User identification system and method

Abstract

A user identification system for an aerosol provision system, the user identification system comprising: a PPG sensor; and a user identification module configured for providing an indication of the identity of a user of the aerosol provision system, wherein the user identification module is configured to: receive a signal from the PPG sensor, identify a value for one or more identification features from the received signal, compare the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and output a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison.

Description

[0001] USER IDENTIFICATION SYSTEM AND METHOD

[0002] Field

[0003] The present disclosure relates to user identification systems for electronic aerosol provision systems such as nicotine delivery systems (e.g. electronic cigarettes and the like).

[0004] Background

[0005] Electronic aerosol provision systems such as electronic cigarettes (e-cigarettes) generally contain a reservoir of a source liquid containing a formulation, typically including nicotine, from which an aerosol is generated, e.g. through heat vaporisation. An aerosol source for an aerosol provision system may thus comprise a heater having a heating element arranged to receive source liquid from the reservoir, for example through wicking / capillary action. While a user inhales on the device, electrical power is supplied to the heating element to vaporise source liquid in the vicinity of the heating element to generate an aerosol for inhalation by the user. Such devices are usually provided with one or more air inlet holes located away from a mouthpiece end of the system. When a user sucks on a mouthpiece connected to the mouthpiece end of the system, air is drawn in through the inlet holes and past the aerosol source. There is a flow path connecting between the aerosol source and an opening in the mouthpiece so that air drawn past the aerosol source continues along the flow path to the mouthpiece opening, carrying some of the aerosol from the aerosol source with it. The aerosol-carrying air exits the aerosol provision system through the mouthpiece opening for inhalation by the user.

[0006] Because such electronic aerosol provision systems often contain nicotine, in many territories across the world their use is regulated. In particular, it is often prohibit to sell such systems to underage persons. However, even if the sale of the aerosol provision systems are regulated and controlled, there are concerns over the unauthorised use of these aerosol provision systems, whether this be in respect of underage persons or other persons.

[0007] Various approaches are described which seek to help address some of these issues.

[0008] Summary

[0009] According to a first aspect of certain embodiments there is provided a user identification system for an aerosol provision system, the user identification system including a PPG sensor and a user identification module configured for providing an indication of the identity of a user of the aerosol provision system. The user identification module is configured to receive a signal from the PPG sensor, identify a value for one or more identification features from the received signal, compare the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and output a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison.

[0010] According to a second aspect of certain embodiments there is provided a system for providing aerosol to a user, the system including the user identification system of the first aspect; and an aerosol provision system comprising a controller for controlling operations of the aerosol provision system.

[0011] According to a third aspect of certain embodiments there is provided a method of identifying a user of an aerosol provision system using a user identification system, the user identification system comprising a PPG sensor and a user identification module. The method includes receiving a signal from the PPG sensor, identifying a value for one or more identification features from the received signal, comparing the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and outputting a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison.

[0012] According to a fourth aspect of certain embodiments there is provided user identification means for an aerosol provision means, the user identification means including PPG sensor means and user identification module means configured for providing an indication of the identity of a user of the aerosol provision means. The user identification module means is configured to receive a signal from the PPG sensor means, identify a value for one or more identification features from the received signal, compare the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and output a result of the comparison to controller means of an aerosol provision means, the controller means configured to control one or more operations of the aerosol provision means responsive to the result of the comparison.

[0013] It will be appreciated that features and aspects of the invention described above in relation to the first and other aspects of the invention are equally applicable to, and may be combined with, embodiments of the invention according to other aspects of the invention as appropriate, and not just in the specific combinations described above.

[0014] Brief Description of the Drawings

[0015] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic overview of a system comprising an aerosol provision system, comprised of an aerosol provision device and a cartridge, and a user identification system comprised of a PPG sensor and a user identification module, in accordance with aspects of the present disclosure;

[0016] Figure 2 shows two graphs of a typical PPG sensor signal representative of a user’s heart beat, including indications of several identification features associated with the PPG sensor signal;

[0017] Figure 3 shows an example method for performing a user identification based on PPG sensor signals in accordance with aspects of the present disclosure;

[0018] Figure 4 shows an implementation of the system of Figure 1 , where the user identification system is provided in a remote device communicatively coupled to the aerosol provision system in accordance with aspects of the present disclosure; and

[0019] Figure 5 shows an implementation of the system of Figure 1 , where the user identification system is provided as part of (i.e. , integrated with) the aerosol provision system in accordance with aspects of the present disclosure.

[0020] Detailed Description

[0021] Aspects and features of certain examples and embodiments are discussed / described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed / described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

[0022] The present disclosure relates to delivery systems encompassing non-combustible aerosol provision systems that release compounds from an aerosol-generating material without combusting the aerosol-generating material, such as electronic cigarettes, tobacco heating products, and hybrid systems to generate aerosol using a combination of aerosol-generating materials. 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.

[0023] Aerosol-generating material is a 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 liquid or gel which may or may not contain an active substance and / or flavourants. In some implementations, 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 implementations, 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 implementations, 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.

[0024] In some embodiments, the or each aerosol-generating material may comprise one or more active constituents, one or more flavours, one or more aerosol-former materials, and / or one or more other functional materials.

[0025] The active substance as used herein may be a physiologically active material, which is a material intended to achieve or enhance a physiological response. The active substance may for example be selected from nutraceuticals, nootropics, psychoactives. The active substance may be naturally occurring or synthetically obtained. The active substance may comprise for example nicotine, caffeine, taurine, theine, vitamins such as B6 or B12 or C, melatonin, cannabinoids, or constituents, derivatives, or combinations thereof. The active substance may comprise one or more constituents, derivatives or extracts of tobacco, cannabis or another botanical.

[0026] In some embodiments, the active substance comprises nicotine. In some embodiments, the active substance comprises caffeine, melatonin or vitamin B12.

[0027] As noted herein, the active substance may comprise or be derived from one or more botanicals or constituents, derivatives or extracts thereof. As used herein, the term "botanical" includes any material derived from plants including, but not limited to, extracts, leaves, bark, fibres, stems, roots, seeds, flowers, fruits, pollen, husk, shells or the like. Alternatively, the material may comprise an active compound naturally existing in a botanical, obtained synthetically. The material may be in the form of liquid, gas, solid, powder, dust, crushed particles, granules, pellets, shreds, strips, sheets, or the like. Example botanicals are tobacco, eucalyptus, star anise, hemp, cocoa, cannabis, fennel, lemongrass, peppermint, spearmint, rooibos, chamomile, flax, ginger, ginkgo biloba, hazel, hibiscus, laurel, licorice (liquorice), matcha, mate, orange skin, papaya, rose, sage, tea such as green tea or black tea, thyme, clove, cinnamon, coffee, aniseed (anise), basil, bay leaves, cardamom, coriander, cumin, nutmeg, oregano, paprika, rosemary, saffron, lavender, lemon peel, mint, juniper, elderflower, vanilla, Wintergreen, beefsteak plant, curcuma, turmeric, sandalwood, cilantro, bergamot, orange blossom, myrtle, cassis, valerian, pimento, mace, damien, marjoram, olive, lemon balm, lemon basil, chive, carvi, verbena, tarragon, geranium, mulberry, ginseng, theanine, theacrine, maca, ashwagandha, damiana, guarana, chlorophyll, baobab or any combination thereof. The mint may be chosen from the following mint varieties: Mentha Arventis, Mentha c.v., Mentha niliaca, Mentha piperita, Mentha piperita citrata c.v..Mentha piperita c.v, Mentha spicata crispa, Mentha cardifolia, Memtha longifolia, Mentha suaveolens variegata, Mentha pulegium, Mentha spicata c.v. and Mentha suaveolens.

