Portable device and method

Abstract

SOLUTION: To provide a portable device for acquiring an electroencephalogram (EEG) signal emitted from a user, the portable device comprising: a flexible support which fits to a local region on the skull of the user; at least one sensor which is arranged on the flexible support so as to form contact between itself and the scalp of the user when the user wears the portable device; an electric circuit for filtering and amplifying an electric signal detected by the at least one sensor;and a housing comprising an electric system for processing a signal from the electric circuit. The at least one sensor comprises: multiple conductive blades which can be deformed by a pressure on the scalp of the user; and at least one point which distributes hair of the user when the portable device is worn to the user, the electric circuit being stored in the flexible support and forming an active electrode with the sensor.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a portable device for acquiring electroencephalographic signals (EEG) or a portable surface electroencephalograph and a method for acquiring electroencephalographic signals using such an electroencephalograph. [Background technology]

[0002] Surface electroencephalographs can measure changes in the diffuse electrical potentials on the surface of the skull. These electrical potential changes are called electroencephalographic or EEG signals. Summary of the Invention [Problem to be solved by the invention]

[0003] The first difficulty concerns the reliability of the device used to acquire the EEG signal. Indeed, given that the intensity of the observed changes in electrical potential is very low (on the order of a few microvolts), acquiring the EEG signal requires maximizing the electrical conductivity between the electrodes and the scalp, i.e. perfect contact between the two. This is very difficult due to the user's hair.

[0004] Currently available devices use several solutions to ensure signal reliability.

[0005] Some surface EEG devices are equipped with gel electrodes. In this case, the contact is achieved by a gel or conductive liquid, which penetrates through the user's hair and easily reaches the scalp. The gel reduces the electrical impedance and reduces interference with the surrounding signals. This solution allows to obtain good electrical conductivity at any location on the scalp. However, this type of device requires technical assistance to place the electrodes. Especially this type of device requires a long time (when the gel is placed, the electrical conductivity is different for each electrode). Furthermore, the use time of the device is limited to a few hours (until the gel dries and the contact cannot be guaranteed).

[0006] Recently, dry surface electroencephalographs, so-called "active electrodes", have been developed. Such electrodes are disclosed, for example, in US patent application US20133066183. The function of dry-active electrodes is to detect and then filter and amplify the changes in electrical potential on the scalp surface. The analog signals thus obtained are converted to digital signals using one or more analog-to-digital converters controlled by a microcontroller. The microcontroller receives and stores these data for analysis or transmits them to other devices.

[0007] In the case of dry-active electrodes, contact with the scalp is achieved using solid conductive electrodes or "sensors" connected to an electrical circuit. This overcomes the impedance increase caused by the absence of gel. The active electrical components allow for signal acquisition comparable to that of gel electrodes. An additional advantage of active electrodes is that the signal can be filtered and / or amplified, thus improving the signal-to-noise ratio. However, the main difficulty with this technology is access to the scalp.

[0008] Current solutions generally use polymer-based sensors and pins that exert high pressure to reach the user's scalp (see, for example, U.S. Patent Application 201514788). While this approach can improve contact with the scalp, it has the drawback of being extremely uncomfortable, especially when used for extended periods of time.

[0009] Yet another difficulty in the design of surface EEG equipment lies in the public acceptability of the EEG signal, which imposes aesthetic and comfort constraints.

[0010] In fact, a medical or research system typically comprises a cover made of elastic or impermeable fabric in which the sensor is placed, an electrical circuit connected to the sensor, and a housing for the acquisition system, three separate parts that must be assembled by the operator / assistant before use.

[0011] Portable electroencephalogram acquisition devices that do not require the assistance of a professional technician to the user have been proposed. For example, US Patent Application 20020029005 discloses a headgear for acquiring electroencephalogram signals. The headgear includes electrodes arranged at predetermined positions and an adjustable elastic band, which ensures contact between the electrodes and the scalp. However, such devices have many separate adjustable parts, making them cumbersome to use.

