Aerosol generating device with substrate sensor

Abstract

The present invention relates to an aerosol generating device comprising a cavity for receiving an aerosol-forming substrate. The aerosol generating device further comprises an upstream airflow channel passing through the cavity. The aerosol generating device further comprises a substrate sensor arranged to fluidly interact with the upstream airflow channel. The substrate sensor is configured to detect the degree of depletion of the aerosol-forming substrate. The present invention further relates to an aerosol generating system comprising an aerosol generating device and an aerosol-generating article or cartridge. The present invention further relates to a method for detecting the degree of depletion of an aerosol-forming substrate of an aerosol-generating article in an aerosol generating device.

Description

[Technical Field]

[0001] The present invention relates to an aerosol-generating device. The present invention further relates to an aerosol-generating system comprising an aerosol-generating device, and an aerosol-generating article comprising an aerosol-forming substrate. The present invention further relates to a method for detecting the depletion of an aerosol-forming substrate of an aerosol-generating article in an aerosol-generating device. [Background technology]

[0002] It is known to provide aerosol-generating devices for producing inhalable vapors. Such devices may heat an aerosol-forming substrate to a temperature at which one or more components of the aerosol-forming substrate volatilize, without burning the aerosol-forming substrate. The aerosol-forming substrate may be provided as part of an aerosol-generating article. The aerosol-generating article may have a rod shape for insertion of the aerosol-generating article into a cavity (such as a heating chamber) of the aerosol-generating device. A heating element may be disposed in or around the heating chamber to heat the aerosol-forming substrate when the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device.

[0003] It would be desirable to have an aerosol generating device that allows a user to know when the aerosol-generating article is depleted.It would be desirable to have an aerosol generating device that allows a user to know the stage of consumption of the aerosol-generating article. Summary of the Invention

[0004] According to an embodiment of the present invention, there is provided an aerosol-generating device which may comprise a cavity for receiving an aerosol-forming substrate. The aerosol-generating device may further comprise an airflow channel passing through the cavity. The aerosol-generating device may further comprise a substrate sensor. The substrate sensor may be disposed within or adjacent to the cavity. The substrate sensor may be configured to detect depletion of the aerosol-forming substrate.

[0005] According to an embodiment of the present invention, there is provided an aerosol-generating device comprising a cavity for receiving an aerosol-forming substrate. The aerosol-generating device further comprises an airflow channel passing through the cavity. The aerosol-generating device further comprises a substrate sensor disposed within or adjacent to the cavity. The substrate sensor is configured to detect depletion of the aerosol-forming substrate.

[0006] According to an embodiment of the present invention, there is provided an aerosol-generating device which may comprise a cavity for receiving an aerosol-forming substrate. The aerosol-generating device may further comprise an upstream airflow channel passing through the cavity. The aerosol-generating device may further comprise a substrate sensor arranged to fluidly interact with the upstream airflow channel. The substrate sensor may be configured to detect depletion of the aerosol-forming substrate.

[0007] According to an embodiment of the present invention, there is provided an aerosol-generating device comprising a cavity for receiving an aerosol-forming substrate, the aerosol-generating device further comprising an upstream airflow channel passing through the cavity, the aerosol-generating device further comprising a substrate sensor disposed in fluid interaction with the upstream airflow channel, the substrate sensor configured to detect depletion of the aerosol-forming substrate.

[0008] Detecting the depletion degree of the aerosol-forming substrate allows the user to know the depletion stage of the aerosol-forming substrate, and therefore the user may know when the aerosol-forming substrate is depleted and when a new aerosol-forming substrate needs to be received into the cavity.

[0009] The substrate sensor may be a pH sensor.

[0010] During the ongoing depletion of the aerosol-forming substrate, the pH value of the aerosol-forming substrate may change, and this change in the pH value of the aerosol-forming substrate may be detected by the sensor.

[0011] The substrate sensor may have a measurement range of 2 pH to 10 pH, preferably 3 pH to 9 pH, most preferably 5 pH to 8 pH.

[0012] The substrate sensor may have a measurement accuracy of ±0.02 pH at pH 7, and preferably the substrate sensor has a measurement accuracy of ±0.01 pH at pH 7.

[0013] The substrate sensor may have a drift of less than 0.05 pH per day at pH 7.

[0014] The aerosol-generating device may be configured to heat the aerosol-forming substrate to a temperature above the temperature at which an aerosol is generated during and between puffs. Between puffs, vaporizable material from the aerosol-forming substrate may be vaporized due to the temperature to which the aerosol-forming substrate is heated between puffs. When a consumer draws on the aerosol-generating device or aerosol-forming substrate, the vaporized vaporizable material may be entrained in an airflow to generate an inhalable aerosol.

