EP4312630A1

EP4312630A1 - Aerosol provision system

Info

Publication number: EP4312630A1
Application number: EP22715669.2A
Authority: EP
Inventors: David LEADLEY
Original assignee: Nicoventures Trading Ltd
Current assignee: Nicoventures Trading Ltd
Priority date: 2021-03-31
Filing date: 2022-03-30
Publication date: 2024-02-07
Also published as: CN117098472A; JP7715824B2; GB202104639D0; JP2024511570A; WO2022208087A1; KR20230150866A; US20240180255A1; JP2025134055A; CA3211714A1; BR112023020144A2

Abstract

Aerosol Generating Device There is provided an aerosol generating device comprising: an air path including an aerosol generating region; a porous element downstream of the aerosol generating region located in the air path; and, a sensor for determining a change in a characteristic of airflow in the air path to indicate a change in a characteristic of the porous element.

Description

AEROSOL PROVISION SYSTEM

Technical Field

The present invention relates to an aerosol generating device, a method of controlling provision of an aerosol in an aerosol provision device, an aerosol generating system and an aerosol provision means.

Background

Aerosol provision systems are known. Common systems use heaters to create an aerosol from an aerosol generating material which is then inhaled by a user. The aerosol generating material from which the aerosol is generated is consumed during use of the aerosol provision system. When a device continues to heat a depleted aerosol generating material, undesirable flavours and aromas may be produced reducing the user experience of the aerosol provision system. Modem systems often use a predetermined time period of active use of a system to indicate depletion of aerosol generating material within the system.

It is desirable for aerosol provision systems to prevent heating of a depleted aerosol generating material and therefore avoid the production of undesirable flavours and aromas.

The present invention is directed toward solving some of the above problems.

Summary

Aspects of the invention are defined in the accompanying claims.

In accordance with some embodiments described herein, there is provided an aerosol generating device comprising: an air path including an aerosol generating region; a porous element downstream of the aerosol generating region located in the air path; and, a sensor for determining a change in a characteristic of airflow in the air path to indicate a change in a characteristic of the porous element. In accordance with some embodiments described herein, there is provided a method of controlling provision of an aerosol in an aerosol provision device, the method comprising: providing an air path comprising an aerosol generating region; providing an aerosol generating medium; providing a porous element downstream of the aerosol generating region; providing a sensor; determining, by the sensor, a change in a characteristic of airflow in the air path subsequently determining a change in a characteristic of the porous element; and, generating or not generating an aerosol in response to the determined change in the characteristic of the porous element.

In accordance with some embodiments described herein, there is provided an aerosol generating device as described above and aerosol generating material located within the aerosol generating region.

In accordance with some embodiments described herein, there is provided aerosol provision means comprising: an air path including an aerosol generating region; a porous element downstream of the aerosol generating region located in the air path; and, sensing means for determining a change in a characteristic of airflow in the air path to indicate a change in a characteristic of the porous element.

Description of Drawings

The present teachings will now be described by way of example only with reference to the following figures:

Figure 1 is a cross-sectional view of an aerosol provision device according to an example; and,

Figure 2 is a cross-sectional view of an aerosol provision device according to an example.

While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description of the specific embodiments are not intended to limit the invention to the particular forms disclosed. On the contrary, the invention covers all modifications, equivalents and alternatives falling within the scope of the present invention as defined by the appended claims.

Detailed Description

Aspects and features of certain examples and embodiments are discussed / described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed / described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

The present disclosure relates to aerosol provision systems, which may also be referred to as aerosol provision systems, such as e-cigarettes. Throughout the following description the term “e-cigarette” or “electronic cigarette” may sometimes be used, but it will be appreciated this term may be used interchangeably with aerosol provision system / device and electronic aerosol provision system / device. Furthermore, and as is common in the technical field, the terms "aerosol" and "vapour", and related terms such as "vaporise", "volatilise" and "aerosolise", may generally be used interchangeably.

Figure 1 illustrates a schematic view of an example of an aerosol generating device 100 according to the present invention. The aerosol generating device 100 has an air path 110 which includes an aerosol generating region 112. The aerosol generating device 100 also has a porous element 120. The porous element 120 is located downstream of the aerosol generating region 112 and is located in the air path 110. The aerosol generating device 100 has a sensor 130. The sensor 130 is for determining a change in a characteristic of airflow in the air path 110. The change in the characteristic of airflow in the air path 110 is used to indicate a change in a characteristic of the porous element 120.