[0012] US Patent Application 20170027466 also discloses a portable electroencephalogram acquisition device that can be used without assistance. The device has a reduced number of adjustable and detachable mechanical parts, making it easy and quick to use even for inexperienced users. To achieve this, the electroencephalogram signal acquisition device has a central part that is located on the top of the head and can accommodate all electrical components. Long and short arms extend from the central part to surround the entire head. Sensors are located at the ends of these arms. At least some of these arms have a resilient heel or spring function. This allows the head to be gripped with sufficient force when applied to the periphery of the device to ensure the required sensor-scalp contact. However, these devices have the disadvantage that they are very uncomfortable to use, in addition to lacking delicacy. This is because if the head position is not kept vertical and straight, the gripping force is transmitted only through the sensor, which creates a significant pressure concentration at one point.

[0013] US Patent Application 2016157777 also discloses a portable brainwave acquisition device. The device comprises a central part located on the top of the head. A long arm and a short arm extend from the central part to surround the entire head. Sensors are located at the ends of the arms. All electrical components can be housed inside the central part or the flexible branches.

[0014] US Patent Application No. 2015112453 and US Patent Application No. 2017258400 disclose portable electroencephalogram acquisition devices, in which at least some of the electrical components can be housed within an assembly that can be connected to one of the electrical connectors of the device. In the device disclosed in US Patent Application No. 2015112453, the assembly is detachably connected.

[0015] Although the above-mentioned devices provide a solution that achieves satisfactory contact with the user's scalp without the need for technical assistance from the operator, they lack the subtlety required for some applications, particularly consumer applications (e.g., video games, workouts, sleep aids, etc.).

[0016] This specification proposes a portable surface electroencephalograph with dry-active electrodes that achieves excellent signal quality, is very easy to use, comfortable to use, and extremely sensitive. Such a portable surface electroencephalograph is suitable for use in hospital environments (e.g., by outpatients visiting a clinic) and can also facilitate the development of new applications for electroencephalography. [Means for solving the problem]

[0017] A first aspect of the present invention relates to a portable device for acquiring electroencephalographic (EEG) signals emitted by a user, the portable device comprising: - Flexible support that conforms to localized areas of the user's skull. a set of sensors for detecting electrical signals generated by the user's neural activity, said set of sensors being arranged on the support so as to form contact with the scalp when the user wears the device; an electrical circuit for filtering and amplifying the electrical signal detected by each of the sensors, which is housed within the flexible support and which forms, together with the sensors, an active electrode; a housing comprising an electrical system for processing signals from the electrical circuit, said housing being mechanically connected to the flexible support and forming, together with the support, a means of connection to a garment or accessory worn by the user;

[0018] In the device described herein, the electrical components responsible for the various electrical functions are distributed between a flexible support and a housing, the latter mechanically cooperating to form a means of connection to clothing or accessories. Both result in a more flexible and thinner support in contact with the user's skull. Typically, the thickness of the support is less than 10 mm, and can even be less than 5 mm. Furthermore, the device can be very easy to use without compromising the quality of the acquired EEG signals. The portable device described herein thus offers at least a performance level comparable to the prior art, while also offering ease of use and ergonomics comparable to consumer applications.

[0019] The portable device is intended for use in humans, but may also be used in certain animals. The device is non-invasive, accurate and comfortable to use, characteristics that make it suitable for use in animal research.

[0020] The number of sensors arranged on the flexible support depends on the application. For example, this number can be more than 2, less than 128, or even more. Depending on the envisaged application, the support covers a limited area of ​​the skull in order to measure brain activity generated in specific areas of the brain, such as the visual cortex, the auditory cortex, the motor cortex, the somatosensory cortex or the prefrontal cortex. Alternatively, the support may cover the entire surface of the skull. The number of sensors can be determined based on the surface covered by the support and the required spatial resolution.

[0021] In one or more embodiments, the flexible support and the housing are mechanically connected using attachment points (e.g., eccentric attachment points) to create a gap between the flexible support and the housing through which the garment and / or accessories can pass, preferably between 2mm and 5mm.

[0022] In one or more embodiments, the attachment points are flexible, allowing for the formation of "clips" or clamps that form the connecting means.

[0023] In one or more embodiments, the attachment points also provide electrical contact between electrical components housed in the flexible support and electrical components housed within the housing.

