Field of invention

The present invention relates to an inhaler or an aerosol generation device.

Background

Known aerosol generation devices often use a heating component, or heater, to heat an aerosol generating liquid in order to generate an aerosol, i.e. by vaporising the liquid, for inhalation by a user. The heating component is typically made of a conductive material which allows an electric current to flow through it when electrical energy is applied across the heating component. The electrical resistance of the conductive material causes heat to be generated as the electric current passes through the material, a process commonly known as resistive heating.

Other aerosol generation devices may use a piezoelectric atomizer which receives electrical energy to produce ultrasonic vibrations. The vibrations are directed at a volume of liquid in order to break the liquid apart into droplets, which are then dispersed into air and inhaled as an aerosol.

These techniques require a power source, such as a battery, to provide electrical energy to the heater or piezoelectric crystal. It has been found that a limited power source can be unsuitable for all applications, for example when a battery cannot be easily recharged or replaced. In certain applications a poorly performing power source may even produce sub-optimal aerosol properties, for example by not generating sufficient heat or vibrational energy in order to generate the desired aerosol properties.

An object of the invention is to provide a more reliable and effective aerosol generation device. Summary

According to the present invention there is provided an inhaler including an aerosol generating system, the inhaler comprising: an air flow channel extending between an air inlet and an air outlet in a mouthpiece for supporting an air flow; a fluid oscillation circuit configured to diverge a portion of air from the air flow channel and return said portion back to the airflow channel such that the air flow in the air flow channel is oscillated; and a liquid injection mechanism configured to inject liquid into the air flow path so that it is vaporised by the oscillation in the airflow channel.

In this way an aerosol can be generated by the inhaler without the need of a power source, heater, or piezoelectric components by oscillating air in the air flow channel using the fluid oscillation circuit. This simplifies the production of the inhaler devices as well as reducing the energy demand in the manufacture or use of a device. The lack of a battery and other electrical components can also significantly reduce the weight of a device and provide substantial environmental benefit, in terms of product delivery and materials used for production. The simplified construction also requires no moving parts to generate an aerosol (as opposed to a piezoelectric atomizer for example) which also reduces the risk of leakage of aerosol generating liquid from a device.

Preferably the fluid oscillation circuit is arranged laterally of the airflow channel. In this way the fluid oscillation circuit is positioned to effectively remove the portion of air from its main direction of air flow between the air inlet and air outlet, and effectively re-introduce the removed portion of air back into the air flow channel to cause the air flow in the airflow channel to oscillate.

Preferably the fluid oscillation circuit has an inlet and an outlet that are positioned between the air inlet and the air outlet of the airflow channel. In this way a portion of the air flow can diverge from the airflow channel through the inlet of the oscillation circuit and be returned to the airflow channel via the outlet of the oscillation circuit. In use the air in the air flow channel preferentially flows against, or sticks to, a side of the air flow channel due to the Coanda effect. Preferably the fluid oscillation circuit causes the air in the air flow channel to oscillate between preferentially flowing along a first side of the air flow channel and preferentially flowing along a second side of the air flow channel. As the air flow oscillates from the first side to the second side in the air flow channel, it is knocked from side to side, striking the inner surface of the air flow channel, and dislodges fluid particles that have been injected via the liquid injection mechanism such that vapour particles are formed.

Preferably the fluid oscillation circuit comprises at least one feedback channel configured to diverge and return the portion of the air flow from and to the air flow channel respectively to cause the air flow to oscillate between a first pattern and a second pattern. In this way the feedback channel provides the inlet and the outlet of the fluid oscillation circuit by which a portion of the air flow in the air flow channel can diverge from and be returned to the airflow channel and create turbulence in the airflow channel.

