Optical spectrum detector for aerosol generators

Abstract

An aerosol generating device (100) for generating an aerosol from an aerosol-forming substrate. The aerosol generating device comprises a housing (10) defining a cavity (11) for at least partially receiving the aerosol-forming substrate. The sensing assembly comprises an emitter configured to emit electromagnetic radiation into the cavity and a receiver configured to receive the electromagnetic radiation from the cavity. The receiver comprises a sensor configured to measure at least one wavelength of the received electromagnetic radiation. The sensing assembly further comprises a shield (148) positioned outside the cavity such that the receiver is between the shield and the cavity, the shield being configured to block the electromagnetic radiation. A first portion of the shield is planar, a second portion of the shield is planar, and the first and second portions of the shield are non-coplanar. An angle between a normal to the plane of the first portion and a normal to the plane of the second portion is substantially the same as an angle between the receiver and the emitter.

Description

[Technical field]

[0001] The present disclosure relates to an aerosol generating device for generating an aerosol from an aerosol-forming substrate, in particular, the present disclosure relates to an aerosol generating device including a sensing assembly. [Background technology]

[0002] Aerosol generating devices configured to generate an aerosol from an aerosol-forming substrate, such as a tobacco-containing substrate, are known in the art. Many known aerosol generating devices generate an aerosol by application of heat to the substrate by a heater assembly. The heater assembly is heated when power is provided by a power source of the aerosol generating device. The generated aerosol can then be inhaled by a user of the device.

[0003] In many cases, the aerosol-forming substrate is receivable within the cavity of an aerosol-generating device. The aerosol-forming substrate may be part of an aerosol-generating article, at least a portion of which is receivable within the cavity of the device and is then heated during use of the device. Because flavor is generated and released by controlled heating of the aerosol-forming substrate without combustion, as occurs, for example, in a lit cigarette, aerosol-generating articles developed for use in such aerosol-generating devices are typically designed specifically for that particular device. For example, the structure of the article and the composition of the substrate are specifically designed to provide a desired experience for the user. Using the wrong type of aerosol-generating article, or a smoking article with a lit tip, can result in a poor user experience and damage the aerosol-generating device.

[0004] Some aerosol generating devices can be used with many different types of aerosol generating articles, each of which provides a different user experience. For example, the aerosol-forming substrates of different aerosol generating articles may have different compositions and therefore generate different aerosols. The aerosol generating device may be configured to control the heating of each of the aerosol generating articles differently, in a manner optimized for the particular type of aerosol generating article. Using heating controls that are not appropriate for the type of aerosol generating article can result in a poor user experience and may damage the aerosol generating device.

[0005] Counterfeiting of aerosol-generating articles is also a problem. Counterfeit aerosol-generating articles may be of lower quality or may not be suitable at all for a particular aerosol generating device.

[0006] Aerosol-generating articles are often designed to be used for a certain number of puffs, for example 10-15 puffs. If a user continues to use the aerosol-generating article after the certain number of puffs has elapsed, the quality and quantity of aerosol generated during a puff may be poor, resulting in a poor user experience and may even damage the aerosol-generating device. This may be because the moisture content of the aerosol-forming substrate changes during use. If the same heating profile is applied to a substrate with a low moisture content, the amount of aerosol generated during heating of the substrate will change over time, which is undesirable.

[0007] The moisture content of the aerosol-forming substrate is not only depleted during heating of the aerosol-forming substrate by the aerosol-generating device, but will also be affected by how and for how long the aerosol-generating article is stored, as well as by inconsistencies in the process of manufacturing the substrate. An aerosol-forming substrate with an abnormally high or low moisture content may require different heating control if a certain amount of aerosol is to be generated.

[0008] It would therefore be desirable to provide an aerosol generating device that can accurately distinguish between different types of aerosol generating articles and identify aerosol generating articles that are suitable or unsuitable for use with the aerosol generating device. It would be desirable to provide an aerosol generating device that is inexpensive and easy to manufacture. It would further be desirable to provide a sensing assembly that does not require modifications to the aerosol generating article or the manufacturing process for the aerosol generating article. It would also be desirable to provide an aerosol generating device that can monitor the quality and usage of the aerosol generating article. Summary of the Invention

[0009] According to an aspect of the present disclosure, there is provided an aerosol generation device for generating an aerosol from an aerosol-forming substrate. The aerosol generation device may comprise a housing defining a cavity for at least partially receiving the aerosol-forming substrate. The aerosol generation device may comprise a sensing assembly. The sensing assembly may comprise an emitter. The emitter may be configured to emit electromagnetic radiation into the cavity. The sensing assembly may further comprise a receiver. The receiver may be configured to receive the electromagnetic radiation from the cavity. The receiver may comprise a sensor. The sensor may be configured to measure at least one wavelength of the received electromagnetic radiation.

[0010] An aerosol-generating device comprising a sensing assembly may advantageously be able to detect the presence and type of an aerosol-generating substrate at least partially received in the cavity based on a measurement of at least one wavelength of the received electromagnetic radiation produced by the sensor. The aerosol-forming substrate may be included in an aerosol-generating article at least partially received in the cavity. In use, the emitter may advantageously emit electromagnetic radiation into the cavity in which the aerosol-forming substrate is at least partially received. Electromagnetic radiation incident on the aerosol-forming substrate or aerosol-generating article may undergo one of absorption, reflection, or transmission. The amount of absorption, reflection, or transmission of electromagnetic radiation at different wavelengths may depend on the chemical structure of the aerosol-forming substrate or article. Thus, the chemical structure of the aerosol-forming substrate or article may affect the electromagnetic radiation received from the cavity by the receiver. Different aerosol-forming substrates or articles may have different chemical structures and therefore may affect the electromagnetic radiation differently. Thus, measurements of the received electromagnetic radiation may advantageously be used to determine the presence and type of an aerosol-forming substrate received in the cavity.

[0011] The receiver sensor is preferably configured to measure the intensity of at least one wavelength of electromagnetic radiation. Measuring may include comparing the intensity of the at least one wavelength of electromagnetic radiation to a threshold value.

[0012] Preferably, the aerosol generating device may include a controller connected to the receiver. The controller may include a memory. Stored in the controller's memory may be data relating known measurements of electromagnetic radiation at particular wavelengths to the chemical structure or type of the aerosol-forming substrate. The controller may be configured to determine the type of aerosol-forming substrate received in the cavity by comparing one or more electromagnetic radiation measurements made by the receiver's sensor at one or more wavelengths to the known measurements stored in the memory.

[0013] The aerosol generating device may further comprise a heater assembly. The heater assembly may be configured to heat an aerosol-forming substrate received in the cavity in use. The controller may be configured to control the heater assembly. The controller of the heater assembly may be based on the type of aerosol-forming substrate determined by the controller. The controller may preferably be configured to control the heater assembly according to a heating profile. The heating profile may be selected or modified according to the type of aerosol-forming substrate at least partially received in the cavity.

[0014] The emitter may comprise at least one LED for emitting electromagnetic radiation. Preferably, the emitter may be configured to emit multiple wavelengths of electromagnetic radiation. The emitter may comprise multiple LEDs, each of the multiple LEDs configured to emit a different wavelength of electromagnetic radiation.

[0015] The receiver sensor may include a photodiode.

[0016] The receiver may be configured to receive multiple wavelengths of electromagnetic radiation, and in particular, the sensor of the receiver may be configured to measure multiple wavelengths of received electromagnetic radiation.

[0017] In other words, the sensing assembly may be configured to perform spectroscopy on the aerosol-forming substrate received in the cavity, or on the aerosol-generating article including the substrate received in the cavity. The apparatus may comprise a controller for performing a spectral analysis on the measured electromagnetic radiation. Based on the spectral analysis, the controller may be configured to determine the presence of an aerosol-forming substrate in the cavity. The controller may be configured to determine the type of aerosol-forming substrate in the cavity.

[0018] Determining the presence and type of an aerosol-forming substrate is used interchangeably herein with determining the presence and type of an aerosol-generating article that includes the aerosol-forming substrate. In either case, the aerosol-generating device may advantageously be configured to determine the presence and type of the aerosol-forming substrate or article based on its chemical composition.

[0019] In one embodiment, electromagnetic radiation emitted by the emitter may be incident on an aerosol-forming substrate, in which case the presence or type of the aerosol-forming substrate may be determined.

[0020] Alternatively, the aerosol-forming substrate may be included in an aerosol-generating article. In that case, the electromagnetic radiation received by the receiver may be affected by the chemical structure of the aerosol-generating article, for example the wrapper or housing of the article. Different aerosol-generating articles may have different chemical structures, for example different wrappers or housings. This may make it possible to distinguish between different aerosol-generating articles.

[0021] "Different aerosol-generating articles" may refer to aerosol-generating articles that include different aerosol-forming substrates.

[0022] Furthermore, a portion of the electromagnetic radiation may pass through the aerosol-generating device to the aerosol-forming substrate such that the electromagnetic radiation received by the receiver may be affected by the chemical structure of both the aerosol-generating article and the substrate.

[0023] The aerosol-forming substrate may be a solid aerosol-forming substrate. Alternatively, the aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material that contains volatile tobacco flavor compounds that are released from the substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol formers are glycerin and propylene glycol.

[0024] When the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of powder, granules, pellets, pieces, spaghetti, strips, or sheets containing one or more of herb leaves, tobacco leaves, tobacco stem pieces, reconstituted tobacco, homogenized tobacco, extruded tobacco, cast leaf tobacco, and expanded tobacco. The solid aerosol-forming substrate may be in loose form or may be provided in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may contain additional tobacco or non-tobacco volatile flavor compounds that are released upon heating of the substrate. The solid aerosol-forming substrate may also contain capsules, for example containing additional tobacco or non-tobacco volatile flavor compounds, which may melt during heating of the solid aerosol-forming substrate.

