol temperature at the mouthpiece outlet is equal to or higher than at the aerosol when being generated at the aerosol-generating unit.

[0072] Optical Sensor / Controlling Aerosol-Droplet Size

[0073] The aerosol-generating device may further comprise an optical sensor arranged within the heating zone or downstream of the heating zone to measure a value indicative of a flow of aerosol that is heated by the dielectric heating unit, and a controller configured to control a parameter of the aerosol exiting the dielectric heating unit based on a signal from the optical sensor, preferably in a closed-loop control configuration, by changing one or more of: a heating power of the dielectric heating unit and / or a flow rate of the aerosol generated by the aerosol-generating unit.

[0074] The optical sensor may include an emitter and a detector / receiver arranged such that light traverses the flow of aerosol, preferably perpendicularly.

[0075] The controller may include a data processor configured to analyze the signal, preferably a time-of-flight signal, to detect one or more of presence or absence of an aerosol, speed of the aerosol, and / or a value indicative of an average size of aerosol droplets.

[0076] The optical sensor may include a laser diffraction measurement device configured to measure and provide for a value that is indicative of the average size of the aerosol droplets.

[0077] The measured value indicative of the flow of aerosol is a time-of-flight signal that measures a time taken by light traversing the flow of aerosol, and a scattering characteristic of the time-of- flight signal is used to perform analysis.

[0078] The value indicative of the average aerosol droplet size exiting the dielectric heating unit may be used by a data processor of the controller, to control the dielectric heating of the heating unit, to allow for a feedback-loop controlled aerosol droplet size generation,

[0079] The aerosol droplet size may be controlled to be suitable for inhalation of at least one of infants, small children, small animals and pets.

[0080] Droplet Size

[0081] A heating power of the dielectric heating unit and / or a flow rate of the aerosol generated may be selected or controlled such that an average aerosol droplet size, in particular the diameter of the aerosol droplet, of the aerosol exiting the dielectric heating unit is in the range below 5 micrometers, preferably from 0.5 micrometers to 4.5 micrometers, in particular from 2 micrometers to 3 micrometers.

[0082] Aerosol-Generating System (Aerosol-Forming Substrate)

[0083] According to a second aspect of the present invention, there is provided an aerosolgenerating system comprising an aerosol-forming substrate; and an aerosol-generating device according to the first aspect for heating the solid aerosol-forming substrate.

[0084] The aerosol-forming substrate may be a solid aerosol-forming substrate.

[0085] The solid aerosol-forming substrate may comprise a tobacco material.

[0086] Aerosol-Generating System (Medical Aerosol)

[0087] According to a third aspect of the present invention, there is provided an aerosol-generating system for inhaling medical aerosol. The system comprises one or more active ingredients dissolved or suspended in a liguid capable of being aerosolized, and an aerosol-generating device according to the first aspect employing dielectric heating to aerosol droplets that have been aerolized from the liguid, thereby decreasing the original droplet size to a smaller magnitude. The system, in particular the aerosol-generating unit, may comprise a vibrator, a membrane, and a reservoir for holding the liquid to be aerosolized, the reservoir is f I uidical ly connected to the membrane, wherein the vibrator is configured to induce vibrations in the membrane upon activation, causing the liquid from the reservoir to pass through the membrane and form an aerosol.

[0088] The system may comprise a container configured to hold the liquid composition under pressure, and a spray nozzle in fluid communication with the container, wherein the nozzle is configured to release the liquid composition as an aerosol upon activation, where the pressure within the container forces the liquid composition through the nozzle.

[0089] The pressure of the liquid composition inside the container may range from 50 kPa to 650 kPa, preferably from 300 kPa to 600 kPa, more preferably from 350 kPa to 550 kPa.

[0090] The liquid composition as used herein refers to the one or more active ingredients dissolved or suspended in the liquid capable of being aerosolized.

[0091] The system may comprise a vibratory mechanism operatively associated with the container or spray nozzle, configured to impart vibratory energy to the liquid composition to facilitate further aerosolization and enhance the dispersion of fine particles within the aerosol.

[0092] The system may comprise an actuator configured to control release of the liquid composition through the spray nozzle and optionally activate the vibratory mechanism.

[0093] According to an alternative aspect, employing dielectric heating to the aerosol droplets may only cause heating of the droplets without causing a reduction of the droplet size.

[0094] 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.

[0095] Aerosol-Generating Device:

[0096] Example Ex1. An aerosol-generating device comprising an aerosol-generating unit configured to generate an aerosol, a dielectric heating unit comprising a radio frequency (RF) power source and a heating zone, and a flow path arranged to traverse the heating zone of the dielectric heating unit, the flow path comprising an upstream inlet configured to receive the aerosol from the aerosol-generating unit, and a downstream outlet configured to discharge the aerosol, wherein the dielectric heating unit is configured to generate an alternating electric field in the heating zone to heat aerosol particulates of the aerosol through dipole rotation as the aerosol passes through the flow path.

[0097] Example Ex1.1. The aerosol-generating device according to the preceding example, wherein the dielectric heating unit is controlled such that a temperature drop of the aerosol along the fluidic extension of the heating zone is avoided or reduced as compared to the absence of any dielectric heating by the dielectric heating unit.

[0098] Example Ex1.2. The aerosol-generating device according to any one of the preceding examples, wherein the dielectric heating unit is controlled to change a temperature gradient of the aerosol that is flowing or moving along the heating zone along the flow path so to have a slower cooling rate as compared to an unheated flow path.

[0099] Example Ex1 .3. The aerosol-generating device according to any one of the preceding examples, wherein the dielectric heating unit is controlled to heat-up the aerosol that is flowing or moving along the heating zone, such that a temperature of the aerosol at the downstream outlet is equal to or higher than a temperature of the aerosol at the upstream inlet.

[0100] Example Ex1 .4. The aerosol-generating device according to any one of the preceding examples, wherein the dielectric heating unit is controlled such that condensation of the aerosol is prevented or reduced compared to a flow path in which no or ineffective heating is provided.

