WO2022008542A1

WO2022008542A1 - User identification using heart rate sensor for vaping devices

Info

Publication number: WO2022008542A1
Application number: PCT/EP2021/068715
Authority: WO
Inventors: Theo Verlaan
Original assignee: Jt International Sa
Priority date: 2020-07-09
Filing date: 2021-07-06
Publication date: 2022-01-13
Also published as: EP4178380A1; JP2023533161A

Abstract

A method of operating an aerosol generation device comprises the steps of detecting a signal from a user's heart using at least two electrodes, comparing the detected signal with a stored signal that is characteristic of a registered user, and performing an action using the aerosol generation device based on the comparison.

Description

USER IDENTIFICATION USING HEART RATE SENSOR FOR

VAPING DEVICES

Field of Invention

The present invention relates to user identification for vaping devices, in particular ECG based user recognition for vaping devices. Background

Vaping devices, such as electronic cigarettes, are becoming increasingly popular consumer products. They are used to deliver a flavour or a stimulant to a user in the form of aerosol without combustion. Such vaping devices typically include a heater arranged to heat a vaporisable product. In operation, the vaporisable product is heated with the heater to vaporise the constituents of the product for the consumer to inhale. In some examples, the product may comprise tobacco in a capsule or may be similar to a traditional cigarette, in other examples the product may be a liquid, or liquid contents in a capsule.

The use of vaping devices is generally restricted to users over a certain age limit. It would therefore be desirable to prevent unauthorized usage of vaping devices, for example by minors.

Summary of Invention

According to a first aspect there is provided a method of operating an aerosol generation device, comprising the steps of: detecting a signal from a user’s heart using at least two electrodes; comparing the detected signal with a stored signal that is characteristic of a registered user; and performing an action using the aerosol generation device based on the comparison.

The result of the comparison may be that the detected signal matches the stored signal that is characteristic of a registered user. Alternatively, the result of the comparison may be that the detected signal does match the stored signal that is characteristic of a registered user. The signal detected and measured from a user of the vaping device is therefore compared to previously stored measurements in a user profile in order to determine whether the user is the same user as that of the user profile, i.e. a registered user. A registered user may also be referred to as an authorised user.

Detecting a signal from a user’s heart and comparing this signal with a stored signal, in order to identify the user of the vaping device, provides a simple to use and secure biometric identification method which can easily be applied to vaping devices. Using user identification to protect vaping devices advantageously avoids unauthorised usage of the vaping device, for example by minors.

The action may comprises unlocking the aerosol generation device. The aerosol generation device can therefore be operated by a user. In other words, the action may comprise a change of state of the aerosol generation device. In particular, the state of aerosol generation device may be changed from a locked state (in which the device can be operated) to an unlocked state (in which the device cannot be operated). Thus, a user is only able to operate the aerosol generation device if the signal detected from the user’s heart matches the stored signal.

The action may comprises locking the aerosol generation device. The aerosol generation device is therefore unable to be operated by a user. In particular, the state of aerosol generation device may be changed from an unlocked state to a locked state. Thus, a user is unable to operate the aerosol generation device if the signal detected from the user’s heart does not match the stored signal. In some cases, the action of locking the aerosol generation device includes keeping the aerosol generation device in a locked state, if it was already in a locked stated. In this case, there is no change of state of the aerosol generation device. Thus, the action may comprises maintaining a state of the aerosol generation device.

The method may further comprise the step of determining one or more features of the signal from the user’s heart for comparison against one or more stored features that are characteristic of the registered user. Comparing features of a user’s heartbeat with stored features provides a quick and convenient method of determining whether the one or more features of the signal from the user’s heart matches the one or more stored features that are characteristic of the registered user. Comparing one or more features in a signal, rather than the whole signal, reduces the computational effort (including the number of resources and/or the amount of time) required to carry out the comparison.