The air that flows through the aerosol generating device 100 enters the device 100 at air inlet 102. The air flows along the air path 110, through the aerosol generating region 112, through the porous element 120 and exits the device 100 at air outlet 104. The air that exits the device 100 at air outlet 104 may be an aerosol and may have flavour compounds or the like entrained in the air or aerosol. The direction of travel of air flowing through the device 100 is shown in Figure 1 by arrow A.

The device 100 may have a heater and wick arrangement in the aerosol generating region 112 so as to produce an aerosol for inhalation. This invention does not focus on this portion of the device 100 and as such it will not be described in detail. It is suffice to say that any aerosol generating mechanism (also referred to herein as aerosol generating component) may be utilised with the invention described herein.

The porous element 120 is removably insertable into the device 100. Access to the device 100 may be provided by an openable door or an unscrew able section or the like such that a user may insert the porous element 120 into the device 100. The porous element 120 contains a flavourant or the like. As the aerosol produced in the aerosol generating region 112 passes through the porous element 120, flavour compounds may be entrained in the aerosol. The porous element 120 allows a user to therefore alter, and therefore personalise, the aerosol that is produced by the device 100.

The porous element 120 may have a plurality of channels through the element 120 which allows airflow to pass through the porous element 120. As airflow passes through the channels, compounds (e.g. flavourants) from the porous element 120 may be entrained into the airflow for inhalation by a user. The airflow that passes through the porous element 120 from the aerosol generating region 112 may be relatively hot and/or relatively wet. Typically aerosols are generated in a temperature range of 50 to 350 degrees Celsius. Moisture in the aerosol may result from the airflow entraining aerosolised e-liquid that may be used in the device 100 to form an aerosol. Such airflow would therefore be relatively hot and relatively wet. Relatively here is in comparison to airflow flowing through the device 100 which has not been heated or entrained any components through the aerosol generating region 112.

As the hot and/or wet airflow passes through the channels of the porous element 120, the channels may begin to structurally degrade. The porous element 120 will structurally degrade as a whole and not just the channels. The porous element 120 may be made of, for example, tobacco which structurally degrades when repeatedly subjected to hot and/or wet airflow. The channels of the porous element 120 therefore may begin to degrade and therefore close as the channels are warped under the impact of the heat and the humidity of the aerosol passing through the porous element 120. In such a way, the porous element 120 may be arranged to become less porous over time of use of the device 100.

The porosity of the porous element 120 will therefore depend in some way on the time of use of the device 100. The porosity of the porous element 120 will also be dependent on the intensity of usage of the device 100. For example, a user that desires an aerosol of a greater temperature and/or of a higher moisture (e.g. aerosolised e-liquid) content will cause greater structural degradation of the porous element 120 and its channels per puff than a user that desires an aerosol of a lower temperature and/or a lower moisture content. As such, the degradation of the porous element 120 is related to the intensity of the usage of the device 100 and not just the time of use. The present invention therefore advantageously provides a solution which can account for differences in the use behaviours of different users.

The channels of the porous element 120 will not necessarily close at the same time, but rather according to a distribution in light of the channels that are more preferentially travelled through by airflow through the porous element 120 than others that are less preferentially travelled through. As such, the channels are likely to close over a period of usage.

As certain channels close, airflow is forced to pass through the remaining open channels. Some of the remaining open channels may subsequently close as the device 100 is further used and hot and/or wet airflow is sent through those channels in the porous element 120. As such, it can be appreciated that the channels in the porous element 120 are gradually closed, until the airflow through the air path 110 can no longer effectively pass through the porous element 120 as it no longer has sufficient open channels to allow effective passing of airflow. Notably, not every channel needs to be closed for the airflow to not pass effectively. Only a sufficient amount of channels need to be closed. In an example, only 40% of channels need to be closed to produce a noticeable change in characteristics of the passing airflow. Different flavoured tobaccos might have different percentage blockage levels, and these can be accounted for accordingly. For example, one porous element with a first flavour may only need 40% of channels to be closed before a noticeable change in characteristics of airflow arises, while a different porous element with a second flavour may need a higher (or lower) percentage of channels to be closed for the same effect. The sensor 130 may be arranged to detect changes in one characteristic or several characteristics of the airflow passing through the air path 110. The sensor 130 in the example shown in Figure 1 is arranged downstream of the porous element 120 and is located in a housing 101 of the device 100. In an example wherein the porous element 120 has been structurally degraded such that a substantially reduced number of channels (c.f the original total number of channels) may allow air to pass through the porous element 120, the pressure in the airflow through the degraded porous element 120 may be different to the airflow through the original, non-degraded porous element 120. Similarly the airflow speed through the fewer remaining open channels may be different.

