WO2022074013A1

WO2022074013A1 - Aerosol generating device

Info

Publication number: WO2022074013A1
Application number: PCT/EP2021/077469
Authority: WO
Inventors: Alec WRIGHT; Andrew ROGAN
Original assignee: Jt International Sa
Priority date: 2020-10-08
Filing date: 2021-10-05
Publication date: 2022-04-14
Also published as: EP4225084A1; JP2023544273A

Abstract

An aerosol generating device (2) comprising: a heating chamber (6) arranged to receive an aerosol substrate (8), the heating chamber (6) operable to heat the aerosol substrate (8) to generate an aerosol; a first heating element (12) that is fixed relative to the heating chamber; and at least one second heating element (14) that is moveable relative to the heating chamber (6), wherein the at least one second heating element (14) is configured to be moved into contact with the aerosol substrate (8) in response to a first temperature being reached during a heating operation of the aerosol generating device (2).

Description

Aerosol Generating Device

The present invention relates to an aerosol generating device. The disclosure is particularly applicable to a portable aerosol generation device, which may be self-contained and low temperature. Such devices may heat, rather than bum, tobacco or other suitable aerosol substrate materials by conduction, convection, and/or radiation, to generate an aerosol for inhalation.

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in the past few years as an aid to assist habitual smokers wishing to quit using traditional tobacco products such as cigarettes, cigars, cigarillos, and rolling tobacco. Various devices and systems are available that heat or warm aerosolisable substances as opposed to burning tobacco in conventional tobacco products.

A commonly available reduced-risk or modified-risk device is the heated substrate aerosol generation device or heat-not-burn (HNB) device. Devices of this type generate an aerosol or vapour by heating an aerosol substrate (i.e. consumable) that typically comprises moist leaf tobacco or other suitable aerosolisable material to a temperature typically in the range 150°C to 300°C. Heating an aerosol substrate, but not combusting or burning it, releases an aerosol that comprises the components sought by the user but not the toxic and carcinogenic by-products of combustion and burning. In addition, the aerosol produced by heating the tobacco or other aerosolisable material does not typically comprise the burnt or bitter taste that may result from combustion that can be unpleasant for the user.

However, within such devices, the aerosol substrate is known to lose structural integrity during the heating process and may shrink and/or begin to release aerosolisable material. This may result in inconsistent heating of the aerosol substrate and adversely affect the aerosol generating properties of the device. Furthermore, if a user removes the aerosol substrate from the device during the heating operation, there is a risk of the user contacting a hot portion of the aerosol substrate.

Therefore, an object of the present invention is to address one or more of these issues.

According to an aspect of the present invention, there is provided an aerosol generating device, comprising: a heating chamber arranged to receive an aerosol substrate, the heating chamber operable to heat the aerosol substrate to generate an aerosol, a first heating element that is fixed relative to the heating chamber; and at least one second heating element that is moveable relative to the heating chamber, wherein the at least one second heating element is configured to be moved into contact with the aerosol substrate in response to a first temperature being reached during a heating operation of the aerosol generating device.

In particular, the second heating element is configured to be moved to reduce a cross-section of the heating chamber.

In this way, the first heating element is stationary and is able to provide constant heating of the aerosol substrate received within the heating chamber. The second heating element is moveable with respect to the aerosol substrate and is able to provide additional heating of the aerosol substrate when required. Moreover, as the second heating element can be moved into contact with the aerosol substrate during a heating operation, the second heating element may be used to impose constraint such that the aerosol substrate is held in position during the heating operation and an efficient heat transfer interface is provided between the second heating element and the aerosol substrate.

In particular, the first heating element delimits a first portion of the heating chamber having invariable cross-section and the second heating element delimits a second portion of the heating chamber having a variable crosssection. Preferably, the at least one second heating element is configured to be moved such that a compressive force is provided to the aerosol substrate during the heating operation of the aerosol generating device. In this way, the compressive force may prevent aerosol generating material from being released from the aerosol substrate. For example, the compressive force may prevent tobacco from falling out of the end of a rod of aerosol substrate. In addition, the compressive force may ensure that optimal contact between the second heating element and the aerosol substrate is maintained during the heating operation, thereby improving the efficiency of heat transfer to the aerosol substrate.

It is known that, if the compressive force is too large, voids may be removed from within the aerosol substrate which are otherwise required for aerosol production and to provide a pressure drop. Conversely, if the compressive force is too small, there may be poor contact between the second heating element and aerosol substrate resulting in an inefficient transfer of heat. Hence, the second heating element may be controlled to provide a consistent (optimal) level of compression against the aerosol substrate during the heating operation.