Preferably, the determined one or more features of the signal are unique to an individual user. More preferably, the one or more features of the signal are features of an electrocardiogram. In this case, the one or more features of the electrocardiogram are unique to an individual user. In particular, the one or more features or characteristics may include at least one of P, Q, R, S and T features in an electrocardiogram. In some cases, the one or more characteristics may comprise parameters derived from combinations of the P, Q, R, S, and T features. As the one or more characteristics are preferably unique to a particular user, the method is able to quickly and easily determine whether one or more characteristics detected from the user’s heart beat correspond (i.e. are the same as) the one or more characteristics of the registered user. Using unique identifiers reduces the chance of unregistered users falsely gaining access to the aerosol generation device.

The one or more characteristics are preferably obtained in the time domain of the signal from the user’s heart. This reduces computational cost and processing time of the signal. Alternatively, the one or more characteristics comprise features of an electrocardiogram obtained in the frequency domain of the signal from the user’s heart.

Preferably, the detected signal is a voltage difference between the two electrodes. Since the heart undergoes various forms of electrical activity, detecting a signal based on a voltage provides a simple and convenient manner in which to detect a signal from a user’s heart.

Preferably, the method further comprises a step of processing the signal from the user’s heart. The processing may comprises one or more of band pass filtering, amplification, and analogue to digital conversion. The processing may reduce noise present in the signal, improving the signal to noise ratio.

In some developments, the method may further comprise determining the stored signal by averaging the signal from the registered user over an extended time period. An extended period may be a period of time that is greater than the period of time for a single heartbeat. Thus, the averaging may comprise averaging signals from two or more heartbeats. Averaging the signal over an extended period of time may result in a stored signal which is a more accurate representation of the signal from the user’s heart, compared to a single heartbeat signal. A more accurate stored signal may result in a more accurate comparison between the detected signal and the stored signal. That is, the method may be able to better distinguish between detected signals which are appear similar to the stored signal. Thus the method can better distinguish between similar signals.

According to another aspect there is provided an aerosol generation device, comprising: a first electrode and a second electrode on a housing of the device for detecting a signal from a user’s heart; a data storage unit configured to store a signal that is characteristic of a registered user; and control circuitry configured to compare the detected signal with the stored signal and to perform an action using the aerosol generation device based on the comparison.

Brief Description of Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawing in which:

Figure 1 shows a vaping device with a heart rate sensor;

Figure 2 is a block diagram of various components of the vaping device;

Figure 3 is a flow diagram of a user identification method;

Figure 4 is a graph showing an electrocardiogram signal; Figure 5 shows an arrangement of electrodes on a vaping device;

Figure 6 shows another arrangement of electrodes on a vaping device; and Figure 7 shows another arrangement of electrodes on a vaping device.

Detailed Description

Generally, the invention relates to an aerosol generation device, which may also be referred to as a vaping device 100, having a sensor for monitoring the heart rate of a user as illustrated in Figure 1.

The vaping device 100 has a main body 101 extending from a first end 102 to a second end 103. The second end 103 is configured as a mouthpiece 103. An air channel or path is defined in the main body 101 between the first and second ends 102, 103. The vaping device 100 in the present example is an electronic cigarette or a vapour generating device. The vaping device 100 works by vaporizing or heating an aerosol source contained inside the vaping devicelOO to release a flavour or a stimulant for a user to inhale through the mouthpiece 103.

The vaping device 100 also includes an activation switch 104 that may be configured to perform at least one of a turn-on and/or a turn-off of a power source within the vaping device 100. The activation switch 104 may be a push button or a touch button disposed at any convenient location on the surface of the main body 101 of the vaping device 100.

Vaping devices are generally restricted to use by persons over a certain age limit, which may vary between countries according to local laws. It is important to be able to identify the user of the vaping device in order to confirm that the intended user is of sufficient age to use the vaping device, and that they are complying with local laws. It is therefore also important to detect unauthorised usage of the vaping device by an intended user, for example by minors, and prevent the vaping device from being activated by the unauthorised user. Biometric user identification provides a suitable method of verifying that a user is authorised to use the vaping device. However, biometric user identification can be difficult to implement due to the limitations provided by vaping devices, for example limited space and user interfaces. Behavioural biometrics, such as when and how often a user interacts with the vaping device, are highly susceptible to errors, for example if a user modifies their typical behaviour and habits in some way such as increasing the frequency of use. Furthermore, behavioural biometrics such as usage habits can be copied or replicated by an unauthorised user in order to falsely gain access to the vaping device. As such, behavioural biometrics do not provide a reliable or secure method of identifying an authorised user.