The sensor 130 may, during initial use of the device 100, calculate base line characteristics for the airflow through the air path 110. This may include for example pressure, temperature, content (such as gaseous content), density of vapour, and humidity of the airflow. From these base line measurements, and with further measurements to provide a base line working range so that natural variations are accounted for, significant deviations from these characteristics (changes in characteristics) may be detected by the sensor 130. The sensor 130 may be a digital sensor and detect internal pressure to indicate to a user a change in the porous element 120. A change in content may be for example an increase from baseline in the oxygen percent in the airflow or the like. This may also be relevant to any other aspect of the content of the airflow e.g. particulate matter in the airflow or other elements e.g. hydrogen, nitrogen or the like.

As the porous element 120 degrades over use, the characteristics of the airflow will change so as to be consistently outside the normal working range established while the porous element 120 was new and therefore un-degraded. The detection of the sensor 130 of the air characteristics may therefore be used to provide a guide as to the condition of the porous element 120. This in turn may be used to determine whether the porous element 120 is structurally degraded to an extent that changing the porous element 120 is advisable or required.

When that determination occurs, an alert may be provided to a user to inform the user that the porous element 120 should be removed from the device 100 and replaced. The alert may take the form of a visual stimulus such as a light from a light emitting diode (LED) located on the housing 101 or the like. The alert may be an aural stimulus such as a noise or a bleep from a speaker. The device 100 may be connected to other devices, such as a smartphone, and the device 100 may provide an alert to the other device or devices that the porous element 120 is to be replaced. The sensor 120 may therefore operate as a feedback mechanism to provide the user with a stimulus for changing the depleted porous element 120 in a timely manner which is personalised to the user.

The sensor 130 may be used to detect changes in more than one characteristic so as to provide additional data as to the likelihood of a structural change in the porous element 120. For example, if humidity, temperature and pressure of the airflow all display a significant change from the established working range, it is likely that the porous element 120 has decayed and needs replacing. Whereas if only temperature has changed, it may be that the porous element 120 does not need replacing. There may be a plurality of sensors to provide detections of a number of characteristics of the airflow through the air path 110.

The sensor or sensors 130 may be located upstream or downstream of the porous element 120 to best detect the relevant characteristic. For example, if humidity is very high upstream of the porous element 120 it may be because the moist airflow is struggling to pass through the porous element 120 as a result of the lack of available intact channels for airflow. At this point, the porous element 120 may need replacing.

The above discussion relates to a porous element 120 having specific channels, however it clearly also applies to an element which may be air permeable and the permeability of the element degrades over use. Any other such element would be a suitable variation of the present disclosure.

During the degradation of the porous element 120, the element 120 may congeal into a solid non-porous (or relatively non-porous) mass. This prevents airflow passing through the element 120. This would, if allowed to continue for a relatively long time, make the device 100 very difficult to inhale on which would decrease user experience of the device 100. The present invention therefore prevents this. Figure 2 illustrates a schematic view of an example of an aerosol generating device 200 according to the present invention. The aerosol generating device 200 has an air path 210 which includes an aerosol generating region 212. The aerosol generating device 200 also has a porous element 220. The porous element 220 is located downstream of the aerosol generating region 212 and is located in the air path 210. The aerosol generating device 200 has a sensor 230. The sensor 230 is for determining a change in a characteristic of airflow in the air path 210. The change in the characteristic of airflow in the air path 210 is used to indicate a change in a characteristic of the porous element 220.

In the example shown in Figure 2, the sensor 230 is connected to a controller 240. The controller 240 is connected in turn to an aerosol generating component 214 such as a heater or vibrator or the like for providing an aerosol from an aerosol generating medium in the device 200. In use, the aerosol generating component 214 is activated by the controller 240 so as to provide an aerosol in the aerosol generating region 212. The aerosol is entrained in the airflow along air path 210. The aerosol passes through the porous element 220 and entrains further components. The aerosol may then exit the device at air outlet 204.