[0101] Example Ex1 .5. The aerosol-generating device according to any one of the preceding examples, wherein a temperature of the aerosol when dielectrically heated by the dielectric heating unit may be lower than a threshold temperature at which droplets of the aerosol evaporate or at which solid particles of the aerosol vaporize.

[0102] Example Ex1 .6. The aerosol-generating device according to any one of examples Ex1 to Ex1 .4, wherein a temperature of the aerosol when dielectrically heated by the dielectric heating unit is equal to or higher than the threshold temperature at which droplets of the aerosol evaporate, thereby causing a droplet size reduction.

[0103] Dielectric Heating Unit i. Resonant cavity, Transmission line:

[0104] Example Ex2. The aerosol-generating device according to any one of the preceding examples, wherein the dielectric heating unit comprises a resonant cavity, a transmission line, or both, and the RF power source includes an electromagnetic (EM) wave source configured to feed an EM wave to the resonant cavity, the transmission line, or both.

[0105] Example Ex2.1.1. The aerosol-generating device according to the preceding example, wherein the EM wave source is configured to generate and feed the EM wave to the resonant cavity, transmission line or both at a frequency in a range from 800 MHz to 25 GHz, preferably between 1 GHz to 5 GHz, preferably around 2.4 GHz or 4.8 GHz. ii. Electrodes

[0106] Example Ex3. The aerosol-generating device according to example Ex1 , wherein the dielectric heating unit comprises at least two electrodes, and the RF power source includes an RF oscillation circuit configured to provide an RF voltage to the at least two electrodes. Example Ex3.1. The aerosol-generating device according to the preceding example, wherein the RF oscillation circuit is configured to operate the at least two electrodes at a radio frequency in a range from 100 MHz to 2 GHz, preferably from 300 MHz to 1 GHz.

[0107] Example Ex3.2. The aerosol-generating device according to example Ex3 or Ex3.1 , wherein the at least two electrodes form a load capacitor that is part of the RF oscillation circuit.

[0108] Example Ex3.2.1. The aerosol-generating device according to the preceding example, wherein the RF oscillation circuit comprises an inverting switching unit with a feedback loop connected between the input and the output of the switching unit, wherein the load capacitor is part of the feedback loop.

[0109] Example Ex3.2.1.1. The aerosol-generating device according to the preceding example, wherein the RF oscillation circuit comprises a delay element for setting a switching frequency of the inverting switching unit.

[0110] Example Ex3.3. The aerosol-generating device according to any of examples Ex3 to Ex3.2.1.1 , wherein the at least two electrodes are shaped as electrode plates opposed to each other.

[0111] Example Ex3.4. The aerosol-generating device according to any of examples Ex3 to Ex3.3 , wherein the at least two electrodes comprise one or more pairs of interdigitated electrodes arranged as parallel strips along a longitudinal extension of a cylindrical, oval, or other tubular arrangement, to form a cylindrical, oval, or other tubular flow path therebetween.

[0112] Example Ex3.4.1. The aerosol-generating device according to the preceding example, wherein the cylindrical flow path includes an inner obstruction arranged at the cylindrical axis, such that the incoming aerosol is forced to pass in close proximity to the inner cylindrical surface that is adjacent to the interdigitated electrodes.

[0113] Example Ex3.4.1 .1. The aerosol-generating device according to the preceding example, wherein the inner obstruction includes an element having a cylindrical shape.

[0114] Flow Path:

[0115] Example Ex3.5. The aerosol-generating device according to any one of the preceding examples Ex3 to Ex3.4.1.1 , wherein the flow path is a space at least in part arranged within the heating zone, preferably between two electrodes of the dielectric heating unit.

[0116] Example Ex3.6. The aerosol-generating device according to any one of the preceding examples Ex3 to Ex3.5, wherein the inner surface of the flow path has hydrophobic properties, or has properties that disfavor an attachment of aerosol-particles thereto, e.g. low wettability, low surface roughness,

[0117] Example Ex3.7. The aerosol-generating device according to any one of the preceding examples Ex3 to Ex3.6, wherein the flow path includes a porous body to increase the heating energy exposure of the aerosol. Example Ex3.8. The aerosol-generating device according to any one of the preceding examples Ex3 to Ex3.7, wherein the flow path includes a membrane having a filtering function, e.g. for filtering out large aerosol particles

[0118] Flow Direction-Changing Elements:

[0119] Example Ex3.9. The aerosol-generating device according to any one of the preceding examples Ex3 to Ex3.8, wherein the flow path comprises flow direction-changing elements to lengthen the exposure of the aerosol to the alternating electric field, thereby exposing the aerosol to more heating energy.

[0120] Example Ex3.10. The aerosol-generating device according to the preceding example, wherein the flow direction-changing elements include baffles or walls.

[0121] Flow Path Shape:

[0122] Example Ex3.11. The aerosol-generating device according to any one of examples Ex3 to Ex3.10, wherein the flow path is formed as a tube or channel defining the upstream inlet and the downstream outlet, with a middle section arranged in the heating zone.

[0123] Example Ex3.11 .1 . The aerosol-generating device according to the preceding example, wherein the tube or channel being made of a dielectric material having a low dielectric constant or relative permittivity, preferably selected from the group consisting of PEEK and polyimide.

[0124] Example Ex3.11.2. The aerosol-generating device according to any one of examples Ex3.11 to Ex3.11.1 , wherein the electrodes are coated with a material that forms the walls of the tube or channel defining the flow path.

[0125] Example Ex3.11.3. The aerosol-generating device according to any one of examples Ex3.11 to Ex3.11.2, wherein the tube or channel is shaped as a meandering, spirally, wavy structure to lengthen the exposure of the aerosol to the alternating electric field, thereby exposing the aerosol to more heating energy.