Preferably the oscillation is generated by a change in the characteristics of the airflow pattern, such as a change in direction and velocity. In this way the returned portion of the air to the air flow in the airflow channel is disrupted such that the flow path, direction and/or velocity of the air flow changes. This means that the air flow in the air flow channel is oscillated from the first pattern/state to a second pattern/state. Preferably the fluid oscillation circuit is configured to oscillate air flow in the air flow channel between a first pattern and a second pattern.

The inhaler may comprise a single feedback channel, wherein air flow in the single feedback channel is in a first direction in the first pattern and in a second direction in the second pattern, wherein the first direction is opposite to the second direction. In this way a portion of the air flow can diverge from the air flow channel into the single feedback channel from a first point along the channel, travelling in the first direction, and be returned to the air flow channel at a second point along the channel to move the air flow from the first pattern (or state) to the second pattern (or state). To shift the air flow from the second pattern to the first pattern, a portion of the air flow diverges from the air flow channel at the second point into the single feedback channel, travels in the second direction, and returns to the air flow channel at the first point along the channel.

The inhaler may comprise first and second feedback channels, wherein the air flow that diverges from the air flow channel is substantially in the first feedback channel in the first pattern, and substantially in the second feedback channel in the second pattern. In this way the first feedback channel is used to shift the air flow from the first pattern/state to the second pattern/state, and the second feedback channel is used to shift the air flow from the second pattern to the first pattern.

Preferably the liquid injection mechanism includes a liquid outlet positioned in the fluid oscillation circuit at a position where the air flow in the air flow channel is against a first side of the air flow channel in the first pattern and against a second side of the air flow channel in the second pattern. In this way as air flow moves between the first and second patterns/states the air flow strikes the liquid provided at the liquid outlet and causes it to be broken into smaller droplets. This allows the droplets to be readily taken up by the airstream and further dispersed into an aerosol by the oscillatory motion caused by the fluid oscillation circuit.

Preferably the liquid injection mechanism is configured to inject liquid at a position in the air flow channel which is upstream of the position at which the at least one feedback channel returns the diverging air flow to the air flow channel. In this way liquid injected into the air flow channel can be broken into smaller liquid droplets at the upstream position and the generated aerosol is further subject to the oscillatory motion of the air flow for longer length along the air flow channel. Alternatively the liquid may be injected at a position in the air flow channel which is downstream of the position at which air flow diverges into the at least one feedback channel. This means that the liquid is injected between the fluid oscillation circuit and the air outlet, which leads to a shorter length in which the liquid may be travels along the fluctuating air flow before it reaches the outlet. It should be understood that the position of liquid injection, the length of travel of liquid oscillation or the desired droplet size may be controlled according to design or operational requirements.

Preferably the inhaler further comprises a liquid reservoir configured to supply liquid to the liquid injection mechanism. In this way the inhaler can portably store and deliver a larger amount of aerosol to a user. This means that an inhaler can be used multiple times to deliver a vapour or aerosol before the reservoir needs to be replenished or replaced. The liquid reservoir may be provided as an insertable capsule to the inhaler or alternatively the inhaler may be as a limited use device which can be disposed after the reservoir is depleted.

The inhaler may further comprise a pump configured to pump liquid from the liquid reservoir to the liquid injection mechanism. In this way liquid can be reliably injected into the air flow channel for dispersion. The pump may be configured to inject controlled volumes of liquid into the air stream according to operational requirements. Liquid may be injected or drawn into the air flow channel using an electric pump or a pressure differential technique such as a Venturi injector pump. Alternatively liquid may also be injected into the air flow channel by use of a wicking mechanism or capillary action.

Preferably a constriction is provided in the air flow channel between the fluid oscillation circuit and the air inlet to facilitate a turbulent air flow in the fluid oscillation circuit. In this way the constriction reduces the cross-sectional area through which air flowing in the air flow channel must pass which increases the air velocity and decreases the pressure, according to the Venturi effect.