Instead, physiological biometrics, such a heartbeat monitoring, can be used to verify that a user is authorised to use the vaping device, as these are inherently more reliable and more secure compared to behavioural biometrics.

As can be seen in Figure 1 , a heart rate sensor 204 is integrated into the activation switch 104 such that when the user touches or presses the switch 104 to turn on the vaping device 100 the sensor 204 measures the heart rate of the user by skin contact, as will be described in detail later.

In some examples, the heart rate sensor 204 is not disposed on the activation switch 104 but on a side surface of the main body 101 of the vaping device 100. The sensor 204 may be provided in the form of a strip or a tag and is placed at a location such that when the user holds the vaping device 100 during use, his or her skin comes in contact with the sensor 204 allowing the sensor 204 to determine the user’s heart rate. Further details of the heart rate sensor 204 and its position on the vaping device 100 will be provided later.

It is to be understood that the vaping device 100 may be of any suitable shape and size and could have different functioning mechanisms. Also, the activation switch 104 may be disposed at either side or bottom of the vaping device 100. Preferably, the heart rate sensor 204 is disposed such that it comes in to contact with the user’s skin during normal use, without requiring the user to specifically locate the sensor 204 and make contact with it. Fig. 2 shows various components of the vaping device 100. The vaping device 100 comprises an aerosol source 201 and a vaporizer 202 that vaporizes the aerosol source 201 to release aerosol containing the flavour and/or stimulant for the user to inhale. In the present example, the aerosol source 201 is a substance containing nicotine. The aerosol source 201 may be in the form of solid or liquid and is heated by the vaporizer 202 (including a heat source) to release the aerosol without combustion. The vaporizer 202 may be powered by a power source 203. The power source 203 is, for example, a lithium ion battery. The power source 203 supplies electric power necessary for an action of the vaping device 100. For example, the power source 203 supplies electric power to all other components or modules included in the vaping device 100.

The vaping device 100 further includes the heart rate sensor 204. Preferably, the heart rate sensor 204 is an electrical sensor that measures the heart rate using electrocardiography (ECG), which is a process of detecting the electrical activity of the heart using electrodes placed on the user’s skin.

The heart rate sensor 204 includes two electrodes 205 which detect the small electrical changes in the electrical activity of the user’s heart during each cardiac cycle (i.e. heartbeat) when the vaping device 100 is held. The signals detected by the heart rate sensor 204 are then processed by a processor to produce understandable pulse or heart rate readings, as will be explained in more detail later.

The vaping device 100 also includes a controller 206 that is configured to control various modules or components in the vaping device 100. The controller 206 is further configured to process the data captured by the heart rate sensor 204, using the processor, to determine the heart rate of the user.

The vaping device 100 may include a memory 209 and other modules 210 such as a visual light emitting element, a display, and a sound emitter. The visual light- emitting element such as an LED may be disposed at the tip of the first end 102. Such an LED may exhibit a first light-emitting mode in a puff state where the aerosol has been being inhaled and a second light-emitting mode different from the first light-emitting mode, in a non-puff state where the aerosol has not been inhaled. Here, the light-emitting mode is defined by a combination of parameters, such as the amount of light of the light-emitting element, the number of light- emitting elements in a lighting state, a colour of the light-emitting element, and a cycle in which lighting of the light-emitting element and non-lighting of the light- emitting element repeat. A different light-emitting mode means that at least any one of the above parameters is different.

The device further includes a locking mechanism 211 which is controlled by the controller 206. When the locking mechanism 211 is in a locked state, operation of the vaping device 100 is prevented. When the locking mechanism 211 is in an unlocked state, operation of the vaping device 100 is allowed.