[0025] As used herein, "homogenized tobacco" refers to a material formed by agglomerating particulate tobacco. The homogenized tobacco may be in the form of a sheet. The homogenized tobacco material may have an aerosol former content of greater than 5% on a dry weight basis. Alternatively, the homogenized tobacco material may have an aerosol former content of 5-30% by weight on a dry weight basis. A sheet of homogenized tobacco material may be formed by agglomerating particulate tobacco obtained by grinding or otherwise combining one or both of tobacco blades and tobacco stems. Alternatively, or additionally, the sheet of homogenized tobacco material may include one or more of tobacco dust, tobacco fines, and other particulate tobacco by-products formed, for example, during tobacco processing, handling, and shipping. The homogenized tobacco material sheet may include one or more inherent binders (i.e., tobacco intrinsic binders), one or more extrinsic binders (i.e., tobacco extrinsic binders), or combinations thereof to aid in the cohesion of the particulate tobacco, but alternatively or in addition, the homogenized tobacco material sheet may include other additives including, but not limited to, tobacco and non-tobacco fibers, aerosol formers, humectants, plasticizers, flavorants, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0026] Optionally, the solid aerosol-forming substrate may be provided on or embedded in a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, pieces, spaghetti, strips, or sheets. Alternatively, the carrier may be a tubular carrier having a thin layer of solid substrate deposited on its inner surface, or on its outer surface, or on both its inner and outer surfaces. Such a tubular carrier may be formed, for example, of paper or paper-like material, non-woven carbon fiber mat, low-mass open mesh metal screen, or perforated metal foil, or any other thermally stable polymeric matrix.

[0027] In a particularly preferred embodiment, the aerosol-forming substrate comprises an assembly of crimped sheets of homogenized tobacco material. As used herein, the term "crimped sheet" refers to a sheet having a plurality of substantially parallel ridges or corrugations. When the aerosol-generating article is assembled, the substantially parallel ridges or corrugations preferably run along or parallel to the longitudinal axis of the aerosol-generating article. This advantageously facilitates assembling the crimped sheets of homogenized tobacco material to form the aerosol-forming substrate. However, it will be appreciated that a crimped sheet of homogenized tobacco material for inclusion in an aerosol-generating article may alternatively or additionally have a plurality of substantially parallel ridges or corrugations that are disposed at an acute or obtuse angle relative to the longitudinal axis of the aerosol-generating article when the aerosol-generating article is assembled. In certain embodiments, the aerosol-forming substrate may comprise an assembly of sheets of homogenized tobacco material that are substantially evenly textured across substantially its entire surface. For example, the aerosol-forming substrate may comprise an assemblage of a crimped sheet of homogenized tobacco material that includes a plurality of substantially parallel ridges or corrugations that are substantially evenly spaced across the width of the sheet.

[0028] The solid aerosol-forming substrate may be deposited on the surface of the carrier, for example in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate may be deposited on the entire surface of the carrier or, alternatively, in a pattern to provide a non-uniform flavour delivery during use.

[0029] The heater assembly may comprise a heating element. In use, power may be supplied to the heating element to heat it. Heat may then be transferred to the received aerosol-forming substrate, for example by conduction through the device housing that forms the chamber.

[0030] The heating element may be a resistive heating element. 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, etc.), carbon, graphite, metals, metals, and composites made of ceramic and metallic materials. Such composites may include doped and undoped ceramics.

[0031] In another embodiment, the heater assembly may include one or more inductor coils and the heating element may include one or more susceptor elements.

[0032] One or more susceptor elements may be configured to be heatable by an alternating magnetic field generated by an inductor coil or coils. In use, power supplied to the inductor coil (e.g., by a power source of the apparatus) may cause the inductor coil to induce eddy currents in the susceptor elements. These eddy currents then cause the susceptor elements to generate heat. Power is supplied to the inductor coil as an alternating magnetic field. The alternating current may have any suitable frequency. The alternating current may preferably be a high frequency alternating current. The alternating current may have a frequency of 100 kilohertz (kHz) to 30 megahertz (MHz). When an aerosol-forming substrate is received in the chamber, the heat generated by the susceptor elements is generated by heating the aerosol-forming substrate to a temperature sufficient to emit an aerosol from the substrate. The susceptor elements may be formed of a material capable of absorbing and converting electromagnetic energy into heat. By way of example and without limitation, the susceptor elements may be formed of a ferromagnetic material, such as steel.

[0033] The aerosol generating device may include a power source that may be configured to supply an electrical current to the resistive heating element.

[0034] The heating element may comprise a substrate layer of flexible material. The substrate layer may comprise a thermally stable polymer, preferably a polyimide.

[0035] The heating element may be disposed on the substrate layer. The heating element may include a wire connection configured for connection with a controller of the aerosol generating device. The heating element may comprise a heating track disposed on the substrate layer. The heating track may comprise a thermally conductive material, preferably a metal such as stainless steel. The heating track may be electrically connected to said wire connection.

[0036] The heating element may take other forms, such as a metal grid(s), a flexible printed circuit board, a molded interconnect (MID), a ceramic heater, a flexible carbon fiber heater, or may be formed using coating techniques such as plasma deposition onto a suitably shaped substrate.

[0037] The cavity may comprise an opening at a first end through which the aerosol-forming substrate may be received. The cavity may be configured to receive the aerosol-forming substrate along the longitudinal axis.

[0038] The emitter and receiver may be parallel to the longitudinal axis.

[0039] The cavity may include a second end opposite the first end, and the emitter and receiver may be positioned to emit and receive electromagnetic radiation into and from, respectively, the second end of the cavity.

[0040] Alternatively, the emitter and receiver may be perpendicular to the longitudinal axis. The emitter and receiver may be positioned to radiate and receive electromagnetic radiation to and from the cavity perpendicular to the longitudinal axis. The emitter and receiver may be positioned to radiate and receive electromagnetic radiation to and from the cavity in a region between a first end and a second end of the cavity. The emitter may be positioned outside the cavity. The receiver may be positioned outside the cavity.

[0041] According to another aspect of the present disclosure, there is provided an aerosol generating device according to the previous aspect, wherein the sensing assembly further comprises a shield. The shield may be positioned outside the cavity. The shield may be positioned such that the receiver is between the shield and the cavity. The shield may also be configured to block electromagnetic radiation.

[0042] The position of the shield may advantageously mean that electromagnetic radiation external to the aerosol generating device is blocked by the shield. This may mean that electromagnetic radiation external to the aerosol generating device is blocked from reaching the receiver. The external electromagnetic radiation may otherwise be received by the receiver and thus picked up as noise. The shield may therefore advantageously improve the accuracy of the sensing assembly and reduce noise. This may improve the signal-to-noise ratio of measurements from the receiver's sensor.

[0043] One source of external electromagnetic radiation may be from the user of the aerosol generating device: for example, the user's hands can generate parasitic capacitance effects on the order of picofarads, which, in the absence of shielding, can be detected as noise by the receiver's sensor.

[0044] As used herein, shielding "blocking" electromagnetic radiation may mean that the shield prevents external electromagnetic radiation from passing through the receiver. The shield may reduce the intensity of externally generated electromagnetic radiation at the receiver by at least 90%, preferably at least 95%, and even more preferably at least 99%. The shield may be effective to reduce the intensity of electromagnetic radiation between the infrared range and the ultraviolet range. Preferably, the shield may be effective to reduce the intensity of electromagnetic radiation having a wavelength between 1 nanometer and 100,000 nanometers, preferably between 200 nanometers and 30,000 nanometers, and even more preferably between 200 nanometers and 15,000 nanometers. The shield may reduce the intensity of externally generated electromagnetic radiation by absorbing or reflecting the radiation.

[0045] The shield may include a conductive material. The shield may be made of a conductive material. The conductive material may have a conductivity of at least 1×10 6 Siemens / meter, preferably at least 1 x 10 7 Siemens / meter, and even more preferably at least 5×10 7 It may have an electrical conductivity in Siemens / meter.

[0046] The shield may include a thermally conductive material. The shield may be made of a thermally conductive material. This may be particularly advantageous when the aerosol generating device further comprises a heater assembly configured to heat an aerosol-forming substrate received in the cavity during use. A shield including a thermally conductive material may advantageously dissipate heat generated by the heater assembly away from the receiver. The receiver may be particularly sensitive to heating and may be damaged by excessive heating. A shield including a thermally conductive material may advantageously prevent the receiver from overheating during use of the aerosol generating device. The shield may be configured to prevent the receiver from exceeding 115 degrees Celsius during use of the aerosol generating device.

[0047] The thermally conductive material may have a thermal conductivity of at least 10 Watts / meter Kelvin, preferably at least 80 Watts / meter Kelvin, preferably at least 100 Watts / meter Kelvin, even more preferably at least 150 Watts / meter Kelvin.

[0048] The shield may include a metal. Preferably, the shield may include at least one of aluminum and stainless steel.

[0049] The shield may have a thickness of 0.1 millimeters to 3 millimeters. Preferably, the shield may have a thickness of 0.2 millimeters. Such a thickness may advantageously be sufficient to ensure that the shield adequately blocks external electromagnetic radiation.

[0050] The shield may be sized and positioned such that the emitter is between the shield and the cavity. This may advantageously ensure that external electromagnetic radiation does not enter the cavity through the emitter. Such a shield may also advantageously dissipate heat from the emitter.

[0051] The shield may have a width of 1 to 10 mm, more preferably 2 to 4 mm, and even more preferably about 3 mm. The shield may have a length of 10 to 30 mm, more preferably 15 to 25 mm, and even more preferably about 22 mm.

[0052] The emitter and receiver may be parallel to one another, in other words, the angle between the emitter and receiver may be about 0 degrees.

[0053] When an angle between an emitter and a receiver is referred to herein (including terms such as parallel and perpendicular), the angle is the angle between the central optical axis of the emitter and the central optical axis of the receiver, which may be the same as the angle defined between the surface of the aerosol-forming substrate or article at least partially received within the cavity and the emitter and receiver.

