Patent Description:
Aerosol provision devices are known. Common devices use heaters to create an aerosol from a suitable medium which is then inhaled by a user. Often suitable media require significant levels of heating prior to generating an aerosol for inhalation. Similarly, current devices offer users a large variety in the media from which inhalable aerosol can be generated. Current devices often require a change in the device, such as the loading of the media, to enable a change in the aerosol generating medium active within the device. Accordingly, it is conventional for such devices to include a replaceable part which can provide a source of energy and a heating element and a consumable or replaceable part which contains an aerosol generating medium which when exhausted is replaced.

It is desirable for aerosol provision devices to rapidly deliver an aerosolised payload to a user. Therefore there is a requirement to avoid long warm up times prior to a user receiving an aerosolised payload.

<CIT> discloses a smoking or inhalation device. <CIT> discloses an electronic vaping device with a plurality of heating elements. <CIT> discloses an electronic vapour provision system. <CIT> discloses a sensor for an aerosol delivery device.

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

Various approaches are described herein which seek to help address or mitigate at least some of the issues discussed above.

According to a first aspect of certain embodiments there is provided an aerosol provision system, as claimed in claim <NUM>.

In some example embodiments the substrate is configured to be moved with respect to the at least one aerosol generating element so that the aerosol can be generated from the different regions of the aerosol generating material. In other examples the at least one aerosol generating element comprises a plurality of aerosol generating elements which may be selectively activated in series (sequentially) or in parallel to generate the aerosol at different rates or for different durations.

In some examples the different regions of the aerosol generating material may be discrete portions or dots, but in other examples aerosol generating material may be a continuous deposit, sheet or medium and the different regions are different sections of a continuous or contiguous deposit of the aerosol generating material on the substrate.

According to the example embodiments, the control circuit controls the at least one aerosol generating element to generate aerosol from different regions of the aerosol generating material in proportion to one or both of a strength of a user's puff (an amount of air drawn per unit time) and a duration of the user's puff (air draw duration).

It will be appreciated that features and aspects of the disclosure described herein in relation to the first and other aspects of the disclosure are equally applicable to, and may be combined with, embodiments of the disclosure according to other aspects of the disclosure as appropriate, and not just in the specific combinations described above.

The present disclosure relates to aerosol provision systems, which may also be referred to as heat not burn 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 "vapour" and "aerosol", and related terms such as "vaporise", "volatilise" and "aerosolise", may generally be used interchangeably.

Aerosol provision systems (e-cigarettes) often, though not always, comprise a modular assembly including both a reusable part (control unit part) and a replaceable (disposable) cartridge part. Often the replaceable cartridge part will comprise the vapour precursor material and the vaporiser and the reusable part will comprise the power supply (e.g. rechargeable battery) and control circuit. It will be appreciated these different parts may comprise further elements depending on functionality. For example, the reusable device part may comprise a user interface for receiving user input and displaying operating status characteristics, and the replaceable cartridge part may comprise a temperature sensor for helping to control temperature. Cartridges are electrically and mechanically coupled to a control unit for use, for example using a screw thread, latching or bayonet fixing with appropriately engaging electrical contacts. When the vapour precursor material in a cartridge is exhausted, or the user wishes to switch to a different cartridge having a different vapour precursor material, a cartridge may be removed from the control unit and a replacement cartridge attached in its place. Devices conforming to this type of two-part modular configuration may generally be referred to as two-part devices. It is also common for electronic cigarettes to have a generally elongate shape. For the sake of providing a concrete example, certain embodiments of the disclosure described herein will be taken to comprise this kind of generally elongate two-part device employing disposable cartridges. However, it will be appreciated the underlying principles described herein may equally be adopted for different electronic cigarette configurations, for example single-part devices or modular devices comprising more than two parts, refillable devices and single-use disposable devices, as well as devices conforming to other overall shapes, for example based on so-called box-mod high performance devices that typically have a more box-like shape. More generally, it will be appreciated certain embodiments of the disclosure are based on approaches for seeking to help more reliably form a seal for an opening in a reservoir wall through which a wick passes in accordance with the principles described herein, and other constructional and functional aspects of electronic cigarettes implementing approaches in accordance with certain embodiments of the disclosure are not of primary significance and may, for example, be implemented in accordance with any established approaches.

<FIG> is a cross-sectional view through an example aerosol provision device <NUM> in accordance with certain embodiments of the disclosure, with a corresponding three dimensional representation shown in <FIG>. As shown in <FIG> and <FIG>, the aerosol provision device <NUM> comprises two main components, namely a reusable part <NUM> and a replaceable part <NUM> also referred to as a consumable. In normal use the reusable part <NUM> and the replaceable/cartridge part <NUM> are releasably coupled together at an interface <NUM>. When the replaceable/cartridge part <NUM> is exhausted or the user simply wishes to switch to a different cartridge part, the cartridge part may be removed from the reusable part and a replacement cartridge part attached to the reusable part in its place. The interface <NUM> provides a structural, electrical and air path connection between the two parts and may be established in accordance with conventional techniques, for example based around a screw thread, latch mechanism, push-fit or friction fit, or bayonet fixing with appropriately arranged electrical contacts and openings for establishing the electrical connection and air path between the two parts as appropriate. The specific manner in which the replaceable part <NUM> mechanically couples to the reusable part <NUM> is not significant to the principles described herein, but for the sake of a concrete example is assumed here to comprise a latching mechanism, for example with a portion of the cartridge being received in a corresponding receptacle in the reusable part with cooperating latch engaging elements (not represented in <FIG>). It will also be appreciated the interface <NUM> in some implementations may not support an electrical and / or air path connection between the respective parts. For example, in some implementations a vaporiser may be provided in the reusable part rather than in the cartridge part, or the transfer of electrical power from the reusable part to the cartridge part may be wireless (e.g. based on electromagnetic induction), so that an electrical connection between the reusable part and the cartridge part is not needed. Furthermore, in some implementations the airflow through the electronic cigarette might not go through the reusable part so that an air path connection between the reusable part and the cartridge part is not needed.