Preferably, the at least one second heating element is configured to be moved out of contact with the aerosol substrate or a compressive force onto the aerosol substrate is released in response to a second temperature being reached during a cooling operation of the aerosol generating device. In this way, the constraint imposed by the second heating element may prevent the aerosol substrate from being removed from the aerosol generating device during the heating operation, i.e. when the device and aerosol substrate are hot, thereby improving the safety of the aerosol generating device.

Preferably, the at least one second heating element is configured to be moved such that contact is maintained with the aerosol substrate during a shrinkage of the aerosol substrate, the shrinkage resulting from the heating operation. Shrinkage of aerosol generating material, such as tobacco, during heating is a known phenomenon. Hence, by providing the second heating element which is moveable to maintain contact with the aerosol substrate during the heating operation, it is possible to compensate for the shrinkage and optimise the heat transfer between the second heating element and the aerosol substrate.

The second heating element may be positioned in the heating chamber downstream of the first heating element. The second heating element may be positioned above the bottom of the heating chamber. The first heating element may be positioned between the mouth of the heating chamber and the first heating element and substantially adjacent the second heating element. The ratio of the length of the first heating element to the length of the second heating element may be between 1 :2 to 4:1 , preferably 1 :1 to 3:1.

Preferably, the aerosol generating device comprises two second heating elements, wherein the two second heating elements are respectively located on opposing sides of the heating chamber such that the aerosol substrate is gripped between the two second heating elements during the heating operation of the aerosol generating device. In particular, the two second heating elements are respectively located on opposing sides of the cross-section of the heating chamber, i.e. in a transverse direction of the heating chamber. In this way, the aerosol substrate is securely held within the heating chamber during the heating operation, thereby providing improved safety and increasing the efficiency of heat transfer to the aerosol substrate. Moreover, as the two second heating elements are arranged to contact either side of the aerosol substrate in a transverse direction, i.e. perpendicular to its length, a symmetrical contact force is provided to the aerosol substrate which helps in preventing a collapse or release of the aerosol substrate.

In one example, the two second heating elements may be formed as two half tubes arranged on opposing side of the heating chamber, such that the aerosol substrate may be gripped between the two half tubes during the heating operation of the aerosol generating device. In this way, a rod of aerosol substrate may be securely enclosed by the two second heating elements, thereby providing optimal heat transfer and firmly holding the aerosol substrate within the heating chamber. In one example, the at least one second heating element may comprise a thin film heater. In other example, the at least one second heating element may be a resistive heating wire, preferably formed in flat coiled shape.

Preferably, the aerosol generating device further comprises an actuator configured to move the at least one second heating element.

Preferably, the actuator is a temperature dependent actuator. In this way, the second heating element may be automatically controlled to move in (and out of) contact with the aerosol substrate during the heating operation, without requiring user input.

Preferably, the temperature dependent actuator comprises a shape memory alloy. Preferably, the shape memory alloy is a two-way shape memory alloy. In this way, the shape memory alloy actuator may be configured to deform at the alloy’s martensitic transformation temperature to move the second heating element into contact with the aerosol substrate during the heating operation of the aerosol generating device. Moreover, the shape memory alloy actuator may be configured to deform during the cooling operation of the aerosol generating device to move the second heating element out of contact with the aerosol substrate.

Preferably, the temperature dependent actuator comprises a bi-metallic element.

Preferably, the actuator is further configured to act as an electric connection to supply power from a power supply to the second heating element.

Preferably, the first heating element is arranged such that it surrounds the aerosol substrate received within the heating chamber. In this way, the heat transfer between the first heating element and the aerosol substrate may be optimised.

In one example, the first heating element may comprises a thin film heater. In another example, the first heating element may comprise a passive or unpowered heater, which receives heat energy via conduction from the second heating element.

Preferably, the aerosol substrate is a rod of aerosol substrate having a first end for insertion into the aerosol generating device and an opposing second end to be received in a mouth of a user, and wherein the at least one second heating element is configured to be moved such that a compressive force is applied adjacent the first end of the rod of aerosol substrate, thereby preventing aerosol substrate from being released out the first end.