[0054] The emitter and receiver may be adjacent to each other. In this way, the emitter and receiver may advantageously be provided on the same chip. This may advantageously reduce the complexity of the sensing assembly.

[0055] The emitter may be located on top of the receiver. The sensing assembly may include an emitter between the shield and the receiver.

[0056] Alternatively, the receiver and emitter may be non-parallel. The angle between the receiver and emitter may be between 20 and 120 degrees, preferably between 60 and 100 degrees, and even more preferably between 70 and 90 degrees. Most preferably, the angle between the receiver and emitter may be about 80 degrees. Such an angle may be particularly advantageous when the aerosol-forming substrate is contained within a rod-shaped aerosol-generating article and the electromagnetic radiation is incident on the article perpendicular to the cylindrical axis of the rod.

[0057] At least a first portion of the shield may be planar. The receiver may be positioned between the first portion of the shield and the cavity. Both the receiver and the emitter may be positioned between the first portion of the shield and the cavity. This may be the case, for example, where the emitter is on top of the receiver.

[0058] The second portion of the shield may be planar. The first and second portions of the shield may be non-coplanar. The receiver may be positioned between the first portion of the shield and the cavity. The emitter may be positioned between the second portion of the shield and the cavity.

[0059] The angle between the normal to the plane of the first portion and the normal to the plane of the second portion may be substantially the same as the angle between the receiver and the emitter when the receiver and the emitter are non-parallel. In other words, the angle between the normal to the plane of the first portion and the normal to the plane of the second portion may be 20 to 120 degrees, preferably 60 to 100 degrees, and even more preferably 70 to 90 degrees. Most preferably, the angle may be about 80 degrees.

[0060] The sensing assembly may further comprise a base. The base may comprise a first side to which at least one of the emitter and receiver is attached. The base may comprise a second side opposite the first side to which the shield is attached. This may advantageously be a simple arrangement that is easy to manufacture. The base may be a printed circuit board (PCB). The base may comprise two or more PCBs. The base may include or consist of one or more flexible PCBs.

[0061] The shield may include at least one clip. The shield may include a first clip at a first end and a second clip at a second end, the first end being at an end of the shield opposite the second end. The one or more clips may be configured to connect the clip to a second side of the substrate. The one or more clips may advantageously provide a simple and low-cost means of mounting the shield onto the substrate. Mounting the shield onto the substrate in this manner advantageously allows for a simple and low-cost manufacturing of the sensing assembly.

[0062] The shield may be connected to a ground contact of the aerosol generating device. The ground contact may be on the substrate. If the substrate comprises a PCB, the ground contact may be on the PCB. At least one clip of the shield may contact the ground contact. Connecting the shield to the ground contact may enable the shield to provide good shielding.

[0063] The shield may be integrally formed. It may include at least one clip.

[0064] According to another aspect of the present disclosure, there is provided an aerosol generating device according to any of the previous aspects, wherein the sensor assembly further comprises a lens. The lens may be configured to focus the electromagnetic radiation received from the cavity onto a sensor of the receiver. The sensor assembly may comprise two or more lenses, each of the one or more lenses configured to focus the electromagnetic radiation received from the cavity onto a sensor of the receiver. The one or more lenses may advantageously increase the amount of electromagnetic radiation received by the receiver. This may advantageously increase the signal-to-noise ratio of the sensing assembly and therefore improve the accuracy of the sensing assembly in detecting the presence and type of an aerosol-forming substrate at least partially received within the cavity.

[0065] The larger the surface area of ​​the lens relative to the surface area of ​​the part of the sensor of the receiver sensitive to electromagnetic radiation, the greater the amount of electromagnetic radiation received by the sensor. The surface area of ​​the lens may be at least ten times, preferably at least twenty times, and even more preferably at least thirty times larger than the surface area of ​​the part of the sensor of the receiver sensitive to electromagnetic radiation.

[0066] The lens may include a porous material. The absorbing material may be configured to substantially block wavelengths of electromagnetic radiation outside a certain wavelength range. The absorbing material may be transparent to electromagnetic radiation having wavelengths that fall within a certain wavelength range. In this manner, the absorbing material may advantageously act as a filter, allowing wavelengths of interest to pass through the lens and blocking selected wavelengths. Thus, the absorbing material may reduce noise and improve the accuracy of the sensing assembly.

[0067] The aforementioned wavelength ranges of interest may correspond to wavelengths of electromagnetic radiation known to be particularly affected by the chemical structure of the aerosol-forming substrate or aerosol-generating article. The absorbing material may be configured to substantially block wavelengths of electromagnetic radiation less than 200 nanometers, preferably less than 950 nanometers, and even more preferably less than 1350 nanometers. The absorbing material may be configured to substantially block wavelengths of electromagnetic radiation greater than 30,000 nanometers, preferably greater than 15,000 nanometers, preferably greater than 2000 nanometers, and even more preferably greater than 1400 nanometers.

[0068] The absorbing material may effectively act as a bandpass filter, substantially blocking wavelengths of electromagnetic radiation above an upper limit and below a lower limit. These limits may be as described above. In other words, the lower limit may be less than 200 nanometers, preferably less than 950 nanometers, and even more preferably less than 1350 nanometers. The upper limit may be greater than 30,000 nanometers, preferably greater than 15,000 nanometers, preferably greater than 2000 nanometers, and even more preferably greater than 1400 nanometers.

[0069] As will be explained in more detail with respect to later aspects of the invention, the target chemical structure of the aerosol-forming substrate may be related to the wettability or water content of the substrate. Different types of aerosol-forming substrates may have different water contents. The water content may vary depending on the amount of aerosol-forming substrate used, the storage method, and manufacturing inconsistencies. It may therefore be particularly advantageous for the aerosol generating device to be configured to measure the water content of the substrate using measurements by the receiver sensor to determine the substrate characteristics. The above range of electromagnetic radiation not blocked by the absorbing material may include a range of wavelengths that are particularly affected by the water content of the substrate.

[0070] Similar to a shield, an absorbing material that blocks electromagnetic radiation can mean that the absorbing material reduces the intensity of externally generated electromagnetic radiation at the receiver by at least 90%, preferably at least 95%, and even more preferably at least 99%, for the wavelengths that are blocked.

[0071] As used herein, a transparent portion or otherwise transparent to a particular wavelength of electromagnetic radiation means that at least 90%, preferably at least 95%, and even more preferably at least 99% of the electromagnetic radiation at that wavelength can pass through the first or second portion without being absorbed.

[0072] The body of the lens may include the absorbing material. Alternatively, the lens may include the absorbing material as a coating.

[0073] The absorbing material may include at least one of cadmium telluride, a chalcogenide glass, or zinc selenide.

[0074] The combination of the shield and lens described above may be particularly advantageous, especially when the lens includes an absorbing material. Both the shield and the lens including the absorbing material are advantageously configured to block undesired electromagnetic radiation from reaching the receiver sensor. In particular, wavelengths of electromagnetic radiation outside the range of wavelengths that are particularly affected by the target chemical structure of the aerosol-forming substrate may be blocked from reaching the receiver sensor. This may advantageously reduce noise at the receiver and thus improve the accuracy of the sensor assembly.

[0075] According to another aspect of the present disclosure, there is provided an aerosol generating device according to any one of the preceding aspects, wherein the sensing assembly further comprises amplification electronics.

[0076] The amplification electronics may be connected to the receiver. The amplification electronics may be configured to amplify a signal generated by the sensor of the receiver.

[0077] The amplification electronics may be analog amplification electronics. The aerosol generating device may further comprise electronics configured to convert an analog output of the amplification electronics to a digital signal. This may be advantageous where the device comprises a controller that operates on digital signals.

[0078] Preferably, the amplification electronics is connected directly to the receiver. If the sensing assembly comprises a printed circuit board (PCB) comprising the receiver, more preferably, the amplification electronics is provided as part of the same printed circuit board. Even more preferably, the amplification electronics and the receiver are provided as a single component. In either case, noise introduced into the signal generated by the receiver before the signal is amplified can be advantageously reduced.

[0079] It can be advantageous to minimize the amount of noise introduced into the signal generated by the receiver's sensor before the signal reaches the amplification electronics. This is because the signal generated by the sensor may be relatively small, for example, the signal may have a current of 50 to 200 nanoamperes. If the number of electrical connections and components between the receiver's sensor and the amplification electronics is not minimized, the signal generated by the sensor may be lost in the noise caused by those connections. The noise is then significantly amplified by the amplification electronics.

[0080] The amplification electronics may be configured to amplify the voltage of the signal generated by the receiver sensor by at least 100,000 times, preferably at least 1 million times, even more preferably 1 million to 10 million times, even more preferably 1 million to 30 million times, and most preferably about 25 million times.

[0081] The combination of the amplification electronics with the above-mentioned shield and at least one of the above-mentioned lenses may be particularly advantageous, especially if the amplification electronics are provided in such a way as to minimize the amount of noise introduced into the signal from the sensor of the receiver, and if combined with the lens, the lens includes an absorbing material. This may be because the aforementioned amplification electronics, shield, and lens including the absorbing material all reduce the noise detected by or generated by the sensing assembly. The reduction in noise may advantageously improve the accuracy of the sensing assembly. Furthermore, when the lens is combined with the amplification electronics, the amplification factor may advantageously be lower to achieve the same output voltage. This is because the lens may increase the signal strength generated at the receiver, requiring less amplification. Reducing the amplification factor may advantageously reduce the amount that the noise is amplified.

[0082] According to another aspect of the present disclosure, there is provided an aerosol generating device according to any of the previous aspects, wherein a first portion of the housing defining the cavity is transparent to at least one wavelength of the electromagnetic radiation emitted by the emitter. It may be preferred that the first portion of the housing is transparent to all of the wavelengths of the electromagnetic radiation emitted by the emitter. The emitter may be configured to emit the electromagnetic radiation into the cavity through the transparent portion.