[0028] In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is tobacco.

[0029] In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is selected from eucalyptus, star anise, cocoa and hemp.

[0030] In some embodiments, the active substance comprises or derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is selected from rooibos and fennel.

[0031] As used herein, the terms "flavour" and "flavourant" refer to materials which, where local regulations permit, may be used to create a desired taste, aroma or other somatosensorial sensation in a product for adult consumers. 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.

[0032] 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 comprises flavour components extracted from cannabis.

[0033] 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 eucolyptol, WS-3.

[0034] The aerosol-former material may comprise one or more constituents capable of forming an aerosol. In some embodiments, the aerosol-former material may comprise one or more of glycerine, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-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.

[0035] The one or more other functional materials may comprise one or more of pH regulators, colouring agents, preservatives, binders, fillers, stabilizers, and / or antioxidants.

[0036] An aerosol-modifying agent is a substance, typically located downstream of the aerosol generation area, that is configured to modify the aerosol generated, for example by changing the taste, flavour, acidity or another characteristic of the aerosol. The aerosol-modifying agent may be provided in an aerosol-modifying agent release component, that is operable to selectively release the aerosol-modifying agent.

[0037] The aerosol-modifying agent may, for example, be an additive or a sorbent. The aerosolmodifying agent may, for example, comprise one or more of a flavourant, a colourant, water, and a carbon adsorbent. The aerosol-modifying agent may, for example, be a solid, a liquid, or a gel. The aerosol-modifying agent may be in powder, thread or granule form. The aerosol-modifying agent may be free from filtration material.

[0038] According to the present disclosure, a “non-combustible” aerosol provision system is one where a constituent aerosol-generating material of the aerosol provision system (or component thereof) is not combusted or burned in order to facilitate delivery of at least one substance to a user.

[0039] In some embodiments, the non-combustible aerosol provision system is an electronic cigarette, also known as a vaping device, electronic cigarette or electronic nicotine delivery system (END), although it is noted that the presence of nicotine in the aerosol-generating material is not a requirement. Throughout the following description the term “e-cigarette” is sometimes used but this term may be used interchangeably with aerosol (vapour) provision system.

[0040] In some embodiments, the non-combustible aerosol provision system is an aerosolgenerating material heating system, also known as a heat-not-burn system. An example of such a system is a tobacco heating system.

[0041] 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 aerosolgenerating material. The solid aerosol-generating material may comprise, for example, tobacco or a non-tobacco product.

[0042] Typically, the non-combustible aerosol provision system may comprise a non-combustible aerosol provision device and a consumable for use with the non-combustible aerosol provision device. In some embodiments, the disclosure relates to consumables comprising aerosol-generating material and configured to be used with non-combustible aerosol provision devices. These consumables are sometimes referred to as articles throughout the disclosure.

[0043] A consumable is an article comprising or consisting of aerosol-generating material, part or all of which is intended to be consumed during use by a user. A consumable may comprise one or more other components, such as an aerosol-generating material storage area, an aerosol-generating material transfer component, an aerosol generation area, a housing, a wrapper, a mouthpiece, a filter and / or an aerosol-modifying agent. A consumable may also comprise an aerosol generator, such as a heater, that emits heat to cause the aerosolgenerating material to generate aerosol in use. The heater may, for example, comprise combustible material, a material heatable by electrical conduction, or a susceptor.

[0044] In some embodiments, the non-combustible aerosol provision system, such as a non- combustible aerosol provision device thereof, may comprise a power source and a controller. The power source may, for example, be an electric power source. In some embodiments, the non-combustible aerosol provision system may comprise an area for receiving the consumable, an aerosol generator, an aerosol generation area, a housing, a mouthpiece, a filter and / or an aerosol-modifying agent.

[0045] An aerosol generator is an apparatus configured to cause aerosol to be generated from the aerosol-generating material. In some embodiments, the aerosol generator is a heater configured to subject the aerosol-generating material to heat energy, so as to release one or more volatiles from the aerosol-generating material to form an aerosol. In some embodiments, the aerosol generator is configured to cause an aerosol to be generated from the aerosol-generating material without heating. For example, the aerosol generator may be configured to subject the aerosol-generating material to one or more of vibration, increased pressure, or electrostatic energy.

[0046] The following description will focus on embodiments in which the aerosol provision system is one in which a source liquid as the aerosol-generating material is vaporised to generate an aerosol for user inhalation. In such embodiments, the article is more commonly referred to as a cartridge. The cartridge mechanically engages with the aerosol provision device as described above. However, it should be appreciated that the principles of the present disclosure are applicable to aerosol provision systems capable of vaporising different aerosol-generating materials, such as solids or gels, as described above.

[0047] The present disclosure relates to a user identification system for use with an aerosol provision system. The user identification system comprises a user identification module and a PPG sensor. The user identification module is arrange to provide an indication of the identity of a user of the aerosol provision system based on identifying a value for one or more identification features from a signal received from the PPG sensor, compare the identified value for the identification features to a corresponding reference value for the features obtained in advance, and output a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison. In this way, the identity of a user, relative to an authorised user known to the user identification module, can be determined using PPG sensor signals. The identity of a user can be determined in a non- invasive and convenient manner using the PPG sensors. By determining the identity of a user, the aerosol provision system can be controlled responsive to that determination; for example, by locking the aerosol provision system (i.e., preventing aerosol generation) when the user is not identified as a known user or by unlocking the aerosol provision system (i.e., allowing aerosol generation) when the user is identified as a known user. Thus, a convenient and non-invasive way of restricting usage of the aerosol provision system 1 may be implemented. Figure 1 schematically represents a system in accordance with certain aspects of the disclosure. The system comprises an aerosol provision system 1 (shown in cross-section in Figure 1) and a user identification system 100.

[0048] The aerosol provision system 1 shown in Figure 1 comprises two main components, namely an aerosol provision device 2 and a replaceable / disposable cartridge 4 (which is an example of a consumable or article). The aerosol provision system 1 of Figure 1 is an example of a modular construction of an aerosol provision system 1. In this regard, the aerosol provision device 2 and the cartridge 4 are able to engage with or disengage from one another at an interface 6. However, as mentioned above, the principles of the present disclosure also apply to other constructions of the aerosol provision system 1, such as one- part or unitary constructions where the device 2 and cartridge 4 may be integrally formed (or in other words, the aerosol provision device 1 is provided with an integrally formed aerosolgenerating material storage area or portion), or for tobacco heating products where a consumable or article comprising tobacco is inserted into an aerosolisation (e.g., heating) chamber of an aerosol provision device.

[0049] In this example, the aerosol provision system 1 is generally elongate and cylindrical in shape. The aerosol provision system 1 may be sized so as to approximate a conventional cigarette. However, it should be understood that the general size and shape of the aerosol provision system 1 is not significant to the principles of the present disclosure. In some other implementations, the aerosol provision system 1 may conform to different overall shapes; for example, the aerosol provision device 2 may be based on so-called box-mod high performance devices that typically have a more box-like shape.

[0050] The device 2 comprises components that are generally intended to have a longer lifetime than the cartridge 4. In other words, the device 2 is intended to be used, sequentially, with multiple cartridges 4. The cartridge 4 comprises components (such as aerosol-generating material) that are consumed when forming an aerosol for delivery to the user during use of the aerosol provision system 1.