The inhaler may further comprise a heater configured to heat air in the air flow channel. The heater may be provided in the fluid oscillation circuit. The heater may be provided between the fluid oscillation circuit and the air outlet. In this way the generated aerosol may be heated to deliver different temperatures of aerosol to a user. The heat may also be used to further vaporise the liquid in the air flow stream in addition to the fluid oscillation circuit. The heater may also be used to dry up or remove any residual liquid in the air flow channel and / or fluid oscillation circuit after use.

The inhaler may further comprise an electrical battery configured to supply electrical power to the heater. In this way the inhaler can be easily transported and used, and the heater may be optionally operated according to user or design requirements.

According to another aspect of the present invention there is provided an electronic cigarette comprising the inhaler as described above and one or more electrical components. In this way electrical components can be placed in the electronic cigarette to increase functionality of the device. The inhaler can function as an aerosol generation device separately from the electrical components, and the electrical components can provide additional functions and information such as use statistics (e.g. puff count, duration of use, battery level) or allow third party device communication with the electronic cigarette. Alternatively the electrical components include an electric heater and / or pump which can increase the performance range of the electronic cigarette. By this we mean that a heater or pump allows the generated aerosol to be delivered at higher temperatures or with a greater liquid content respectively according to design or operational requirements.

According to another aspect of the present invention there is provided a method of generating an aerosol in an inhaler comprising the steps of: providing an air flow in an air flow channel that extends between an air inlet and an air outlet in a mouthpiece; oscillating the air flow in the air flow channel by using a fluid oscillation circuit configured to diverge a portion of air from the air flow channel and return said portion back to the air flow channel; and injecting liquid into the air flow path so that it is vaporised by the oscillation of the air flow in the fluid oscillation circuit. In this way aerosol may be generated and delivered to a user by oscillating an air and liquid flow in the airflow channel of the inhaler. Brief description of the drawings

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

Figure 1 is a schematic cross-sectional view of an aerosol generation device in a first embodiment of the invention;

Figure 2A is a schematic cross-sectional view of a first fluid oscillation circuit according to the invention;

Figure 2B is another schematic cross-sectional view of the first fluid oscillation circuit according to the invention;

Figure 3A is a schematic cross-sectional view of a second fluid oscillation circuit according to the invention;

Figure 3B is a schematic perspective view of the second fluid oscillation circuit according to the invention; and

Figure 4 is a schematic cross-sectional view of another aerosol generation device in a second embodiment of the invention.

Detailed description

Figure 1 shows a schematic cross-sectional view of an inhaler 10 in an embodiment of the present invention. The inhaler 10 has an air inlet 12 at one end and a mouthpiece 14 and air outlet 16 at the other end. An air flow channel 18 connects the air inlet 12 and the air outlet 16, along which an air stream received from the air inlet 12 travels through the air flow channel 18 and is directed toward the air outlet 16 along an air flow path. A constriction 20 may be provided in the air flow channel 18 after the air inlet 12 in order to reduce the cross-sectional area of air flow in the inhaler 10 and increase the flow velocity in the air flow channel 18. In use, a jet of air is formed from the air inlet 12 when a user inhales at the mouthpiece 14. The jet of air travels along the side wall of the air flow channel 18 through the fluid oscillation circuit toward the air outlet 16. The initial flow velocity entering the air inlet 12 is therefore controlled by the inhalation of the user, and the constriction 20 facilitates a turbulent air flow and flow velocity through the air flow channel 18. An expansion 22 is provided in the air flow channel 18 toward the air outlet 16 in order to reduce the flow velocity of the air before it reaches a user’s mouth. It should be understood that the constriction 20 and the expansion 22 are optional features that are included in the inhaler 10 to control the flow velocity in the air flow channel 18.