[0083] The first part of the housing may separate the emitter from the cavity. Thus, the first part of the housing may protect the emitter from debris and dirt that may accumulate within the cavity. In particular, the emitter may be protected from residue from the aerosol-forming substrate that may accumulate during use of the aerosol generating device. The first part may also advantageously be easy to clean so that the device can be easily maintained.

[0084] An airflow path may be defined through the aerosol generating device from the air inlet to the air outlet. The airflow path may pass through the cavity. The emitter may be separated from air flowing through the airflow path by a transparent first portion of the housing. The air may carry debris or dirt. Thus, the first portion may protect the emitter from air passing through the airflow path.

[0085] The first portion of the housing may be sized and positioned to correspond to the viewing angle of the emitter, which may advantageously ensure that substantially all of the electromagnetic radiation emitted by the emitter in use passes into the cavity.

[0086] A second portion of the housing defining the cavity may be transparent to at least one wavelength of electromagnetic radiation to be received by the receiver. The receiver may be configured to receive the electromagnetic radiation from the cavity through the second transparent portion.

[0087] The second portion of the housing may have the corresponding features and advantages described with respect to the first portion, but only with respect to the receiver and not with respect to the emitter.

[0088] Providing the first and second housing parts may advantageously extend the life of the sensing assembly. Without the first and second housing parts, the sensing assembly may degrade over time as it becomes covered with dirt, debris, and substrate residue. A degraded sensing assembly may reduce the amount of electromagnetic radiation entering the cavity from the emitter or received by the receiver from the cavity, which will reduce the accuracy and sensitivity of the sensing assembly.

[0089] As discussed above, the combination of at least one of the first and second housing parts may be particularly advantageous in combination with at least one of the shield, the lens, or the amplification electronics. Each of these features provides benefits related to noise reduction and improved accuracy of the sensing assembly. An aerosol generating device with a combination of these features may advantageously have an even more accurate sensing assembly, and an assembly whose accuracy does not degrade over time.

[0090] According to another aspect of the present disclosure, there is provided an aerosol generating device according to any one of the preceding aspects, wherein the sensing assembly further comprises a substrate having a first side to which at least one of the emitter and the receiver is attached, and both the emitter and the receiver may be attached to the first side.

[0091] The substrate may comprise a fixed portion. The flexible portion may be configured such that the emitter is movable relative to the receiver by bending the flexible portion. As mentioned above, the angle between the receiver may preferably be between 20 and 120 degrees, preferably between 60 and 100 degrees, even more preferably between 70 and 90 degrees. Most preferably, the angle between the receiver and the emitter may be about 80 degrees. A substrate with a flexible portion may advantageously allow the angle between the emitter and the receiver to be controlled in a simple manner during the manufacturing process. Using a substrate with a flexible portion may advantageously remove the need to pre-mold the substrate to a desired shape. It may be possible to modify the angle between the emitter and the receiver during or after the manufacture of the aerosol forming device.

[0092] The substrate may be angled so that the emitter is adjacent to a different portion of the cavity relative to the receiver and the angle between the central optical axis of the emitter and the receiver is between 20 degrees and 120 degrees, preferably between 60 degrees and 100 degrees, and even more preferably between 70 degrees and 90 degrees. Most preferably, the angle between the receiver and the emitter may be about 80 degrees.

[0093] The substrate may comprise a first portion comprising the emitter. The substrate may comprise a second portion comprising the receiver. The substrate may include a third portion between the first and second portions. At least the third portion may be flexible such that the first portion is moveable relative to the second portion. This may allow for control of the angle between the emitter and receiver, as discussed above.

[0094] Preferably, the first portion of the substrate may be rigid, and the second portion of the substrate may be rigid, such that the flexible third portion acts as a hinge between the rigid first and second portions.

[0095] The third portion of the substrate may preferably be opaque to the wavelength of the electromagnetic radiation emitted by the emitter, which may advantageously ensure that the electromagnetic radiation emitted by the emitter is not directly received by the receiver before being reflected or absorbed and emitted by the aerosol-forming substrate received within the cavity.

[0096] The substrate may comprise one or more PCBs.The substrate may consist of one or more flexible PCBs.At least a third portion of the substrate may include or consist of a flexible PCB.

[0097] Preferably, the first and second portions of the substrate may comprise rigid PCBs and the third portion may comprise a flexible PCB.

[0098] The combination of a substrate in combination with at least one of the above-mentioned shield, the above-mentioned lens, the above-mentioned amplification, and the above-mentioned transparent portion may be particularly advantageous.

[0099] A particularly preferred combination may be a substrate comprising a flexible portion as described above and a shield as described above, when the shield comprises a first and a second planar portion, the second portion being planar in a different plane than the first portion, since the shield may advantageously hold the substrate such that the flexible portion can be bent at a desired angle.

[0100] The shield may preferably be attached to a second side of the substrate opposite the first side. The shield may be rigid.

[0101] A first portion of the shield may be attached to a first portion of the substrate, and a second portion of the shield may be attached to a second portion of the substrate.

[0102] This arrangement may allow for a simple manufacturing process. Advantageously, the act of attaching the shield to the substrate may hold the substrate at a desired angle.

[0103] Preferably, as mentioned above, the shield may include at least one clip, which may advantageously provide a simple, low-cost means of mounting the shield onto a substrate, further simplifying the manufacturing process.

[0104] The shield may preferably include two clips: a first clip may attach a first portion of the shield to a first portion of the base, and a second clip may attach a second portion of the shield to a second portion of the base.

[0105] According to another aspect of the present disclosure, there is provided an aerosol generating apparatus as described in any one of the preceding aspects, further comprising a controller configured to receive a signal from the receiver, the controller configured to determine a material property of the aerosol-forming substrate at least partially received in the cavity, or an aerosol-generating article including the aerosol-forming substrate, based on the measured intensity of the electromagnetic radiation received at the receiver.

[0106] The controller may preferably be configured to perform a spectral analysis of the measured intensity of the electromagnetic radiation to determine a material property of the aerosol-forming substrate or an aerosol-generating article comprising the aerosol-forming substrate. Based on the determined material property, the controller may be configured to determine the type of the aerosol-forming substrate at least partially received within the cavity. A controller configured to determine the material property of the aerosol-forming substrate may advantageously mean that the type of the aerosol-forming substrate may be directly determined based on the inherent material properties of the aerosol-forming substrate. The aerosol-forming substrate, or an aerosol-generating article comprising the aerosol-forming substrate, does not need to include a printed barcode, taggant or other indicia of the type of substrate.

[0107] Where the controller is configured to determine a material property of an aerosol-generating article that includes an aerosol-forming substrate, the material property may be a material property of a wrapper of the aerosol-generating article.

[0108] Preferably, the material property determined by the controller may be a material property of the aerosol-forming substrate. The material property determined by the controller may be a chemical property of the aerosol-forming substrate. The material property may be the presence or amount of a chemical component of the aerosol-forming substrate. If the aerosol-forming substrate comprises tobacco, the material property may relate to the tobacco content of the aerosol-forming substrate or some other chemical property of the tobacco.

[0109] Preferably, the material property determined by the controller may be the wettability or moisture content of the aerosol-forming substrate. The controller may be configured to determine a value related to the moisture content of the aerosol-forming substrate received within the cavity based on the measured intensity of the electromagnetic radiation received at the receiver.

[0110] Based on the determined value for the water content, the controller may be configured to determine the type of aerosol-forming substrate received in the cavity. Different types of aerosol-forming substrates may have different water contents from each other. Aerosol-forming substrates typically include an aerosol former such as glycerin. The amount or type of aerosol former present in the aerosol-forming substrate may determine its wettability. Thus, the controller may advantageously be configured to distinguish between aerosol-forming substrates that include different amounts or types of aerosol formers based on the determined water content in the aerosol-forming substrate.

[0111] The apparatus may further comprise a heating assembly for heating the aerosol-forming substrate. The heating assembly may be controlled by a controller. The controller may be configured to control the heating assembly with a heating profile selected based on the determined type of the aerosol-forming substrate.

[0112] The controller may be configured to repeatedly determine a value related to the moisture content of the aerosol-forming substrate received in the cavity during use of the aerosol generating device. Preferably, the controller may be configured to modify the heating profile based on a change in the determined moisture content of the aerosol-forming substrate. The change in the determined moisture content may be relative to an expected moisture content of the determined type of aerosol-forming substrate. Alternatively or additionally, the change in the determined moisture content may be a change in the determined moisture content over time. For example, the change in the determined moisture content may be a change in the determined moisture content during or between puffs.

[0113] The moisture content of the aerosol-forming substrate may decrease over time. The decrease in moisture content may be the result of heating the aerosol-forming substrate by the aerosol generating device during use. Alternatively or additionally, the decrease in moisture content may be the result of the aerosol-forming substrate drying out during storage, especially if the aerosol-forming substrate is improperly stored. As the wettability of the aerosol-forming substrate changes, a different heating profile may be required to heat the substrate to generate the same amount of aerosol. Modifying the heating profile based on the determined change in moisture content may advantageously provide that a consistent amount of aerosol may be generated. For example, the maximum temperature reached during heating may increase as the moisture content decreases, which may advantageously explain the decrease in the amount of aerosol former in the aerosol-forming substrate when the wettability decreases.

[0114] The controller may be configured to stop heating of the aerosol-forming substrate by the heater assembly when a value related to the moisture content of the aerosol-forming substrate falls below a predetermined value.

[0115] The emitter may be configured to emit electromagnetic radiation having a wavelength between 1100 nanometers and 1500 nanometers. Preferably, the emitter may be configured to emit electromagnetic radiation having a wavelength between 1350 nanometers and 1400 nanometers.

[0116] The receiver may be configured to receive electromagnetic radiation having a wavelength between 1100 nanometers and 1500 nanometers. Preferably, the receiver may be configured to receive electromagnetic radiation having a wavelength between 1350 nanometers and 1400 nanometers.