[0051] In the example modular configuration of Figure 1, the device 2 and the cartridge 4 are releasably coupled together at the first interface 6. When the aerosol-generating material in the cartridge 4 is exhausted or the user simply wishes to switch to a different cartridge 4 (e.g., containing a different aerosol-generating material), the cartridge 4 may be removed from the device 2 and a replacement cartridge 4 attached to the device 2 in its place. The interface 6 provides a structural connection between the device 2 and cartridge 4 and may be established in accordance with broadly conventional techniques, for example based around a screw thread, latch mechanism, bayonet fixing or magnetic coupling. In some implementations, the interface 6 may also provide an electrical coupling between the device 2 and the cartridge 4 using suitable electrical contacts. The electrical coupling may allow for power and / or data to be supplied to / from the cartridge 4.

[0052] It should also be understood that in some implementations, the cartridge 4 may be refillable. That is, the cartridge 4 may be refilled with aerosol-generating material when the cartridge 4 is depleted, using an appropriate mechanism such as a one-way refilling valve or the like. The cartridge 4 may be removed from the device 2 in order to be refilled. In other examples, the cartridge 4 may be configured so as to be refilled while attached to the device 2.

[0053] In implementations where the aerosol provision system 1 is a one-part or unitary system, the aerosol provision system 1 may be designed to be disposable once the aerosol-generating material is exhausted. Alternatively, the aerosol provision system 1 may be provided with a suitable mechanism, such as a one-way valve or the like, to enable the integrated cartridge 4 (or integrated aerosol-generating material storage area) to be refilled with aerosol-generating material.

[0054] In Figure 1, the cartridge part 4 comprises a cartridge housing 42, an aerosol-generating material storage area 44, an aerosol generator 48, an aerosol-generating material transport component 46, an outlet or opening 50, and an air path 52.

[0055] The cartridge housing 42 supports other components of the cartridge 4 and provides the mechanical interface 6 with the device 2. The cartridge housing 42 is formed from a suitable material, such as a plastics material or a metal material. In the described implementation, the cartridge housing 42 is generally circularly symmetric about a longitudinal axis along which the cartridge 4 couples to the device 2. In this example the cartridge 4 has a length of around 4 cm and a diameter of around 1.5 cm. However, it will be appreciated the specific geometry, and more generally the overall shapes, may be different in different implementations. The cartridge 4 comprises a first end, broadly defined by the interface 6, and a second end which is opposite the first end and includes the opening 50. The second end including the opening is intended to be received in / by a user’s mouth and may be referred to as a mouthpiece end of the cartridge 4.

[0056] Within the cartridge housing 42 is an aerosol-generating material storage area 44, which may be referred to herein as a reservoir 44. The cartridge 42 of Figure 1 is configured to store a liquid aerosol-generating material, which may be referred to herein as a source liquid, e-liquid or liquid. The source liquid may be broadly conventional, and may contain nicotine and / or other active ingredients, and / or one or more flavours, as described above. In some implementations, the source liquid may contain no nicotine. The reservoir 44 is suitably configured to hold or retain liquid therein. The reservoir 44 in this example has an annular shape with an outer wall defined by the cartridge housing 42 and an inner wall that defines an air path 52 through the cartridge 4. The reservoir 44 is closed at each end with end walls to contain the liquid. The reservoir 44 may be formed in accordance with conventional techniques, for example it may comprise a plastics material and be integrally moulded with the cartridge housing 42.

[0057] The cartridge 4 further comprises an aerosol generator 48. The aerosol generator 48 is an apparatus configured to cause aerosol to be generated from the aerosol-generating material (e.g., the source liquid). The cartridge 4 further comprises the aerosol-generating material transport component 46, which is configured to transport the aerosol-generating material from the aerosol-generating material storage area 44 (e.g., reservoir 44) to the aerosol generator 48. In some implementations, the aerosol-generating material transport component 46 may be integrated with the aerosol generator 48 to form a combined aerosol generator 48 and aerosol-generating material transport component 46.

[0058] The aerosol generator 48 is configured to cause aerosol to be generated from the aerosolgenerating material. In some implementations, the aerosol generator 48 is a heater 48. The heater 48 is configured to subject the aerosol-generating material to heat energy, so as to release one or more volatiles from the aerosol-generating material to form an aerosol. By way of example, the heater 48 may take the form of an electrically resistive wire or trace intended to have electrical current passed between ends thereof, or a susceptor element which is intended to generate heat upon exposure to an alternating magnetic field. However, in other implementations, the aerosol generator 48 is configured to cause an aerosol to be generated from the aerosol-generating material without heating. For example, the aerosol generator 48 may be configured to subject the aerosol-generating material to one or more of vibration, increased pressure, or electrostatic energy.

[0059] The aerosol-generating material transport element 46 is configured to transport aerosolgenerating material from the aerosol-generating material storage area 44 (reservoir 44) to the aerosol generator 48. The nature of the aerosol-generating material may dictate the form of the aerosol-generating material transport element 46. For example, for a liquid or viscous gel aerosol-generating material, the aerosol-generating material transport element 46 is configured to transport the liquid or viscous gel aerosol-generating material using capillary action. For example, the aerosol-generating material transport element 46 may comprise a porous material (e.g., ceramic) or a bundle of fibres (e.g., glass or cotton fibres) capable of transporting liquid / viscous gel using capillary action.

[0060] In the described implementation of Figure 1, the aerosol generator 48 is a heater 48 taking the form of a coil of metal wire, such as a nickel chrome alloy (Cr20Ni80) wire. The aerosol- generating material transport element 46 in the implementation of Figure 1 is a wick 46 taking the form of a bundle of fibres, such as glass fibres. The heater 48 is wound around the wick 46 as seen in Figure 1 such that the heater 48 is provided in the proximity of the wick 46 and therefore also to any liquid held in the wick 46. In some other implementations, the aerosol generator 48 may comprise a porous ceramic wick 46 and an electrically conductive track disposed on a surface of the porous ceramic wick acting as the heater 48. In yet other implementations, the heater 48 and wick 46 may be combined into a single component, e.g., a plurality of sintered steel fibres forming a planar structure.

[0061] The heater 48 and wick 46 are located towards an end of the reservoir 44. In this example, the wick 46 extends transversely across the cartridge air path 52 with its ends extending into the reservoir 44 of liquid through openings in the inner wall of the reservoir 44. The openings in the inner wall of the reservoir are sized to broadly match the dimensions of the wick 46 to provide a reasonable seal against leakage from the liquid reservoir 44 into the cartridge air path 52 without unduly compressing the wick 46, which may be detrimental to its fluid transfer performance. The wick 46 is therefore configured to transport liquid from the reservoir 44 to the vicinity of the heater 48 via a capillary effect.

[0062] The wick 46 and heater 48 are arranged in the cartridge air path 52 such that a region of the cartridge air path 52 around the wick 46 and heater 48 in effect defines a vaporisation region for the cartridge 4. This vaporisation region is the region of the cartridge 4 where vapour is initially generated. In use, electrical power may be supplied to the heater 48 to vaporise an amount of liquid drawn to the vicinity of the heater 48 by the wick 46.

[0063] Aerosol is delivered to the user via the outlet 50 provided at the mouthpiece end of the cartridge 4. During use, the user may place their lips on or around the mouthpiece end of the cartridge 4 and draw air / aerosol through the outlet 50. More specifically, air is drawn into and along the air path 52, past the aerosol generator 48 where aerosol is entrained into the air, and the combined aerosol / air is then inhaled by the user through the opening 50. Although Figure 1 shows the mouthpiece end of the cartridge 4 as being an integral part of the cartridge 4, a separate mouthpiece component may be provided which releasably couples to the end of the cartridge 4.