[0126] Aerosol-Generating Unit:

[0127] Example Ex4. The aerosol-generating device according to any one of the preceding examples, wherein the aerosol-generating unit is further configured to cause and / or allow a discharge of the aerosol with a certain flow rate. i. Caused (i.e., Active) Discharge:

[0128] Example Ex4.1. The aerosol-generating device according to the preceding example, wherein the aerosol-generating unit comprises a push aerosol type configuration configured to, upon activation, push out the aerosol via a downstream outlet, thereby causing a discharge of the aerosol with a certain flow rate

[0129] Example Ex4.2. The aerosol-generating device according to any one of examples Ex4 to Ex4.1 , wherein the aerosol-generating unit comprises at least one of a pressurizing device, a mechanical aerosol generation such as vibrating membranes, and / or an aerosol spray, to cause a discharge of the aerosol with a certain flow rate. ii. Allowed (i.e., Passive) Discharge:

[0130] Example Ex4.3. The aerosol-generating device according to example Ex4, wherein the aerosol-generating unit comprises a pull aerosol type configuration that, upon an airflow generated by a user inhalation or puff, allows the aerosol to be discharged through the downstream outlet at a flow rate corresponding to an inhaling or puffing power applied by the user. iii. Aerosol-Generating Chamber (Heating Chamber) to Receive an Aerosol-Forming Substrate:

[0131] Example Ex5. The aerosol-generating device according to any one of the preceding examples, wherein the aerosol-generating unit comprises an aerosol-generating chamber which is arranged to receive an aerosol-forming substrate, wherein the aerosol-generating chamber comprises an heating element, which in operation heats the aerosol-forming substrate by one or more of dielectric heating, inductive heating, resistive heating, and / or radiative , such as infrared, heating, thereby generating the aerosol.

[0132] Example Ex5.1. The aerosol-generating device according to the preceding example, wherein an inner surface of the aerosol-generating chamber has a smallest width or diameter that is greater than a smallest width or diameter respectively of an inner surface of the flow path. a) Dielectric Heater:

[0133] Example Ex6. The aerosol-generating device according to any one of examples Ex5 to Ex5.1 , wherein the heating element of the aerosol-generating unit comprises a dielectric heating element comprising at least two electrodes, a resonant cavity, and / or a transmission line which in operation heats the aerosol-forming substrate by dipole rotation when subjected to an alternating electric field inside the aerosol-generating chamber.

[0134] Example Ex7. The aerosol-generating device according to any one of examples Ex3 to Ex3.11.2 and the preceding example, wherein the at least two electrodes of the dielectric heating element and the at least two electrodes of the dielectric heating unit are electrically isolated from each other, such as by an air gap, and / or differently controlled from each other.

[0135] Example Ex8. The aerosol-generating device according to any one of examples Ex3 to Ex3.11.2 and the example Ex6, wherein the at least two electrodes of the dielectric heating element of the aerosol-generating unit and the at least two electrodes of the dielectric heating unit are connected to each so as to form a contiguous single capacitor, wherein a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating element of the aerosol-generating unit and a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating unit are different, thereby causing different electrical field strengths within the heating chamber and the flow path, respectively.

[0136] Example Ex8.1. The aerosol-generating device according to the preceding example, wherein a width of the at least two electrodes of the dielectric heating unit is narrower / wider in a direction perpendicular to a flow of the aerosol as compared to the two electrodes of the dielectric element of the aerosol-generating unit.

[0137] Example Ex8.2. The aerosol-generating device according to any one of examples Ex8 to Ex8.1 , wherein an opening is provided at the connection portion serving as an air inlet.

[0138] Example Ex8.3. The aerosol-generating device according to any one of examples Ex8 to Ex8.2, wherein a distance between electrodes of an electrode pair (including a positive and a negative electrode) of the at least two electrodes of the dielectric heating element of the aerosolgenerating unit is from 10 times to 1.5 times, preferably from 5 times to 1.5 times, in particular from 3 times to 2 times smaller or greater than a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating unit so as to cause different electrical field strengths between the respective electrode pairs. b) Resistive Heater:

[0139] Example Ex8.4. The aerosol-generating device according to any one of examples Ex5 to Ex5.1 , wherein the heating element of the aerosol-generating unit comprises an aerosolgenerating resistive heating element arranged within the aerosol-generating chamber, which in operation heats the aerosol-forming substrate by joule heating. c) Inductive Heater:

[0140] Example Ex8.5. The aerosol-generating device according to any one of examples Ex5 to Ex5.1 , wherein the heating element of the aerosol-generating unit comprises an aerosolgenerating inductive heating element comprising one or more coils, which in operation heats one or more susceptors arranged or received inside the aerosol-generating chamber inside, in contact, or in close proximity to the aerosol-forming substrate. d) Combination of Allowed (i.e., Passive) and Caused (i.e., Active) Discharges:

[0141] Example Ex8.6. The aerosol-generating device according to any one of examples Ex5 to Ex5.1 , wherein the aerosol-generating unit comprises a medical nebulizer spray, such as a ventolin inhaler, that, upon activation, causes a dose of aerosol to be pushed out via a downstream outlet while an inhalation is performed by a user that can have some pulling effect.

[0142] Temperature Control:

[0143] Example Ex9. The aerosol-generating device according to any one of the preceding examples, further comprising a temperature sensor arranged to measure a temperature of the aerosol, preferably arranged at or close to the downstream outlet of the flow path, and a controller configured to control the aerosol temperature of the flow of aerosol exiting the heating unit based on a signal from the temperature sensor, preferably in a closed-loop temperature control configuration, by changing one or more of: a heating power of the dielectric heating unit and / or a flow rate of the flow of aerosol generated by the aerosol-generating unit.

[0144] Example Ex9.1. The aerosol-generating device according to the preceding example, wherein the heating power of the heating unit is changed by increasing the power supply voltage to the RF power source, or by increasing a frequency of the RF power source, or both.

[0145] Example Ex9.2. The aerosol-generating device according to any one of examples Ex9 to Ex9.1 , wherein the flow rate of the aerosol-generating unit is changed by opening up a flow path cross-section of a nozzle of the aerosol-generating unit.