The inhaler 10 further comprises a reservoir 24 in which a liquid may be stored and injected into the air flow channel 18 via a liquid injection aperture 26. There may be one or more liquid injection points, or apertures, along the air flow channel 18 to introduce liquid into the air flow channel 18. The liquid in the air flow channel 18 is atomised into smaller droplets each time the air flow changes its flow pattern or state. By this we mean that as the jet of air flows through the air flow channel 18 the jet of air will have a flow pattern with certain characteristics, such as the average flow velocity, the position of the jet of air within the air flow channel 18 or the degree of turbulence. The jet of air within the air flow channel 18 is likely to be positioned toward a portion of the curved interior wall of the channel 18 due to the Coanda effect, as will be explained in further detail below. The distribution of liquid droplets in the jet of air will also affected by the flow pattern. It should be understood that the viscosity of the liquid used in the inhaler 10 can be controlled to affect the average droplet size provided in the aerosol.

The inhaler 10 further comprises at least one fluid oscillation circuit. In an advantageous embodiment, the fluid oscillation circuit 28 comprising a first feedback loop 30 and a second feedback loop 32. The first and second feedback loops 30, 32 each have a flow divergence opening 34 and 36 respectively and a flow return opening 40, 42 respectively. The flow divergence openings 34 and 36 are arranged at opposing sides of the air flow channel 18 at a first position 38 along the length of the air flow channel 18. Each flow divergence opening 34, 36 is configured to receive a portion of air flowing through the air flow channel 18 such that the portion of air diverges from the air in the air flow channel 18 and flows through its respective feedback loop 30, 32. Similarly each flow return opening 40, 42 are also arranged at opposing sides of the air flow channel 18 at a second position 44 along the length of the air flow channel 18 such that the returned portion of air causes a disturbance, or turbulence in the air flow channel 18, such that the air stream in the air flow channel 18 shifts from one flow pattern to another. This flow oscillation technique provided by the fluid oscillation circuit 28 is further explained with reference to Figures 2A and 2B.

The length of a feedback loop(s), for a single-loop system or a double-loop system, may control the oscillation frequency of the fluid oscillation circuit 28, where a longer loop leads to a lower frequency and a shorter loop leads to a higher frequency. A typical length range for a feedback loop between may be from 10 mm to 200 mm which would give a corresponding frequency from around 220 Hz to 4000 Hz. A typical range for the cross-sectional area of the feedback loop may be from 1.2 x 10 ⁵ m ² to 1.2 x 10 ³ m ² It should also be understood that the initial flow velocity in the air flow channel 18 also affects the oscillation frequency of the inhaler 10, where a higher velocity leads to a higher frequency and vice versa. A person skilled in the art would understand how to design the constriction 20 and feedback loops 30, 32 to achieve a desired Reynolds number and predicted flow pattern.

The invention uses a principle called the Coanda effect, which relates to the tendency of a fluid jet to preferentially flow along a convex or curved surface. This means that when air flows through the air flow channel 18, the air flows against one side of the air flow channel 18 (due to the Coanda effect) such that the air flow is in the first pattern or first flow pattern. The pattern of flow primarily relates to the position of a jet of air flowing in the air flow channel 18, where the jet of air in a first pattern means that it flows against a first inner portion of the channel and the jet of air in a second pattern means that it flows against a second inner portion of the channel.

A flow pattern may also include different flow characteristics, such as velocity or degree of turbulence depending on the design of the air flow channel and fluid oscillation circuit. However it should be understood that there will always be variations in a flow due to the natural variations in an inhalation of a person.

The fluid oscillation circuit 28 causes air flowing through the air flow channel 18 to fluctuate between different portions of the inner wall of the channel 18 where air flows against one portion of the air flow channel 18 in a first pattern and flow against another portion of the channel 18 in a second pattern. As air continuously passes through the inhaler 10, the air flow path will continuously oscillate between the two flow patterns due to portions of the air flow sequentially diverging from and returning to a central stream of airflow.