[0064] The device 2 comprises an outer housing 12, an optional indicator 14, an inhalation sensor 16 located within a chamber 18, a controller or control circuitry 20, a power source 26, an air inlet 28 and an air path 30.

[0065] The device part 2 comprises an outer housing 12 with an opening that defines an air inlet 28 for the aerosol provision system 1, a power source 26 for providing operating power for the aerosol provision system 1 , a controller or control circuitry 20 for controlling and monitoring the operation of the aerosol provision system 1, and an inhalation sensor (puff detector) 16 located in a chamber 18. The device 2 further comprises an optional indicator 14.

[0066] The outer housing 12 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 cartridge 4 so as to provide a smooth transition between the two parts at the interface 6. In this example, the device 2 has a length of around 8 cm so the overall length of the aerosol provision system 1 when the cartridge 4 and device 2 are coupled together is around 12 cm. However, and as already noted, it will be appreciated that the overall shape and scale of an aerosol provision system 1 implementing the present disclosure is not significant to the principles described herein.

[0067] The outer housing 12 further comprises an air inlet 28 which connects to an air path 30 provided through the device 2. The device air path 30 in turn connects to the cartridge air path 52 across the interface 6 when the device 2 and cartridge 4 are connected together. In this regard, the interface 6 is also arranged to provide a connection of the respective air paths 30 and 52, such that air and / or aerosol is able to pass along the coupled air paths 30, 52. In other implementations, the device 2 does not comprise an air path 30 and instead the cartridge 4 comprises the air path 52 and a suitable air inlet which permits air to enter into the air path 52 when the cartridge 4 and device 2 are coupled.

[0068] The power source 26 in this example is a battery 26. The battery 26 may be rechargeable and may be of a broadly conventional type, for example of the kind normally used in aerosol provision systems and other applications requiring provision of relatively high currents over relatively short periods. The battery 26 may be, for example, a lithium ion battery. The battery 26 may be recharged through a suitable charging connector provided at or in the outer housing 12, for example a USB connector. Additionally or alternatively, the device 2 may comprise suitable circuitry to facilitate wireless charging of the battery 26.

[0069] The control circuitry 20 is suitably configured / programmed to control the operation of the aerosol provision system 1. The control circuitry 20 may be considered to logically comprise various sub-units / circuitry elements associated with different aspects of the aerosol provision system's operation and may be implemented by provision of a (micro)controller, processor, ASIC or similar form of control chip. The control circuitry 20 may be arranged to control any functionality associated with the system 1. By way of non-limiting examples only, the functionality may include the charging or re-charging of the battery 26, the discharging of the battery 26 (e.g., for providing power to the heater 48), in addition to other functionality such as controlling visual indicators (e.g., LEDs) / displays, communication functionality for communicating with external devices, etc. The control circuitry 20 may be mounted to a printed circuit board (PCB). Note also that the functionality provided by the control circuitry 20 may be split across multiple circuit boards and / or across components which are not mounted to a PCB, and these additional components and / or PCBs can be located as appropriate within the aerosol provision device. For example, functionality of the control circuit 20 for controlling the (re)charging functionality of the battery 26 may be provided separately (e.g. on a different PCB) from the functionality for controlling the discharge of the battery 26.

[0070] As noted above, when the device 2 and the cartridge 4 are coupled together at interface 6, the interface 6 provides an electrical connection between the device 2 and the cartridge 4. More particularly, electrical contacts on the device 2, which are coupled to the power source 26, are electrically coupled to electrical contacts on the cartridge, which are coupled to the heater 48. Accordingly, under suitable control by the control circuitry 20, electrical power from the power source 26 is able to be supplied from the power source 26 to the heater 48, thereby allowing the heater 48 to vaporise liquid in the proximity of the heater 48 held in the wick 46.

[0071] In the example of Figure 1, the aerosol provision device 2 comprises a chamber 18 containing the inhalation sensor 16, which in this example is a pressure sensor 16. However, the inhalation sensor 16 may be any suitable sensor, such as an air flow sensor, for sensing when a user inhales on the mouthpiece end of the cartridge 4 and subsequently draws air along the air paths 30, 52. Accordingly, the presence of the chamber 18 is optional and its presence may depend on the characteristics of the selected inhalation sensor 16.

[0072] The pressure sensor 16 is in fluid communication with the air path 30 in the device 2 (e.g. the chamber 18 branches off from the air path 30 in the device 2). Thus, when a user inhales on the opening 50, there is a drop in pressure in the chamber 18, which if sufficient, is detected by the pressure sensor 16. The aerosol provision system 1 is controlled to generate aerosol in response to detecting an inhalation by a user. That is, when the pressure sensor 16 detects a drop in pressure in the pressure sensor chamber 18, the control circuitry 20 responds by causing electrical power to be supplied from the battery 26 to the aerosol generator 48 sufficient to cause vaporisation of the liquid held within the wick 46. This is an example of an aerosol provision system which is said to be “puff actuated”. The pressure sensor 16 may be used to start and / or end the power supply to the heater 48 (e.g., when the pressure sensor detects the absence of an inhalation).

[0073] In other implementations, the aerosol provision system 1 includes a button or other user actuatable mechanism. When the button or other user actuatable mechanism is actuated by the user, the control circuitry 20 caused power to be supplied to the heater 48 as described above. This is an example of an aerosol provision system which is said to be “button actuated”. The button may be used to start and / or end power supply to the heater 48 (e.g., when the button is released by the user). In some implementations, both a button (or other user actuatable mechanism) and an inhalation sensor 16 may be used to control the delivery of power to the heater 48, e.g., by requiring both the button press and a pressure drop indicative of an inhalation to be present before supplying power to the heater 48.

[0074] The user identification system 100 is shown comprised of two main parts: a photoplethysmography (PPG) sensor 102 and a user identification module 104.

[0075] The PPG sensor 102 is a sensor configured to obtain and output a plethysmogram through optical means in accordance with broadly conventional techniques. A typical plethysmogram is shown in Figure 2 (explained in more detail below). A typical PPG sensor 102 comprises a light source, such as an LED or the like, and a photodetector. The light sensor illuminates a region of the user’s skin, and the photodetector receives a corresponding light signal (this may be reflected from or transmitted through the user’s skin depending on the configuration of the PPG sensor 102). In accordance with the present disclosure, the PPG sensor 102 may be any conventional PPG sensor.

[0076] The user identification module 104 is capable of receiving the output signal from the PPG sensor 102 and performing processing thereon. Thus, the user identification module 104 may be embodied as a suitable computer, (micro)controller or the like having suitable processing capabilities. In addition, the user identification 104 may be provided with suitable communication capabilities, i.e., it may have a suitable input / output interface, to allow reception and transmission of various signals. The user identification module 104 may be arranged to receive / transmit the signals via a wired or wireless (such as Bluetooth™) mechanism depending on the implementation at hand.

[0077] As will be explained in more detail below, the user identification module 104 is configured to obtain an output signal from the PPG sensor 102, analyse the signal from the PPG sensor 102 and identify a value (or multiple values) for certain characteristic features from the received signal, and then perform a comparison of the identified value(s) for the characteristic features to corresponding reference value(s) obtained in advance. The reference values obtained in advance may be determined for a given user, for example during a learning or training phase of operation of the PPG sensor 102 for the given user. Hence, the comparison is performed to compare current values for the characteristic feature(s) against reference values corresponding to a particular user. Accordingly, based on the result of the comparison, the identification module 104 is capable of outputting a result of the comparison to e.g., the control circuitry 20 of the aerosol provision system 1, which may be considered indicative of an identification of the current user to a previously determined or identified user.