[0146] Example Ex9.3. The aerosol-generating device according to any one of examples Ex9 to Ex9.1 , wherein the temperature sensor is a resistance temperature detector.

[0147] Example Ex9.3.1. The aerosol-generating device according to the preceding example, wherein the resistance temperature detector comprises a resistive track made of a material with a positive temperature coefficient (PCT) or a negative temperature coefficient (NTC).

[0148] Mouthpiece Outlet and Nucleation Chamber

[0149] Example Ex10. The aerosol-generating device according to any one of the preceding examples, further comprising a mouthpiece outlet and a mouthpiece channel in flow connection with the downstream outlet of the flow path and the mouthpiece outlet, wherein the dielectric heating unit is controlled such that a temperature drop of the aerosol between aerosol generation at the aerosol-generating unit and the mouthpiece outlet is avoided or reduced as compared to the absence of any dielectric heating by the dielectric heating unit.

[0150] Example Ex10.1. The aerosol-generating device according to the preceding example, wherein the dielectric heating unit is controlled such that a such that condensation of the aerosol is prevented or reduced within the mouthpiece channel.

[0151] Example Ex10.2. The aerosol-generating device according to any one of examples Ex9 to Ex9.2, wherein the dielectric heating unit is controlled such that a temperature at the mouthpiece outlet is equal to or higher than a temperature of the aerosol when generated at the aerosolgenerating unit.

[0152] Example Ex11 . The aerosol-generating device according to any one of the preceding examples, further comprising a nucleation chamber with one or more air inlets, wherein the nucleation chamber is positioned between the mouthpiece channel and the dielectric heating unit, wherein the nucleation chamber is configured to receive the aerosol flow from the downstream outlet and to discharge the aerosol flow by infusing it with airflow from the air inlets, forming a combined aerosol to be inhaled by a consumer through the mouthpiece outlet.

[0153] Example Ex11.1. The aerosol-generating device according to the preceding example, wherein the dielectric heating unit is controlled such as to avoid that the aerosol temperature drops below a threshold temperature at which the aerosol condensates before reaching the nucleation chamber and / or the mouthpiece outlet.

[0154] Example Ex11.2. The aerosol-generating device according to any one of examples Ex11 to Ex11.1 , wherein the dielectric heating unit is controlled such as to heat up the aerosol in a manner that the aerosol temperature at the mouthpiece outlet is equal to or higher than at the aerosol when being generated at the aerosol-generating unit.

[0155] Optical Sensor / Controlling Aerosol-Droplet Size:

[0156] Example Ex12. The aerosol-generating device according to any one of the preceding examples, further comprising an optical sensor arranged within the heating zone or downstream of the heating zone to measure a value indicative of a flow of aerosol that is heated by the dielectric heating unit, and a controller configured to control a parameter of the aerosol exiting the dielectric heating unit based on a signal from the optical sensor, preferably in a closed-loop control configuration, by changing one or more of: a heating power of the dielectric heating unit and / or a flow rate of the aerosol generated by the aerosol-generating unit.

[0157] Example Ex12.1. The aerosol-generating device according to the preceding example, wherein the optical sensor includes an emitter and a detector / receiver arranged such that light traverses the flow of aerosol, preferably perpendicularly.

[0158] Example Ex12.1.1. The aerosol-generating device according to the preceding example, wherein the controller includes a data processor configured to analyze the signal, for example a time-of-flight (ToF) signal, to detect one or more of presence or absence of an aerosol, speed of the aerosol, and / or a value indicative of an average size of aerosol droplets.

[0159] Example Ex12.2. The aerosol-generating device according to any one of examples Ex12 to Ex12.1.1 , wherein the optical sensor includes a laser diffraction measurement device configured to measure and provide for a value that is indicative of the average size of an aerosol droplet.

[0160] Example Ex12.3. The aerosol-generating device according to any one of examples Ex12 to Ex12.2, wherein the measured value indicative of the flow of aerosol is a time-of-flight (ToF) signal that measures a time taken by light traversing the flow of aerosol, and a scattering characteristic of the time-of-flight signal is used to perform analysis.

[0161] Example Ex12.4. The aerosol-generating device according to any one of examples Ex12 to Ex12.3, wherein a value indicative of the average aerosol droplet size exiting the dielectric heating unit is used by a data processor of the controller, to control the dielectric dielectric heating of the heating unit, to allow for a feedback-loop controlled aerosol droplet size generation,

[0162] Example Ex12.5. The aerosol-generating device according to any one of examples Ex12 to Ex12.4, wherein the aerosol droplet size is controlled to be suitable for inhalation of at least one of infants, small children, small animals and pets.

[0163] Droplet Size Example Ex13. The aerosol-generating device according to any one of the preceding examples, wherein a heating power of the dielectric heating unit and / or a flow rate of the aerosol generated is selected or controlled such that an average aerosol droplet size, in particular the diameter of the aerosol droplet, of the aerosol exiting the dielectric heating unit is in the range below 5 micrometers, preferably from 0.5 micrometers to 4.5 micrometers, in particular from 2 micrometers to 3 micrometers.

[0164] Aerosol-Generating System (Solid Aerosol-Forming Substrate):

[0165] Example Ex14. An aerosol-generating system comprising an aerosol-forming substrate; and an aerosol-generating device according to any one of the preceding examples for heating the solid aerosol-forming substrate.

[0166] Example Ex14.1. The aerosol-generating system according to example Ex14, wherein the aerosol-forming substrate is a solid aerosol-forming substrate.

[0167] Example Ex14.2. The aerosol-generating system according to example Ex14 or example Ex14.1 , wherein the solid aerosol-forming substrate comprises a tobacco material.