The replaceable part <NUM> may in accordance with certain embodiments of the disclosure be broadly conventional apart from where modified in accordance with the approaches described herein in accordance with certain embodiments of the disclosure. In <FIG>, the replaceable part <NUM> comprises a housing <NUM> formed of a plastics material. In other examples the housing <NUM> may be at least partly formed from paper and/or card. For example, the housing <NUM> may be paper wrapped around one or more (cylindrical) portions of aerosol generating material. The replaceable housing <NUM> may support other components of the replaceable part <NUM> and provides the mechanical interface <NUM> with the reusable part <NUM>. The replaceable housing is generally circularly symmetric about a longitudinal axis along which the replaceable part couples to the reusable part <NUM>. In this example the replaceable part has a length of around <NUM> and a diameter of around <NUM>. However, it will be appreciated the specific geometry, and more generally the overall shape and materials used, may be different in different implementations.

Broadly speaking, however, in accordance with the principles of the present disclosure, the replaceable part <NUM> comprises or consists of one or more portions of aerosol generating material. The replaceable part <NUM> is the component which provides the aerosol generating material to the reusable part <NUM> and, when engaged with the reusable part <NUM>, is able to be used to generate aerosol for user inhalation.

In some examples, the replaceable part <NUM> consists of, and is formed entirely of, the aerosol generating material. In these examples, the substrate <NUM> as used herein may refer to either the replaceable part <NUM> or the aerosol generating material. That is, the replaceable part, aerosol generating material and substrate may be one and the same. In these examples, the reusable part <NUM> may be configured to receive the aerosol generating material, e.g., via a suitable receptacle acting as the interface <NUM>.

In other examples, the reusable part <NUM> may comprise a support on which the aerosol generating material may be deposited. In these implementations, the combination of the support and aerosol generating material may be referred to as the substrate <NUM>. In these examples, the reusable part <NUM> may consist of, or comprise, the substrate <NUM>. In one example, the substrate <NUM> may be housed in the replaceable part <NUM>, e.g., in a plastic housing, and the plastic housing of the replaceable part <NUM> is configured to engage with the reusable part <NUM> at the interface <NUM>. Alternatively, the replaceable part <NUM> may consist of the substrate <NUM> and the reusable part <NUM> may be configured to receive the substrate <NUM>, e.g., via a suitable receptacle acting as the interface <NUM>. The support may, for example, be or comprise paper, card, paperboard, cardboard, reconstituted material, a plastics material, a ceramic material, a composite material, glass, a metal, or a metal alloy. In some embodiments, the support comprises a susceptor. In some embodiments, the susceptor is embedded within the material. In some alternative embodiments, the susceptor is on one or either side of the material.

For the purposes of a concrete disclosure, the replaceable part <NUM> comprises a replaceable housing <NUM> within which the substrate <NUM> is housed. However, it should be appreciated that certain aspects of the present disclosure may be equally applied regardless of the form of the replaceable part <NUM>.

As shown in <FIG>, within the replaceable housing <NUM> is a layer providing a substrate <NUM> on which is disposed aerosol generating material. The substrate is supported by one or more walls of the housing <NUM> in close proximity to a heating layer <NUM> which may protrude from the reusable part <NUM> into the replaceable part <NUM>. As shown in <FIG>, the replaceable part <NUM> in some examples includes an air channel <NUM>, <NUM>. The reusable part <NUM> comprises an outer housing <NUM> with an opening that defines an air inlet <NUM> for the e-cigarette, a battery <NUM> for providing operating power for the electronic cigarette, control circuitry <NUM> for controlling and monitoring the operation of the electronic cigarette, a user input button <NUM> and a visual display <NUM>.

The outer housing <NUM> may be formed, for example, from a plastics or metallic material and in this example has a circular cross-section generally conforming to the shape and size of the replaceable part <NUM> so as to provide a smooth transition between the two parts at the interface <NUM>. In this example, the reusable part has a length of around <NUM> so the overall length of the e-cigarette when the replaceable part and reusable part are coupled together is around <NUM>. However, and as already noted, it will be appreciated that the overall shape and scale of an electronic cigarette implementing an embodiment of the disclosure is not significant to the principles described herein.

The air inlet <NUM> connects to an air path <NUM> through the reusable part <NUM>. The reusable part air path <NUM> in turn connects to the replaceable part air path <NUM> across the interface <NUM> when the reusable part <NUM> and replaceable part <NUM> are connected together. Thus, when a user inhales on the mouthpiece opening <NUM>, air is drawn in through the air inlet <NUM>, along the reusable part air path <NUM>, across the interface <NUM>, through the vapour generation region <NUM> in the vicinity of the aerosol generating material, along the replaceable part air path <NUM>, through an air channel <NUM> and out through the mouthpiece opening <NUM> for user inhalation.

Therefore according to the example shown in <FIG>, the replaceable part <NUM> includes an air channel <NUM>. However, in other embodiments, the replaceable part <NUM> may not include an air channel. In these embodiments, the replaceable part <NUM> is configured with an arrangement of the substrate to the effect that when the replaceable part <NUM> is engaged with the reusable part <NUM>, the substrate <NUM> is disposed with respect to the air channel <NUM> formed in the reusable part <NUM> so that air passing through an air channel <NUM>, of the reusable <NUM> part drawn by user inhalation carries the aerosol generated by the substrate <NUM> of the replaceable part <NUM> to the user. For example, the substrate <NUM> may be disposed in the air channel <NUM>, such that air may pass over one or more surfaces of the substrate <NUM>.

A battery <NUM> in this example may be rechargeable and may be of a conventional type, for example of the kind normally used in electronic cigarettes and other applications requiring provision of relatively high currents over relatively short periods. The battery <NUM> may be recharged through a charging connector in the reusable part <NUM> housing <NUM>, for example a USB connector (not shown).

The user input button <NUM> in this example is a conventional mechanical button, for example comprising a spring mounted component which may be pressed by a user to establish an electrical contact. In this regard, the input button may be considered an input device for detecting user input and the specific manner in which the button is implemented is not significant. For example, other forms of mechanical button(s) or touch-sensitive button(s) (e.g. based on capacitive or optical sensing techniques) may be used in other implementations.