[0078] Figure 2 shows a typical plethysmogram (herein referred to as PPG signal). Figure 2 shows the amplitude, A, of PPG signal (along the y-axis in arbitrary units) as a function of time, t (along the x-axis in arbitrary units). The PPG signal typically detects changes of blood volume or blood flow by illuminating a region of a user’s skin with light (e.g., infrared light) and measuring the changes in light absorption. Accordingly, the PPG signal is representative of a user’s heart beat and / or heart rate. It should be appreciated that certain regions of a user’s skin are more suited to obtaining accurate and precise PPG signals compared to others. For example, the finger tip is generally considered a suitable location for obtaining a PPG signal.

[0079] Without wishing to be bound by theory, the PPG signal typically shows the systolic (contraction) and diastolic (relaxation) phases of a heart beat. Figure 2 shows various points (represented by black dots) along the curve of Figure 2. Generally, the peaks of the curve correspond to the maximum blood volume achieved in the systolic (contraction) phase of the heart beat (and in effect correspond to the maximum blood volume measured in the corresponding vessels) while the troughs of the curve correspond to the minimum blood volume achieved in the diastolic (relaxation) phase of the heart beat (and in effect correspond to the minimum blood volume measured in the corresponding vessels). The systolic phase is generally defined from a trough to the dicrotic notch (shown as point D in Figure 2) and the diastolic phase is defined from the dicrotic notch D to the subsequent trough.

[0080] While it is generally accepted that a person’s heart rate (i.e. the beats per minute) is relatively variable and can vary based on certain factors, such as whether the person is exercising or relaxing for example, the present inventors have identified that certain features or characteristics of a user’s heart beat (as measured via a PPG signal) either remain relatively consistent between heart beats for a given user or are capable of being made consistent with suitable processing of the PPG signal. Moreover, it has been found that at least some of these features allow for potential differentiation between different users. That is to say, for a given user, values for certain so-called identification features or characteristics in the PPG signal are specific to a given user.

[0081] Figure 2 shows two versions of the same typical PPG signal; however, the top graph in Figure 2 shows a first set of features or characteristics of a PPG signal, while the bottom graph shows a second set of features or characteristics of a PPG signal. Taking the top graph first, the following identification features of the PPG signal are able to be defined:

[0082] • a time, ti, between the minimum (i.e. trough) and maximum (i.e. peak) of a given PPG signal in the systolic phase;

[0083] • a time, t2, between the minimum (i.e., trough) and the dicrotic notch, D, of a given PPG signal (which may also be considered the time or duration of the systolic phase);

[0084] • a time difference, At, between the times ti and t2, corresponding to the time between the maximum (i.e. peak) and the dicrotic notch, D, of a given PPG signal;

[0085] • a width or time, Wi, between the mid-point in the amplitude of the rising edge of a peak (i.e., the middle point between the trough and peak in the systolic phase) and the dicrotic notch, D, of a given PPG signal;

[0086] • a width or time, W2, between the mid-point in the amplitude of the rising edge of a peak (i.e., the middle point between the trough and peak in the systolic phase) and the mid-point in the amplitude of the falling edge of a peak (i.e., the middle point between the peak in the subsequent, i.e., later in time, trough) of a given PPG signal;

[0087] • a pulse time interval, tPj, defined between two corresponding points on consecutive pulses (in Figure 2, this is shown as the mid-point of the rising edge of consecutive peaks);

[0088] • an amplitude, y, between the dicrotic notch and the amplitude of the preceding trough (which may also be defined as the difference between the amplitude at the dicrotic notch and the amplitude at the trough);

[0089] • an area, A1, between the minimum (i.e., trough) and dicrotic notch, D, of a given PPG signal (also corresponding to the area of the systolic phase); and

[0090] • an area, A2, between the dicrotic notch, D, and the subsequent minimum (i.e., trough) of a given PPG signal.

[0091] Each of these features is indicated on one of the graphs in Figure 2 for convenience. Although not shown on Figure 2, a further identification feature of the PPG signal can be defined as the root mean square difference of successive pulse to pulse intervals (herein RMSSD). For example, this may be calculated as the square root of the square of tPj of a first pulse minus tPj of a second, consecutive pulse (e.g., RMSSD = / (tPj(1) - tPj(2))2).

[0092] Based on one or more of the abovementioned features, a user identification process in which a PPG sensor signal can be used to identify a user (or to determine whether a user of the PPG sensor 102 is a particular user) has been proposed. According to a first implementation, the user identification module 104 is configured to determine a degree to which an identification feature (i.e., one or more of the features above) of an obtained PPG signal (e.g., from a user) corresponds to an identification feature of PPG signals obtained in advance from an authorised or known user. More particularly, the user identification module 104 is configured to determine to what extent the obtained PPG signal belongs to the authorised or known user.

[0093] According to the first implementation, the user identification module 104 determines a measure, M, according to the following equation:

[0094] M = (Fstore- FM)2(1) where FM is equal to the value of the measured feature of the obtained PPG signal (i.e., the signal currently obtained from the PPG sensor 102) and Fstore is equal to a reference value obtained in advance of feature as determined from a plurality of PPG signals obtained in advance from the authorised user.

[0095] Equation (1) above in effect performs a comparison between a measured value of a particular feature of current PPG sensor signal (i.e., the term FM in equation 1) and a reference value of the same feature of a PPG sensor signal obtained in advance and corresponding to a particular (i.e., authorised) user (i.e., the term Fstore in equation 1).

[0096] In order to describe the process of performing a user identification using Equation (1), reference is made to Figure 3. Figure 3 is a flow diagram representing a method of performing a user identification process using the user identification system 100 according to a first implementation.

[0097] The method starts at step S1, where the reference value for one or more features of the PPG signal (i.e., the one or more features described above) are determined.

[0098] To determine the reference value of a feature of a PPG sensor signal obtained in advance and corresponding to a particular user (i.e., the term Fstore in equation 1), in some implementations, one or more historic PPG sensor signals corresponding to the particular user are obtained in advance of performing any identification process. In some implementations, a single historic PPG sensor signal covering a single heart beat (similar to that shown in Figure 2, for example) is obtained from the particular user. However, to help provide a more reliable and / or accurate identification process, a plurality of historic PPG sensor signals covering a plurality of heart beats are obtained from the particular user.

[0099] For example, in some implementations, at step S1, a first user may perform a learning process using the user identification module 104 and PPG sensor 102. More particularly, the first user may be instructed to perform one or more measurements using the PPG sensor 102 to provide a one or more PPG sensor signals that are then recorded and stored by the user identification module 104. In the case of obtaining multiple PPG sensor signals, the plurality of PPG sensor signals may be obtained over a prolonged period of time, including on different days and / or at different times of the day, in order to record the first user’s PPG signal in a variety of circumstances and thereby help improve the accuracy of the identification process. Regardless, these PPG sensor signals obtained during the learning phase are considered to represent historic PPG sensor signals belonging to the first user.