[0015] The substrate sensor may be configured to measure the rate of depletion, preferably the pH value, of the aerosol-forming substrate between puffs.

[0016] Measuring the depletion rate of the aerosol-forming substrate between puffs may have the advantage of accurately determining the depletion rate. During a puff, air may flow through the device, and the vaporized vaporizable material of the aerosol-forming substrate may be entrained in the airflow. Measuring the exact depletion rate of the aerosol-forming substrate during a puff may be difficult. However, between puffs, no airflow flows through the device, so the measurement of the depletion rate of the vaporized vaporizable material from the aerosol-forming substrate may be more accurate. Furthermore, due to the lack of airflow through the aerosol-generating device, the vaporized vaporizable material from the aerosol-forming substrate may reach the substrate sensor, improving the accuracy of the measurement between puffs.

[0017] The substrate sensor may be disposed within the cavity or adjacent to the upstream end of the cavity.

[0018] The upstream end of the cavity may be the base of the cavity. When the aerosol-forming substrate is received in the cavity, the aerosol-forming substrate may be disposed adjacent to the upstream end of the cavity. In other words, when the aerosol-forming substrate is received in the cavity, the aerosol-forming substrate may be received immediately downstream of the upstream end of the cavity. By positioning the substrate sensor within or adjacent to the upstream end of the cavity, the substrate sensor may be positioned in an area adjacent to the area where the vaporizable material of the aerosol-forming substrate is vaporized in the cavity. In particular, between puffs, the vaporized vaporizable material from the aerosol-forming substrate may expand and flow slightly toward the substrate sensor due to the small distance between the aerosol-forming substrate and the substrate sensor, allowing for accurate measurement.

[0019] The substrate sensor may be disposed adjacent to the airflow channel. The airflow channel may be a central airflow channel. The substrate sensor may be in direct contact with the airflow channel. The substrate sensor may be part of the airflow channel. The substrate sensor may comprise one or more air channels that are part of the airflow channel. Preferably, the substrate comprises at least two, and preferably multiple, air channels that are part of the airflow channel. The air channels may be arranged in a ring-shaped arrangement to allow lateral airflow from all directions toward the opening at the upstream end of the cavity.

[0020] The airflow channel may enter the cavity at an upstream end of the cavity. The cavity may include an opening that allows air to flow from the airflow channel into the cavity. The opening may be centrally disposed at the upstream end of the cavity. The substrate sensor may be disposed immediately adjacent to the opening at the upstream end of the cavity. The substrate sensor may partially form the opening. The opening may be disposed within the substrate sensor. The opening may be part of the substrate sensor.

[0021] The substrate sensor may be configured to detect the nicotine content of the aerosol drawn through the airflow channel.

[0022] The substrate sensor may be configured to detect the nicotine content of the aerosol-forming substrate. The substrate sensor may be configured to detect the nicotine content of the vaporized vaporizable material of the aerosol-forming substrate. The substrate sensor may be configured to detect the nicotine content during a puff. Alternatively, the substrate sensor may be configured to detect the nicotine content between puffs. As a further alternative, the substrate sensor may be configured to detect the nicotine content of the aerosol generated during a puff and of the vaporized vaporizable material of the aerosol-forming substrate.

[0023] The substrate sensor may be configured to detect the pH value of the aerosol drawn through the airflow channel.

[0024] The substrate sensor may be configured to detect a pH value of the aerosol-forming substrate. The substrate sensor may be configured to detect a pH value of the vaporized vaporizable material of the aerosol-forming substrate. The substrate sensor may be configured to detect a pH value during a puff. Alternatively, the substrate sensor may be configured to detect a pH value between puffs. As a further alternative, the substrate sensor may be configured to detect a pH value of the aerosol generated during a puff and of the vaporized vaporizable material of the aerosol-forming substrate.

[0025] The aerosol generating device may further comprise a controller, which may be configured to generate a signal based on the output of the substrate sensor when depletion of the aerosol-forming substrate falls below a predetermined threshold.

[0026] The signal may be indicative of the degree of depletion of the aerosol-forming substrate.The aerosol generating device may be configured to output the signal to a consumer.

[0027] The signal may be one or more of a user interface signal, a light signal, an acoustic signal, and a vibration signal.

[0028] The signal may include information to the user when the aerosol-forming substrate needs to be updated. The signal may include information to the user when the aerosol-forming substrate is depleted. The signal may include information to the user about the interval between changes of the aerosol-forming substrate.

[0029] The controller may be configured to terminate operation of the aerosol generating device after a predetermined time or number of puffs by the user if the depletion of the aerosol-forming substrate may fall below a predetermined threshold.