[0117] Water is particularly effective at absorbing electromagnetic radiation having wavelengths between 1100 nanometers and 1500 nanometers, particularly between 1350 nanometers and 1400 nanometers, and therefore it may be advantageous for the emitter and receiver to emit and receive such wavelengths of electromagnetic radiation when the material property of the target of the aerosol-forming substrate is wettability or water content.

[0118] The combination of a controller configured to determine material properties of an aerosol-forming substrate at least partially received within the cavity based on the measured intensity of electromagnetic radiation received at the substrate using at least one of the above-mentioned shields, the above-mentioned lenses, the above-mentioned amplification, the above-mentioned transparent portions, or the above-mentioned flexible substrate may be particularly advantageous.

[0119] For the material properties of the aerosol-forming substrate to be accurately determined based on the measured intensity of the electromagnetic radiation receiver, it may be preferable for the signal received at the receiver to have a high signal-to-noise ratio. At least the shields, lenses, amplifying electronics, and transparent parts are features that may increase the signal generated by the receiver or reduce the noise associated with the signal.

[0120] According to another aspect of the present disclosure, there is provided a sensing assembly for an aerosol generating device for generating an aerosol from an aerosol-forming substrate. The aerosol generating device may include a housing. The housing may define a cavity. The cavity may be for at least partially receiving the aerosol-forming substrate.

[0121] The sensing assembly may comprise an emitter for emitting electromagnetic radiation into the cavity of the aerosol generation device. The sensing assembly may comprise a receiver for receiving electromagnetic radiation from the cavity of the aerosol generation device. The receiver may comprise a sensor. The sensor may be configured to measure at least one wavelength of the received electromagnetic radiation.

[0122] The sensing assembly may include any of the features described in relation to any one of the preceding aspects of the present disclosure.

[0123] The sensing assembly may preferably include a shield. The shield may be external to the receiver such that the receiver may be positioned between the shield and the cavity of the aerosol device. The shield may also be configured to absorb electromagnetic radiation.

[0124] Alternatively or additionally, the sensing assembly may comprise a lens. The lens may be configured to focus the electromagnetic radiation received from the cavity onto the receiver sensor. The lens may comprise a porous material. The absorbing material may be configured to substantially block wavelengths of electromagnetic radiation having a wavelength less than 200 nanometers, preferably less than 950 nanometers, and even more preferably less than 1350 nanometers. The absorbing material may be configured to substantially block wavelengths of electromagnetic radiation having a wavelength greater than 30,000 nanometers, preferably greater than 15,000 nanometers, preferably greater than 2000 nanometers, and even more preferably greater than 1400 nanometers. The absorbing material may effectively act as a bandpass filter, substantially blocking wavelengths of electromagnetic radiation above an upper limit and below a lower limit. These limits may be as described above. In other words, the lower limit may be less than 200 nanometers, preferably less than 950 nanometers, and even more preferably less than 1350 nanometers. The upper limit may be greater than 30,000 nanometers, greater than 15,000 nanometers, preferably greater than 2000 nanometers, and even more preferably greater than 1400 nanometers.

[0125] Alternatively or additionally, the sensing assembly may comprise amplification electronics. The amplification electronics may be connected to the receiver. The amplification electronics may be configured to amplify the signal generated by the sensor in the receiver. Preferably, the amplification electronics is directly connected to the receiver. When the sensing assembly comprises a printed circuit board with the receiver, it is more preferred that the amplification electronics is provided as part of the same printed circuit board. Even more preferred, the amplification electronics and the receiver are provided as a single component.

[0126] Alternatively or additionally, the sensing assembly may further comprise a base having a first side to which at least one of the emitter and receiver is attached. Both the emitter and the receiver may be attached to the first side. The base may comprise a flexible portion as described above.

[0127] Alternatively, or additionally, the sensing assembly may be configured for use in an aerosol generating device according to any one of the preceding aspects.

[0128] In particular, the sensing assembly may be configured for use in an aerosol generating device, where a first portion of the housing defining the cavity is transparent to at least a portion of the wavelengths of electromagnetic radiation emitted by the emitter. The emitter may be configured to emit the electromagnetic radiation into the cavity through the transparent portion. A second portion of the housing defining the cavity may be transparent to at least a portion of the wavelengths of electromagnetic radiation received by the receiver. The receiver may be configured to receive the electromagnetic radiation from the cavity through the second transparent portion.

[0129] The sensing assembly may be configured for use in an aerosol generating device that includes a controller as described above.

[0130] The present invention is defined in the claims. However, 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 of any other example, embodiment, or aspect described herein.