Over use, as described above, the porous element 220 may degrade and airflow through the porous element 220 is affected. As the sensor 230 detects the change in characteristics of the airflow, the sensor 230 may send a signal to the controller 240 which in turn controls the aerosol generating component 214 to cease operation of the aerosol generating component 214. In this way, the device 200 may be prevented from activating when the porous element 220 is degraded to a predetermined amount. This may then be signalled to a user so that the user is aware of the need to replace the porous element 220.

Prevention of activation of the device 200 as described above may provide a number of safety advantages. For example, preventing the device 200 operating while the temperature of the airflow is overly high may prevent operation of the aerosol generating component 214 outside of intended temperature range. This will help avoid decreasing the lifetime of the aerosol generating component 214 and therefore increase the lifetime of the device 200 as a whole. Furthermore, if the aerosol generating component 214 begins to provide too much thermal energy to the airflow, the sensor 230 may detect this, provide a signal to the controller 240 which may prevent further operation of the device 200 thereby preventing burn out or the like of the aerosol generating component 214. Other such issues, which arise from incorrect operation of the device 200, may be detected by the sensor 230 and prevented by the controller 240. Therefore the power override managed by the sensor 230 and controller 240 is generally advantageous to the lifetime of the device 200.

The prevention of operation of the device 200 may occur in response to the controller 240 detecting that the change in the characteristic is outside predetermined acceptable values of the characteristic. This predetermined acceptable value may be programmed into the device 200 during production. Such a pre-programmed value may have been calculated as a result of lab tests or the like. Alternatively, the predetermined values may be based on the working range for the base line of the characteristic, taken by the sensor 230 and stored by the controller 240 during initial use of the porous element 220 when no, or limited, degradation has occurred. The controller 240 may compare the reading from the sensor 230 to the predetermined value and prevent or allow activation of the device 200 accordingly. For example, if the reading is within a predetermined acceptable range, the controller 240 will allow the device 200 to activate. Whereas, if the reading is outside a predetermined acceptable range, the controller 240 will prevent the device 200 from activating.

Other characteristics of airflow including pressure, as discussed above, may be used in the determination of whether the device 200 is to activate. Preventing operation of the device 200 when the pressure of the airflow is significantly outside of standard operational conditions could assist in limiting use of the device 200 at altitudes which could cause leakage from the device 200. Furthermore, the prevention of operation of the device 200 is temporary in that once the element 220 is replaced or the device 200 is moved to an area where airflow is more suitable for usage with the device 200, the device 200 will operate. There is, therefore, no requirement for the device 200 to be reset in any electrical manner. As such, this improves the user experience of the device 200.

The degradation of the porous element 220 as described above may occur over, a predetermined range of puffs, though, as discussed, this will depend on the intensity of the usage of a particular user. Further, the size of the porous element 220 will impact the number of puffs that can occur prior to such degradation that the porous element 220 impacts performance of the device 200. This number of puffs may be around 30 puffs for a smaller porous element 220, around 50 puffs for a larger porous element 220, or around 60, or more, puffs for an even larger element 220. The device 200 described herein can account for the individual user’s usage habits which renders the present invention highly accurate in its indication to a user of when the porous element 220 is to be replaced.

In an example, the porous element 220 is passed through by relatively wet aerosol en route to the air outlet 204. The moisture content of the porous element 220 will increase over usage of the device 200, as moisture condenses in the channels of the porous element 220. At a predetermined moisture content, the porous element 220 may become structurally degraded and the user is informed that a replacement porous element 220 is to be provided into the device 200 for continued use of the device 200. Moisture content as used herein refers to how many molecules of water are in the porous element 220 as a fraction of the total of the porous element 220. A deposition rate, in relation to the above, may be in the region of 0 to 2 mg per puff regarding any of PG, VG, water or others. Alternatively, the deposition rate may be up to 5 mg per puff.

In an example, the porous element 220 may be sufficiently degraded when subjected to airflow at around 5°C to around 250°C for a predetermined period of time. This is not necessarily puff-dependent as different users may have different puff lengths or the like. The lower temperature range (just above freezing, for example) discussed above may be suitable for water aerosol generating by a nebuliser or the like. The higher temperature range discussed above may be suitable for a porous element 220 placed directly next to an atomizer. In relation to the above temperature range, a preferred range may be around 40°C to around 120°C.