The ECG-based user recognition system will now be described in more detail.

In general two electrodes, A and B, are brought into contact with the skin of a user during use of the vaping device 100. The two electrodes A, B measure an ECG of the user and compare the ECG measurements to ECG measurements stored within a user profile. If the ECG measurements match the user profile, the user is an authorised user and the vaping device 100 is unlocked. If the ECG measurements do not match the user profile, the user is not an authorised user and the vaping device 100 is locked.

In order for the vaping device 100 to know whether a user is authorised to the vaping device or not, an authorised user of the vaping device 100, for example the owner of the vaping device, first needs to set up a user profile for the particular vaping device 100 in question. The user profile comprises an ECG of the authorised user which will form the basis of an identification ECG. The vaping device 100 can then compare subsequent ECGs to the identification ECG in order to determine if a subsequent user is the authorised user.

In order to determine the identification ECG of the authorised user, when a user first uses the vaping device 100, they will hold the vaping device 100 such that their skin comes into contact with the two electrodes A, B. The electrodes A, B detect the electrical changes as a result of the depolarization and repolarization cycles of the cardiac muscle during each cardiac cycle or heartbeat. The two electrodes A, B measure a voltage difference which form the input signals input into the processor within the controller 206. The heart rate sensor-to-skin contact typically has a resistance of 10k - 100k Ohms.

The identification ECG of the user can be measured and determined within a few heartbeats, for example one or more heartbeats. This typically takes around 1 to 2 seconds to measure.

After the initial signals have been detected by the two electrodes A, B, they are then cleaned up to remove noise. As will be understood, a number of different known signal cleaning methods can be used, either alone or in combination, for example DC mode rejection, signal range limitation, and high-frequency (HF) rejection such as for signals above 150 Hz. These techniques are well known in the field of signal processing and so will not be described further.

Optionally, the heart rate sensor 204 may also include a reference electrode R, which is also configured to come into contact with a user’s skin when the user holds the vaping device 100. The reference electrode R measures a reference signal which is used to isolate the input circuit ground from the earth ground, thereby improving the signal-to-noise ratio. Additionally, the reference signal may also be used for common mode rejection if the input is provided with an operational amplifier having a high common-mode rejection ratio (CMRR). Input circuits having this configuration are well known in the art and will not be discussed further. If the reference electrode R is present in the heart rate sensor 204, the isolation and common mode rejection steps are preferably preformed in the analogue domain, but they could be performed in the digital domain.

In order to generate a sufficient ECG, the input signal detected by the heart rate sensor 240 preferably has a bandwidth of around 0.5 Hz to 150 Hz. Within this range, the signal is preferably within +/- 6bB, and more preferably within +/- 3dB. As will be appreciated, this can be achieved using any suitable bandpass filter, for example a bandpass filter constructed from a high-pass filter at 0.5 Hz (which in some cases may be a single pole filter) and a low-pass filter at 150 Hz (which in some cases may be a double pole filter). In some arrangements, steeper filters may be used such as four or six pole filters). Although in this example the filtering is done in the analogue domain, using analogue signals from the two electrodes and using standard filters built out of operational amplifiers (op amps), in other examples the filtering can be done in the digital domain, after converting the analogue signals to digital signals. In this latter case the bandwidth can be reduced to around 0.5 Hz to 60 Hz, adjusting the low- and high-pass filters accordingly, with only a minor loss in signal accuracy. This latter example has the advantage of simplifying signal processing.

In order to reduce the effect of signal attenuation as a result of the high- and low- pass filters, the signal can be amplified at this stage before it is further processed. For example, in some cases it may be preferably to amplify the signal by a factor of 1000. Amplifying the signal at this stage can help the quality and performance of the later signal processing steps.

After the signal has been acquired, and optionally amplified, the analogue signals are converted to digital signals using standard analogue-to-digital (AD) conversion methods. Amplifying the analogue signal can improve the performance of the AD conversion process.