[0131] Example 1. An aerosol generating apparatus for generating an aerosol from an aerosol-forming substrate, the aerosol generating apparatus comprising: a housing defining a cavity for at least partially receiving the aerosol-forming substrate; and A sensing assembly comprising: an emitter configured to emit electromagnetic radiation into the cavity; An aerosol generation device comprising a sensing assembly comprising: a receiver configured to receive electromagnetic radiation from the cavity, the receiver comprising a sensor configured to measure at least one wavelength of the received electromagnetic radiation. Example 2. 2. The aerosol generating device of example 1, wherein the aerosol-forming substrate is contained within an aerosol-generating article that is at least partially receivable within the cavity. Example 3. An aerosol generating device as described in embodiment 1 or 2, wherein the receiver sensor is configured to measure the intensity of at least one wavelength of electromagnetic radiation. Example 4. 4. The aerosol generating device of example 3, wherein the measuring comprises comparing the intensity of at least one wavelength of electromagnetic radiation to a threshold value. Example 5. 5. An aerosol generation apparatus according to any one of Examples 1 to 4, comprising a controller connected to the receiver. Example 6. 6. An aerosol generating device as described in Example 5, wherein the controller comprises a memory. Example 7. The aerosol generating device of Example 6, wherein the controller memory stores data relating to known measurements of electromagnetic radiation at specific wavelengths and the chemical structure or type of the aerosol-forming substrate. Example 8. An aerosol generating device as described in Example 7, wherein the controller is configured to determine the type of aerosol-forming substrate received in the cavity by comparing one or more electromagnetic radiation measurements made by the receiver sensor at one or more wavelengths with known measurements stored in the memory. Example 9. 9. An aerosol generating device according to any one of the preceding embodiments, wherein the emitter comprises at least one LED for emitting electromagnetic radiation. Example 10. 10. An aerosol generating device according to any one of the preceding embodiments, wherein the emitter is configured to emit multiple wavelengths of electromagnetic radiation. Example 11. An aerosol generating device as described in Example 10, wherein the emitter comprises a plurality of LEDs, each of the plurality of LEDs being configured to emit electromagnetic radiation of a different wavelength. Example 12. 12. The aerosol generating apparatus according to any one of Examples 1 to 11, wherein the receiver sensor comprises a photodiode. Example 13. 13. An aerosol generating device according to any one of claims 1 to 12, wherein the receiver is configured to receive multiple wavelengths of electromagnetic radiation. Example 14. An aerosol generating device according to any one of Examples 1 to 13, wherein the cavity has an opening at a first end for receiving the aerosol-forming substrate and is configured to receive the aerosol-forming substrate along the longitudinal axis. Example 15. 15. The aerosol generating device of example 14, wherein the emitter and receiver are parallel to the longitudinal axis. Example 16. 16. The aerosol generating device of example 15, wherein the emitter is above the receiver. Example 17. An aerosol generating device as described in Example 15 or 16, wherein the cavity has a second end opposite the first end, and the emitter and receiver are positioned to emit and receive electromagnetic radiation at and from the second end of the cavity, respectively. Example 18. 15. The aerosol generating device of embodiment 14, wherein the emitter and receiver are perpendicular to the longitudinal axis. Example 19. 19. The aerosol generating device of Example 18, wherein the emitter and receiver are positioned to emit and receive electromagnetic radiation into and from the cavity perpendicular to the longitudinal axis. Example 20. An aerosol generating device described in any one of Examples 1 to 19, wherein the sensing assembly further comprises a shield configured to block electromagnetic radiation. Example 21. 21. An aerosol generating device as described in Example 20, wherein the shield is positioned outside the cavity and the receiver is positioned between the shield and the cavity. Example 22. 22. An aerosol generating device as described in embodiment 20 or 21, wherein the shield comprises an electrically insulating material. Example 23. Conductive material has a density of at least 1 × 10 6 Siemens / meter, preferably at least 1 x 10 7 Siemens / meter, and even more preferably at least 5×10 7 23. The aerosol generating device of example 22 having an electrical conductivity of Siemens / meter. Example 24. 24. The aerosol generating apparatus of any one of Examples 20 to 23, wherein the shield comprises a thermally conductive material. Example 25. An aerosol generating device described in any one of Examples 20 to 24, wherein the shield is configured to prevent the receiver from exceeding 115 degrees Celsius during use of the aerosol generating device. Example 26. An aerosol generating device described in any one of Examples 20 to 25, wherein the thermally conductive material has a thermal conductivity of at least 10 Watts / meter Kelvin, preferably at least 80 Watts / meter Kelvin, preferably at least 100 Watts / meter Kelvin, and even more preferably at least 150 Watts / meter Kelvin. Example 27. 27. The aerosol generating apparatus according to any one of Examples 20 to 26, wherein the shield comprises a metal. Example 28. 28. An aerosol generating device according to any one of Examples 20 to 27, wherein at least a first portion of the shield is planar. Example 29. 29. The aerosol generating device of Example 28, wherein the receiver is positioned between the first portion of the shield and the cavity. Example 30. 30. The aerosol generating device of example embodiment 29, wherein both the receiver and the emitter are positioned between the first portion of the shield and the cavity. Example 31. 30. An aerosol generating device as described in Example 28 or 29, wherein the second portion of the shield is planar. Example 32. 32. An aerosol generating device as described in Example 31, wherein the first and second portions of the shield are non-coplanar in a plane different from the plane of the first portion. Example 33. An aerosol generating device as described in Example 31 or 32, wherein the receiver is positioned between the first portion of the shield and the cavity, and the emitter is positioned between the second portion of the shield and the cavity. Example 34. An aerosol generating device described in any one of Examples 31 to 33, wherein the angle between the normal to the plane of the first part and the normal to the plane of the second part is substantially the same as the angle between the receiver and the emitter. Example 35. An aerosol generating device described in any one of Examples 20 to 34, wherein the sensing assembly further comprises a substrate, the substrate comprising a first side to which at least one of the emitter and the receiver is attached. Example 36. 36. The aerosol generating device of Example 35, wherein the substrate comprises a second side opposite the first side to which the shield is attached. Example 37. 37. An aerosol generating device as described in Example 35 or 36, wherein the substrate comprises or consists of a printed circuit board (PCB). Example 38. 38. An aerosol generating device according to any one of Examples 35 to 37, wherein the shield comprises at least one clip. Example 39. An aerosol generating device as described in Example 38, wherein the shield has a first clip at a first end and a second clip at a second end, the first end being at an opposite end of the shield relative to the second end. Example 40. 40. The aerosol generating device of Example 39, wherein the one or more clips are configured to connect the clip to the second side of the substrate. Example 41. 41. The aerosol generating device according to any one of Examples 20 to 40, wherein the shield is integrally formed. Example 42. 42. The aerosol generating apparatus according to any one of Examples 20 to 41, wherein the angle between the receiver and the emitter is 20 to 120 degrees, preferably 60 to 100 degrees, even more preferably 70 to 90 degrees, and most preferably about 80 degrees. Example 43. An aerosol generating device described in any one of Examples 1 to 42, wherein the sensor assembly further comprises a lens. Example 44. An aerosol generating device as described in Example 43, wherein the lens is configured to focus the electromagnetic radiation received from the cavity onto the receiver sensor. Example 45. An aerosol generating device as described in Example 44, wherein the surface area of ​​the lens is at least 10 times, preferably at least 20 times, and even more preferably at least 30 times, greater than the surface area of ​​a portion of the sensor of the receiver sensitive to electromagnetic radiation. Example 46. 46. ​​The aerosol generating device of any one of Examples 43 to 45, wherein the lens comprises an absorbing material. Example 47. An aerosol generating device as described in Example 46, wherein the absorbing material is configured to substantially block wavelengths of electromagnetic radiation outside the wavelength range. Example 48. 48. An aerosol generating device as described in Example 47, wherein the absorbing material is transparent to wavelengths of electromagnetic radiation within a certain wavelength range. Example 49. An aerosol generating device described in any one of Examples 46 to 48, wherein the absorbing material is configured to substantially block wavelengths of electromagnetic radiation less than 200 nanometers, preferably less than 950 nanometers, and even more preferably less than 1350 nanometers. Example 50. An aerosol generating device described in any one of Examples 46 to 49, wherein the absorbing material is configured to substantially block electromagnetic radiation having a wavelength greater than 30,000 nanometers, preferably greater than 15,000 nanometers, preferably greater than 2000 nanometers, and even more preferably greater than 1400 nanometers. Example 51. 51. The aerosol generating device of any one of Examples 46 to 50, wherein the body of the lens comprises an absorbing material. Example 52. 51. An aerosol generating device according to any one of Examples 46 to 50, wherein the lens comprises an absorbing material as a coating. Example 53. 52. The aerosol generating apparatus of any one of Examples 46 to 51, wherein the absorbing material comprises at least one of cadmium telluride, chalcogenide glass, or zinc selenide. Example 54. An aerosol generating device described in any one of Examples 1 to 53, wherein the sensing assembly further comprises amplification electronics. Example 55. 55. The aerosol generating device of Example 54, wherein the amplification electronics are connected to the receiver. Example 56. An aerosol generating device as described in Example 55, wherein the amplification electronics are configured to amplify the signal generated by the receiver sensor. Example 57. 57. The aerosol generating apparatus according to any one of Examples 54 to 56, wherein the amplifying electronics is an analog amplifying electronics. Example 58. 58. The aerosol generating apparatus of any one of Examples 54 to 57, wherein the amplifying electronics is directly connected to the receiver. Example 59. An aerosol generating device described in any one of Examples 54 to 58, wherein the sensing assembly comprises a printed circuit board including a receiver and the amplification electronics are provided as part of the same printed circuit board. Example 60. An aerosol generating device described in any one of Examples 54 to 59, wherein the amplification electronics and the receiver are provided as a single component. Example 61. An aerosol generating device described in any one of Examples 1 to 60, wherein a first portion of the housing defining the cavity is transparent to at least one wavelength of the electromagnetic radiation emitted by the emitter. Example 62. An aerosol generating device as described in Example 61, wherein the emitter is configured to emit electromagnetic radiation into the cavity through the transparent portion. Example 63. 63. An aerosol generating device as described in embodiment 61 or 62, wherein the first portion of the housing separates the emitter from the cavity. Example 64. An aerosol generating device described in any one of Examples 61 to 63, wherein an airflow path is defined through the aerosol generating device from the air inlet to the air outlet, the airflow path passes through the cavity, and the emitter is separated from the air flowing through the airflow path by a transparent first portion of the housing. Example 65. An aerosol generating device described in any one of Examples 61 to 64, wherein a second portion of the housing defining the cavity is transparent to at least one wavelength of electromagnetic radiation received by the receiver, and the receiver is configured to receive electromagnetic radiation from the cavity through the second transparent portion. Example 66. An aerosol generating device described in any one of Examples 1 to 65, wherein the sensing assembly further comprises a substrate having a first side to which at least one of the emitter and receiver is attached. Example 67. 67. The aerosol generating device of Example 66, wherein both the emitter and the receiver are attached to the first side. Example 68. 68. An aerosol generating device as described in Example 66 or 67, wherein the substrate comprises a flexible portion. Example 69. An aerosol generating device as described in Example 68, wherein the flexible portion is configured such that the emitter is movable relative to the receiver by bending the flexible portion. Example 70. 70. The aerosol generating apparatus of Example 69, wherein the substrate is curved such that the emitter is adjacent to a different portion of the cavity relative to the receiver and the angle between the emitter and the receiver is between 20 degrees and 120 degrees, preferably between 60 degrees and 100 degrees, even more preferably between 70 degrees and 90 degrees, and most preferably about 80 degrees. Example 71. 71. The aerosol generating device of any one of Examples 66 to 70, wherein the substrate comprises a first portion comprising an emitter and a second portion comprising a receiver. Example 72. An aerosol generating device as described in Example 71, wherein the substrate includes a third portion between the first portion and the second portion, and at least the third portion is flexible such that the first portion is movable relative to the second portion. Example 73. The aerosol generating apparatus of any one of Examples 55 to 72, wherein the substrate comprises one or more PCBs. Example 74. 74. The aerosol generating device of Example 73, wherein the substrate comprises one or more flexible PCBs. Example 75. An aerosol generating device described in any one of Examples 1 to 74, further comprising a controller configured to receive a signal from the receiver, the controller configured to determine material properties of an aerosol-forming substrate at least partially received within the cavity based on the measured intensity of the electromagnetic radiation received by the receiver. Example 76. An aerosol generating apparatus as described in Example 75, wherein the controller is configured to perform a spectral analysis of the measured intensity of the electromagnetic radiation to determine material properties of the aerosol-forming substrate. Example 77. 77. The aerosol generating device of Example 76, wherein the controller is configured to determine a type of aerosol-forming substrate at least partially received within the cavity based on the determined material properties. Example 78. 78. An aerosol generating apparatus as described in Example 76 or 77, wherein the material property determined by the controller is a chemical property of the aerosol-forming substrate. Example 79. 79. The aerosol generating apparatus of any one of Examples 76 to 78, wherein the material property is the presence or amount of a chemical component of the aerosol-forming substrate. Example 80. 80. An aerosol generating apparatus according to any one of Examples 76 to 79, wherein the material property determined by the controller is the wettability or water content of the aerosol-forming substrate. Example 81. An aerosol generating device as described in Example 80, wherein the controller is configured to determine a value related to the moisture content of the aerosol-forming substrate received within the cavity based on the measured intensity of the electromagnetic radiation received at the receiver. Example 82. 82. The aerosol generating device of Example 81, wherein the controller is configured to determine the type of aerosol-forming substrate received in the cavity based on the determined value for the water content. Example 83. An aerosol generating device as described in Example 82, wherein the device further comprises a heating assembly for heating the aerosol-forming substrate, the heating assembly being controlled by a controller, and the controller being configured to control the heating assembly according to a heating profile selected based on the determined type of the aerosol-forming substrate. Example 84. An aerosol generating device described in any one of Examples 81 to 83, wherein the controller is configured to determine a value related to the moisture content of an aerosol-forming substrate repeatedly received within the cavity during use of the aerosol generating device. Example 85. 85. The aerosol generating apparatus of example 84, wherein the controller is configured to modify the heating profile based on the determined change in moisture content of the aerosol-forming substrate. Example 86. An aerosol generating device as described in Example 84 or 85, wherein the controller is configured to stop heating the aerosol-forming substrate by the heater assembly when a value related to the moisture content of the aerosol-forming substrate falls below a predetermined value. Example 87. 1. A sensing assembly for an aerosol generating device for generating an aerosol from an aerosol-forming substrate, the sensing assembly comprising: a housing defining a cavity for at least partially receiving the aerosol-forming substrate, the sensing assembly comprising: an emitter for emitting electromagnetic radiation into a cavity of the aerosol generating device; a receiver for receiving electromagnetic radiation from a cavity of the aerosol generation device, the receiver comprising a sensor configured to measure at least one wavelength of the received electromagnetic radiation; A sensing assembly comprising: a shield external to the receiver such that the receiver can be positioned between the shield and a cavity of the aerosol device apparatus, the shield being configured to absorb electromagnetic radiation.