[0100] Once the historic PPG sensor signals have been obtained, the user identification module 104 is configured to determine a reference value for one or more features of the PPG signal. For example, the user identification module 104 may determine a reference value for the root mean square difference of successive pulse to pulse intervals (RMSSD), the amplitude, y, between the dicrotic notch and the amplitude of the preceding trough, the time, t2, between the minimum (i.e. , trough) and the dicrotic notch, D, etc. When there are a plurality of historic PPG sensor signals, the reference value determined by the user identification module 104 for a given feature may be an average value across all the historic PPG sensor signals from the first user for the feature.

[0101] Accordingly, it should be appreciated that the reference value obtained for a particular feature corresponds to the first (or authorised user) and is obtained or determined in advance of any user identification process being performed.

[0102] In some implementations, instead of performing a learning process as part of step S1, the user identification module 104 may be provided with suitable reference values to use for the corresponding features for the first user. For example, the user identification module 104 may be programmed by a user with suitable reference values or the reference values may be obtained from medical records or other sources. In other words, the principles of the present disclosure extent to the user identification module 104 being provided with, rather than determining, the reference values for the respective features.

[0103] Once the reference values for the corresponding features are determined or obtained, the user identification module 104 is then capable of performing a user identification process.

[0104] At step S2, the user identification module 104 receives a sensor signal form the PPG sensor 102. The sensor signal represents a current PPG sensor signal. It should be appreciated that the current PPG sensor signal may or may not be provided by the first user. Indeed, the PPG sensor signal may be provided by a second user.

[0105] At step S3, the user identification module 104 is configured to determine a value for a given identification feature of the PPG sensor signal. The process that is performed here may be similar to the process performed in step S1 for the historic PPG sensor signals. That is, the user identification module 104 is configured to obtain a value from the current PPG sensor signal for the root mean square difference of successive pulse to pulse intervals (RMSSD), the amplitude, y, between the dicrotic notch and the amplitude of the preceding trough, the time, t2, between the minimum (i.e. , trough) and the dicrotic notch, D, etc. It may be that the current PPG sensor signal covers a plurality of heart beats, and if so, the user identification module 104 may be configured to obtain an average value across each of the distinct heart beats in the current PPG sensor signal.

[0106] At step S4, the user identification module is configured to compare the determined value for a given identification feature of the current PPG sensor signal to the reference value for the given identification feature obtained in advance (i.e., at step S1). In accordance with equation (1), the comparison is based on determining the square of the difference between the determined value for a given identification feature of the current PPG sensor signal to the reference value for the given identification feature obtained in advance. It should be appreciated that if this difference is large, then the measure M of equation (1) is also large. A large difference between the determined value for a given identification feature of the current PPG sensor signal to the reference value for the given identification feature obtained in advance is indicative of the fact the feature of the current PPG sensor signal has a low correlation with the feature of the historic PPG sensor signals. Conversely, if this difference is small, then the measure M of equation (1) is also small, where a small difference between the determined value for a given identification feature of the current PPG sensor signal to the reference value for the given identification feature obtained in advance is indicative of the fact the feature of the current PPG sensor signal has a high correlation with the feature of the historic PPG sensor signals.

[0107] At step S5, the user identification module is configured to output a result of the comparison to the control circuitry 20 of the aerosol provision system 1. In some implementations, the user identification module 104 may output the measurement M to the control circuitry 20, and the control circuitry 20 is subsequently configured to perform one or more actions on the basis of the value of the measurement M. In other implementations, the user identification module 104 is configured to output a result of the comparison indicating that the (current) user is considered identified as the specific (or first) user on the basis of the measurement M being below a threshold. As noted above, if the difference between the determined value for a given identification feature of the current PPG sensor signal and the reference value for the given identification feature obtained in advance is small, this is indicative that the feature of the current PPG sensor signal (provided by the current user) has a high correlation with the feature of the historic PPG sensor signals (provided by the first user), and thus there is a high degree of confidence that the current user is the first user. Accordingly, by setting the threshold to an appropriate value, when the measurement M is below that value, the user identification mechanism 104 is configured to output a result of the comparison to the control circuitry 20 of the aerosol provision system 1 indicating that the current user is considered to be the first user. Accordingly, the control circuitry 20 of the aerosol provision system 1 is configured to perform an action in response to the output.

[0108] Based on the result of the comparison, the control circuitry 20 of the aerosol provision system 1 is configured to perform an action.

[0109] In the implementation of Figure 3, at step S6a, the control circuitry 20 is configured to cause the aerosol provision system 1 to perform an unlock operation, or remain in an unlock state, when the result of the comparison indicates the user is considered identified. That is to say, when the measurement M indicates that the difference is small, and therefore is indicative of a high correlation between the feature of the current PPG sensor signal and the feature of the historic PPG sensor signals, the control circuitry 20 may be configured to either perform an unlock operation (e.g., where use of the heater 48 is permitted when the pressure sensor 16 detects a user inhalation and / or when a user actuates a button, as described above) or to remain in an unlocked state if the aerosol provision system 1 is currently in an unlocked state.

[0110] Conversely, at step S6b, the control circuitry 20 is configured to cause the aerosol provision system 1 to perform a lock operation, or remain in a locked state, when the result of the comparison indicates the user is not considered identified. That is to say, when the measurement M indicates that the difference is large, and therefore is indicative of a low correlation between the feature of the current PPG sensor signal and the feature of the historic PPG sensor signals, the control circuitry 20 may be configured to either perform an lock operation (e.g., where use of the heater 48 is prevented when the pressure sensor 16 detects a user inhalation and / or when a user actuates a button, as described above) or to remain in an locked state if the aerosol provision system 1 is currently in an locked state.

[0111] Accordingly, it can be seen that by using certain identification features from a PPG sensor signal provided by a PPG sensor 102, it is possible to identify to some degree of confidence whether a current user interacting with the PPG sensor 102 is a specific user known or identified to the user identification module 104 in advance. Based on this identification, it is possible to control features of the electronic aerosol provision system 1 , and in particular to provide lock or unlock operations to help restrict usage of the aerosol provision system 1 by unauthorised (or unidentified) users.

[0112] Equation (1) represents a first implementation of an algorithm used by the user identification module 104. However, certain modification may be made accordingly. Equation (2) represents a first modification to equation (1).

[0113] M = (Fstore- FM / FV)2(2)

[0114] In equation (2), a value FV is included. The value FV is a value corresponding to the average variability of the given feature as determined from a plurality of PPG signals corresponding to several users (which may or may not include the first or authorised user).

[0115] In effect, the value FV serves to normalise the difference between the determined value for a given identification feature of the current PPG sensor signal and the reference value for the given identification feature obtained in advance based on typical variability observed from a plurality of different users. That is to say, for some of the identification features listed above, even for a given user some variability may be observed, e.g., from day to day, in terms of the actual value that is obtained for that identification feature. The value FV can be used to help to determine whether or not that variability is within an expected limit for the particular feature or whether it is outside of that limit.

[0116] For example, suppose we consider the time ti from Figure 2. In this example, and by way of example only, the average value (i.e. mean or median) obtained from the historic PPG signals may be set at say, 0.34 s. A value for the feature ti from a current PPG signal may be observed to be 0.26 s. This represents a difference of 0.08 s. However, if the value of FV for the feature ti is e.g., 0.12 s, then it can be seen that the 0.08 / 0.12 is less than 1. This would mean that the difference of 0.08 s is not abnormal as compared to the normal variation indicated by the value FV. Conversely, if the value of FV for the feature ti is e.g., 0.04 s, then it can be seen that the 0.08 / 0.04 is greater than 1. This would mean that the difference of 0.08 s is considered abnormal as compared to the normal variation indicated by the value FV. Because equation (2) squares the normalised difference, it should be realised that any value greater than 1 is going to have a more significant impact on the measurement M than a value that is less than 1.