Preferably, the compressive force is applied adjacent the first end of the rod of aerosol substrate across between 1/6th and 1/4th of a length of the rod of aerosol substrate. More preferably, the compressive force is applied adjacent the first end of the rod of aerosol substrate across 1/6th of a length of the rod of aerosol substrate. In this way, the second heating element is positioned to only provide compression to the region of aerosol substrate where compression is most desired, i.e. at the end of the rod of aerosol substrate where there is a risk of aerosol substrate falling out. Moreover, as the second heating element is positioned to contact a region of the rod of aerosol substrate opposite to the mouth end of the rod of aerosol substrate, energy is not wasted heating nonaerosol generating material, e.g. non-tobacco material (NTM).

Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:

Figure 1A is a schematic cross-sectional view of an aerosol generating device in an embodiment of the invention, wherein two second heating elements are retracted from an aerosol substrate;

Figure 1 B is a schematic cross-sectional view of the aerosol generating device, wherein the two second heating elements are in contact with the aerosol substrate; and

Figure 2 is a flowchart showing method steps for operation of the aerosol generating device. Figure 1A illustrates an aerosol generating device 2 according to an embodiment of the invention, comprising a housing 4 and a heating chamber 6 for receiving an aerosol substrate 8 (e.g. a consumable). The heating chamber 6 is operable to heat the aerosol substrate 8 to generate an aerosol (also referred to as a vapour) for inhalation by a user.

In this embodiment, the heating chamber 6 is tubular and is configured for receiving a cylindrical rod of aerosol substrate 8, such as a rod of tobacco or other aerosol generating material. The rod of aerosol substrate 8 has a first end 7 and an opposed second end 8. The second end 7 is a mouth end configured for insertion into a mouth of the user. In use, the user may insert the first end 7 of the aerosol substrate 8 through a hole 10 in the housing 4 such that the aerosol substrate 8 is positioned within the heating chamber 6, and the first end 7 abuts an end portion 11 of the heating chamber 6 that is opposite to the hole 10 in the housing 4. The length of the heating chamber 6 is shorter than the length of the rod of aerosol substrate 8 such that the second end 9 of the aerosol substrate 8 protrudes through the hole 10 in the housing 4 (i.e. out of the heating chamber 6) and can be received in the mouth of the user.

The skilled person will appreciate that in alternative embodiments, the heating chamber 6 may not be tubular. For example, the heating chamber 6 may be formed as a cuboidal, conical, hemi-spherical or other shaped cavity, and be configured to receive a complementary shaped aerosol substrate 8.

A first heating element 12 is located within the housing 4 and is fixed (i.e. stationary, immoveable) with respect to the heating chamber 6. Thus, the first heating element 12 is fixed with respect to the aerosol substrate 8 received within the heating chamber 6. The first heating element 12 is tubular and defines a wall of the heating chamber 6. The aerosol substrate 6 received within the heating chamber 6 interfaces with the first heating element 12 along a central portion of the length of the aerosol substrate 8. For example, the first heating element 12 may contact the rod of aerosol substrate 8 along 1/4 to 3/4 of the length of the rod of aerosol substrate 8 from the second end 11 , or along 1/4

skilled person will appreciate that, in alternative embodiments, the first heating element 12 may not define a wall of the heating chamber 6 but may be located inside or outside the heating chamber 6. Moreover, there may be a plurality of first heating elements 12 which are each fixed with respect to the received aerosol substrate 8.

The first heating element 12 comprises a heating material (such as stainless steel, titanium, nickel, Nichrome etc.). In one example, the first heating element 12 may comprise a thin-film heater which, for example, surrounds the aerosol substrate 8.

A pair of second heating elements 14 are respectively disposed either side of the cross-section of the heating chamber 6, towards the end portion 11 of the heating chamber 6. Each second heating element 14 is coupled to a respective actuator 16 that is coupled to the housing 4. The actuator 16 is configured to move the second heating element 14 with respect to the heating chamber 6, i.e. with respect to the aerosol substrate 8 received within the heating chamber 6. Each second heating element 14 is moveable perpendicular to the surface of the aerosol substrate 8 (e.g. perpendicular to the length of the rod of aerosol substrate 8) to alter the level of contact between the second heating element 14 and the aerosol substrate 8.

Each second heating element 14 comprise a heating material suitable for converting electrical energy into heat (such as stainless steel, titanium, nickel, Nichrome etc.). In one example, the second heating element 14 may comprise a thin-film heater. In another example, the second heating element 14 may comprise a resistive heating wire, preferably formed in a coiled shape to optimize contact with the aerosol substrate 8.