[0132] Features described with respect to one example or embodiment may also be applicable to other examples and embodiments.

[0133] The embodiments will now be further described with reference to the following figures: [Brief description of the drawings]

[0134] [Figure 1] FIG. 1 is a schematic cross-sectional view of a first aerosol generating device. [Diagram 2] FIG. 2 is a perspective view of a cutaway portion of the aerosol generating device of FIG. 1 showing a sensing assembly of the aerosol generating device. [Diagram 3]3 is another perspective view of the cutaway portion of the aerosol generating device of FIG. 1, showing the sensing assembly from a different direction. [Figure 4] FIG. 4 shows a cross-section of an aerosol-generating article and the emitter and receiver of the sensing assembly of FIGS. [Diagram 5] FIG. 5 shows a perspective view of the clip of the sensing assembly, shown separate from the remainder of the aerosol generating device. [Figure 6] FIG. 6 shows the PCB of the sensing assembly separate and flat from the rest of the aerosol generating device. [Figure 7] FIG. 7 shows the lenses of the sensing assembly. [Figure 8] FIG. 8 shows a schematic cross-sectional view of a second aerosol generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0135] 1 is a schematic cross-sectional view of a first aerosol generating device 100. The aerosol generating device 100 comprises a cavity 10 defined by a device housing 11. The cavity 10 is tubular and has a base 12 at an upstream end. The cavity 10 is configured to receive an aerosol-generating article 200.

[0136] The aerosol-generating article 200 is received within the cavity 10. The aerosol-generating article 200 contains an aerosol-forming substrate 202. The aerosol-forming substrate is a solid tobacco-containing substrate. In particular, the aerosol-forming substrate is an assembly of homogenized tobacco sheets. As shown in Figure 1, the aerosol-generating article 200 and the cavity 10 are configured such that when the aerosol-generating article is received within the cavity 10, a mouth end of the aerosol-generating article 200 protrudes from the cavity 10 and from the aerosol generating device. This mouth end forms a mouthpiece 204 through which a user of the aerosol generating device may draw smoke in use.

[0137] The aerosol generating device 100 together with the aerosol generating article 200 may be referred to as an aerosol generating system.

[0138] The aerosol generating device 100 comprises a heater assembly including a heating element 110. The heating element 110 surrounds the cavity 10 along with a portion of the cavity in which the aerosol-forming substrate of the aerosol-generating article 200 is received. In an alternative embodiment, the heating element 110 forms part of a housing 11 that defines a portion of the cavity that receives the aerosol-forming substrate. The heating element 110 is a resistive heating element.

[0139] The airflow channel 120 extends from an air inlet 122 of the aerosol generating device 100. Upstream of the cavity, the airflow channel 120 is defined primarily by airflow channel walls 124. Downstream of the airflow channel walls 124, the airflow channel 120 passes through an air inlet defined in the base 12 of the cavity. The airflow channel 120 then extends through the cavity 10. When an aerosol-generating article 200 is received within the cavity 10, the airflow channel 120 passes through the aerosol-generating article 200 and extends through the mouthpiece 204.

[0140] The aerosol generating device 100 further comprises a power source 130 in the form of a rechargeable battery for powering the heating element 110, which is controllable by a controller 132. The power source is connected to the controller and the heating element 110 via electrical wires and connections not shown in the figures. The aerosol generating device may comprise further elements not shown in the figures, such as a button for activating the aerosol generating device.

[0141] The aerosol generation device 100 further comprises a sensing assembly 140. The sensing assembly is more clearly shown in Figure 2, which is a perspective view of the sensing assembly with a cut-away portion of the aerosol generation device.

[0142] The sensing assembly 140 comprises an emitter 142. The emitter comprises a plurality of LEDs. Each of the LEDs is configured to emit electromagnetic radiation of a different wavelength. The emitter 142, and in particular the plurality of LEDs of the emitter, are configured to emit electromagnetic radiation into the cavity 10. The emitter 142 is configured to emit electromagnetic radiation having a wavelength between 1350 and 1400 nanometers.

[0143] Cavity 10 includes a first transparent portion 143. Emitter 142 is separated from cavity 10 by the first transparent portion and is configured to emit electromagnetic radiation into the cavity through the transparent portion. Providing the first transparent portion protects the emitter from debris and dirt that may accumulate within cavity 10 after extended use of the device, and allows for easy cleaning.

[0144] The sensing assembly 140 further comprises a receiver 144. The receiver 144 is configured to receive electromagnetic radiation from the cavity. In particular, the receiver 144 is configured to receive electromagnetic radiation from the cavity emitted by the emitter 142 and then reflected or transmitted by the aerosol-generating article 200 towards the receiver. The receiver 144 comprises a sensor 146 (shown in FIG. 7) in the form of a photodiode. The sensor 146 is configured to measure multiple wavelengths of the received electromagnetic radiation. In particular, the sensor 146 is configured to measure the intensity of multiple wavelengths of the received electromagnetic radiation. The receiver 144 is configured to receive electromagnetic radiation having a wavelength between 1350 and 1400 nanometers.

[0145] The cavity 10 includes a second transparent portion, not shown in the figures. The receiver 144 is separated from the cavity 10 by the second transparent portion and is configured to receive electromagnetic radiation from the cavity 10 through the second transparent portion.

[0146] The sensing assembly 140 further comprises a shield 148. The shield 148 is not shown in FIG. 2 but is shown in FIG. 3, which shows another cutaway perspective view of the aerosol generating device 100, but looking towards the cavity from the opposite direction. The shield 148 is positioned outside the cavity 10. Both the receiver 144 and the emitter 142 are positioned between the shield and the cavity, the shield being configured to block electromagnetic radiation. In this way, electromagnetic radiation that is outside the cavity 10 and the sensing assembly 140 is prevented from reaching the emitter 142 and, more importantly, the receiver 144. This means that the amount of external electromagnetic radiation received at the receiver 144 is substantially reduced or eliminated, and therefore is not detected as noise at the receiver.

[0147] The shield 148 is made of aluminum, which is electrically conductive and therefore reflects or absorbs external electromagnetic radiation. Aluminum is also a thermally conductive material. The shield 148 being made of a thermally conductive material means that the shield is suitable for dissipating heat from the receiver 144 and the emitter 142. As can be seen in FIG. 1, the sensing assembly 140 is positioned relatively close to the heating element 110. Therefore, when an electric current passes through the heating element 110 and heats it, heat will inevitably be transferred from the heating element 110 to the sensing assembly 140 during use of the aerosol generating device. The emitter 142 and the receiver 144 can be damaged if they are overheated. The shield 148 dissipating heat from the emitter 142 and the receiver 144 reduces the risk of the emitter 142 and the receiver 144 being damaged.

[0148] The sensing assembly 140 further comprises a substrate in the form of a PCB 150. A first portion 152 of the PCB 150 comprises the emitter 142. A second portion 154 of the PCB 150 comprises the receiver 144. Both the first portion 152 and the second portion 154 of the PCB are planar. The PCB 150 further comprises a flexible third portion 156. As shown most clearly in Figures 2 and 3, the third portion 156 is curved such that the angle between the normal of the first portion 152 and the normal of the second portion 154 is 80 degrees. This also means that the angle between the central optical axis of the emitter 142 and the central optical axis of the receiver 144 is 80 degrees. This provides optimal optical performance.

[0149] The third portion 156 is opaque to the wavelengths of electromagnetic radiation emitted by the emitter 142. This ensures that the electromagnetic radiation emitted by the emitter 142 is not directly received by the receiver 144.

[0150] The angle between the aerosol-generating article 200, the emitter 142, and the receiver 144 is most clearly shown in Figure 4, which shows a cross section of the aerosol-generating article 200 and the emitter 142 and receiver 144 separate from the rest of the device 10. The optimum angle between the central optical axis of the emitter 142 and the central optical axis of the receiver 144 is 80 degrees. The angle is represented by the numeral 159 in Figure 4.

[0151] Figure 5 shows the shield 148 separate from the rest of the sensing assembly 140. As can be seen in Figure 5, the shield 148 comprises two clips, a first clip 160 at a first end and a second clip 162 at a second end. The clips are used to attach the shield 148 to a PCB 150. The shield is rigid enough to maintain and hold the first portion 152 of the PCB relative to the second portion 154 such that the angle between the normal of the first portion 152 and the normal of the second portion 154 is 80 degrees.

[0152] 6 shows the PCB 150 separate from and laid flat on the rest of the aerosol generating device 100. The PCB 150 of the sensing assembly 140 further comprises analog amplification electronics 166 configured to amplify signals generated by the sensor of the receiver 144. The amplification electronics 166 is mounted on a fourth portion of the PCB. By providing the amplification electronics 166 on the same PCB 150 as the receiver 144, there can be a direct electrical connection between the amplification electronics and the receiver 144. This minimizes the number of electrical connections between the amplification electronics 166 and the receiver 144, and therefore the amount of noise introduced into signals generated by the sensor 146 of the receiver 144 before those signals are amplified.

[0153] The PCB 150 further comprises a connector 168. The connector 168 is used to connect the PCB 150 to the rest of the electronics of the aerosol generating device 100, in particular the controller 132 and the power supply 130.

[0154] The flexible third portion 156 of the PCB 150 has already been described. The PCB 150 includes a further flexible portion that allows the PCB 150 to be folded into the shape shown in FIGS.

[0155] Figure 7 shows a lens 170 that is part of the sensing assembly 140 and is not shown in Figures 1-6. The lens is positioned adjacent to the receiver 144 and is configured to focus the electromagnetic radiation received from the cavity 10 onto the receiver's sensor. Because the surface area of ​​the lens is much larger than the surface area of ​​the sensor 146 of the receiver 144, the lens effectively increases the amount of electromagnetic radiation incident on the sensor 146.