[0030] The controller may be configured and the aerosol generating device may operate if the depletion of the aerosol-forming substrate falls below a predetermined threshold.

[0031] The depletion of the aerosol-forming substrate may be the nicotine content or pH value of the aerosol drawn through the airflow channel.

[0032] The depletion of the aerosol-forming substrate may be the nicotine content or pH value of the aerosol during a user's inhalation. The depletion of the aerosol-forming substrate may be the nicotine content or pH value of the vaporized vaporizable material of the aerosol-forming substrate between uses of the aerosol-generating device. The depletion of the aerosol-forming substrate may be the nicotine content or pH value of both the aerosol during a user's inhalation and the vaporized vaporizable material of the aerosol-forming substrate between uses of the aerosol-generating device.

[0033] The aerosol-generating device may further include an activation button, and the substrate sensor may be configured to begin detecting depletion of the aerosol-forming substrate after a predetermined time period after pressing the activation button, or after a predetermined number of user puffs after pressing the activation button.

[0034] Alternatively, the substrate sensor may be configured to perform detection of the depletion rate of the aerosol-forming substrate immediately after the activation button is pressed. As a further alternative, the substrate sensor may be configured to perform an aerosol-forming substrate depletion rate analysis immediately after the activation button is pressed, and to allow activation of the aerosol-generating device only if the depletion rate of the aerosol-forming substrate is found not to be below a predetermined threshold.

[0035] The substrate sensor may be configured to continuously detect depletion of the aerosol-forming substrate during operation of the aerosol-generating device or when the aerosol-forming substrate is nearing estimated depletion, which may be based on a predetermined time after pressing the activation button or a predetermined number of puffs taken by the user after pressing the activation button.

[0036] The present invention further relates to an aerosol-generating system comprising an aerosol-generating device as described herein, and to an aerosol-generating article comprising an aerosol-forming substrate.

[0037] The present invention further relates to a method for detecting the depletion of an aerosol-forming substrate of an aerosol-generating article in an aerosol-generating device as described herein, the method comprising: - detecting the degree of depletion of the aerosol-forming substrate by means of a substrate sensor.

[0038] As used herein, the terms "proximal," "distal," "downstream," and "upstream" are used to describe the relative position of a component or portion of a component of an aerosol generating device with respect to the direction in which a user draws on the aerosol generating device during use.

[0039] The aerosol generating device may have a mouth end through which the aerosol exits the aerosol generating device and is delivered to the user during use. The mouth end may also be referred to as the proximal end. During use, a user draws on the proximal or mouth end of the aerosol generating device to inhale the aerosol generated by the aerosol generating device. Alternatively, the user may directly draw on an aerosol-generating article inserted into an opening at the proximal end of the aerosol generating device. The opening at the proximal end may be the opening of a cavity. The cavity may be configured to receive the aerosol-generating article. The aerosol generating device has a distal end opposite the proximal or mouth end. The proximal or mouth end of the aerosol generating device may also be referred to as the downstream end, and the distal end of the aerosol generating device may also be referred to as the upstream end. Components, or portions of components, of an aerosol generating device may be described as being upstream or downstream of one another based on their relative positions between the proximal, downstream, or mouth end of the aerosol generating device and the distal or upstream end of the aerosol generating device.

[0040] As used herein, "aerosol-generating device" relates to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-forming substrate may be part of an aerosol-generating article, for example part of a smoking article. The aerosol-generating device may be a smoking device that interacts with the aerosol-forming substrate of the aerosol-generating article to generate an aerosol that is inhalable directly through the user's mouth into the user's lungs. The aerosol-generating device may be a holder. The device may be an electrically heated smoking device. The aerosol-generating device may comprise a housing, an electrical circuit, a power source, a heating chamber, and a heating element.

[0041] As used herein in relation to the present invention, the term "smoking", in relation to a device, article, system, substrate or otherwise, does not refer to conventional smoking, in which the aerosol-forming substrate is completely or at least partially combusted. The aerosol-generating device of the present invention is arranged to heat the aerosol-forming substrate to a temperature below the combustion temperature of the aerosol-forming substrate but above the temperature at which one or more volatile compounds of the aerosol-forming substrate are released, in order to form an inhalable aerosol.

[0042] The aerosol generating device may comprise an electrical circuit. The electrical circuit may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of a controller. The electrical circuit may comprise further electronic components. The electrical circuit may be configured to regulate the supply of power to the heating element. Power may be supplied to the heating element continuously following activation of the aerosol generating device, or may be supplied intermittently, such as with each puff. Power may be supplied to the heating element in the form of current pulses. The electrical circuit may be configured to monitor the electrical resistance of the heating element and to control the supply of power to the heating element, preferably depending on the electrical resistance of the heating element.