In this example, each second heating element 14 is formed as a half tube arranged to interface with the rod of aerosol substrate 8 when moved into contact the aerosol substrate 8. Hence, when the two half tubular second heating elements 14 are moved into contact with the aerosol substrate 8, the aerosol substrate 8 is enclosed by the two second heating elements 14, i.e. the two second heating elements 14 form an interface around the entire circumference of the rod of aerosol substrate 8. However, the skilled person will appreciate that the second heating elements 14 may be formed in alternative shapes. For example, the second heating elements 14 may be substantially flat.

Each second heating element 14 is configured to move between a retracted position (as illustrated in Figure 1A) and an extended position (as illustrated in Figure 1 B). In the retracted position, the second heating element 14 is retracted with respect to the aerosol substrate 8 such that the second heating element 14 does not contact the aerosol substrate 8. In the extended position, the second heating element 14 is arranged to contact the aerosol substrate 8.

Each actuator 16 is configured to move the respective second heating element 14 in and out of contact with the aerosol substrate 8. Each actuator 16 may be configured to move the respective second heating element 14 in response to an operating condition of the aerosol generating device. For example, the second heating element 14 may be configured to be moved from the retracted position to the extended position during a heating operation of the aerosol generating device 2. Thus, the second heating elements 14 are operable to provide additional heating to the aerosol substrate 8 during the heating operation, in addition to the heating provided by the first heating element 12.

In the extended position, a (compressive) force may be applied to the aerosol substrate 8 by the contacting second heating element 14. In this way, the force may prevent a user from removing the aerosol substrate 8 from the heating chamber 6 whilst the aerosol substrate 8 is hot, thereby improving the safety of the aerosol generating device 2. Moreover, the force may prevent aerosol generating material from being released from the aerosol substrate 8. This effect is further improved by providing the two second heating elements 14 on opposing sides of the aerosol substrate 8 such that the aerosol substrate 8 is gripped between the two second heating elements 14 during the heating operation. In particular, the two second heating elements 14 are provided on opposing sides of the cross-section of the heating chamber 6. In other words, the two second heating elements 14 are provided on opposing sides of the heating chamber 6 in a transverse direction with respect to the aerosol substrate 8 or the heating chamber 6.

The second heating element 14 may be configured to be moved from the extended position to the retracted position during a cooling operation of the aerosol generating device 2, such that the contact force is removed from the aerosol substrate 8 and the aerosol substrate 8 may be removed from the heating chamber 6 by the user.

Each second heating element 14 is arranged towards the end portion 11 of the housing 4. In other words, the second heating elements 14 are arranged such that, in the extended position, they contact the rod of aerosol substrate 8 towards its first end 7, which corresponds to a region of the aerosol substrate 8 comprising a high density or quantity of aerosol generating material. For example, each second heating element 14 may be arranged such that it contacts the rod of aerosol substrate 8 along between 1 /6th and 1 /4th of the length of the rod of aerosol substrate 8, adjacent the first end 7. Preferably, each second heating element 14 may be arranged such that it contacts the rod of aerosol substrate 8 along 1 /6th of the length of the rod of aerosol substrate 8, adjacent the first end 7. In a further example, each second heating element may be arranged such that it contacts the rod of aerosol substrate 8 along 3/4 to 7/8 of the length of the rod of aerosol substrate 8 from the second end 11. For example, the length of the second heating element 14 may be between approximately 15 and 17.5 mm. The skilled person will appreciate that each second heating element 14 may be alternatively arranged to contact the aerosol substrate 8 in a region comprising aerosol generating material, e.g. a region comprising a high density of aerosol generating material.

Advantageously, as each second heating element 14 contacts the rod of aerosol substrate 8 adjacent the first end 7 (which is opposed to the mouth end 11) and provides a compressive force perpendicular to the length of the rod of aerosol substrate 8, aerosol generating material held within the aerosol substrate 8 is prevented from falling out of the first end 7 of the rod of aerosol substrate 8. In use, power may be supplied to each second heating element 14 from a power source such as a battery (not depicted) such that the temperature of each second heating element 14 increases and heat energy is transferred to the aerosol substrate 8 to produce an aerosol for inhalation by the user.