[0156] The lens 170 includes an absorbing material that acts as a bandpass filter, absorbing electromagnetic radiation above and below certain wavelengths, but allowing transmission of wavelengths in between. Such absorbing materials are known and may be selected to achieve a desired filtering effect. In particular, the absorbing material may be selected such that the transmission window includes the wavelengths of electromagnetic radiation emitted by the emitter 142 and received by the receiver 144, but filters out other wavelengths that would otherwise introduce noise into the signal detected by the sensor 146 of the receiver 144.

[0157] In some embodiments, the absorbing material is applied to the surface of the lens as a coating, hi other embodiments, the lens 170 itself is made of the absorbing material.

[0158] In use of the aerosol-generating device 100, the aerosol-generating article 200 is received within the cavity 10 as shown in FIG. 1. The sensing assembly 140, in conjunction with the controller 132, can detect the presence of the aerosol-generating article 200. The emitter 142 of the sensing assembly 140 emits electromagnetic radiation at multiple wavelengths. This radiation is then reflected and / or transmitted by the aerosol-generating article 200. Because the viewing angles of the emitter 142 and the receiver 144 substantially overlap when the angle between the central optical axis of the emitter and the central optical axis of the receiver is 80 degrees, a significant amount of the reflected and / or transmitted electromagnetic radiation is received by the sensor 146 of the receiver 144. The sensor 146 measures the intensity of the various wavelengths of the received electromagnetic radiation. In doing so, the sensor 146 generates electrical signals. These electrical signals are sent directly to the amplification electronics 166 for amplification before being received by the controller 132. The controller 132 is configured to perform a spectral analysis on the measurements of the intensity of the electromagnetic radiation at different wavelengths. This involves comparing the intensities of different wavelengths of electromagnetic radiation to a known distribution of intensities emitted by the emitter 142. Based on the spectral analysis, the controller is configured to determine the presence of the aerosol-generating article 200.

[0159] The controller 132 is also configured to determine the type of aerosol-generating article 200 based on the spectral analysis. Different types of aerosol-generating articles 200 can be received in the cavity 10. In particular, aerosol-generating articles having aerosol-forming substrates of different chemicals can be received in the cavity 10. Because the aerosol-generating articles and the aerosol-forming substrates have different chemical and / or other material properties, different aerosol-generating articles 200 reflect or transmit the wavelengths of electromagnetic radiation emitted by the emitter 142 to different degrees. This means that the spectrum of the electromagnetic radiation received by the receiver 144 is different for different aerosol-generating articles 200. The spectrum of a particular type of aerosol-generating article is predictable. Therefore, based on the spectral analysis, the controller 132 can determine the type of aerosol-generating article 200 received in the cavity 10.

[0160] The controller 132 is configured to control the heating elements according to an appropriate heating profile for the determined type of aerosol-generating article 200 .

[0161] Based on this spectral analysis, the controller is also configured to determine a material property of the aerosol-generating article received within the cavity 10. In particular, the controller 132 is configured to determine a material property of the aerosol-forming substrate of the aerosol-generating article 200. The material property determined by the controller is the wettability or water content of the aerosol-forming substrate.

[0162] The controller 132 is configured to determine a value associated with the moisture content of the aerosol-forming substrate received within the cavity based on the measured intensity of the electromagnetic radiation received at the receiver. As described above, the emitter 142 and the receiver 144 are configured to emit and receive, respectively, wavelengths of electromagnetic radiation having wavelengths between 1350 nanometers and 1400 nanometers. Water is particularly effective at absorbing electromagnetic radiation in this range. Thus, the intensity of the radiation received by the receiver 144 is highly dependent on the moisture content of the aerosol-forming substrate, and the controller can determine a value associated with the moisture content of the aerosol-forming substrate based on a spectral analysis of the electromagnetic radiation received by the receiver 144.

[0163] Different types of aerosol-forming substrates typically have different amounts or types of aerosol formers and therefore different moisture contents from each other. The wettability or moisture content of the aerosol-forming substrate depends on the amount or type of aerosol formers present in the aerosol-forming substrate. Thus, the controller 132 is configured to identify aerosol-forming substrates that include different amounts or types of aerosol formers based on the determined moisture content in the aerosol-forming substrate.

[0164] The moisture content of the aerosol-forming substrate decreases over time. The decrease in moisture content can be the result of at least one of heating of the aerosol-forming substrate by the aerosol generating device during use, which depletes the aerosol-forming substrate, or the aerosol-forming substrate drying out during storage, especially if the aerosol-forming substrate is improperly stored. The controller 132 is configured to repeatedly determine a value related to the moisture content of the aerosol-forming substrate during use of the device and during different periods of use of the device. Thus, changes in the moisture content of the aerosol-forming substrate can be detected by the controller 132. When the wetness of the aerosol-forming substrate changes, the controller 132 is configured to implement different heating profiles to heat the substrate. This ensures that a constant amount of aerosol is generated during each puff, despite changes in the wetness of the aerosol-forming substrate.

[0165] FIG. 8 is a schematic cross-sectional view of a second aerosol generating device 800. The aerosol generating device 800 is similar to the first aerosol generating device 100, and similar features are numbered accordingly. The second aerosol generating device 800 also operates according to the same principle as the first aerosol generating device 100. The main difference between the first aerosol generating device 100 and the second aerosol generating device 800 is the location of the sensing assembly. In the second aerosol generating device 800, the sensing assembly 802 is located at the base 12 of the cavity 10, rather than in the side wall of the cavity, as in the first aerosol generating device 100. The sensing assembly 802 is similar to the sensing assembly 140. For example, the sensing assembly 802 comprises an emitter, a receiver, a PCB, a lens, and amplification electronics. However, the angle between the central optical axis of the emitter and the central optical axis of the receiver is different. In particular, the angle between the central optical axis of the emitter and the central optical axis of the receiver is 180 degrees, and the emitter is positioned on top of the receiver. Furthermore, because the emitter is on top of the receiver, only a single transparent portion 804 in the housing is required. The emitter radiates through the transparent portion 804 into the cavity 10, and the receiver receives electromagnetic radiation from the cavity 10 through the transparent portion 804.

Claims

1. An aerosol generating apparatus for generating an aerosol from an aerosol-forming substrate, the aerosol generating apparatus comprising: a housing defining a cavity for at least partially receiving the aerosol-forming substrate; and A sensing assembly comprising: an emitter configured to emit electromagnetic radiation into the cavity; a receiver configured to receive electromagnetic radiation from the cavity, the receiver including a sensor configured to measure at least one wavelength of the received electromagnetic radiation; a shield positioned outside the cavity such that the receiver is between the shield and the cavity, the shield configured to block electromagnetic radiation; a first portion of the shield is planar, a second portion of the shield is planar, and the first and second portions of the shield are non-coplanar; an angle between a normal to the plane of the first portion and a normal to the plane of the second portion is substantially the same as an angle between the receiver and the emitter; An aerosol generating device, wherein the receiver and the emitter are non-parallel.

2. The shield is at least 1×10 6 10. The aerosol generating device of claim 1, comprising an electrically conductive material having an electrical conductivity of Siemens per meter.

3. 3. The aerosol generating device of claim 1, wherein the shield comprises a thermally conductive material having a thermal conductivity of at least 10 watts per meter-Kelvin.

4. 2. The aerosol generating device of claim 1, wherein the angle between the emitter and the receiver is between 60 degrees and 100 degrees or about 0 degrees.

5. 2. The aerosol generating device of claim 1, wherein the receiver is positioned between the first portion of the shield and the cavity, and the emitter is positioned between the second portion of the shield and the cavity.

6. 10. The aerosol generating device of claim 1, further comprising at least one lens configured to focus electromagnetic radiation received from the cavity onto the sensor of the receiver, the lens comprising an absorbing material configured to substantially block wavelengths of electromagnetic radiation outside a certain wavelength range.

7. 7. The aerosol generating device of claim 6, wherein the absorbing material is configured to substantially block wavelengths of electromagnetic radiation below 200 nanometers and above 30,000 nanometers.

8. 2. The aerosol generating device of claim 1, wherein a first portion of the housing defining the cavity is transparent to at least some of the wavelengths of the electromagnetic radiation emitted by the emitter, and the emitter is configured to emit the electromagnetic radiation into the cavity through the transparent portion.

9. 2. The aerosol generating device of claim 1, wherein the sensing assembly further comprises a substrate having a first side to which the emitter and receiver are attached, a first portion of the substrate including the emitter, and a second portion of the substrate including the receiver, and the substrate further comprises a third portion between the first and second portions, and at least the third portion is flexible so that the first portion is movable relative to the second portion.

10. 10. The aerosol generating device of claim 1, wherein the sensing assembly further comprises amplification electronics directly connected to the receiver.

11. 2. The aerosol generating device of claim 1, further comprising a controller configured to receive a signal from the receiver, the controller configured to determine material properties of the aerosol-forming substrate at least partially received within the cavity, or an aerosol-generating article including the aerosol-forming substrate, based on the measured intensity of the electromagnetic radiation received by the receiver.

12. 12. The aerosol generating device of claim 11, wherein the material property determined by the controller is the wettability or water content of the aerosol-forming substrate.

13. 1. A sensing assembly for an aerosol-generating device for generating an aerosol from an aerosol-forming substrate, the aerosol-generating device comprising a housing defining a cavity for at least partially receiving the aerosol-forming substrate, the sensing assembly comprising: an emitter for emitting electromagnetic radiation into the cavity of the aerosol generating device; a receiver for receiving electromagnetic radiation from the cavity of the aerosol generation device, the receiver comprising a sensor configured to measure at least one wavelength of the received electromagnetic radiation; a shield external to the receiver to prevent external electromagnetic radiation from passing to the receiver, the shield being configured to absorb electromagnetic radiation; a first portion of the shield is planar, a second portion of the shield is planar, and the first and second portions of the shield are non-coplanar; an angle between a normal to the plane of the first portion and a normal to the plane of the second portion is substantially the same as an angle between the receiver and the emitter; A sensing assembly wherein the receiver and the emitter are non-parallel.

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