The display <NUM> is provided to provide a user with a visual indication of various characteristics associated with the aerosol provision device, for example current power setting information, remaining battery power, and so forth. More generally, the manner in which the display is provided and information is displayed to a user using the display is not significant to the principles described herein. For example, some embodiments may not include a visual display and may include other means for providing a user with information relating to operating characteristics of the aerosol provision device, for example using audio signalling or haptic feedback, or may not include any means for providing a user with information relating to operating characteristics of the aerosol provision device.

Control circuitry <NUM> is suitably configured / programmed to control the operation of the electronic cigarette to provide functionality in accordance with the established techniques for operating electronic cigarettes. For example, the control circuitry <NUM> may be configured to control a supply of power from the battery <NUM> to a heat controller, which controls the heating layer <NUM> to generate vapour from a portion of one or more doses of the material in the replaceable part <NUM> for user inhalation via the mouthpiece outlet <NUM> in response to user activation of the input button <NUM>, or in other implementations in response to other triggers, for example in response to detecting user inhalation. The control circuitry (processor circuitry) <NUM> may be considered to logically comprise various sub-units / circuitry elements associated with different aspects of the aerosol provision device's operation, for example user input detection, power supply control, display driving, and so on. It will be appreciated the functionality of the control circuitry <NUM> can be provided in various different ways, for example using one or more suitably programmed programmable computer(s) and / or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s) configured to provide the desired functionality.

As will be explained in more detail below, the control circuitry may also include a memory and a clock/timer in order to estimate an amount of gel which has been used during a puff and therefore an amount remaining. Accordingly the control circuitry can determine whether a gel portion has been exhausted.

The term puff as used herein refers to a continuous or effectively continuous draw of air through the air channel by a user to inhale vapour from the aerosol provision device.

The aerosol provision system in <FIG> and <FIG> differs from conventional electronic cigarettes in a manner in which portion of the aerosol generating material are heated to generate an aerosol for user inhalation in response to an amount of air drawn by the user though the air channel <NUM>, <NUM> through the mouth piece <NUM>. As will be explained with reference to <FIG>, <FIG> the control circuit <NUM> controls the heater layer <NUM> selectively energise different heating elements of the heating layer <NUM> in response to an amount of air flow in the air channel <NUM>, <NUM> as detected by an air flow detector <NUM>. According to example embodiments of the present technique therefore the aerosolisable provision device is configured to provide a puff response, that is, an amount of heating and/or aerosol is generated in response to and in proportion with a user's puff strength/duration. The device finds particular application with Tobacco Heated Product (THP) devices. Previously proposed arrangements have tended to include a single heater to generate vapour for example from a reconstituted tobacco rod (taking a form similar to a combustible cigarette) which heats an entire tobacco rod to provide aerosol during a usage session. However a single larger heating element which heats a relatively large mass of consumable can take a reasonably long time (e.g., <NUM> seconds to a minute) to reach an operational temperature and begin vaporising the consumable. Equally, it is quite difficult to rapidly change the temperature of heaters because heaters have a thermal response time comparable to or greater than the typical length of a puff.

The present technique is therefore based on the realisation that puff response can be achieved in THP when using relatively smaller heaters arranged to heat relatively smaller patches of gel, whereby the thermal response time of the heater/system may be relatively quicker.

An example consumable is a flat substrate <NUM> as shown in <FIG> and <FIG> (e.g., of paper/card) having a plurality of aerosol generating material (gel) portions <NUM> located on a surface thereof, each having a pre-defined mass. Each of the gel portions <NUM> may be heated by an individual heater <NUM> positioned below the flat substrate <NUM> or in close proximity according to an arrangement which may vary in accordance with physical characteristics of the aerosol provision device.

A more detailed arrangement is shown in <FIG> in which an exploded view is shown of the substrate <NUM> on which the portions of the aerosol generating material <NUM> are shown above the heating layer <NUM>, which is shown above a control layer <NUM>. It will be appreciated that the arrangement of the control layer <NUM>, the heating layer <NUM> and the substrate <NUM> is for illustrative purposes only and may not conform to a practical configuration of an aerosol provision device embodying the invention.

Although the example shown in <FIG> shows separate portions, dots or discrete portions of the aerosol generating material, which form different regions, in other examples, the aerosol generating material may be a continuous deposit, sheet or medium and the different regions are different sections of a continuous or contiguous deposit of the aerosol generating material on the substrate.

As shown in <FIG>, the heating layer <NUM> includes a plurality of aerosol generating elements, each of the aerosol generating elements comprising a controllable cell <NUM>. The heating layer <NUM> therefore provides adjacent each of the gel portions <NUM> in the substrate <NUM> a controllable cell which can generate heat for that gel portion. An example representation of one of the cells <NUM> is shown in <FIG>. In <FIG>, the cell is shown to comprise a heating element or heater <NUM> which is connected to a circuit which includes connection to a power supply <NUM> and a variable resistor or potentiometer <NUM> or similar device which can vary an amount of current supplied by the circuit to the heating element <NUM>. A control channel or conductor <NUM> connects a control input on the potentiometer <NUM> to the controller <NUM>. A signal applied to the control channel <NUM> from the controller <NUM> to the potentiometer <NUM> can vary an amount of current supplied to the heating element <NUM> from the power supply <NUM>.

In the example described below, the source of energy for heating <NUM> is a heater, e.g., a resistive heater, which supplies energy (in the form of heat) to the aerosol generating medium to generate heat. The device <NUM> may have a plurality of chambers or regions that may or may not be separate from one another. The device <NUM> may have a power chamber (not shown) comprising a power source for supplying power to the source of energy for heating <NUM>. The source of energy for heating <NUM> in the described example is an electrically resistive heater <NUM>. However, in other examples, the source of energy for heating <NUM> may be a chemically activated heater which may or may not operate via exothermic reactions or the like. The source of energy for heating <NUM> may be part of an inductive heating system, wherein the source of energy for heating <NUM> is the source of energy for inductive heating, such as a coil of copper wire, and the substrate <NUM> may be or may contain a susceptor or the like. The susceptor may for example be a sheet of aluminium foil or the like. For the purposes of providing a concrete example, the source of energy for heating is herein described as a resistive heater, but it should be appreciated that references different heaters or heating system components are envisaged for use in the present device.