In reference to Figure 1 as an example the first pattern/state, or first flow pattern/state, is when air flowing along the air flow channel 18 preferentially flows against the lower surface of the channel 18. Conversely the air flow in a second pattern/state, or second flow pattern/state, is when it travels preferentially against the upper surface of the channel 18. The Coanda effect occurs as soon as air is received from the air inlet 12 into the air flow channel 18 causing the air flow to be in the first pattern or second pattern, i.e. even before it reaches the fluid oscillation circuit 30. It should be understood that the size of air inlet 12 may be changed to account for different styles of inhalation or air flow, according to user preferences. For example a variable obstruction can be arranged in the airflow channel such that the airflow rate can be modified.

Aerosol is generated in the air flow channel 18 by the oscillating air flow (i.e. the jet of air moving between the two flow patterns/states) striking against liquid injected into the air flow channel 18 through the liquid injection aperture 26. In other words as the air flow oscillates in the air flow channel 18 the air is flowing periodically and perpendicularly against the liquid injected from the liquid inlet 26. The liquid is broken into smaller droplets when the jet of air is struck against the liquid, and the droplets are further drawn into the jet of air and carried toward the air outlet 16. Liquid may be injected at any position along the air flow channel 18 (i.e. before, after or within the fluid oscillation circuit 28). This means that the fluid oscillation circuit 28 is capable of shifting the flow pattern of the air along substantially the full length the air flow channel 18.

Other liquid dispersion mechanisms may also occur as air and liquid travel along the air flow channel 18. For example liquid that is being carried in the jet of air may be further broken into smaller droplets each time the air flow changes pattern. This may be caused by the fluid flow (of air and liquid) being struck against the inner wall of the air flow channel when the air flow moves from one pattern to the other or simply by the force and change in direction of the fluid flow as the jet of air shifts between the two patterns.

The inhaler 10 is able to provide different distributions of droplet sizes based on the inhalation of a user. This increases the flexibility of aerosol delivery to a user, and allows a user to adjust his or her own intake according to personal preferences. A weaker inhalation may cause the air flow to oscillate at a lower frequency and thereby the injected liquid will be broken into fewer and larger droplets. This may often lead to a stronger taste of the aerosol liquid. A stronger inhalation may cause oscillations at a higher frequency and break the injected fluid up into smaller particles.

Figures 2A and 2B schematically show how an air flow oscillates between a first flow pattern and a second flow pattern in a two-feedback loop fluid oscillation circuit. The first and second flow divergence openings 34, 36 in the air flow channel 18 are preferably oppositely arranged in the air flow channel 18 such that when a jet of air reaches the first position 38, a portion of the jet will diverge through the flow divergence opening that is opposite to the side of the air flow channel which the jet of air is preferentially flowing against. In Figure 2A the air flow is preferentially against the left side of the air flow channel 18. For the purpose of explanation air flowing against the left side of the air flow channel 18 is in the first flow pattern. When the air reaches the first position 38, a portion of the air diverges from the air flow channel 18 through the first flow divergence opening 34 (opposite to the left side of the air flow channel) into the first feedback loop 30. The diverged portion of air flows round the first feedback loop 30 and is returned to the air flow channel 18 through the first flow return opening 40 at second position 44, upstream of the first position 38. The returned portion of air disrupts the air in the air flow channel at the second position 44, where the turbulence causes the air to shift from the left side of the air flow channel 18 to the right side of the air flow channel 18. In other words the air flow in the air flow channel 18 shifts from first flow pattern (along the left side of the channel 18) to the second pattern (along the right side of the channel 18).

When the air preferentially flows against the right side of the air flow channel 18 (in the second pattern), the flow follows the illustration provided by Figure 2B. Figure 2B shows a similar flow pattern to Figure 2A except at the first position 38, a portion of air diverges through the second flow divergence opening 36 (opposite to the right side of the air flow channel) into the second feedback loop 32 and is returned to the air flow channel 18 via the second flow return opening 42, thereby disrupting the airflow to cause it to move back into the first pattern.