[0043] The aerosol generating device may include a power source, typically a battery, within the main body of the aerosol generating device. In one embodiment, the power source is a lithium-ion battery. Alternatively, the power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery (e.g., a lithium-cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery). Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity that allows for storage of energy sufficient for one or more use experiences; for example, the power source may have a capacity sufficient to continuously generate aerosol for approximately a six-minute period, or a multiple of six minutes. In another example, the power source may have a capacity sufficient to provide a predetermined number of puffs or discontinuous activation of the heating element.

[0044] The cavity of the aerosol generating device may have an open end into which the aerosol-generating article is inserted. The open end may be a proximal end. The cavity may have a closed end opposite the open end. The closed end may be a base of the cavity. The closed end may be closed except for the provision of an air opening disposed within the base. The base of the cavity may be flat. The base of the cavity may be circular. The base of the cavity may be disposed upstream of the cavity. The open end may be disposed downstream of the cavity. The cavity may have an elongated extension. The cavity may have a longitudinal central axis. The longitudinal axis may be a direction extending along the longitudinal central axis between the open end and the closed end. The longitudinal central axis of the cavity may be parallel to the longitudinal axis of the aerosol generating device.

[0045] The cavity may be configured as a heating chamber. The cavity may have a cylindrical shape. The cavity may have a hollow cylindrical shape. The cavity may have a shape corresponding to the shape of the aerosol-generating article to be received within the cavity. The cavity may have a circular cross-section. The cavity may have an elliptical or rectangular cross-section. The cavity may have an inner diameter corresponding to the outer diameter of the aerosol-generating article.

[0046] An airflow channel may extend through the cavity. Ambient air may be drawn through the airflow channel into the aerosol-generating device, into the cavity, and toward the user. Downstream of the cavity, a mouthpiece may be disposed, or the user may inhale the aerosol-generating article directly. The airflow channel may extend through the mouthpiece.

[0047] In any aspect of the present disclosure, the heating element may include an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold, and silver. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminum-, titanium-, zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold-, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timetal®, and iron-manganese-aluminum-based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated in, or coated with the insulating material, or vice versa, depending on the required energy transfer kinetics and external physicochemical properties.

[0048] As described, in any of the aspects of the present disclosure, the heating element may be part of the aerosol-generating device. The aerosol-generating device may include an internal heating element, an external heating element, or both an internal and an external heating element, where "internal" and "external" refer to the aerosol-forming substrate. The internal heating element may take any suitable form. For example, the internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different conductive portions or an electrically resistive metal tube. Alternatively, the internal heating element may be one or more heated needles or rods that pass through the center of the aerosol-forming substrate. Other alternatives include a heated wire or filament, such as Ni-Cr (nickel-chromium), platinum, tungsten, or alloy wire or heating plate. Optionally, the internal heating element may be disposed within or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal with a well-defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as a ceramic material, and then sandwiched in another insulating material, such as glass. The heater thus formed may be used to both heat the heating element and monitor its temperature during operation.

[0049] The external heating element may take any suitable form. For example, the external heating element may take the form of one or more flexible heating foils on a dielectric substrate such as polyimide. The flexible heating foils may be shaped to fit the periphery of the substrate-receiving cavity. Alternatively, the external heating element may take the form of a metal grid, a flexible printed circuit board, a molded-in circuit component (MID), a ceramic heater, a flexible carbon fiber heater, or may be formed using a coating technique such as plasma deposition on a suitably shaped substrate. The external heating element may also be formed using a metal that has a well-defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating material. The external heating element thus formed may be used both to heat the external heating element and to monitor the temperature of the external heating element during operation.

[0050] As an alternative to an electrically resistive heating element, the heating element may be configured as an induction heating element. The induction heating element may include an induction coil and a susceptor. Generally, the susceptor is a material capable of generating heat when penetrated by an alternating magnetic field. When placed within the alternating magnetic field, if the susceptor is conductive, the alternating magnetic field typically induces eddy currents. If the susceptor is magnetic, another effect that typically contributes to heating is commonly referred to as hysteresis loss. Hysteresis loss occurs primarily due to the movement of magnetic domain blocks within the susceptor as their magnetic orientation aligns with the alternating induced magnetic field. Another effect that contributes to hysteresis loss is when magnetic domains expand or contract within the susceptor. Generally, all of these changes, which occur at the nanoscale or below within the susceptor, generate heat within the susceptor, hence the term "hysteresis loss." Thus, if the susceptor is both magnetic and conductive, both hysteresis loss and the generation of eddy currents will contribute to the heating of the susceptor. If the susceptor is magnetic but not conductive, hysteresis loss will be the only means by which the susceptor will heat when penetrated by an alternating magnetic field. According to the present invention, the susceptor may be conductive or magnetic, or both conductive and magnetic. The alternating magnetic field generated by one or several induction coils heats the susceptor, which then transfers heat to the aerosol-forming substrate, thereby forming the aerosol. Heat transfer may be primarily by conduction. Such heat transfer is best when the susceptor is in intimate thermal contact with the aerosol-forming substrate.