[0168] Aerosol-Generating System (Medical Aerosol):

[0169] Example Ex15. An aerosol-generating system for inhaling medical aerosol comprising one or more active ingredients dissolved or suspended in a liguid capable of being aerosolized and an aerosol-generating device according to any one of the preceding examples Ex1 to Ex13 employing dielectric heating to aerosol droplets that have been aerolized from the liguid, thereby decreasing the original droplet size to a smaller magnitude.

[0170] Example Ex15.1. The aerosol-generating system according to example Ex15, wherein the system, in particular the aerosol-generating unit, comprises a vibrator, a membrane, and a reservoir for holding the liguid to be aerosolized, the reservoir is fluidically connected to the membrane, wherein the vibrator is configured to induce vibrations in the membrane upon activation, causing the liguid from the reservoir to pass through the membrane and form an aerosol.

[0171] Example Ex15.2. The aerosol-generating system according to example Ex15, comprising a container configured to hold the liguid composition under pressure, and a spray nozzle in fluid communication with the container, wherein the nozzle is configured to release the liguid composition as an aerosol upon activation, where the pressure within the container forces the liguid composition through the nozzle.

[0172] Example Ex15.3. The aerosol-generating system according to example Ex15.2, wherein the pressure of the liguid composition inside the container ranges from 50 kPa to 650 kPa, preferably from 300 kPa to 600 kPa, more preferably from 350 kPa to 550 kPa.

[0173] Example Ex15.4. The aerosol-generating system according to example Ex15.2 or example Ex15.3, comprising a vibratory mechanism operatively associated with the container or spray nozzle, configured to impart vibratory energy to the liquid composition to facilitate further aerosolization and enhance the dispersion of fine particles within the aerosol.

[0174] Example Ex15.5. The aerosol-generating system according to any one of examples Ex15 to Ex15.4, comprising an actuator configured to control release of the liquid composition through the spray nozzle and optionally activate the vibratory mechanism.

[0175] As used herein, the term “aerosol-generating device” may relate to a device that interacts with an aerosol-forming substrate to generate an aerosol.

[0176] As used herein, the term “aerosol-forming substrate” may relate to a liquid or solid substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate.

[0177] As used herein, the term “aerosol-generating system” may relate to a combination of an aerosol-generating device and an aerosol-forming substrate. The aerosol-forming substrate may be arranged in vicinity to the aerosol-generating device so as to enable generation of an aerosol.

[0178] As used herein, the term “aerosol” may relate to a suspension of particulates including fine solid particles and / or liquid droplets in a gas, typically air.

[0179] As used herein, the term “puff” may mean the action of a user drawing an aerosol into their body through their mouth or nose.

[0180] As used herein, the term “relative permittivity” may refer to the real part of the complex, frequency-dependent relative permittivity, measured at a temperature of 20 degrees Celsius, in an alternating electric field with at a very low frequency (VLF) of 1 Kilohertz or less, as defined in the international standard IEC 62631-2-1 :2018. It will be appreciated that the frequency value of 1 Kilohertz is included here solely as a general reference and other definitions may use different frequencies. The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0181] Figure 1 is a schematic illustration of an aerosol-generating system according to embodiments of the disclosure;

[0182] Figure 2 is a schematic illustration of a closed-loop temperature control circuit for use in the aerosol-generating system of Figure 1 , according to embodiments of the disclosure;

[0183] Figure 3 is a schematic illustration of a passively actuated aerosol-generating unit, in particular a heated tobacco products (HTP) device, for use in the aerosol-generating system of Figure 1 , according to embodiments of the disclosure;

[0184] Figure 4 is a schematic illustration of a passively actuated aerosol-generating unit, in particular a HTP device, for use in the aerosol-generating system of Figure 1 , according to another embodiment of the disclosure; Figure 5 is a schematic illustration of an optical sensor for use in the aerosol-generating device of Figure 1 , preferably for the purpose of controlling aerosol-droplet size exiting the dielectric heating unit, according to embodiments of the disclosure;

[0185] Figure 6 is a schematic illustration of an electrode arrangement for use in the aerosolgenerating system of Figure 1 , according to embodiments of the disclosure. The above and other features and advantages of example embodiments will become more apparent by describing in detail, example embodiments with reference to the attached drawings. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Example embodiments may, however, be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein. Accordingly, while example embodiments are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but to the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of example embodiments. Like numbers refer to like elements throughout the description of the Figures.

[0186] Figure 1 is a schematic illustration of an aerosol-generating system 10 comprising an aerosol-generating device 100 for generating an aerosol based on an aerosol-forming substrate (not shown) and post-heating said generated aerosol according to an embodiment of the disclosure. The device 100 comprises two units: a first unit being an aerosol-generating unit 110 that can receive the aerosol-forming substrate, and a second unit being a dielectric heating unit 120 including two opposing electrodes 130, 135 defining a heating zone 140 therebetween. The electrodes 130, 135 are fed by an radio frequency (RF) power source 150 including an RF oscillation circuit configured to provide an RF voltage to the two electrodes 130, 135, for example but not limited to a circuit as described in European patent application 23201969.5 where the electrodes 130, 135 form a load capacitor CL that is part of the RF oscillation circuit, in particular forms part of a feedback loop of the RF oscillation circuit. Alternatively, the dielectric heating unit 120 may comprise a resonant cavity, a transmission line, or both, and the RF power source 150 includes an electromagnetic (EM) wave source configured to feed an EM wave to the resonant cavity, the transmission line, or both.

[0187] The aerosol-generating unit 110 can be any type of device that can generate an aerosol, and to which a certain flow rate can be departed, either actively, passively or a combination of both.

[0188] “Actively” actuated aerosol-generating units as used herein may include means in a push aerosol type configuration, for example pressurizing devices, mechanical aerosol generation means such as vibrating membranes, or aerosol sprays. “Passively” actuated aerosol-generating units as used herein may include means in a pull aerosol type configuration, for example e-cigarettes that vaporize a liquid, heat-not-burn (HnB) devices in particular heated tobacco products (HTP) that heat a tobacco in leaf or some other aerosol-forming substrates in solid form by generating an airflow by human inhalation or pufftaking.