In a particular example, the porous element 220 may be a flavour pod which is replaceable in a device 200. The flavour may be any of tobacco and glycol and may include extracts (e.g., licorice, hydrangea, Japanese white bark magnolia leaf, chamomile, fenugreek, clove, menthol, Japanese mint, aniseed, cinnamon, herb, wintergreen, cherry, berry, peach, apple, Drambuie, bourbon, scotch, whiskey, spearmint, peppermint, lavender, cardamon, celery, cascarilla, nutmeg, sandalwood, bergamot, geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, piment, ginger, anise, coriander, coffee, or a mint oil from any species of the genus Mentha), flavour enhancers, bitterness receptor site blockers, sensorial receptor site activators or stimulators, sugars and/or sugar substitutes (e.g., sucralose, acesulfame potassium, aspartame, saccharine, cyclamates, lactose, sucrose, glucose, fructose, sorbitol, or mannitol), and other additives such as charcoal, chlorophyll, minerals, botanicals, or breath freshening agents. They may be imitation, synthetic or natural ingredients or blends thereof.

The sensor 230 may be able to detect the orientation of the device 200. This is advantageous as the sensor 230 can indicate the orientation to the controller 240 which may prevent activation of the device 200 when the device 200 is in an orientation which is dangerous for usage. For example, in an example the device 200 comprises a liquid supply and a wick arrangement for the production of an aerosol. The device 200 generates an aerosol by heating the liquid when in the wick. If the device 200 is in an orientation wherein the liquid is prevented from reaching the wick in sufficient quantities or at a sufficient rate to prevent burning of the wick, the sensor 230 may provide a signal to the controller 240 and the controller 240 may prevent activation of the device 200. The sensor 230 may be a gyroscope or magnetic element or the like which may be used to obtain a measurement on the orientation of the device 200. Such a sensor 230 and controller 240 arrangement can therefore assist in preventing hot puff. Hot puff can provide an unpleasant experience for the user as well as possibly damaging the heater by operating above the intended operational temperature for the heater.

In an example of the aerosol generating component 214 provided herein, the aerosol generating component 214 may have one or more heaters. In an example, the aerosol generating component 214 may have two heaters. The two heaters may have the same or different operational temperatures. The two heaters may provide thermal energy to different sections of the aerosol generating medium, to enable a more personalised aerosol to be produced. The heaters may be used in tandem (to reduce the usage per puff of each heater and therefore extend the lifetime of the heater) or alternatively. There may be more than one controller 240 connected to the more than one heaters.

In an example the sensor 230 is a pressure sensor. Such a pressure sensor 230 may also be used as a secondary activation signal provider. As the user inhales on the device 200, the sensor 230 notes the change in pressure of the airflow. The sensor 230 may detect that the airflow pressure change is to initiate operation of the device 200. In this way, the arrangement disclosed herein allows for a device 200 which requires no effort from the user to activate, rather just an inhalation of the device 200. This arrangement can also help limit the risk of overheating of the device 200 as a result of activation of the device 200 prior to actual use of the device 200.

The disclosed arrangement may be implemented in systems which have a replaceable consumable such as the porous element 220. The arrangement may also be used in systems which are themselves discarded after use. The alert to the user would then be in relation to when a new system was required rather than when a new element 220 is to be provided.

Thus there has been described an aerosol generating device comprising: an air path including an aerosol generating region; a porous element downstream of the aerosol generating region located in the air path; and, a sensor for determining a change in a characteristic of airflow in the air path to indicate a change in a characteristic of the porous element.

The aerosol provision system may be used in a tobacco industry product, for example a non combustible aerosol provision system.

In one embodiment, the tobacco industry product comprises one or more components of a non-combustible aerosol provision system, such as a heater and an aerosolizable substrate.

In one embodiment, the aerosol provision system is an electronic cigarette also known as a vaping device.

In one embodiment the electronic cigarette comprises a heater, a power supply capable of supplying power to the heater, an aerosolizable substrate such as a liquid or gel, a housing and optionally a mouthpiece.

In one embodiment the aerosolizable substrate is contained in or on a substrate container. In one embodiment the substrate container is combined with or comprises the heater.

In one embodiment, the tobacco industry product is a heating product which releases one or more compounds by heating, but not burning, a substrate material. The substrate material is an aerosolizable material which may be for example tobacco or other non-tobacco products, which may or may not contain nicotine. In one embodiment, the heating device product is a tobacco heating product.

In one embodiment, the heating product is an electronic device.