During the AD conversion, the bit depth is chosen according to known methods so as obtain a suitable signal-to-noise ratio for further processing. The sampling frequency, as well as any anti-aliasing filtration, is also chosen according to known methods and so these will not be discussed.

Once the signals and data are in the digital domain the process of feature extraction can begin. An ECG is a graph a voltage versus time of the electrical activity of the heart, and it comprises a number of peaks and troughs which correspond to different stages of the cardiac cycle. These peaks and troughs constitute the features which can be extracted from the ECG. There are three main components to an ECG that each have a unique pattern associated with them, as can be seen in Figure 4. The first component is the P- wave which represents atrial depolarization. The second component is the QRS complex which represents ventricular depolarization. The third component is the T-wave which represents ventricular repolarization. These three components comprise the features which are to be extracted during the feature extraction process.

Changes in the structure of the heart and its surroundings change the pattern of these three components. Thus, different individuals will each have an ECG comprising a unique pattern of these three components. It is therefore possible to distinguish between these different individuals based on their ECGs.

The data measured by the heart rate sensor 204 represents a voltage fluctuation over a period time in seconds. The measured data is first processed in order to identify the specific number of heartbeats that were detected and measured, using techniques well known in the art for examples by counting R-peaks within data signal. The data is normalised for both time and amplitude. Provided that more than one heartbeat has been detected and measured by the heart rate sensor 204, each individual heartbeat within the measured data can be identified and then averaged in order to provide an average heartbeat of the user in question. The identification and averaging steps are carried out using standard techniques that are well known in the field of electrocardiography. Once an individual heartbeat has been identified, the three main components of the ECG are then extracted from the data. These extracted features can be stored in a user profile in the memory 209 of the vaping device 100. Since these extracted features will be unique to a particular user, these extracted features can be used to determine whether a subsequent user is the same as the authorised user that created the saved user profile.

During subsequent use of the vaping device 100, measured data from the heart rate sensor 204 undergoes AD conversion, as described previously, the individual heartbeats within the measured data are identified, and then these heartbeats are averaged. Based on the averaged data, features present within the averaged data are then analysed. The features that are present can be any or all of the three main components of an ECG, namely the P-wave, the QRS complex, and the T-wave. For example, in some cases only the P-wave and the QRS complex may be identified and analysed. However, in other cases, all of the P-wave, the QRS complex, and the T-wave may be identified and analysed.

Any of the known morphology of the ECG, when displayed in the time domain, can be used for the analysis. In the present example illustrated in Figure 4, the P, Q, R, S, and T values of the ECG curve are used, either alone or in combination with each other. Alternatively, in some examples, only a subsection of the P, Q, R, S, and T vales could be used, for easier processing. It should be understood that features of the ECG in the frequency domain could also be used to determine the unique ECG pattern of a user. However the computational cost of carrying out this data processing is higher and so this method is less preferable.

The determined P, Q, R, S, and T values (or a subset thereof) are then compared with the corresponding P, Q, R, S, and T values (or a subset thereof) stored within the user profile of the authorised user in the memory 209 of the vaping device 100. If the determined values match the stored values, the controller 206 determines that the current user is the authorised user and the vaping device 100 is unlocked. If the determined values do not match the stored values, the controller 206 determines that the current user is not the authorised user and the vaping device 100 is locked and use of the vaping device is therefore prevented.

In order to improve the accuracy of the comparison, the vaping device 100 can be calibrated. Calibration is carried out in a similar manner to the initial set-up and detection steps described above, however many more heartbeats are detected and averaged during calibration. More heartbeats are required during calibration in order to provide sufficient source data from which the relevant features can be extracted and subsequently stored in the user profile. The more heartbeats that can be detected during calibration, and thus the more heartbeats that contribute to the source data, the more accurately the feature extraction process can be carried out, and the corresponding ECG stored in the user profile will more closely match the actual ECG of the authorised user.

In some examples, during calibration, between 50 and 200 heartbeats are detected providing a large sample of source data for the feature extraction process. The features extracted from the large pool of test or sample data will represent a sufficient average of the authorised user’s ECG, to be stored a user profile in the vaping device 100.