[0051] As used herein, the term "aerosol-generating article" refers to an article comprising an aerosol-forming substrate capable of emitting a volatile compound capable of forming an aerosol. For example, the aerosol-generating article may be a smoking article that generates an aerosol that can be inhaled directly through the user's mouth into the user's lungs. The aerosol-generating article may be disposable.

[0052] As used herein, the term "aerosol-forming substrate" relates to a substrate capable of emitting one or more volatile compounds capable of forming an aerosol. Such volatile compounds may be emitted by heating the aerosol-forming substrate. The aerosol-forming substrate may conveniently be part of an aerosol-generating article or a smoking article.

[0053] The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosol-forming substrate may be a liquid aerosol-forming substrate contained in a replaceable cartridge connectable to the aerosol-generating device or contained in a refillable liquid storage portion of the aerosol-generating device. The aerosol-forming substrate may include both solid and liquid components.

[0054] The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds that are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol formers are glycerin and propylene glycol.

[0055] The aerosol-generating substrate preferably comprises a homogenized tobacco material, an aerosol former, and water. Providing a homogenized tobacco material may improve aerosol generation and the nicotine content and flavor profile of the aerosol generated during heating of the aerosol-generating article. Specifically, the process of making homogenized tobacco involves grinding tobacco leaves, which allows for more efficient release of nicotine and flavor upon heating.

[0056] Below is provided a non-exhaustive list of non-limiting examples, any one or more of the features of these examples may be combined with any one or more features described above, for example, with any one or more features of other examples, embodiments, or aspects described herein.

[0057] Example 1. An aerosol generating device, a cavity for receiving an aerosol-forming substrate; an airflow channel through the cavity; a substrate sensor; An aerosol-generating device, wherein a substrate sensor is disposed within or adjacent to the cavity, and the substrate sensor is configured to detect depletion of the aerosol-forming substrate.

[0058] Example 2. An aerosol generating device according to Example 1, wherein the substrate sensor is a pH sensor.

[0059] Example 3. An aerosol generating device according to the preceding examples, wherein the substrate sensor has a measurement range of 2 pH to 10 pH, preferably 3 pH to 9 pH, most preferably 5 pH to 8 pH.

[0060] Example 4. An aerosol generating device according to either of the two preceding examples, wherein the substrate sensor has a measurement accuracy of ±0.02 pH at pH 7, preferably wherein the substrate sensor has a measurement accuracy of ±0.01 pH at pH 7.

[0061] Example 5. An aerosol generating device according to any of the three preceding examples, wherein the substrate sensor has a drift of less than 0.05 pH per day at pH 7.

[0062] Example 6. An aerosol generating device according to any preceding example, wherein the substrate sensor is disposed within or adjacent to the upstream end of the cavity.

[0063] Example 7. An aerosol generating device according to any preceding example, wherein the substrate sensor is configured to detect the nicotine content of the aerosol drawn through the airflow channel.

[0064] Example 8. An aerosol generating device according to any preceding example, wherein the substrate sensor is configured to detect the value of aerosol pH drawn through the airflow channel.

[0065] Example 9. The aerosol generating apparatus according to any preceding example, wherein the aerosol generating apparatus further comprises a controller, and the controller is configured to generate a signal based on the output of the substrate sensor when depletion of the aerosol-forming substrate falls below a predetermined threshold.

[0066] Example 10. An aerosol generating device according to the preceding example, wherein the signal is one or more of a user interface signal, a light signal, an acoustic signal, and a vibration signal.

[0067] Example 11. An aerosol generating device according to either of the two preceding examples, wherein the controller is configured to terminate operation of the aerosol generating device if the depletion of the aerosol-forming substrate is below a predetermined threshold after a predetermined time or a predetermined number of puffs by the user.

[0068] Example 12. An aerosol generating device according to any preceding example, wherein the depletion of the aerosol-forming substrate is the nicotine content or pH value of the aerosol drawn through the airflow channel.