The heater <NUM> provides thermal energy, heat, to the surrounding environment of the heater <NUM>. At least some portion of the substrate <NUM> is within the area of effect of the heater <NUM>. The area of effect of the heater <NUM> is the area within which the heater <NUM> may provide heat to an item.

The substrate <NUM> of the present example includes aerosol generating medium disposed on a surface thereof. However, in other implementations, the substrate <NUM> may be formed exclusively of aerosol generating medium. In yet other implementations, the substrate <NUM> may have a layered structure from a plurality of materials. In one example, the substrate <NUM> may have a layer formed from at least one of thermally conductive material, inductive material, permeable material or impermeable material.

The source of aerosol generating medium may take any suitable form or construction. In one embodiment, the source of aerosol generating medium may include a substrate (for example, paper, card, foil) including a first and second side, with the aerosol generating medium disposed on the first side of the substrate. The substrate in this instance may act as a carrier for the aerosol generating medium. In some implementations, the substrate may be, or may include, a metallic element that is arranged to be heated by a varying magnetic field. In such implementations, the source of energy for heating <NUM> may include an induction coil, which, when energised, causes heating within the metallic element of the source <NUM>. The degree of heating may be affected by the distance between the metallic element and the induction coil. In yet further alternative implementations, the source of aerosol generating medium may consist entirely (or substantially entirely) of aerosol generating medium (i.e., without a carrier). For the purposes of describing a concrete example, the source <NUM> described herein includes a substrate with aerosol generating medium disposed on the first side of the substrate, while the source of energy for heating <NUM> is herein a resistive heater.

In an example the aerosol forming material is disposed on the substrate <NUM> such that the distance from the source of energy for heating <NUM> to the aerosol forming material is within the range of <NUM>, <NUM>, <NUM>, <NUM>. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. In some cases, there may be a minimum spacing between the source of energy for heating <NUM> and aerosol forming material on the substrate <NUM> of at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>.

Although the cell <NUM> shown in <FIG> includes the power supply <NUM> it will be appreciated that providing each cell with its own separate power supply <NUM> is just one example. Alternatively each cell could be connected to a single power supply such as the power supply <NUM>.

The cell shown in <FIG> provides an individually controllable heater <NUM> which can be controlled by the controller <NUM> to produce an amount of heat provided to heat the gel portion <NUM>. Since the substrate <NUM> includes a plurality of gel portions <NUM> and the heating layer <NUM> includes a corresponding number of cells with individual heaters <NUM> as illustrated in <FIG>, the controller <NUM> can control the heaters in series or in parallel to cause one or more of the gel portions to generate an aerosol.

In certain embodiments, the controller <NUM> is configured to control the cells <NUM> of the heating layer to vary an amount of heat and therefore aerosol generated by a gel portion or portions <NUM> in response to and in proportion with an amount of air drawn by a user through the air channel <NUM>, <NUM>. The amount of air drawn though the air channel <NUM>, <NUM> is detected by the air-flow sensor <NUM>.

The air-flow sensor <NUM> could be a pressure transducer or an anemometer such as a hot wire anemometer, an acoustic sensor or a sensor which measures the cooling effect from water.

In one example, the power supply to the heater <NUM> of a cell can be varied in response to a strength of the user's puff, as measured by the air flow sensor <NUM>. For example, a strength of the puff in terms of a magnitude of a signal detected by the air flow sensor <NUM> is proportional to an applied electrical power to the heater. Suppose a first puff causes a first power level Pfirst to be delivered to the heater <NUM> of a cell <NUM>, a second puff causes a power level Psecond to be supplied to the heater <NUM> of a cell. In the event that Psecond is greater than Pfirst, a greater amount of aerosol can be generated more quickly because the greater power vaporises the gel portion <NUM> relatively more quickly and generates relatively more aerosol per unit time. In the event that the puff duration as measured by the air flow sensor <NUM> is longer than the time necessary to vaporise all of a gel portion <NUM>, then power can subsequently be applied to a second gel portion <NUM> by the heater <NUM> of another cell <NUM>, while the heater <NUM> of the first cell <NUM> is turned off, to continue generating the aerosol for that puff. As a result of a configuration of the plurality of smaller heaters compared with a smaller number of larger heaters (e.g. one) the heaters have a relatively small mass. As a result, the heaters can reach operating temperature more quickly than a larger heater.

An amount of aerosol generated by each gel portion can be considered to be approximately proportional to an amount of cumulative energy applied to the gel portion from the power generated by the heater with respect to time. Therefore by recording an indication of an amount of power which is being applied to a gel portion over time, the controller <NUM> can be configured to estimate an amount of aerosol the gel portion will produce until exhausted and therefore an amount of aerosol remaining before the gel portion is exhausted. To this end, the controller <NUM> can include a memory for storing an amount of time for which an amount of heat has been applied to a gel portion <NUM>, the time being measured with respect to a clock <NUM>, <NUM>. The recorded time and power can be used to calculate a cumulative amount of energy which has been applied to a gel portion <NUM> and therefore the amount of gel still remaining. Alternatively, the air flow sensor <NUM> can be used to determine an amount of air drawn through the air channel in the vicinity of the vapour generating region <NUM> to detect an amount of vapour generated by a gel portion, so that the controller <NUM> can activate the different cells and determine whether it is necessary to activate another gel portion if one becomes exhausted. In a second example, a heater <NUM> of a cell <NUM> can be operated to supply a fixed power Pfixed to provide a set amount of aerosol from a corresponding gel portion <NUM> per unit time. If a strength of a user's puff is stronger than a default puff strength, for which Pfixed has been correspondingly set, then an additional power Padd is simultaneously supplied to a heater <NUM> of a second of the plurality of cells <NUM> to generate an aerosol from a second portion of gel <NUM> to increase a total volume of aerosol entering the air channel supplied per unit time. Hence, Pfixed + Padd may be equal to Psecond in the above example. However activating two heaters <NUM> from two different cells <NUM> in parallel can produce the aerosol more quickly than a single heater <NUM> from a single cell <NUM>. This can also be thought of as increasing the surface area of the active part of the heater arrangement. As with the first example, if the duration of the puff is greater than the time necessary to deplete a gel portion <NUM>, then another gel portion <NUM> can be heated to maintain the volume of aerosol per unit time generated.