By performing the calibration process on the vaping device 100, privacy concerns are minimized. This is because many users are cautious about having their data stored on an external device or in the cloud as they have less control over their data. Preferably, the user profile is stored in an encrypted format in the memory to prevent attacks. Any suitable data encryption method can be used and so this aspect will not be discussed further.

In summary, the ECG-based user recognition method 300 shown in Figure 3 includes detecting ECG signals of a user using a heart rate sensor 204. Analogue signal measurements are received 301 by the electrodes and cleaned 302 to reduce noise. Optional reference signals may also be detected 310 and combined with the analogue signals to reduce noise. The cleaned signals are then passed through a filter 303, and optionally amplified. The filtered signals are then converted to digital signals 304 and processed to extract ECG features 305. The extracted features are then compared 306 to stored features in order to determine whether the current user of the vaping device 100 matches the user of the user profile 307. If the extracted features match those of the user profile, the vaping device 100 is unlocked 308. If the extracted features do not match the user profile, the vaping device remains locked 309

To implement the ECG-based user recognition method 300, the vaping device 100 is provided with at least two electrodes, namely a first electrode and a second electrode, on a housing of the vaping device. The housing may also be referred to as the main body of the vaping device. The first and second electrodes are for detecting a signal (in particular an ECG signal) from a user’s heart. An analogue input module is configured to receive the detected signal (which may also be referred as measurements) from the electrodes. A (analogue or digital) filter module is configured to filter the measurements, and an AD converter is configured to convert the filtered measurements. A data storage unit, which may also be referred to as a memory, is configured to store user profile data and measurement results. That is, the data storage unit is configured to store a signal that is characteristic of a registered user. A processing unit is provided with software to control the calibration and measurement process, as well as for controlling the vaping device (including normal operation and locking and unlocking). The processing unit comprises control circuitry configured to compare the detected signal with the stored signal and to perform an action using the aerosol generation device based on the comparison.

As the skilled person will appreciate, the construction of the heart rate sensor and electrodes could take a number of different configurations. Some of these configurations will be described in further detail below.

Traditional ECG measurements are made using contact points, or electrodes, that require the use of gel to ensure good contact is made between the user and the contact point. However, this form of contact point is not suitable for vaping devices 100. This is because it is not practical for a user to carry round suitable gel, and apply the gel, each time they want to use the vaping device 100. Further, applying gel to a user’s hands results in reduced ability of the user to grip the vaping device 100 which could be dangerous, especially if the vaping device 100 comprises components which may become hot during use. Finally, there is also a risk that some of the gel, left over after the ECG measurement has been taken, comes into contact with other electronics present within the vaping device 100, which may result in short circuits which is dangerous.

Accordingly, the present disclosure provides dry electrodes for use in the above- described ECG measurement system. The dry electrodes are placed around the vaping device 100, as will be described in more detail below, in order to form a heart rate sensor 204 that is suitable for vaping devices 100. It should be noted that by dry electrodes we mean that no gel, or other liquid-based substance, is required in order for a user to make sufficient contact with the ECG electrodes in the heart rate sensor 204.

As has been described, at least two electrodes, namely electrodes A and B, are needed to obtain ECG measurements from a user. The ECG measurements taken from the user rely on the two electrodes A, B having a good contact with the user’s skin, which will typically be the user’s hand when they are holding the vaping device 100. Optionally, a third reference electrode, namely electrode R, can also be included which improves the ECG measurements taken by electrodes A and B. Good contact between the user and the reference electrode R is desirable.

It is important that the at least two electrodes A, B are electrically isolated from the vaping device 100. The at least two electrodes A, B are in electrical connection with an electrical circuit in the vaping device 100 that carries out the signal processing, as has been explained. The at least two electrodes A, B are made from any suitable electrically conductive material.

Vaping devices 100 comes in two general forms. The first form comprises a long- pen-like cylindrical shape having a circular or oval-like cross section. This form of vaping device 100 is illustrated in Figure 1. The second form comprises a box-like shape having a shorter length and greater width than the first form and is shown in Figure 7.