[0117] By normalising the difference, differences between the determined value for a given identification feature of the current PPG sensor signal and the reference value for the given identification feature obtained in advance which are abnormal can be more easily identified and any thresholds set in respect of the measurement M can be set with greater accuracy. Additionally, as will be discussed in more detail below, normalising the difference also allows for multiple different identification features of the PPG signal to be used in the identification process. In this regards, it should be appreciated that the value FV corresponds to the average variability for a given feature, and thus will vary on a feature by feature basis.

[0118] In some implementations, the value FV is determined from a plurality of PPG signals obtained in advance corresponding to a plurality of different users (which may or may not include the first or authorised user). Such a variation may be determined in advance and, e.g., by a manufacturer of the identification system 100, based on conducting trials or otherwise obtaining PPG signals from a plurality of users. In other implementations, the value FV is determined from the plurality of historic PPG signals obtained from the first or authorised user. In other words, the historic PPG signals may be used to obtain both the average value for a given feature corresponding to the first user and an average variability for that given feature corresponding to the variability observed in the first user.

[0119] In principle, the user identification module 104 may be configured to implement equation (1) or equation (2) in respect of any of the identification features listed above. However, certain ones of the identification features have been observed to provide more accurate results in respect of successfully determining whether a current user is identified as an authorised or known user.

[0120] Data (i.e. , PPG signals) was obtained from a total of 19 subjects over a plurality of instances. For each PPG signal obtained, amplitude and duration normalisation was performed to allow meaningful comparison. That is, each individual PPG sensor reading was normalised in terms of amplitude (by subtracting the minimum amplitude from PPG sensor signal and dividing by the difference of the maximum amplitude (i.e., the peak) by the minimum amplitude (i.e., the trough)) and in duration using interpolation. It was observed from the subjects’ data that intra subject variability of time and amplitude based parameters was relatively large. Inter subject variability of these parameters was observed to be generally low (although not zero), and thus are deemed less suitable candidates for use in a user identification process. However, the greatest variability between subjects was observed in the features RMSSD and the tPj, with the feature RMSSD showing the greatest variability (followed by tPj and ti). Using these identification features in equation (2) and varying the threshold used to assess whether measurement M corresponds to an authorised user or not, these identification features were also seen to have the largest receiver operator characteristic (ROC) curve of 0.7227 for the feature RMSSD and 0.7437 for the feature tPj, and smallest equal error rate (ERR) of 0.3348 for the feature RMSSD and 0.3371 for the feature tPj. In terms of performing the authorisation above, a given user’s data set was used as the authorised or known user while the remaining 18 subject’s data sets were used as intruders and the identification performance was assessed based on the true acceptance rate (i.e., genuine users being identified as such) and true rejection rates (i.e., non-genuine users being identified as such) while varying the threshold used to compare against the measurement M.

[0121] Thus, in accordance with some implementations, the user identification system 100 is configured to identify a value for the identification feature of RMSSD or tPj from the current PPG signal, and compare this identified value for the identification feature of RMSSD or tPj to a corresponding reference value for the identification features of RMSSD or tPj obtained in advance from the historic PPG sensor signals.

[0122] In respect of using a single identification feature in the user identification process, either of the identification features RMSSD or tPj have been shown to yield suitable authentication performance, as noted above.

[0123] However, an improvement in the authentication performance (e.g., in respect of the true acceptance rate - i.e. , the percentage of genuine users identified as the authorised user - and true rejection rate - i.e., the percentage of imposter users that were not identified as the authorised user) can be realised when using multiple identification features.

[0124] In some implementations, the user identification module 104 is configured to use at least two of the one or more identification features when performing the comparison between the identified value for the at least two identification features to a corresponding reference value for the at least two identification features obtained in advance. In some implementations, the at least two identification features include the root mean square difference of successive pulse to pulse intervals (RMSSD) and the pulse time interval (tPj) between two corresponding points on consecutive pulses. However, it should be appreciated that in other implementations, a different combination of identification features may be used.

[0125] In other implementations, the user identification module 104 is configured to use at least four of the one or more identification features when performing the comparison between the identified value for the at least four identification features to a corresponding reference value for the at least four identification features obtained in advance. In some implementations, the at least four identification features including the root mean square difference of successive pulse to pulse intervals (RMSSD), the pulse time interval (tPj) between two corresponding points on consecutive pulses, the time (ti) between the minimum and maximum of a pulse, and the width or time (W2) between the mid-point in the amplitude of the rising edge of a peak and the mid-point in the amplitude of the falling edge of a peak. However, it should be appreciated that in other implementations, a different combination of identification features may be used.

[0126] In such implementations where multiple identification features are considered, equation (2) may be modified as follows: where FMiis equal to the value of the measured feature i of the obtained PPG signal (i.e. , the signal currently obtained from the PPG sensor 102), Fstorei is equal to a reference value obtained in advance of feature i as determined from a plurality of PPG signals obtained in advance from the authorised user, and FVj is equal to the normalisation parameter for feature i.

[0127] In accordance with equation (3), by defining the measure M as the summation of the squares of the normalised differences between the determined value for a given identification feature of the current PPG sensor signal FMj and the reference value for the given identification feature obtained in advance Fstorei for a plurality of identification features

[0128] N, it has been observed that more accurate determination of the identification of a user relative to the use of a single identification feature (as described above) can be achieved.

[0129] For example, by considering RMSSD, tPj, ti and W2 as the identification features, the authentication performance of the user identification module 104 is improved. More particularly, in such an implementation, as compared to using solely the RMSSD as described above, the ROC of the multi-feature model is improved to 0.82 with an EER of

[0130] O.26. Correspondingly, the true acceptance rate (and true rejection rate) is 0.74.

[0131] Thus, it has generally been described above that a user identification module 104 is configured to providing an indication of the identity of a user of an aerosol provision system 1 , based on identifying a value for one or more identification features from a PPG signal received from a PPG sensor 102, comparing the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and outputting a result of the comparison to the aerosol provision system 1 .

[0132] While it has been described above the user identification module 104 is configured to obtain historic PPG sensor signals to determine the reference value for the one or more identification features, in some implementations, when the user identification module 104 outputs a result of the comparison indicating the user is considered to be identified (that is the current user is the given or authorised user), the user identification module 104 is configured to update the reference value for the identification features using the identified value from the current PPG sensor signal. For example, with reference to Figure 3, after or in parallel with step S6a, the user identification module 104 is configured to update the reference value at step S1 for the given identification feature with the value determined at step S3. This may include replacing the reference value at step S1 with the determined value at step S3 or, in other implementations, including the determined value at step S3 (potentially along with the corresponding PPG signal) in the historic PPG signals. In this way, should there be any minor variations in the user’s heart rate characteristics, for example, with time, the user identification module 104 is capable of providing a reference value for the identification features(s) that remains relevant to the given (authorised) user.

[0133] With reference back to Figure 1, the user identification system 100 is shown schematically in relation to the aerosol provision system 1.

[0134] Figure 4 schematically shows an implementation in which the user identification system 100 is implemented in a remote device 110. The remote device 110 is provided remote from the aerosol provision system 1, but includes suitable circuitry to communicatively couple with the aerosol provision system 1 such that e.g., the result of the comparison is able to be communicated to the control circuitry 20 of the aerosol provision system 1.