In each example, the total amount of power supplied to the heater arrangement (or the active parts of the heater arrangement in contact with the gel) at any one time is proportional to the strength of the detected puff.

In another example, the user's previous puff data, as measured by the air flow sensor <NUM> e.g. strength, duration or frequency can be stored in a memory and then used to predict future puff behaviour of the user e.g. the next puff to be taken. This means, the controller <NUM> can be configured to deliver a specific power level to the heater <NUM> of a cell <NUM> before the user takes a puff, so that the aerosol is ready immediately for inhalation by the user. Thus the controller <NUM> can be configured to activate the required number of cells to produce the predicted required volume of aerosol. Similarly to previous examples, if it is determined that the predicted puff will deplete the gel portion <NUM> before the end of the duration of the predicted puff, then another gel portion <NUM> can be heated to maintain the volume of aerosol predicted to be required.

According to the example embodiments described above with reference to <FIG>, <FIG>, each of the gel portions is provided with a corresponding cell <NUM> and a heater <NUM>. However in other embodiments a single heating element may be provided and the gel portions moved with respect to the heater. Such an arrangement is disclosed in our copending <CIT> the contents of which are incorporated herein by reference. <CIT> discloses an aerosol provision device in which a plurality of gel portions on a substrate is rotated past a single heater. An example is shown in <FIG>.

As for the example embodiments explained above with reference to <FIG>, <FIG>, the example embodiment shown in <FIG> includes a substrate <NUM> within the device <NUM> which has a first surface <NUM> which has a plurality of gel portions <NUM> of aerosol generating medium disposed thereon. The substrate <NUM> has a second surface <NUM> which faces the first surface <NUM>. The second surface <NUM> faces the first surface <NUM> and one or both of the first surface <NUM> and second surface <NUM> may be smooth or rough. As for the above examples, the device <NUM> has a source of energy for heating <NUM> arranged to face the second surface <NUM> of the substrate <NUM>. The source of energy for heating <NUM> is an element of the aerosol provision device <NUM> which transfers energy from a power source, such as a battery (not shown), to the aerosol generating medium <NUM> to generate aerosol from the aerosol generating medium <NUM>. The device <NUM> has a movement mechanism <NUM> arranged to move the substrate <NUM>, and in particular portions <NUM> (or, in some cases, doses) of aerosol generating medium disposed thereon. The portions <NUM> of aerosol generating medium are rotationally movable relative to the heater <NUM> such that portions of the aerosol generating medium are presented, in this case individually, to the heater <NUM>. The device <NUM> is arranged such that at least one portion <NUM> of the aerosol generating medium is rotated around an axis A at an angle θ to the second surface <NUM>. The substrate <NUM> in this implementation is substantially flat. The substrate <NUM> in this implementation may be formed of partially or entirely of paper or card.

According to this example embodiment shown in <FIG>, an amount of power supplied to the heater <NUM> and a rotation of the substrate is controlled by the controller <NUM> in response to a strength of a puff from the user as measured by an air flow sensor <NUM>. That is to say that a signal indicative of an amount of air being drawn by the user through the aerosol provision device <NUM> generated by the air flow sensor <NUM> is fed to the controller <NUM> which controls an amount of heat produced by the heater <NUM> and therefore the amount of aerosol generated. As for the above example, an amount of power supplied to the heater <NUM> can be controlled to be proportional to the puff strength from the user as indicated by an amount of air drawn by the user. Therefore an amount of power supplied to the heater is controlled in proportion with the amount of air drawn. If a duration of a user's puff continues for a time which exceeds an amount of vapour which can be generated from a gel portion or a remaining amount of a gel portion then the controller <NUM> can control the rotation mechanism to rotate the substrate so that a new portion of the gel can be heated to generate vapour.

As will be appreciated for the example embodiment shown in <FIG>, in contrast to the example embodiments presented in <FIG>, <FIG>, with only a single heater, vapour can be only generated from one gel portion <NUM> at a time. However a plurality of heaters <NUM> can also be included with the aerosol provision device of <FIG> so that if there is a demand to increase an amount of vapour included in an aerosol generated in proportion to a user's puff strength or duration of a user's puff then more than one heater can be activated.

The above embodiments have been described with respect to a plurality of discrete gel portions in which one or more discrete heaters are used to heat a single gel portion which may be continuous or dis-continuous. However, in other examples, the gel may be continuous and multiple heaters could be used to vaporise the gel. For instance, in the case of the second example embodiments with reference to <FIG>, a heater surface may be split into segments, which may either be activated or not based on the strength of the user's puff, or they may already be activated and moved towards/away from the consumable. One example is shown in <FIG> in which the gel <NUM> is formed on a disk shaped substrate <NUM>. Two heating elements <NUM>, <NUM> are arranged below different sections <NUM>, <NUM> of the gel into which a continuous surface of the gel is divided <NUM>, <NUM>, <NUM>, <NUM>. As for the example of <FIG>, the substrate can be rotated as the gel sections are exhausted.

In some examples, a humidity sensor is also included to determine an amount of water vapour in surrounding air, which is used by the controller <NUM> to adjust an amount of heat applied to a gel portion or adjust an estimate of an amount of the gel remaining before activating another gel portion. Air humidity can affect a rate at which vapour is generated when heat is applied to a gel portion to form an aerosol. As such a user may need to draw more air depending on the air humidity. Therefore by estimating a measure of the air humidity, the controller can determine more accurately an amount of gel remaining in the gel portion with respect to an amount of heat (energy) already imparted to the gel portion and therefore when it is necessary to switch to a new gel portion.

According to the above examples, the controller <NUM> manages the heating elements <NUM>, <NUM>, <NUM> to generate the vapour from the gel portions in an open loop manner in the sense that the estimate of an amount of vapour generated from a gel portion is determined without directly measuring whether the vapour is being produced by a gel portion. This can provide a more simple arrangement for controlling the heating elements to generate the vapour, but may have a disadvantage in that a manufacturing tolerance for a consumable which includes the gel portions may be required to be high in order to avoid gel portions either being exhausted before the controller switches to a new gel portion <NUM> or the controller switching to a new gel portion when gel in a previous portion still remains.