The heart rate sensor position and arrangements of electrodes on the vaping device 100 varies depending on the particular form of the overall vaping device 100 to which the heart rate sensor 204 is being applied. The following description will provide details about the arrangements of the heart rate sensor electrodes A, B on different forms of vaping device 100.

The pen-like vaping device will be considered first.

Some pen-like vaping devices, such as the vaping device 100 of Figure 1 , have a preferred direction of orientation in the user’s hand as a result of the provision of the activation element 104. The activation element 104 defines a preferred orientation direction because the activation element 104 must be able to be activated simply and easily by a user when they pick up the vaping device 100.

In this case, since the user will generally be holding the vaping device 100 in the same configuration each time they pick up the vaping device 100, it is not necessary for the two electrodes A and B to be completely circumferential. That is, it is not necessary for the two electrodes A and B to be accessible by the user around the entire circumference of the vaping device 100. Instead, it is sufficient that only a portion of the circumference of the vaping device 100 provides access to the two electrodes A, B by the user when the user is holding the vaping device 100 during usage. The portion of the circumference that provides access to the electrodes A, B is a portion of that circumference that coincides with the user’s grip when the user is holding the vaping device 100.

As can be seen in Figure 5, one electrode (for example electrode A), is located substantially opposite to the activation element 104. That is to say, electrode A is located on one side of a vertical plane that passes through the longitudinal axis of the vaping device 100 and the activation element 104 is located on the other side of the same plane.

The second electrode (in this case electrode B), is spaced apart from the first electrode A along the length of the vaping device 100. Thus electrode B is located closer to a distal end of the vaping device 100 (and therefore further away from the mouthpiece end 103) than electrode A. In use, the second electrode B will contact the user’s thumb when the user is gripping the vaping device 100 during operation of the vaping device 100. In some examples, electrode B extends around a greater proportion of the circumference of the vaping device 100 compared to electrode A. This ensures that the second electrode B is compatible with both left- and right-handed users.

As illustrated in Figure 5, at least a portion of a first electrode (for example electrode A) is provided on one side of a vertical plane that passes through the longitudinal axis of the vaping device 100 and at least a portion of a second electrode (for example electrode B) is provided on the other side of the same plane.

When present, the optional reference electrode R can be located between electrodes A and B.

Other pen-like vaping devices do not have a preferred direction of orientation during use of the vaping device 100. This is the case for vaping devices which are not provided with an activation element 104 or an on/off switch, as shown in Figure 6. In this case, the orientation of the vaping device 100 during use is not defined and so the user is able to hold the vaping device in any orientation that is comfortable for them and still allows operation of the vaping device 100.

For this form of pen-like device, there is a high chance that the user may end up gripping the vaping device in a manner which does not result in contact between the user and both electrodes A and B. In order to ensure that a user always comes into contact with both electrodes A and B, independent of how the user grips the vaping device 100, both electrodes A and B are substantially circumferential, extending around substantially the entire circumference of the vaping device 100. In some examples, at least one of the electrodes (and in further cases, both electrodes) extends fully around the entire circumference of the vaping device 100 such that the at least one electrode takes the form of a ring on an outer surface of the vaping device 100.

Further, for the form of vaping device illustrated in Figure 6, the distance between the two electrodes A and B is as large as possible, to ensure better measurements being taken from each electrode. A greater distance between electrodes A and B means that more skin can be measured, resulting in more consistent results than would be achieved over a shorter measuring distance. In addition, the voltage drop over a larger distance is higher than over shorter distances (which have a smaller voltage drop) which gives a better measuring accuracy. The only requirement is that the two electrodes A, B are positioned such that a typical grip of the vaping device 100 by a user results in the user making skin contact with both electrodes. A, B When present, optional reference electrode R can be located between the two electrodes A and B.

We will now consider the box-like vaping device, which is illustrated in Figure 7.