Aerosol is generated by injecting liquid into the left side of air flow channel 18 upstream of the fluid oscillation circuit 28 via aperture 26. This means that each time the air flow moves from the second pattern to the first pattern (i.e. from the right side of the channel 18 to the left side of the channel 18) the air flow strikes the liquid injected into the channel 18 at the aperture and breaks it into droplets to generate an aerosol. The droplets at the liquid injection aperture 26 grow or increase in size when the airflow isn’t flowing on that side of the airflow channel (i.e. when the air flow is preferentially flowing along the side of the air flow channel that is opposite to the aperture). The growth of a droplet is then terminated when the airflow passes over the injection point and carries the droplet into the jet stream or strikes the droplet into smaller vapour particles. It should be understood that the aperture 26 can also be provided at the right side of the channel 18, where an aerosol would be generated as the air flow shifts from the first pattern to the second pattern. In other words the liquid injection aperture 26 can be arranged at either side of or at multiple positions along the air flow channel 18, where the oscillating air flow will strike the injected liquid to create vapour particles. In another example the aperture 26 is positioned in the oscillating air region within and beyond the fluid oscillation circuit 28. This has the advantage of further reducing the droplet sizes.

Figures 3A and 3B show an alternative fluid oscillation circuit 50 which comprises only a single feedback loop 52. The fluid oscillation circuit 50 comprises one inlet channel 54 and two outlets channels 56, 58. The feedback loop 52 is positioned downstream of the inlet channel 54 and upstream of a split point 60 where the air flow path is split to flow toward the first outlet channel 56 or the second outlet channel 58. The walls of the inlet channel 54 and the outlet channels 56, 58 are configured such that air flowing along one side of the inlet channel 54 will move away from inlet channel 54 as it passes the split point 60 and stick to the wall of the outlet channel which is opposite to the attached air flow in the inlet channel 54. This is provided by constricting the inlet channel 54 as it approaches the split point 60 and expanding outwards to the two outlet channels beyond the split point 60. The feedback loop 52 has a first opening 62 and a second opening 64 which are provided at opposing sides of the split point 60 in the air flow channel 18. Upper and lower liquid injection points 66, 68 are positioned downstream of the feedback loop 52 and upstream of the two outlet channels 56, 58. In this embodiment the liquid injection points 66, 68 have been arranged downstream of the feedback loop 52, but it should be understood that the liquid injection point(s) may be positioned in different arrangements or combinations in the fluid oscillation circuit. For example in another embodiment of the invention, liquid injection point or points can also be positioned upstream of the feedback loop along the inlet channel 54.

By way of example with reference to Figure 3A, when air flows along the lower side of the inlet channel 54 (due to the Coanda effect) it leaves the inner wall of the inlet channel 54 at the split point 60 and follows a similar flow trajectory and sticks to the inner wall of the first outlet channel 56. Conversely, air flowing along the upper side of the inlet channel 54 separates from the inlet channel 54 wall at the split point 60 and continues onto the inner wall of the second outlet channel 58.

For the purpose of explanation, air flows along the lower side of the inlet channel 54 and through the first outlet channel 56 in the first flow pattern, and flows along the upper side of the inlet channel 54 and through the second outlet channel 58 in the second pattern.

When air flows through the fluid oscillation circuit 50 in the first pattern, a portion of the air diverges from the air flow path and enters the first opening 62 as the remaining air carries on to flow through the first outlet channel 56. The diverged portion of air flows through the feedback loop 52 and is returned to the air flow path via the second opening 64. The returned portion of air causes the air to flow toward the second outlet channel 58 which thereby moves the air flow path from the first pattern to the second pattern. Conversely in the second pattern, a portion of air diverges from the air flow path into the second opening 62 and flows through the feedback loop 52 (in an opposite direction to the flow in the first state) to re-enter the air flow path through the first opening 60, thereby causing the air flow to shift from the second pattern to the first pattern.