As will be appreciated, in other example embodiments a detector may be used to provide an estimate of vapour produced from the gel in the aerosol and therefore to detect when a gel portion has been exhausted and stops generating vapour, before or during switching. One example of such a detector is an optical obstruction or turbidity type sensor in which the amount of vapour present is determined from an amount of light absorbed.

As a further example embodiment a temperature sensor could be provided proximate the heating elements or a temperature sensor could be provided for each heating element. Such example embodiments are shown in <FIG>, which correspond to the examples of <FIG>. As shown in <FIG>, each of the controllable cells includes a temperature sensor <NUM>, which is connected the controller <NUM>. The temperature sensor can therefore measure the temperature in or around the gel portion <NUM>. An alternative is shown in <FIG> in which a single temperature sensor <NUM> is provided for the plurality of controllable cells with associated gel portions <NUM>. For the arrangement in <FIG>, it may be sufficient for a temperature sensor <NUM> to be disposed in the vicinity of the consumable. According to these example embodiments, the temperature sensor or sensors <NUM> can be used to detect a rate of change of temperature. As will be appreciated, whilst there is gel in a gel portion <NUM>, the temperature in the vicinity of the gel portion will remain substantially constant, because the gel is absorbing the heat as the heat energy is being converted into vapour, however once the vapour is exhausted the temperature around the heater will increase rapidly. An example is illustrated graphically in <FIG>, which shows a plot <NUM> of temperature with respect to time. During a first section there is an increase in temperature until a gel portion <NUM> begins to generate vapour. After the heater <NUM> reaches an ambient temperature and the gel is generating vapour the temperature around the gel portion remains relatively constant as shown in section <NUM>. However as the gel is exhausted the heat begins to rise with time as shown in a section <NUM>. By comparing the rate of change of temperature with respect to time ΔT/Δt with a threshold, the controller <NUM> can detect when the gel portion has become exhausted. Accordingly the controller <NUM> can be configured to detect if the rate of change of the temperature exceeds a predefined limit corresponding to an exhaustion of the gel and then switch off the heater and switch to another gel portion.

In further example embodiments an aerosol provision system for generating aerosol for user inhalation may comprise a replaceable part <NUM> and a reusable part <NUM>. The replaceable part <NUM> comprises a housing and a substrate <NUM> disposed within the housing, the substrate <NUM> comprising aerosol generating material <NUM> for generating the aerosol for user inhalation. The reusable part <NUM> comprises a housing <NUM> including an interface configured to operatively engage with the replaceable part <NUM>, and an air channel configured at least partially in the housing to provide a passage of air drawn by the user to receive the aerosol generated from the aerosol generating material, a detector <NUM> for detecting the passage of air drawn through the air channel; an aerosol generating element disposed with respect to the interface and configured, in use, to generate aerosol from the aerosol generating material, and a control circuit <NUM>. The control circuit is configured to receive a signal from the detector indicating an amount of air drawn by the user and to control the aerosol generating element in response to the detector detecting the amount of air through the air channel to generate the aerosol in proportion to the amount of air drawn by the user through the air channel. As indicated above, the aerosol generating material may be an amorphous solid, such as a gel or the like.

In some examples, the aerosol generating element may be a heater and the control circuit is configured to control an amount of heat generated by the heater in proportion to an amount of air drawn by the user through the air channel to generate the aerosol from the aerosol generating material in accordance with an amount of air drawn by the user through the air channel.

In some embodiments, the non-combustible aerosol provision system is an electronic cigarette, also known as a vaping device or electronic nicotine delivery system (END), although it is noted that the presence of nicotine in the aerosol generating material is not a requirement.

In some embodiments, the non-combustible aerosol provision system is a tobacco heating system, also known as a heat-not-burn system.

In some embodiments, the non-combustible aerosol provision system is a hybrid system to generate aerosol using a combination of aerosol generating materials, one or a plurality of which may be heated. Each of the aerosol generating materials may be, for example, in the form of a solid, liquid or gel and may or may not contain nicotine. In some embodiments, the hybrid system comprises a liquid or gel aerosol generating material and a solid aerosol generating material. The solid aerosol generating material may comprise, for example, tobacco or a non-tobacco product.

Typically, the non-combustible aerosol provision system may comprise a non-combustible aerosol provision device and an article for use with the non-combustible aerosol provision device. However, it is envisaged that articles which themselves comprise a means for powering an aerosol generating component may themselves form the non-combustible aerosol provision system.

In some embodiments, the non-combustible aerosol provision device may comprise a power source and a controller. The power source may, for example, be an electric power source.

In some embodiments, the article for use with the non-combustible aerosol provision device may comprise an aerosol generating material, an aerosol generating component, an aerosol generating area, a mouthpiece, and/or an area for receiving aerosol generating material.

In some embodiments, the aerosol generating component is a heater capable of interacting with the aerosol generating material so as to release one or more volatiles from the aerosol generating material to form an aerosol.

In some embodiments, the substance to be delivered may be an aerosol generating material. Aerosol generating material, which also may be referred to herein as aerosol generating material, is material that is capable of generating aerosol, for example when heated, irradiated or energized in any other way. Aerosol generating material may, for example, be in the form of a solid, liquid or gel which may or may not contain nicotine and/or flavourants. In some embodiments, the aerosol generating material may comprise an "amorphous solid", which may alternatively be referred to as a "monolithic solid" (i.e. non-fibrous). In some embodiments, the amorphous solid may be a dried gel. The amorphous solid is a solid material that may retain some fluid, such as liquid, within it. In some embodiments, the aerosol generating material may for example comprise from about 50wt%, 60wt% or 70wt% of amorphous solid, to about 90wt%, 95wt% or 100wt% of amorphous solid.

In some embodiments, the aerosol generating material may comprise one or more polyhydric alcohols, such as propylene glycol, triethylene glycol, <NUM> ,<NUM>-butanediol and glycerin; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and/or aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

In certain embodiments, the aerosol-generating material comprises a gelling agent comprising a cellulosic gelling agent and/or a non-cellulosic gelling agent, an active substance and an acid.

The gelling agent may comprise one or more compounds selected from cellulosic gelling agents, non-cellulosic gelling agents, guar gum, acacia gum and mixtures thereof.