In this case, a user has two main grip options: gripping the front of the device or gripping the rear of the device. Here front and rear are used to refer to two parallel sides of a box located opposite to each other. If no an activation element 104, or on/off switch, is present then the same constraints that applied to the pen-like vaping device apply here. Thus, as before, due to the lack of a defined orientation during use, the two electrodes A, B extend around substantially the entire perimeter of the vaping device. Here, perimeter is used to mean the side walls of the box-like structure rather than top and bottom/base faces.

If an activation element 104, or an on/off switch, is present then the same constraints that applied to the pen-like vaping device apply here. The present disclosure will consider the case in which no activation element or on/off switch is provided, as can be seen in Figure 7.

As before, the two electrodes A, B extend around at least a portion of perimeter of the vaping device. Again, perimeter is used to mean the side walls of the box-like structure rather than top and bottom/base faces. Alternatively, at least one of the electrodes (for example electrode A) may partially extend over a part of the base of the vaping device, as well over a part of a side wall of the vaping device 100. This is illustrated in Figure 7 by the alternative placement of electrode A shown in dashed lines. In this case, the electrode A can be thought of as being at least partially wrapped around an edge of the vaping device 100, for example a lower body edge when the vaping device 100 is held in its operative configuration. Having an electrode which at least partially extends over more than one face of the box-like vaping device 100 ensures good contact between the user and the electrode when the user grips the vaping device 100. In some cases, this electrode positioning could be mirrored, meaning that there are two of the same electrode located at corresponding positions on either side of a plane. For example, there could be two A electrodes and one B electrode. This mirrored arrangement provides increased compatibility of the vaping device for both left- and right- handed users.

A number of other configurations of the two electrodes A, B could also be implemented on both the pen-like and box-like vaping devices. In an alternative configuration the activation element may comprise a first electrode, for example electrode A, as shown in Figure 1.

Whilst the electrodes A and B have been illustrated as having a continuous surface across the contacting surface of the electrode, in another alternative configuration, the electrodes A and B may comprise a multi-electrode surface. In this case, each electrode of the multi-electrode surface must be electrically connected within the vaping device. As an example, electrode A may comprise a plurality of sub electrodes (for example electrodes A1 , A2, and A3) and these sub-electrodes are electrically connected together, and operate together, to form electrode A. By providing multiple sub-electrodes rather than one main electrode, the contact surface area of each sub-electrode compared to the contact surface area of a single electrode can be reduced, whilst still maintaining functionality. This may help reduce the manufacturing cost of the vaping device as fewer materials are required to form each electrode. A multi-electrode configuration also provides increased design options when manufacturing the vaping device whilst maintaining function.

Claims

1. A method of operating an aerosol generation device, comprising the steps of: detecting a signal from a user’s heart using at least two electrodes; comparing the detected signal with a stored signal that is characteristic of a registered user; and performing an action using the aerosol generation device based on the comparison.

2. The method of claim 1 , wherein the action comprises unlocking the aerosol generation device.

3. The method of claim 1 or claim 2, further comprising the step of determining one or more features of the signal from the user’s heart for comparison against one or more stored features that are characteristic of the registered user.

4. The method of claim 3, wherein the one or more characteristics include at least one of P, Q, R, S and T features in an electrocardiogram or parameters derived from combinations of these features.

5. The method of claim 3, wherein the one or more characteristics are in the frequency domain of the signal from the user’s heart.

6. The method of any of the preceding claims wherein the detected signal is a voltage difference between the two electrodes.

7. The method of any of the preceding claims comprising a step of processing the signal from the user’s heart, wherein the processing comprises one or more of band pass filtering, amplification, and analogue to digital conversion.

8. The method of any of the preceding claims, further comprising determining the stored signal by averaging the signal from the registered user over an extended time period.

9. An aerosol generation device, comprising: a first electrode and a second electrode on a housing of the device for detecting a signal from a user’s heart; a data storage unit configured to store a signal that is characteristic of a registered user; and control circuitry configured to compare the detected signal with the stored signal and to perform an action using the aerosol generation device based on the comparison.