[0024] In one or more embodiments, the attachment points are detachable.

[0025] In one or more embodiments, the electrical signal processing system contained within the rigid housing includes one or more analog-to-digital converters (ADCs) that convert signals from the filtering and amplifying electrical circuitry into digital signals, and a microprocessor that, among other things, transmits and / or stores the digital signals in an external processing unit. The rigid housing may of course also house other electrical components, such as a battery and / or other types of sensors (e.g., acceleration sensors and / or gyroscopes).

[0026] In one or more embodiments, the flexible support is openwork, for example comprising multiple branches on which at least some of the sensors are located, such that this structure provides a more flexible support and allows for improved conformance to the shape of the skull.

[0027] For example, the sensors are distributed among at least two and at most six branches.

[0028] In one or more embodiments, the branches are parallel, which allows for a more uniform pressure to be applied to the sensor even when clothing or equipment does not cover the entire support, making it easier for the user to understand the movement movements required to properly position the device.

[0029] In one or more embodiments, two or more branches may be connected to a central section using flexible lateral branches.

[0030] In one or more embodiments, three or more branches may be arranged in a parallel comb shape.

[0031] In one or more embodiments, each sensor is movably secured to a flexible support, for example using a spring-type mechanical connection, which improves contact with the scalp.

[0032] In one or more embodiments, the spring-type mechanical connection comprises spring fingers that form contact points with the base of the sensor, allowing the sensor to move about several axes.

[0033] In one or more embodiments, the spring fingers ensure electrical contact between the sensor and the filter and amplifier circuitry.

[0034] In one or more embodiments, each sensor is disposed in a recess in the flexible support and includes a base in electrical contact with the filter and amplifier circuitry.

[0035] In one or more embodiments, the sensor comprises a number of conductive blades disposed on said base, said conductive blades forming line contact with the skull when the device is worn by a user.

[0036] Such line contact increases the contact surface area, improving sensitivity and user comfort.

[0037] In one or more embodiments, the conductive blades are arranged substantially parallel. Advantageously, at least some of the sensors are arranged on parallel branches of the support, such that the conductive blades are parallel to the branches.

[0038] In one or more embodiments, each sensor includes two conductive blades, the number two being a good compromise because it allows for good distribution of the contact pressure while still maintaining good measurement accuracy.

[0039] In one or more embodiments, the end-to-end distance between the two blades is greater than 2 mm, which allows hair to pass through the gap. To avoid loss of precision, the gap is less than 50 mm, preferably less than 10 mm. For example, the gap is greater than 2 mm and less than 6 mm.

[0040] In one or more embodiments, the conductive blade includes a conductive polymer coating that forms a conductive layer that penetrates into contact with the user's scalp.

[0041] In one or more embodiments, the support has at least one point (which may or may not be conductive) that first penetrates into contact with the scalp when the support is positioned on the scalp. The effect of having this point is to part the hair when the device is worn, thereby exposing the user's skull to the conductive blade.

[0042] A second aspect of the invention relates to a garment or accessory for acquiring electroencephalogram (EEG) signals, comprising the portable device of the first aspect.

[0043] The garment or accessory may be, for example, a headband, headgear, a headset, or the like.

[0044] A third aspect of the present invention relates to a method of acquiring electroencephalographic (EEG) signals emitted by a user using the portable device of the first aspect, the method comprising the following steps: - measuring electrical signals generated by the user's neural activity using a sensor in contact with the user's scalp. - processing electrical signals from the electrical circuitry of the portable device with an electrical processing system disposed in the housing.

[0045] In one or more embodiments, the step of processing the electrical signal includes analog / digital conversion of the electrical signal from the filter and amplifier circuitry and transmitting the digital signal to an external processing unit and / or storing the digital signal. [Brief description of the drawings]