In some embodiments, the cellulosic gelling agent is selected from the group consisting of: hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethylcellulose (CMC), hydroxypropyl methylcellulose (HPMC), methyl cellulose, ethyl cellulose, cellulose acetate (CA), cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP) and combinations thereof.

In some embodiments, the gelling agent comprises (or is) one or more of hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose (HPMC), carboxymethylcellulose, guar gum, or acacia gum.

In some embodiments, the gelling agent comprises (or is) one or more non-cellulosic gelling agents, including, but not limited to, agar, xanthan gum, gum Arabic, guar gum, locust bean gum, pectin, carrageenan, starch, alginate, and combinations thereof. In preferred embodiments, the non-cellulose based gelling agent is alginate or agar.

The aerosol-generating material may comprise an acid. The acid may be an organic acid.

In some of these embodiments, the acid may be at least one of a monoprotic acid, a diprotic acid and a triprotic acid. In some such embodiments, the acid may contain at least one carboxyl functional group. In some such embodiments, the acid may be at least one of an alpha-hydroxy acid, carboxylic acid, dicarboxylic acid, tricarboxylic acid and keto acid. In some such embodiments, the acid may be an alpha-keto acid.

In some such embodiments, the acid may be at least one of succinic acid, lactic acid, benzoic acid, citric acid, tartaric acid, fumaric acid, levulinic acid, acetic acid,
malic acid, formic acid, sorbic acid, benzoic acid, propanoic and pyruvic acid.

Suitably the acid is lactic acid. In other embodiments, the acid is benzoic acid. In other embodiments the acid may be an inorganic acid. In some of these embodiments the acid may be a mineral acid. In some such embodiments, the acid may be at least one of sulphuric acid, hydrochloric acid, boric acid and phosphoric acid. In some embodiments, the acid is levulinic acid.

The inclusion of an acid is particularly preferred in embodiments in which the aerosol-generating material comprises nicotine. In such embodiments, the presence of an acid may stabilise dissolved species in the slurry from which the aerosol-generating material is formed. The presence of the acid may reduce or substantially prevent evaporation of nicotine during drying of the slurry, thereby reducing loss of nicotine during manufacturing.

In some embodiments, the aerosol-generating material comprises one or more cannabinoid compounds selected from the group consisting of: cannabidiol (CBD), tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), cannabichromene (CBC), cannabicyclol (CBL), cannabivarin (CBV), tetrahydrocannabivarin (THCV), cannabidivarin (CBDV), cannabichromevarin (CBCV), cannabigerovarin (CBGV), cannabigerol monomethyl ether (CBGM) and cannabielsoin (CBE), cannabicitran (CBT).

The aerosol-generating material may comprise one or more cannabinoid compounds selected from the group consisting of cannabidiol (CBD) and THC (tetrahydrocannabinol).

The aerosol-generating material may comprise cannabidiol (CBD).

The aerosol-generating material may comprise nicotine and cannabidiol (CBD).

The aerosol-generating material may comprise nicotine, cannabidiol (CBD), and THC (tetrahydrocannabinol).

The aerosol generating material may comprise one or more active constituents, one or more carrier constituents and optionally one or more other functional constituents.

The active constituent may comprise one or more physiologically and/or olfactory active constituents which are included in the aerosol generating material in order to achieve a physiological and/or olfactory response in the user. The active constituent may for example be selected from nutraceuticals, nootropics, and psychoactives. The active constituent may be naturally occurring or synthetically obtained. The active constituent may comprise for example nicotine, caffeine, taurine, or any other suitable constituent. The active constituent may comprise a constituent, derivative or extract of tobacco or of another botanical. In some embodiments, the active constituent is a physiologically active constituent and may be selected from nicotine, nicotine salts (e.g. nicotine ditartrate/nicotine bitartrate), nicotine-free tobacco substitutes, other alkaloids such as caffeine.

In some embodiments, the active constituent is an olfactory active constituent and may be selected from a "flavour" and/or "flavourant" which, where local regulations permit, may be used to create a desired taste, aroma or other somatosensorial sensation in a product for adult consumers. In some instances such constituents may be referred to as flavours, flavourants, cooling agents, heating agents, or sweetening agents. They may include naturally occurring flavour materials, botanicals, extracts of botanicals, synthetically obtained materials, or combinations thereof (e.g., tobacco, cannabis, licorice (liquorice), hydrangea, eugenol, Japanese white bark magnolia leaf, chamomile, fenugreek, clove, maple, matcha, menthol, Japanese mint, aniseed (anise), cinnamon, turmeric, Indian spices, Asian spices, herb, wintergreen, cherry, berry, red berry, cranberry, peach, apple, orange, mango, clementine, lemon, lime, tropical fruit, papaya, rhubarb, grape, durian, dragon fruit, cucumber, blueberry, mulberry, citrus fruits, Drambuie, bourbon, scotch, whiskey, gin, tequila, rum, spearmint, peppermint, lavender, aloe vera, cardamom, celery, cascarilla, nutmeg, sandalwood, bergamot, geranium, khat, naswar, betel, shisha, pine, honey essence, rose oil, vanilla, lemon oil, orange oil, orange blossom, cherry blossom, cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, wasabi, piment, ginger, coriander, coffee, hemp, a mint oil from any species of the genus Mentha, eucalyptus, star anise, cocoa, lemongrass, rooibos, flax, ginkgo biloba, hazel, hibiscus, laurel, mate, orange skin, rose, tea such as green tea or black tea, thyme, juniper, elderflower, basil, bay leaves, cumin, oregano, paprika, rosemary, saffron, lemon peel, mint, beefsteak plant, curcuma, cilantro, myrtle, cassis, valerian, pimento, mace, damien, marjoram, olive, lemon balm, lemon basil, chive, carvi, verbena, tarragon, limonene, thymol, camphene), 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. They may be in any suitable form, for example, liquid such as an oil, solid such as a powder, or gasone or more of 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, cardamom, 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. They may be in any suitable form, for example, oil, liquid, or powder.