In one embodiment, the first heating element 12 may be an active or powered heater and power may be supplied to the first heating element 12 such that the temperature of the first heating element 12 increases. In this case, the first heating element 12 and second heating element 14 may be independently controlled, i.e. the second heating element 14 may be powered separately from the first heating element 12 and/or the first heating element 12 and the second heating element 14 may be heated to different temperatures. For example, the first heating element 12 may only be powered at the start of the heating operation during an initial heating or “ramp-up” stage of the aerosol substrate 8. The first heating element 12 may be switched off for the remainder of the heating operation. Advantageously, this may reduce the time taken to achieve a first puff (i.e. aerosol generation and inhalation) of the aerosol substrate 8, after which power supply to the first heating element 12 is stopped. Additionally or alternatively, as the first heating element 12 is arranged to contact a region of the aerosol substrate 8 comprising a lower density or quantity of aerosol generating material than the region contacted by the second heating elements 14, the first heating element 12 may be powered (and heated) to a lower temperature than the second heating elements 14, thereby resulting in an energy saving.

In an alternative embodiment, the first heating element 12 may be a passive or unpowered heating element, such as a heater cup. In this case, the first heating element 12 does not receive electrical power to generate heat energy, but instead receives heat energy via conduction from the second heating element 14. As the first heating element 12 is not powered, and each second heating element 14 only generates and transfers heat to a region of the aerosol substrate 8 containing aerosol generating material (or a high density or quantity of aerosol generating material), less energy may be wasted heating regions of the aerosol substrate 8 which contain less or no aerosol generating material. For example, if the aerosol substrate 8 is a rod of tobacco, power is not wasted directly heating the portion of the rod of tobacco near the second end 11 (mouth end) which contains non-tobacco material (NTM).

The actuator 16 may be a temperature dependent actuator configured to move the second heating element 14 in response to a change in temperature. In this example, the actuator 16 comprises a shape memory alloy actuator. For example, the actuator 16 may comprise Ni-Ti, Cu-AI-Ni, Cu-Zn-AI or other suitable shape memory alloys. The shape memory alloy exhibits the shape memory effect such that it deforms (i.e. undergoes a phase transformation) as a function of temperature to move the second heating element 14. In particular, the actuator 16 may be configured to deform at a first temperature during the heating operation of the aerosol generating device 2, such that the second heating element 14 is moved into contact with the aerosol substrate 8. The first temperature may correspond to the martensitic transformation temperature of the shape memory alloy. Moreover, the actuator 16 may be further configured to continue to deform (i.e. actuate) above the first temperature such that the second heating element is moved further in the direction (i.e. towards) the aerosol substrate 8 as the temperature increases. As the aerosol substrate 8 is prone to shrinking during heating, this mode of operation ensures that contact is maintained with the aerosol substrate 8 during the heating operation and/or ensures a compressive (e.g. constant compressive force) is provided to the aerosol substrate 8 during the heating operation.

The actuator 16 may also be configured to deform (i.e. actuate) at a second temperature during the cooling operation of the aerosol generating device 2, such that the second heating element 14 is moved out of contact with the aerosol substrate 8. Preferably, the actuator 16 comprises a two-way shape memory alloy, but in other examples, the actuator 16 may comprise a one-way shape memory alloy.

The skilled person will appreciate that, in alternative examples, the actuator 16 may comprise other shape memory alloy elements, such as shape memory alloy actuatable arms or other expandable shape memory elements configured to move the second heating element 14 as a function of temperature. Alternatively, the actuator 16 may be a bimetallic strip actuator.

The actuator 16 may be further configured to operate as an electrical connection, i.e. conduct electricity, between the power supply and the second heating element 14.

Figure 2 illustrates a method of operation 20 for the aerosol generating device 2 in accordance with an embodiment of the invention.

At step 22, the user inserts the aerosol substrate 8 through the hole 10 in the housing 4 and into the heating chamber 6.

At step 24, the heating operation is started and power is supplied to the second heating element 14. This causes the temperature of the second heating element 14 to increase. The actuator 16 and aerosol substrate 8 also increase in temperature. The second heating element 14 may be powered using the actuator 16 as an electrical connection to conduct electricity from the power supply.

In one embodiment, the first heating element 12 may also be powered at step 24 such that the first heating element 12 increases in temperature. The first heating element 12 may be powered/heated to a lower temperature than the second heating element 14. Additionally or alternatively, the first heating element 12 may only be powered during an initial stage or “ramp-up” stage of the heating operation and switched off once a first puff from the aerosol substrate 8 has been produced.

In an alternative embodiment, the first heating element 12 may not receive power, but instead may be indirectly heated via conduction from the second heating element 14.