[0189] “Combined” actuated aerosol-generating units may include medical nebulizers where the aerosol is both pushed by the dispenser and pulled by the human inhalation. An example of such a type of device is a ventolin inhaler where one pushes the nebulizer spray for a dose and at the same time an inhalation is performed that can have some pulling effect.

[0190] Referring back to Figure 1 , the dielectric heating unit 120 is arranged to form a flow path 160 in the heating zone 140. The flow path 160 is configured to receive a flow of aerosol from the aerosol-generating unit 110 at an upstream inlet 162, pass the aerosol with the flow through an alternating RF electric field generated between the electrodes 130, 135, and discharge the flow of aerosol downstream from the electrodes 130, 135 at a downstream outlet 164. While the flow path 160 is simply the space between the two electrodes 130, 135 in this embodiment, in other embodiments, it can also be a tube, channel, or other traversing structure arranged between the electrodes 130, 135, for example a channel defining an inlet and an outlet, with a middle section arranged between the electrodes 130, 135 that is made of a low dielectric material, for example PEEK or polyimide, or the electrodes 130, 135 themselves are coated with a material that forms the walls of a tube or channel defining the flow path 160.

[0191] To expose the aerosol to more heating energy in the heating zone 140, a tube or channel may be formed as a meandering or wavy structure, spirally shaped flow path, porous body, flow direction changing baffles or walls, with the aim of lengthening the flow path 160 of the aerosol that is exposed to the RF alternating electric field of the electrodes 130, 135.

[0192] While the electrodes 130, 135 are shown to be two opposing plates in this embodiment, other types of electrodes arrangements are also possible, for example but not limited to more than one pair of interdigitated electrodes, as described in European patent application 23201969.5 for example, arranged as parallel strips in a longitudinal extension of a cylindrical arrangement, to form a cylindrical flow path therebetween.

[0193] The aerosol-generating device 100 can be configured to heat-up an aerosol that is flowing along the flow path 160 between the electrodes 130, 135, such that a temperature of the aerosol at the downstream outlet 164 is higher than a temperature of the aerosol at the upstream inlet 162, with a high level of efficiency and substantially increased heating power. As another variant, it is possible that a cooling or heating rate of the aerosol that flows from the upstream inlet 162 to the downstream outlet 164 is controlled, for example to ascertain that the aerosol-temperature does not drop below a predefined threshold level. In this respect, it is possible that the temperature of the aerosol traversing the dielectric heating unit 120 drops, but to a lesser extent as compared to the absence of any dielectric post-heating, i.e. dielectric heating of aerosol after its generation.

[0194] Different applications can be embodied with the device: For example, with preliminary referral to Figures 2 and 4, aerosol-generating systems exist where a flow path from the aerosolgenerating unit 110, for example a heating element with an aerosol-forming substrate, nebulizer, or spray, towards a mouthpiece outlet is relatively long, and thereby the aerosol travelling along the flow path 160 is subject to undesired cooling, as usually this flow path 160 is not heated. This can lead to condensation and humidity build-up and aerosol deposits along the flow path 160, or an aerosol that is unsatisfactory in taste for human consumption. For example, in the context of aerosol-generating devices of heated tobacco products (HTP), the aerosol could be cooled down to a value where a nucleation in a nucleation chamber and air infusion is no longer bringing about the desired results.

[0195] As another application, with preliminary referral to Figure 5, by applying an alternating RF electric field to the aerosol by the dielectric heating unit 120, aerosol droplets will be subjected to dipole movement which in turn leads to the breaking up of the droplets into smaller particles. For example, the droplets of the aerosol could be heated to cause evaporation, thereby reducing the original droplet size to a smaller value. As a non-limiting example, an average droplet size exiting the aerosol-generating unit 110 could be about 5pm, for example for human inhalation to deliver medication or pharmaceutical aerosol. By subjecting the aerosol to the alternating RF electric field via the dielectric heating unit 120, the droplets of the aerosol exiting the downstream outlet 164 can be made smaller, for example to an average size of about 1 pm to 2 .m. This reduction of the droplet size can be beneficial for inhalation by smaller living beings, for example infants, small children, small animals (dogs, cats, as compared to horses), as their airways tend to have smaller geometries as compared to adult living beings. This leads to a more efficient delivery of the medication to living beings of smaller size.

[0196] Figure 2 is a schematic view of a closed-loop temperature control circuit 200 for use in the aerosol-generating system 10 of Figure 1 , according to embodiments of the disclosure.

[0197] The closed-loop temperature control circuit 200 comprises a temperature sensor 210 for direct or indirect temperature measurement of the aerosol or flow of aerosol downstream from the aerosol-generating unit 110 and / or downstream of the dielectric heating unit 120. In this example, the temperature sensor 210 is arranged close to the downstream outlet 164 of the dielectric heating unit 120. In a non-limiting example, the temperature sensor 210 may be a PTC type sensor. A value indicative of the temperature of the aerosol or aerosol flow can be fed back to a controller 220 of the device 100, and the controller 220 can control either the heating power 222 of the dielectric heating unit 120, for example by increasing the power supply voltage to the RF oscillator forming the RF power source 150, a flow rate 224 of the aerosol exiting the aerosolgenerating unit 110 , for example by opening up a flow path cross-section of a nozzle, or both, to thereby have an impact on the aerosol temperature exiting the dielectric heating unit 120.

[0198] Figure 3 is a schematic illustration of an aerosol-generating system having an aerosolgenerating unit 110 embodied as a passively actuated aerosol-generating unit 310, in particular as a HTP device, for use in the aerosol-generating system 10 of Figure 1 , according to embodiments of the disclosure.

[0199] The passively actuated aerosol-generating unit 310 can heat-up a solid aerosol-forming substrate 301 received between its electrodes 312, 314 to a specific temperate that allows to form an aerosol 370. A nucleation chamber 380 in form of an air gap between the passively actuated aerosol-generating unit 310 and the dielectric heating unit 120 is provided to infuse the generated aerosol with airflow from air inlets 382, 384, forming a combined aerosol to be inhaled by a human / consumer after being post-heated by the dielectric heating unit 120. In this Figure, an airflow and its direction through the device is indicated by arrows.