Liquid is injected into air flow downstream of the single feedback loop 52 via upper and lower injection points 66, 68. As air moves from the lower side of the air flow channel to the upper side of the air flow channel, aerosol is generated when the air strikes upper side of the channel which knocks the liquid injected from the upper injection point 66 and breaks the injected liquid into droplets. The generated aerosol is then delivered to the user via outlet channel 56. Similarly aerosol is generated when the air moves from the second pattern to the first pattern and the flowing jet of air knocks liquid injected into the channel via lower injection point 68. It should be understood that the alternative fluid oscillation circuit 50 may be interchanged with the fluid oscillation circuit 28 in Figure 1 to provide an inhaler according to the present invention. The two outlet channels 56, 58 in the alternative fluid oscillation circuit 50 may be combined downstream of the circuit in the inhaler such that a combined flow is provided to a user at the air outlet 16.

Figure 4 shows an aerosol generation device 80 in another embodiment of the invention. The aerosol generation device 82 has a main channel 82 extending between an air inlet 84 and a vapour outlet 86, where the channel 82 is configured to receive air stream from the air inlet 84 and direct the air stream toward the vapour outlet 86 along an air flow path. A mouthpiece 88 is arranged around the vapour outlet 86 for a user to comfortably inhale vapour generated by the device 80.

A fluid oscillation circuit 90 is provided in the aerosol generation device 80 which may be the circuit described in reference to Figures 2A and 2B or Figures 3A and 3B. The device 80 further comprises a liquid injection mechanism 92 comprising a liquid store 94, a pump 96 and liquid lines leading to liquid injectors 98. In use the pump 96 pushes liquid in the store 94 through the lines to be injected into the main channel 82 via the injectors 98, thereby introducing liquid into the air flow. In this embodiment the liquid injectors 98 are arranged upstream of the fluid oscillation circuit 90 in Figure 4. However it should be understood that the injectors 98 may be positioned at any point along the main channel 82, i.e. upstream, within or downstream of the fluid oscillation circuit 90 in order to inject liquid into the air stream.

Aerosol is generated when liquid is injected into the main channel 82. This may be on the left side or the right side or even both sides of the main channel 82. As air flows through the main channel 82 the fluid oscillation circuit 90 causes the air to continually fluctuate between a first pattern and a second pattern, where in the first pattern the air preferentially flows against the left side of the main channel 82 and in the second pattern the airflows preferentially against the right side of the channel 82. When the air shifts pattern, the air flow strikes the opposite of the channel 82 and breaks any liquid that has been injected at that side of the channel 82 into droplets. These droplets are taken up by the air flow to create an aerosol. In use the liquid is continually injected or replenished at the injection points and the oscillatory motion of the air flow will produce a steady stream of aerosol at the vapour outlet 86.

The pump 96 is powered by a battery 100 in the device. It should be clear that it is not essential for the pump 96 to be electric-powered, and can be another liquid injection mechanism such as a Venturi pump, a wick, or a liquid line that uses capillary action to draw liquid from the store 94 to the main channel 82. The battery 100 is also used to provide electrical energy to a heater 102 arranged around the main channel 82 downstream of the fluid oscillation circuit 90. By providing the heater 102 downstream of the circuit 90 the aerosol generated by the fluid oscillation circuit 90 can be heated to a user’s preference before it is delivered to a user via the vapour outlet 86.

As explained above the heater 102 can also be positioned at any point along the main channel 82, where the position of the heater can provide different functions to the device, such as increased vaporisation within the circuit 90 or a drying function of the feedback loop(s) and channel 82.

The aerosol generation device 80 also comprises a printed circuit board 104 to control the electrical components in the device 80, and a charging port 106 for charging the battery 100.

Different configurations for arranging the heater 102, liquid injection mechanism 92 and other electrical components would readily occur to a person skilled in the art. Importantly it should be understood that the fluid oscillation circuit and aerosol generation technique described in the present invention can be used to provide a non-electric aerosol generation device or provide increased functionality to electric aerosol generation devices in the art.