[0135] The remote device 110 may include, for example, a wearable device (such as a smartwatch or the like), a smartphone, or similar remote device. In such implementations, it should be appreciated that the PPG sensor 102 is integrated with the remote device 110 and is therefore arranged such that a user is able to interact with the PPG sensor 102 when interacting with the remote device 110.

[0136] Figure 5 schematically shows an implementation in which the user identification system 100 is implemented in the aerosol provision system 1.

[0137] In the implementation of Figure 5, the user identification system 100, and in particular the PPG sensor 102 and user identification module 104, are provided as part of the aerosol provision system 1 and, more particularly, the aerosol provision device 2. The PPG sensor 102 is provided at least partially on the outer surface of the hosing 12 of the aerosol provision device 2. In particular, the PPG sensor 102 comprises a sensing surface arranged such that a user of the aerosol provision system 1 is able to contact the sensing surface when holding the aerosol provision system 1. Additionally, in this implementation, the user identification module 104 may be provided as a separate module as shown in Figure 5 and provided in (e.g., wired) communication with the control circuitry 20, or alternatively the user identification module 104 may be integrated with the control circuitry 20.

[0138] Regardless of whether the user identification system 100 is part of a remote device 110 or the aerosol provision system 1, it has been found that the accuracy in respect of determining values for the one or more identification features from the PPG signals from the PPG sensor 102 improves when the PPG sensor signal is obtained over a duration of 20 seconds or more (or put another way, includes over 20 seconds or more worth of data). In this way, the PPG sensor signal is able to capture a number of heart beats and thus when determining a value for any of the identification features, variability between heart beats can be accounted for or reduced e.g., by taking an average value. In addition, it has also be found that the accuracy is improved when the user makes good contact with a sensing surface of the PPG sensor 102. Thus, as described above in respect of Figure 5, suitable placement of the PPG sensor 102 whether implemented in a remote device or an aerosol provision system 1 is important in some implementations.

[0139] Additionally, it should be appreciated that while other heart rate sensors exist, such as electrocardiogram (ECG) based heart rate sensors, PPG sensors 102 generally offer a greater user convenience. For example, in ECG based heart sensors, electrodes have to generally be attached to a user’s body. While this may be acceptable in a hospital setting, for example, it adds a degree of inconvenient for a user when using an aerosol provision system (particularly noting that such systems are often used intermittently for short periods of time). Thus, PPG sensors 102 generally offer improved user convenience compared to other types of heart rate sensors, for example ECG sensors.

[0140] Thus, there has been described a user identification system for an aerosol provision system, the user identification system including a PPG sensor and a user identification module configured for providing an indication of the identity of a user of the aerosol provision system. The user identification module is configured to receive a signal from the PPG sensor, identify a value for one or more identification features from the received signal, compare the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and output a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison. Also described is a system for providing aerosol to a user, and a method of identifying a user of an aerosol provision system.

[0141] 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 aerosol provision system function are not directly relevant to the principles underlying the examples described herein.

[0142] In order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and / or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. other than those specifically described herein, and it will thus be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims. The disclosure may include other inventions not presently claimed, but which may be claimed in future.

Claims

CLAIMS1. A user identification system for an aerosol provision system, the user identification system comprising: a PPG sensor; and a user identification module configured for providing an indication of the identity of a user of the aerosol provision system, wherein the user identification module is configured to: receive a signal from the PPG sensor, identify a value for one or more identification features from the received signal, compare the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and output a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison.

2. The user identification system of claim 1, wherein the user identification module is configured to output a result of the comparison indicating the user is considered identified on the basis of a calculation utilising a difference between the identified value and reference value for one or more identification features being below a threshold.

3. The user identification system of claim 2, wherein the calculation includes normalising the difference between the identified value and the reference value for each of the one or more identification features.

4. The user identification system of claim 3, wherein normalising the difference between the identified value and the reference value for each of the one or more identification features includes normalising on the basis of a normalisation parameter dependent on the given identification feature.

5. The user identification system of claim 4, wherein the normalisation parameter is based on one or more PPG sensor signals corresponding to a plurality of different users.

6. The user identification system of any of claims 3 to 5, wherein the calculation includes a summation of a normalised difference between the identified value and thereference value for each of the one or more identification features, and comparing the summation of the normalised differences to the threshold.

7. The user identification system of any of claims 1 to 6, wherein the reference value for the one or more identification features obtain in advance is obtained from one or more received signals from the PPG sensor obtained at an earlier time.

8. The user identification system of claim 6, wherein the reference value for a given identification feature is an average value of corresponding values identified in the one or more received signals from the PPG sensor obtained at an earlier time.

9. The user identification system of any of the preceding claims, wherein the received signal from the PPG sensor is normalised for at least one of: amplitude and duration.

10. The user identification system of any of the preceding claims, wherein the one or more identification features is selected from the group comprising: an average pulse-to-pulse interval, a root mean square difference of successive pulse-to-pulse intervals, a time between a middle point of a rising edge and a middle point of a fall edge of a pulse, and a time between the minimum and maximum point of a pulse.

11. The user identification system of any of the preceding claims, wherein the user identification module is configured to perform the comparison on the basis of identified values for at least two of the one or more identification features.

12. The user identification system of any of the preceding claims, wherein the user identification module is configured to perform the comparison on the basis of identified values for at least four of the one or more identification features.

13. The user identification system of any of the preceding claims, wherein, when the user identification module is configured to output a result of the comparison indicating the user is considered identified, the user identification module is configured to update the reference value of the corresponding one or more identification features obtained in advance using the identified value of the one or more identification features.

14. A system for providing aerosol to a user, the system comprising: the user identification system of any of claims 1 to 13; andan aerosol provision system comprising a controller for controlling operations of the aerosol provision system.

15. The system of claim 14, wherein the controller is configured to cause the aerosol provision system to perform an unlock operation, or remain in an unlock state, when the result of the comparison indicates the user is considered identified.

16. The system of claims 14 or 15, wherein the controller is configured to cause the aerosol provision system to perform a lock operation, or remain in a lock state, when the result of the comparison indicates the user is considered unidentified.

17. The system of any of claims 14 to 16, wherein the PPG sensor, controller and user identification module are provided in the aerosol provision system.

18. The system of claim 17, wherein the PPG sensor comprises a sensing surface arranged such that a user is able to contact the sensing surface when holding the aerosol provision system.

19. The system of any of claims 14 to 16, wherein the system includes a remote device communicatively coupled to the aerosol provision system, wherein the PPG sensor and user identification module are provided in the remote device.

20. The system of any of claims 14 to 19, wherein the aerosol provision system is formed of an aerosol provision device and a detachable consumable, the consumable comprising an aerosol-generating material storage area for storing an aerosol generating material.

21. A method of identifying a user of an aerosol provision system using a user identification system, the user identification system comprising a PPG sensor and a user identification module, wherein the method comprises: receiving a signal from the PPG sensor, identifying a value for one or more identification features from the received signal, comparing the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and outputting a result of the comparison to a controller of an aerosol provision system, the controller configured to control one or more operations of the aerosol provision system responsive to the result of the comparison.

22. User identification means for an aerosol provision means, the user identification means comprising:PPG sensor means; and user identification module means configured for providing an indication of the identity of a user of the aerosol provision means, wherein the user identification module means is configured to: receive a signal from the PPG sensor means, identify a value for one or more identification features from the received signal, compare the identified value for the one or more identification features to a corresponding reference value for the one or more identification features obtained in advance, and output a result of the comparison to controller means of an aerosol provision means, the controller means configured to control one or more operations of the aerosol provision means responsive to the result of the comparison.

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