[0069] Example 13. An aerosol generating device according to any preceding example, wherein the aerosol generating device further comprises an activation button, and wherein the substrate sensor is configured to begin detecting depletion of the aerosol-forming substrate after a predetermined time period after pressing the activation button, or after a predetermined number of user puffs after pressing the activation button.

[0070] Example 14. An aerosol generating device according to the preceding examples, wherein the substrate sensor is configured to continuously detect the degree of depletion of the aerosol-forming substrate during operation of the aerosol generating device or when the aerosol-forming substrate is nearing estimated depletion, the depletion estimation being preferably based on a predetermined time after pressing the activation button or based on a predetermined number of puffs taken by the user after pressing the activation button.

[0071] Example 15. An aerosol-generating system comprising an aerosol-generating device according to any preceding example and an aerosol-generating article comprising an aerosol-forming substrate.

[0072] Example 16. A method for detecting the degree of depletion of an aerosol-forming substrate of an aerosol-generating article in an aerosol-generating device according to any one of Examples 1 to 14, comprising: - detecting the degree of depletion of the aerosol-forming substrate by means of a substrate sensor.

[0073] Features described with respect to one embodiment may be equally applied to other embodiments of the invention.

[0074] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0075] [Figure 1] 1A, 1B, and 1C show an aerosol generating device with a substrate sensor. [Figure 2] 2A and 2B show a more detailed view of the interaction between an aerosol-generating article, including an aerosol-forming substrate, and a substrate sensor. [Figure 3] 3A and 3B show a more detailed view of the substrate sensor. [Figure 4] FIG. 4 shows a further embodiment of an aerosol-generating device that utilizes a liquid aerosol-forming substrate. [Figure 5] FIG. 5 shows an alternative positioning of the substrate sensor in the embodiment of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0076] 1A shows an aerosol-generating device 10. The aerosol-generating device 10 comprises a cavity 12 for receiving an aerosol-forming substrate 14. The aerosol-forming substrate 14 is part of an aerosol-generating article 16 that is partially received within the cavity 12 of the aerosol-generating device 10. During use, a consumer may suck directly on the proximal end of the aerosol-generating article 16.

[0077] 1B shows a diagram of the aerosol-generating device 10 without the aerosol-generating article 16 received within the cavity 12. A heating element 18 is disposed at least partially surrounding the cavity 12. The heating element 18 may be disposed within a distal or upstream portion of the cavity 12. More specifically, the heating element 18 comprises an induction coil surrounding the distal portion of the cavity 12. In addition, a susceptor is disposed within the aerosol-forming substrate 14 of the aerosol-generating article 16. The induction coil creates an alternating magnetic field that heats the susceptor within the aerosol-forming substrate 14 within the aerosol-generating article 16 when the aerosol-generating article 16 is received within the cavity 12.

[0078] A substrate sensor 22 is disposed adjacent the upstream end 20 of the cavity 12. The substrate sensor 22 is configured to detect the depletion rate of the aerosol-forming substrate 14 when the aerosol-forming substrate 14 is received within the cavity 12.

[0079] The aerosol generating device 10 further comprises a controller 24 and a power source in the form of a battery 26 .

[0080] 1C shows an aerosol-generating device 10 as shown in FIG. 1B, but with an aerosol-generating article 16 received within the cavity 12. As can be seen, the aerosol-forming substrate 14 of the aerosol-generating article 16 is positioned proximate to a substrate sensor 22. The substrate sensor 22 can thus detect the depletion rate of the aerosol-forming substrate 14. The substrate sensor 22 may be configured to detect the depletion rate of the aerosol-forming substrate 14 during use, between uses, or during and between uses.

[0081] The substrate sensor 22 is configured as a pH sensor or a nicotine content sensor.

[0082] During use, air is drawn by a user through the aerosol-forming substrate 14 disposed within the cavity 12. Thus, during use, the substrate sensor 22 may be configured to detect the depletion rate of the aerosol-forming substrate 14 by measuring the pH value or nicotine content of the aerosol drawn through the cavity 12. For this purpose, the substrate sensor 22 may also be positioned at a different position within the cavity 12, for example, in a downstream portion of the cavity 12. Preferably, the substrate sensor 22 is positioned upstream of the aerosol-generating article 16. Preferably, the substrate sensor 22 is positioned facing the upstream end of the aerosol-generating article 16.