[0046] Other advantages and features of the present invention will become apparent from the following detailed description and from the accompanying drawings, in which: [Figure 1A] 1A to 1C are views of a portable EEG signal acquiring device according to a first embodiment of the present invention, viewed from different directions. [Figure 1B] 1A to 1C are views of a portable EEG signal acquiring device according to a first embodiment of the present invention, viewed from different directions. [Figure 1C] 1A to 1C are views of a portable EEG signal acquiring device according to a first embodiment of the present invention, viewed from different directions. [Figure 1D] 1A to 1C are views of a portable EEG signal acquiring device according to a first embodiment of the present invention, viewed from different directions. [Figure 1E] 1A to 1C are views of a portable EEG signal acquiring device according to a first embodiment of the present invention, viewed from different directions. [Figure 2A] 5A to 5C are views of a portable EEG signal acquiring device according to a second embodiment of the present invention, viewed from different directions. [Figure 2B] 5A to 5C are views of a portable EEG signal acquiring device according to a second embodiment of the present invention, viewed from different directions. [Figure 2C] 5A to 5C are views of a portable EEG signal acquiring device according to a second embodiment of the present invention, viewed from different directions. [Figure 3A]13A to 13C are views of a portable EEG signal acquiring device according to a third embodiment of the present invention, viewed from different directions. [Figure 3B] 13A to 13C are views of a portable EEG signal acquiring device according to a third embodiment of the present invention, viewed from different directions. [Figure 4] FIG. 1 shows an example of an electrical architecture for acquiring and processing EEG signals using a portable device according to the present invention. [Figure 5A] FIG. 2 shows an example of a sensor according to the present invention. [Figure 5B] FIG. 2 shows an example of a sensor according to the present invention. [Figure 5C] FIG. 4 is a diagram showing another example of a sensor according to the present invention. [Figure 6] FIG. 1 shows an example of a sensor movably fixed to a flexible support. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] 1A-1D respectively show a front view, a first side view, a rear view and a second side view of a portable EEG signal acquiring device 1 according to a first example of the present invention, and FIG 1E shows the device worn by a user.

[0048] The portable device shown in Figures 1A to 1D comprises a flexible support 11 that fits over a localized area of ​​the user's head (the occipital area behind the skull) and a housing 12 that is mechanically and electrically connected to the flexible support 11. On this support, a sensor 13 is placed that detects the electrical signals generated by the neural activity of the user. In addition, a ground or "bias" electrode 13B is provided to eliminate common mode from the signals measured on other users. As will be described in more detail later, each sensor may comprise multiple conductive blades (e.g., two conductive blades 131, 132). These may be arranged substantially parallel, for example, to form a line contact with the scalp when the user wears the device. These conductive blades may also be deformable by pressure on the user's scalp. Each sensor comprises an electrical circuit that filters and amplifies the electrical signal (not shown in Figures 1A-1D), forming an active electrode. The signal from the filtering and amplifying electrical circuit is processed by an electrical system. As will be shown below, this electrical system comprises, for example, one or more analog / digital converters (ADC) and a microcontroller. This allows, among other things, the stored and / or transmitted processed signals to an external device. The electrical circuitry for filtering and amplifying the active electrodes is housed in the flexible support. The electrical system, on the other hand, is housed in the housing 12. By separating the electrical components in the flexible support (where the sensors are arranged) and in the housing, respectively, the design of the flexible support 11 (particularly its shape, thickness, mechanical elasticity) can be varied. For example, the thickness Xs of the flexible support can advantageously be less than 10 mm, for example between 2 mm and 10 mm, and even more advantageously less than 5 mm, for example between 2 mm and 5 mm. The housing may of course house other electrical components necessary for the operation of the device, for example a battery and / or other types of sensors (for example an accelerometer and / or a gyroscope). In the example of Figs. 1A-1D, the housing 12 is also provided with an on / off switch and a connection port 123 (for example a USB port).

[0049] Furthermore, as shown in Fig. 1A-1E, the support 11 and the housing 12 cooperate to form a connection means to a garment or accessory worn by the user. In this example, the housing 12 is connected to the support 11 by means of an eccentric attachment 121. This forms a gap (a few millimeters, for example 2 mm to 5 mm) between the housing and the support. The garment and / or accessory can pass through this gap. In this example, the attachment point is flexible. It can therefore form a clamp or "clip" through which the garment and / or accessory (for example, the headband 101 shown in Fig. 1E) can pass. The elasticity of the headband allows the flexible support to be pressed against the user's skull 100. The attachment point 121 also forms an electrical connection between the filter and amplifier circuitry of the active electrodes and the electrical system of the housing. For example, the attachment point comprises a sleeve. The electrical connection can pass through this sleeve. The attachment point may be detachable.