[0200] In this embodiment, the passively actuated aerosol-generating unit 310 comprises a dielectric heating element formed by the two electrodes 312, 314 shaped and arranged as opposing plates to receive the aerosol-forming substrate 301 therebetween and heat the aerosolgenerating substrate 301 so that one or more active ingredients can be aerosolized. However, the passively actuated aerosol-generating unit 310 is not limited to any specific heating technology. In other embodiments, an inductive heater to heat one or more susceptors (e.g. within the substrate 301), a resistive heater, infrared heater or other radiative-type heater unit can be used.

[0201] Figure 4 shows another non-limiting example of an aerosol-generating system having a passively actuated aerosol-generating unit 310 for use in the aerosol-generating system 10 of Figure 1 , according to embodiments of the disclosure. In contrast to the system as shown in Figure 3, the system comprises a mouthpiece 402 that may be removably attachable to a device 400. The heating arrangement of the device 400 is substantially similar to the one in Figure 3 but differs from it in that a nucleation chamber 480 is arranged between the dielectric heating unit 120 (i.e. the second unit) and the mouthpiece 402.

[0202] First air inlets 492 are provided upstream to the passively actuated aerosol-generating unit 410 including a heater and an aerosolization chamber or area 460 enabling a user for pulling of air through the aerosol-forming substrate 401 , thereby generating aerosol for consumption when the aerosol-forming substrate 401 is heated. Optionally, additional air can be provided by vents, ducts, channels (not shown) that lead into aerosolization chamber or area 460 for aiding the aerosol-formation, similarly as illustrated in Figure 3. The dielectric heating unit 120 is arranged downstream from the first unit 410 to heat the generated aerosol, or to apply a desired spatial temperature profile along the traversing longitudinal axis, to avoid that the aerosol drops below a predefined temperature threshold before reaching the nucleation chamber 480.

[0203] The nucleation chamber 480 can be infused with air from second air inlets 482. After the nucleation chamber 480, the aerosol is delivered to the human consumer via an outlet channel 403 and a mouthpiece outlet 404 of the mouthpiece 402. In other embodiments the mouthpiece outlet 404 may form part of the device 400 itself and may constitute an interface means to engage with a separate mouthpiece.

[0204] Compared to article / stick-type HTP devices, where the nucleation chamber 480 and air infusion is located in the article / stick and therefore close to the mouthpiece outlet 404 where the inhalation occurs, the flow path length from aerosol-generation to nucleation and / or downstream outlet is substantially longer and could subject the aerosol to undesired cooling. By having the dielectric heating unit 120, however, cooling and condensation of the aerosol flowing within the device 400 before reaching the mouthpiece 402 or mouthpiece outlet 404 can be reduced or avoided.

[0205] As another embodiment of an aerosol-generating system for generating an aerosol and heating same can be embodied as a device for inhaling medical aerosol, where one or more active ingredients are dissolved or suspended in an aerosolisable liquid, for example water and / or aerosol former. While aerosol droplets typically have a droplet size dimension suitable for adults, i.e. , about the size of 5 .m, they are less or not suitable for infants, small children, or small animals and pets, and may need to be reduced. In this embodiment, the reduction is carried out by the use of the dielectric heating unit 120. A vibrating membrane nebulizer, as shown for example in WO2022 / 079249, this reference herewith incorporated by reference in its entirety, can be used as the aerosol-generating unit 110 arranged upstream to the dielectric heating unit 120. The dielectric heating unit 120 is configured to depart dipole movement to the aerosol via the oscillating electric field, to cause evaporation and thereby realizing droplet size reduction of the aerosol.

[0206] Figure 5 is a schematic illustration of an optical sensor 500 for use in the aerosol-generating device of Figure 1 , preferably for the purpose of controlling aerosol-droplet size exiting the dielectric heating unit 120, according to embodiments of the disclosure.

[0207] That is, the optical sensor 500 can be used to monitor the heated aerosol by the dielectric heating unit 120. The optical sensor 500 includes an emitter 510 and a detector / receiver 520 arranged such that light 530 traverses the aerosol-flow perpendicularly. A controller (not shown) may be used to analyze the signal received from the optical sensor 500. Scattering and other characteristics of the received light 530 could be analyzed, for example to detect presence or absence of an aerosol, and / or to detect speed of the aerosol, and / or to also detect a value indicative of an average size of aerosol droplets. For example, time-of flight principles could be applied, and the scatting characteristics of the time-of-flight signal may be used to perform analysis, for example, as disclosed in PCT / CN2023 / 116459 which is incorporated here by reference in its entirety.

[0208] In the present embodiment, the optical sensor 500 is arranged to measure the aerosol that is traversing the alternating electric field generated by the electrodes 130, 135 of the dielectric heating unit 120. In other examples, the optical sensor 500 can be arranged at the downstream outlet 164 away from the alternating RF electric field. Signals from the optical sensor 500 can be used to control the aerosol generation, the flow velocity, or both, similar to the one described in the closed-loop temperature control circuit 200 of Figure 2. For example, a value indicative of the average aerosol droplet size exiting the dielectric heating unit 120 can be used by a data processor of the controller 220 to control the dielectric heating of the dielectric heating unit 120, to allow for a feedback-loop controlled droplet size generation.

[0209] Figure 6 is a schematic illustration of an alternative electrode arrangement, where in contrast to the embodiment shown in Figure 3, where the pair of electrodes 312, 314 of the dielectric heating element of the aerosol-generating unit 110 and the pair of electrodes 130, 135 of the dielectric heating unit 120 are electrically isolated from each other, in this embodiment, the pair of electrodes 612, 614 of the first unit for heating the (solid) aerosol-forming substrate 601 and the pair of electrodes 130, 135 of the dielectric heating unit 120 (second unit) are connected to each so as to form a contiguous single capacitor with two heating zones of different capacitance.