In some embodiments, the flavour comprises menthol, spearmint and/or peppermint. In some embodiments, the flavour comprises flavour components of cucumber, blueberry, citrus fruits and/or redberry. In some embodiments, the flavour comprises eugenol. In some embodiments, the flavour comprises flavour components extracted from tobacco. In some embodiments, the flavour may comprise a sensate, which is intended to achieve a somatosensorial sensation which are usually chemically induced and perceived by the stimulation of the fifth cranial nerve (trigeminal nerve), in addition to or in place of aroma or taste nerves, and these may include agents providing heating, cooling, tingling, numbing effect. A suitable heat effect agent may be, but is not limited to, vanillyl ethyl ether and a suitable cooling agent may be, but not limited to eucalyptol, WS-<NUM>.

The carrier constituent may comprise one or more constituents capable of forming an aerosol. In some embodiments, the carrier constituent may comprise one or more of glycerine, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, <NUM>,<NUM>-butylene glycol, erythritol, meso-Erythritol, ethyl vanillate, ethyl laurate, a diethyl suberate, triethyl citrate, triacetin, a diacetin mixture, benzyl benzoate, benzyl phenyl acetate, tributyrin, lauryl acetate, lauric acid, myristic acid, and propylene carbonate.

The one or more other functional constituents may comprise one or more of pH regulators, colouring agents, preservatives, binders, fillers, stabilizers, and/or antioxidants.

In some embodiments, the article for use with the non-combustible aerosol provision device may comprise aerosol generating material or an area for receiving aerosol generating material. In some embodiments, the article for use with the non-combustible aerosol provision device may comprise a mouthpiece. The area for receiving aerosol generating material may be a storage area for storing aerosol generating material. For example, the storage area may be a reservoir. In some embodiments, the area for receiving aerosol generating material may be separate from, or combined with, an aerosol generating area.

While the above-described embodiments have in some respects focussed on some specific example aerosol provision systems, it will be appreciated the same principles can be applied for aerosol provision systems using other technologies. That is to say, the specific manner in which various aspects of the aersol provision system function are not directly relevant to the principles underlying the examples described herein.

For example, whereas the above-described embodiments have primarily focused on aerosol provision systems comprising a vaporiser comprising a resistance heater coil, in other examples the vaporiser may comprise other forms of heater, for example a planar heater, in contact with a liquid transport element. Furthermore, in other implementations a heater-based vaporised might be inductively heated. In yet other examples, the principles described above may be adopted in devices which do not use heating to generate vapour, but use other vaporisation technologies, for example piezoelectric excitement.

Furthermore, and as already noted, whereas the above-described embodiments have focused on approaches in which the aerosol provision system comprises a two-part device, the same principles may be applied in respect of other forms of aerosol provision system which do not rely on replaceable cartridges, for example refillable or one-time use devices.

Thus there has been described an aersol provision system for generating aerosol for user inhalation. The aerosol provision system comprises a replaceable part <NUM>, the replaceable part comprising a housing providing an air channel <NUM> and a substrate <NUM> disposed within the air channel, the substrate <NUM> comprising aerosol generating material <NUM> for generating the aerosol for user inhalation; and a reusable part <NUM>. The reusable part comprises a housing <NUM> including an interface configured to operatively engage with the replaceable part <NUM>, and an air channel configured at least partially in the housing and to connect to the air channel of the replaceable part to provide a passage of air drawn by the user to receive the aerosol generated from the aerosol generating material, a detector <NUM> for detecting the passage of air drawn through the air channel; at least one aerosol generating element disposed with respect to the interface and configured, in use, to generate aerosol from the aerosol generating material, and a control circuit <NUM>. The control circuit is configured to receive a signal from the detector indicating an amount of air drawn by the user and to control the at least one aerosol generating element in response to the detector detecting the amount of air through the air channel, wherein the at least one aerosol generating element is configured with respect to the substrate of the replaceable part to generate aerosol selectively from different regions of the aerosol generating material in accordance with the amount of air drawn by the user to generate a selectable amount of the aerosol. In this example the replaceable part includes an air channel.

The heater may comprise one or more electrically resistive heaters, including for example one or more nichrome resistive heater(s) and/or one or more ceramic heater(s). The one or more heaters may comprise one or more induction heaters which includes an arrangement comprising one or more susceptors which may form a chamber into which an article comprising aerosolisable material is inserted or otherwise located in use. Alternatively or in addition, one or more susceptors may be provided in the aerosolisable material. Other heating arrangements may also be used.

Claim 1:
An aerosol provision system for generating aerosol for user inhalation, the aerosol provision system comprising:
a replaceable part (<NUM>) comprising a substrate (<NUM>) providing aerosol generating material (<NUM>) for generating the aerosol for user inhalation; and
a reusable part (<NUM>) comprising:
a housing (<NUM>) including an interface configured to operatively engage with the replaceable part (<NUM>), and an air channel (<NUM>) configured at least partially in the housing (<NUM>) to provide a passage of air drawn by user inhalation to receive the aerosol generated from the aerosol generating material (<NUM>),
a detector (<NUM>) configured to detect the passage of air drawn through the air channel (<NUM>);
at least one aerosol generating element disposed with respect to the interface and configured, in use, to generate aerosol from the aerosol generating material (<NUM>), and
a control circuit (<NUM>) configured to receive a signal from the detector (<NUM>) indicating an amount of air drawn by the user and to control the at least one aerosol generating element to generate the aerosol selectively from different regions of the aerosol generating material (<NUM>) in response to the amount of air drawn through the air channel (<NUM>);
characterised in that:
the at least one aerosol generating element comprises a plurality of aerosol generating elements each of which is spatially positioned with respect to the substrate (<NUM>) so that when activated each of the plurality of aerosol generating elements can generate the aerosol selectively from the different regions of the aerosol generating material (<NUM>), and the control circuit (<NUM>) is configured to activate one or more of the plurality of aerosol generating elements separately in response to the user drawing air through the air channel (<NUM>) to generate the aerosol selectively from the different regions of the aerosol generating material (<NUM>) in response to one or both of the amount of air drawn by the user through the air channel (<NUM>) and the duration of a draw of air through the air channel (<NUM>); and
wherein the control circuit (<NUM>) is configured to control the plurality of aerosol generating elements to activate more than one of the aerosol generating elements if the amount of air drawn by the user through the air channel (<NUM>) exceeds a predetermined threshold amount.