[0083] Between uses, the heating element 18 is configured to heat the aerosol-forming substrate 14 of the aerosol-generating article 16 to a temperature above the vaporization temperature of the vaporizable material of the aerosol-forming substrate 14. The vaporized vaporizable material of the aerosol-forming substrate 14 expands slightly and reaches the substrate sensor 22. The substrate sensor 22 can thus optimally detect the depletion rate of the aerosol-forming substrate 14 between puffs. Alternatively, the substrate sensor 22 may be configured to detect the depletion rate of the aerosol-forming substrate 14 from a distance. Exemplarily, the substrate sensor 22 may include a light source and a detector to detect the depletion rate of the aerosol-forming substrate from a distance.

[0084] The substrate sensor 22 may be a pH sensor and may utilize a silica fiber-based electrode, which has high accuracy and small dimensions.

[0085] The measurement range of the substrate sensor 22 may be about 2 pH to 10 pH, preferably about 3 pH to 9 pH, and most preferably 5 pH to 8 pH. The accuracy of the substrate sensor 22 may have a resolution of ±0.02 pH at pH=7. Generally, the accuracy may be ±0.1 pH at pH=7. The substrate sensor 22 may utilize automatic sensor calibration performed by the controller. The substrate sensor 22 may have a drift of less than 0.05 pH per day at pH=7 (1 minute sampling interval). The substrate sensor 22 may have a measurement temperature range of +5 to +50°C. The substrate sensor 22 may have a response time (t90) at 25°C, a standard ISO room temperature range, of less than 30 seconds, preferably less than 20 seconds, and most preferably less than 10 seconds.

[0086] The sensor should monitor the pH value and send a signal depending on the value, so that a different light signal is turned on, i.e., for example, a green light or a red light when the experience is coming to an end.

[0087] FIG. 2 shows a more detailed view of an aerosol-generating article 16 with an aerosol-forming substrate 14 in the airflow, during use in FIG. 2A and between uses in FIG. 2B. As can be seen in FIG. 2A, during use, air is drawn into the aerosol-generating article 16 at its upstream end 20. The air travels through the aerosol-generating article in a downstream direction 28, and the vaporized vaporizable material of the aerosol-forming substrate 14 is entrained in the airflow. Downstream, the vaporized vaporizable material of the aerosol-forming material forms small droplets, so that the aerosol is ultimately delivered to the consumer. Due to the adjacent placement of a substrate sensor 22 at the upstream end 20 of the aerosol-generating article 16, the air flowing past the substrate sensor 22 can be checked for pH or nicotine content by the substrate sensor 22. Thus, the substrate sensor 22 may detect the rate of depletion of the aerosol-forming substrate 14.

[0088] 2B shows a situation between uses. In this case, no air flows through the aerosol-generating article 16. However, the heating element 18 still heats the aerosol-forming substrate 14 to a high temperature above the vaporization temperature of the vaporizable material of the aerosol-forming substrate 14, creating vaporized vaporizable material of the aerosol-forming substrate 14. This vaporized vaporizable material of the aerosol-forming substrate 14 may reach the substrate sensor 22. Additionally or alternatively, the substrate sensor 22 may be able to detect the depletion rate of the vaporized vaporizable material of the aerosol-forming substrate 14 from a distance.

[0089] 2 further illustrates the aerosol-generating article 16 in more detail. Downstream of the aerosol-forming substrate 14, a hollow tubular section 30 of the aerosol-generating article 16 is provided. Downstream of the hollow tubular section 30, a filter element 32 is disposed. The filter element 32 is configured to cool the airflow for aerosol generation. Downstream of the filter element 32, and forming the downstream-most section of the aerosol-generating article 16, a downstream filter plug 34 is disposed.

[0090] 3 shows a more detailed view of the configuration of the substrate sensor 22. The substrate sensor 22 comprises a number of laterally arranged and ring-shaped air channels 36. All of these air channels 36 lead to a central portion of the substrate sensor 22 where the actual detection takes place. The air then flows downstream into the cavity 12. The central portion of the substrate sensor 22 may be part of or form an opening 38 leading into the cavity 12. The substrate sensor 22 is centrally disposed in the longitudinal axis of the aerosol-generation device 10, which is simultaneously the longitudinal axis of the cavity 12.

[0091] Figure 4 shows an alternative aerosol generating device. Elements similar to those from the previous embodiment will be indicated with the same reference numerals and will not be described again.

[0092] The aerosol-generating device 10 of the embodiment of FIG. 4 is configured to utilize a liquid aerosol-forming substrate 14. The liquid aerosol-forming substrate 14 is provided in a cartridge 40. The cartridge 40 may be configured to be replaceable or refillable. In the case of a refillable cartridge 40, the cartridge 40 may be part of the aerosol-generating device 10 and may be labeled as a liquid reservoir. The cartridge 40 or liquid reservoir may be received within the cavity 12. A mouthpiece 42 is disposed downstream of the cartridge 40. The mouthpiece 42 includes an air outlet 44 at its downstream end through which inhalable aerosol can exit the mouthpiece 42. An airflow channel 46 fluidly connects an air inlet 48 with an aerosolization zone 50.