[0210] As shown, a distance di between electrodes 612, 614 of the first unit and a distance d2 between electrodes 130, 135 of the second unit is different, causing a change of capacity along the device longitudinal axis, and thereby causing different electrical field strengths applied to the substrate 601 and the aerosol 602. With this electrode arrangement, only single RF power source including an RF oscillation circuit is required, leading to more overall efficiency of the device / system.

[0211] In the shown example, an opening 682 is provided in between the connection portion of the electrode pairs serving as an air inlet.

Claims

CLAIMS1 . An aerosol-generating device comprising an aerosol-generating unit configured to generate an aerosol, a dielectric heating unit comprising a radio frequency (RF) power source and a heating zone, and a flow path arranged to traverse the heating zone of the dielectric heating unit, the flow path comprising an upstream inlet configured to receive the aerosol from the aerosol-generating unit, and a downstream outlet configured to discharge the aerosol, wherein the dielectric heating unit is configured to generate an alternating electric field in the heating zone to heat aerosol particulates of the aerosol through dipole rotation as the aerosol passes through the flow path.

2. The aerosol-generating device according to the preceding claim, wherein the dielectric heating unit comprises a resonant cavity, a transmission line, or both, and the RF power source includes an electromagnetic (EM) wave source configured to feed an EM wave to the resonant cavity, the transmission line, or both.

3. The aerosol-generating device according to claim 1 , wherein the dielectric heating unit comprises at least two electrodes, and the RF power source includes an RF oscillation circuit configured to provide an RF voltage to the at least two electrodes.

4. The aerosol-generating device according to any one of the preceding claims, wherein the aerosol-generating unit is further configured to cause and / or allow a discharge of the aerosol with a certain flow rate.5 The aerosol-generating device according to any one of the preceding claims, wherein the aerosol-generating unit comprises an aerosol-generating chamber which is arranged to receive an aerosol-forming substrate, wherein the aerosol-generating chamber comprises a heating element, which in operation heats the aerosol-forming substrate by one or more of dielectric heating, inductive heating, resistive heating, and / or radiative heating, thereby generating aerosol.

6. The aerosol-generating device according to the preceding claim, wherein the heating element comprises a dielectric heating element comprising at least two electrodes, a resonant cavity, or a transmission line which in operation heats the aerosol-forming substrate by dipole rotation when subjected to an alternating electric field inside the aerosol-generating chamber.

7. The aerosol-generating device according to claim 3 and the preceding claim, wherein the at least two electrodes of the dielectric heating element of the aerosol-generating unit and the at least two electrodes of the dielectric heating unit are electrically isolated from each other, such as by an air gap, and / or differently controlled from each other.

8. The aerosol-generating device according to claim 3 and claim 6, wherein the at least two electrodes of the dielectric heating element of the aerosol-generating unit and the at least two electrodes of the dielectric heating unit are connected to each so as to form a contiguous single capacitor, wherein a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating element of the aerosol-generating unit and a distance between electrodes of an electrode pair of the at least two electrodes of the dielectric heating unit are different, thereby causing different electrical field strengths within the heating chamber and the flow path, respectively.

9. The aerosol-generating device according to any one of the preceding claims, further comprising a temperature sensor arranged to measure a temperature of the aerosol, preferably arranged at or close to the downstream outlet of the flow path, and a controller configured to control the aerosol temperature of the flow of aerosol exiting the heating unit based on a signal from the temperature sensor, preferably in a closed-loop temperature control configuration, by changing one or more of: a heating power of the dielectric heating unit and / or a flow rate of the flow of aerosol generated by the aerosol-generating unit.

10. The aerosol-generating device according to any one of the preceding claims, further comprising a mouthpiece outlet and a mouthpiece channel in flow connection with the downstream outlet of the flow path and the mouthpiece outlet, wherein the dielectric heating unit is controlled such that a temperature drop of the aerosol between aerosol generation at the aerosol-generating unit and the mouthpiece outlet is avoided or reduced as compared to the absence of any dielectric heating by the dielectric heating unit.

11. The aerosol-generating device according to the preceding claim, further comprising a nucleation chamber with one or more air inlets, wherein the nucleation chamber is positioned between the mouthpiece channel and the dielectric heating unit, wherein the nucleation chamber is configured to receive the aerosol flow from the downstream outlet and to discharge the aerosol flow by infusing it with airflow from the air inlets, forming a combined aerosol to be inhaled by a consumer through the mouthpiece outlet.

12. The aerosol-generating device according to any one of the preceding claims, further comprising an optical sensor arranged within in the heating zone or downstream of the heatingzone to measure a value indicative of a flow of aerosol that is heated by the dielectric heating unit, and a controller configured to control a parameter of the aerosol exiting the dielectric heating unit based on a signal from the optical sensor, preferably in a closed-loop control configuration, by changing one or more of: a heating power of the dielectric heating unit and / or a flow rate of the aerosol generated by the aerosol-generating unit.

13. The aerosol-generating device according to any one of the preceding claims, wherein a heating power of the dielectric heating unit and / or a flow rate of the aerosol generated is selected or controlled such that an average aerosol droplet size, in particular the diameter of the aerosol droplet, of the aerosol exiting the dielectric heating unit is in the range below 5 micrometers, preferably from 0.5 micrometers to 4.5 micrometers, in particular from 2 micrometers to 3 micrometers.

14. An aerosol-generating system comprising an aerosol-forming substrate; and an aerosolgenerating device according to any one of the preceding claims for heating the aerosol-forming substrate.

15. An aerosol-generating system for inhaling medical aerosol comprising one or more active ingredients dissolved or suspended in a liquid capable of being aerosolized and an aerosolgenerating device according to any one of claims 1 to 13 employing dielectric heating to aerosol droplets that have been aerolized from the liquid, thereby decreasing the original droplet size to a smaller magnitude.

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