At step 26, the temperature of the actuator 16 (and/or the second heating element 14) reaches or exceeds the first temperature (Ti). This causes the actuator 16 to move the second heating element 14 into contact with the aerosol substrate 8 at step 28, and preferably provide a compressive force to the aerosol substrate 8. The second heating element 14 contacts the aerosol substrate 8 towards the first end 7. For the embodiment where the actuator 16 comprises a shape memory alloy, the first temperature corresponds to the martensitic transformation temperature of the shape memory alloy. The shape memory alloy undergoes a temperature-induced phase transformation, e.g. changes from austenite to martensitic, which result in a shape change of the shape memory alloy, and causes the actuator 16 to move the second heating element 14 towards and into contact with the aerosol substrate 8. The shape memory alloy may be configured to further deform at higher temperatures (e.g. as the phase transformation progresses), thereby moving the second heating element 14 further in the direction of the aerosol substrate 8. This may ensure that contact is maintained with the aerosol substrate 8 during the heating operation and/or ensures that a compressive force is applied to the aerosol substrate 8 throughout the heating operation. Due to the contact and/or compressive force, the user may be prevented from removing the aerosol substrate 8 from the heating chamber 6, and aerosol generating material may be prevented from being released from the aerosol substrate 8.

At step 30, the cooling operation is initiated, e.g. by the user. For example, the cooling operation may comprise switching off power supply to the second heating element 14 (and optionally the first heating element 12 if powered). This results in the temperature of the second heating element 14 (and the first heating element 12) decreasing. In addition, the actuator 16 and aerosol substrate 8 decrease in temperature.

At step 32, the temperature of the actuator 16 (and/or the second heating element 14) reaches or drops below the second temperature (T₂). This causes the actuator 16 to retract and move the second heating element 14 out of contact with the aerosol substrate 8 at step 34, thereby allowing the user to remove the aerosol substrate 8 from the heating chamber 6.

Claims

1. An aerosol generating device, comprising: a heating chamber arranged to receive an aerosol substrate, the heating chamber operable to heat the aerosol substrate to generate an aerosol; a first heating element that is fixed relative to the heating chamber; and at least one second heating element that is moveable relative to the heating chamber, wherein the at least one second heating element is configured to be moved into contact with the aerosol substrate in response to a first temperature being reached during a heating operation of the aerosol generating device.

2. The aerosol generating device of claim 1 , wherein the at least one second heating element is configured to be moved such that a compressive force is provided to the aerosol substrate during the heating operation of the aerosol generating device.

3. The aerosol generating device of any preceding claim, wherein the at least one second heating element is configured to be moved out of contact with the aerosol substrate or a compressive force onto the aerosol substrate is released in response to a second temperature being reached during a cooling operation of the aerosol generating device.

4. The aerosol generating device of any preceding claim, comprising two second heating elements, wherein the two second heating elements are respectively located on opposing sides of the heating chamber such that the aerosol substrate is gripped between the two second heating elements during the heating operation of the aerosol generating device.

5. The aerosol generating device of any preceding claim, further comprising an actuator configured to move the at least one second heating element.

6. The aerosol generating device of claim 5, wherein the actuator is a temperature dependent actuator.

7. The aerosol generating device of claim 6, wherein the temperature dependent actuator comprises a shape memory alloy.

8. The aerosol generating device of claim 7, wherein the shape memory alloy is a two-way shape memory alloy.

9. The aerosol generating device of claim 6, wherein the temperature dependent actuator comprises a bi-metallic element.

10. The aerosol generating device of claims 5 to 9, wherein the actuator is further configured to act as an electric connection to supply power from a power supply to the first heating element.

11. The aerosol generating device of any preceding claim, wherein the first heating element is arranged such that it surrounds the aerosol substrate received within the heating chamber.

12. The aerosol generating device of any preceding claim, wherein the first heating element comprises a thin film heater.

13. The aerosol generating device of any preceding claim, wherein the aerosol substrate is a rod of aerosol substrate having a first end for insertion into the aerosol generating device and an opposing second end to be received in a mouth of a user, and wherein the at least one second heating element is configured to be moved such that a compressive force is applied adjacent the first end of the rod of aerosol substrate, thereby preventing aerosol substrate from being released from the first end. 17

14. The aerosol generating device of claim 13, wherein the compressive force is applied adjacent the first end of the rod of aerosol substrate across between 1/6^th and 1/4^th of a length of the rod of aerosol substrate.