In one embodiment, the tobacco heating product comprises a heater, a power supply capable of supplying power to the heater, an aerosolizable substrate such as a solid or gel material.

In one embodiment the heating product is a non-electronic article.

In one embodiment the heating product comprises an aerosolizable substrate such as a solid or gel material, and a heat source which is capable of supplying heat energy to the aerosolizable substrate without any electronic means, such as by burning a combustion material, such as charcoal.

In one embodiment the heating product also comprises a filter capable of filtering the aerosol generated by heating the aerosolizable substrate.

In some embodiments the aerosolizable substrate material may comprise an aerosol or aerosol generating agent or a humectant, such as glycerol, propylene glycol, triacetin or diethylene glycol.

In one embodiment, the tobacco industry product is a hybrid system to generate aerosol by heating, but not burning, a combination of substrate materials. The substrate materials may comprise for example solid, liquid or gel which may or may not contain nicotine. In one embodiment, the hybrid system comprises a liquid or gel substrate and a solid substrate. The solid substrate may be for example tobacco or other non-tobacco products, which may or may not contain nicotine. In one embodiment, the hybrid system comprises a liquid or gel substrate and tobacco.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for a superior electronic aerosol provision system. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

Claims

1. An aerosol generating device comprising: an air path including an aerosol generating region; a porous element downstream of the aerosol generating region located in the air path; and, a sensor for determining a change in a characteristic of airflow in the air path to indicate a change in a characteristic of the porous element.

2. An aerosol generating device according to claim 1, wherein the sensor is arranged to determine a change in at least one of the following characteristics: pressure of airflow in the air path; temperature of airflow in the air path; humidity of airflow in the air path; density of vapour in the air path; change in content of the airflow in the air path and, direction of airflow of the air path.

3. An aerosol generating device according to claim 1 or 2, further comprising a controller; the controller arranged to receive a signal relating to the determination of the sensor of a change in a characteristic of airflow in the air path, wherein the controller is arranged to prevent activation of the aerosol generating device in response to a predetermined value of the determination of the sensor.

4. An aerosol generating device according to any of claims 1 to 3, wherein the porous element is arranged to become less porous over time of use.

5. An aerosol generating device according to any of claims 1 to 4, wherein the porous element comprises a plurality of channels through the porous element through which air can pass, wherein the porous element is arranged such that, over a predetermined amount of use, a majority of the plurality of channels close to prevent air passing through said channels.

6. An aerosol generating device according to any of claims 1 to 6, wherein a majority of the plurality of channels of the porous element are arranged to close when the porous element is subjected to airflow at around 40 to 120°C for a predetermined period of time.

7. An aerosol generating device according to any of claims 1 to 6, wherein the porous element comprises a flavourant.

8. An aerosol generating device according to claim 7, wherein the flavourant is at least one of menthol, fruit, tobacco, or blends thereof.

9. A method of controlling provision of an aerosol in an aerosol provision device, the method comprising: providing an air path comprising an aerosol generating region; providing an aerosol generating medium; providing a porous element downstream of the aerosol generating region; providing a sensor; determining, by the sensor, a change in a characteristic of airflow in the air path subsequently determining a change in a characteristic of the porous element; and, generating or not generating an aerosol in response to the determined change in the characteristic of the porous element.

10. A method according to claim 9, wherein generating or not generating an aerosol in response to the determined change in the characteristic of the porous element comprises: determining whether the characteristic is outside predetermined acceptable values of the characteristic; and, generating an aerosol when the characteristic is within predetermined acceptable values and not generating an aerosol when the characteristic is outside predetermined acceptable values.

11. A method according to claim 10, further comprising indicating to a user that an aerosol has not been generated as a result of the characteristic being outside predetermined acceptable values.

12. A method according to any of claims 9 to 11, wherein the characteristic of airflow in the air path is at least one of: temperature of airflow in the air path; pressure of airflow in the air path upstream of the porous element; pressure of airflow in the air path downstream of the porous element; humidity of airflow in the air path; density of vapour in the air path; content of airflow in the air path and, orientation of air path.

13. An aerosol provision system comprising: an aerosol generating device according to any of claims 1 to 8 and aerosol generating material located within the aerosol generating region.

14. Aerosol provision means comprising: an air path including an aerosol generating region; a porous element downstream of the aerosol generating region located in the air path; and, sensing means for determining a change in a characteristic of airflow in the air path to indicate a change in a characteristic of the porous element.