[0093] The heating element 18 is disposed adjacent to the aerosolization zone 50. The heating element 18 is disposed in fluid communication with the aerosolization zone 50. The heating element 18 may be configured as a resistive heating element 18, preferably a mesh heater, or as an induction heating element 18. The heating element 18 is electrically connected to the controller 24 via a heating connection 52.

[0094] A mouthpiece 42 is disposed downstream of the aerosolization zone 50. An airflow channel 46 fluidly connects the aerosolization zone 50 with the mouthpiece 42. A substrate sensor 22 is disposed adjacent to, and preferably abutting, the aerosolization zone 50. The substrate sensor 22 is disposed in fluid communication with the aerosolization zone 50. The substrate sensor 22 may be part of the cartridge 40 or may be separate from the cartridge 50 as part of the aerosol generation device 10. The substrate sensor 22 is electrically connected to the controller 24 via a sensor connection 54.

[0095] 5, the substrate sensor 22 may be disposed downstream of the aerosolization zone 50. In other words, the substrate sensor 22 may be disposed downstream of the cartridge 40. In this case, the substrate sensor 22 is disposed in fluid communication with the airflow channel 46 downstream of one or both of the aerosolization zone 50 and the cartridge 40.

Claims

1. An aerosol generating device, comprising: a cavity for receiving an aerosol-forming substrate; an airflow channel through the cavity; a substrate sensor disposed at a base of the cavity; the substrate sensor is a pH sensor; the substrate sensor is configured to detect a pH value of the aerosol drawn through the airflow channel, the pH value indicating the degree of depletion of the aerosol-forming substrate; The aerosol generating device further comprises a controller configured to generate a signal based on the output of the substrate sensor when the depletion level of the aerosol-forming substrate falls below a predetermined threshold, the signal indicating the depletion level of the aerosol-forming substrate.

2. 2. The aerosol generating device according to claim 1, wherein the substrate sensor has a measurement range of 2 pH to 10 pH.

3. 2. The aerosol generating device of claim 1, wherein the substrate sensor has a measurement accuracy of ±0.02 pH at pH 7.

4. 10. The aerosol generating device of claim 1, wherein the substrate sensor has a pH drift of less than 0.05 per day at pH 7.

5. 2. The aerosol generating device of claim 1, wherein the substrate sensor is disposed within or adjacent to the base of the cavity.

6. 2. The aerosol generating device of claim 1, wherein the signal is one or more of a user interface signal, a light signal, an acoustic signal, and a vibration signal.

7. 7. The aerosol generating device of claim 6, wherein the controller is configured to terminate operation of the aerosol generating device if the depletion of the aerosol-forming substrate is below the predetermined threshold after a predetermined time or a predetermined number of puffs by the user.

8. 2. The aerosol generating device according to claim 1, wherein the degree of depletion of the aerosol-forming substrate is the pH value of the aerosol drawn through the airflow channel.

9. 2. The aerosol generating device of claim 1, wherein the aerosol generating device further has an activation button, and the substrate sensor is configured to begin detecting the depletion of the aerosol-forming substrate a predetermined time after pressing the activation button, or a predetermined number of puffs taken by the user after pressing the activation button.

10. 10. The aerosol generating device of claim 9, wherein the substrate sensor is configured to continuously detect the degree of depletion of the aerosol-forming substrate during operation of the aerosol generating device or when the aerosol-forming substrate is close to being estimated to be depleted.

11. An aerosol generating device as described in claim 10, wherein the estimated depletion is based on the specified time after pressing the activation button, or based on the specified number of puffs taken by the user after pressing the activation button.

12. 2. The aerosol generating device of claim 1, wherein the airflow channel passes between a sidewall of the aerosol-forming substrate and a sidewall defining the cavity.

13. 2. The aerosol generating device according to claim 1, wherein the substrate sensor is disposed so as to face the upstream end of the aerosol-forming substrate.

14. An aerosol generating system comprising the aerosol generating device according to any one of claims 1 to 13, and one of an aerosol-generating article comprising an aerosol-forming substrate and a cartridge comprising a liquid aerosol-forming substrate.

15. A method for detecting the depletion of an aerosol-forming substrate of an aerosol-generating article or cartridge in an aerosol-generating device according to any one of claims 1 to 11, comprising: - detecting by a substrate sensor the pH value of the aerosol drawn through the airflow channel, which indicates the degree of depletion of the aerosol-forming substrate.

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