[0050] The shape of the support is preferably designed to ensure an even pressure distribution between the different sensors when worn by a user. In the example of Figures 1A-1D, the flexible support 11 is openwork and comprises outer branches 111, 112 connected to a central part 110 by means of lateral branches 113, 114. This gives the assembly flexibility. The sensors are placed on the outer branches and on the central part. In this example, the central part 110 is substantially circular and is superimposed on the housing. The circular shape of the housing allows it to be easily gripped by hand.

[0051] In the example of Figures 1A-1E, two outer branches are shown positioned outside the central portion. These outer branches allow the sensor to be positioned in the region of interest on the skull. Other branches supporting sensors may be provided as needed (e.g., a third branch and a fourth branch for positioning the sensor on the lateral portion of the skull).

[0052] It is clear that the flexible support 11 may also have other shapes, in particular an openwork shape.

[0053] 2A-2C show a second example portable EEG signal acquisition device 20 herein.

[0054] 2A and 2B are front and side views, respectively. FIG. 2C shows device 20 when worn by a user using headband 101. The portable device comprises a flexible support 21 that fits over a localized area of ​​the user's skull, and a rigid housing 22 that is electrically and mechanically connected to flexible support 21. Flexible support 21 supports sensors (sensor 13 in the above example). Each sensor comprises a filter and amplifier circuit (not shown) and forms an active electrode.

[0055] In this example the support 21 is again openwork and has good flexibility. In this example the support 21 has a given number of branches 211-215, all arranged in parallel. In these branches the sensors are arranged. Ground electrodes are not shown in these figures, but of course these may be provided as in the previous examples. In this example again the branches 211-215 with sensors are connected by lateral branches 216-217, which gives the assembly flexibility.

[0056] In this example, the housing 22 and the support 21 (housing 22 connected to support 21 with attachment 221) cooperate to form a means of connection to clothing or accessories, similar to the previous example. As shown in FIG. 2C, a headband 101 may be inserted into a gap formed between the support 21 and the housing 22 to secure the device 20 to the user's skull 100.

[0057] 3A-3B show a third example portable EEG signal acquisition device 30 herein.

[0058] In this example again the portable device 30 comprises a flexible support 31 and a housing 32. The support 31 and the housing 32 are mechanically connected to form a means of connection to a garment or appliance. Furthermore, the support 31 and the housing 32 are electrically connected. In this example the support 31 is an openwork. The support 31 forms a central part 310 and a set of outer branches 311-314. The outer branches 311-314 are connected to the central part by means of lateral branches 315-318. This gives the support flexibility. In this example, as in Figures 1A-1E, the central part 310 of the support is substantially circular. This shape is superimposed on the shape of the housing 32. This allows it to be easily grasped by the user. The set of sensors 13 and the ground electrode 13B are arranged on the central part of the support 31 and on the outer branches.

[0059] In the examples shown in the aforementioned figures, especially in Figs. 1E, 2C and 3B, the portable device (10, 20 and 30, respectively) is pressed against the user's skull by means of a headband 101. It will be easily understood that the connection means formed by the housing and the support can be applied to any other type of garment or accessory. Examples of such garments or accessories are headsets, any type of headgear (e.g. with an elastic band passing between the support and the housing), audio headsets (worn on top of the skull), virtual or augmented reality headsets, safety hats, bicycle helmets, surgical caps, protective masks, etc. The connection means formed by the support and the housing can also be applied to garments or accessories worn by the user. In the connection means formed by the flexible support and the housing, any type of device, scratch tag, snap fastener, mechanical or magnetic clip, etc. may be provided to ensure fastening to the garment or accessory.

[0060] The portable device may be "clipped" to a garment or accessory before it is actually worn by the user, or conversely, the portable device may be "clipped" to a garment or accessory after it is worn by the user.

[0061] As shown in the previous figures, the conductive blades are preferably all parallel, so that the support can be positioned on the skull by a movement parallel to the orientation of the conductive blades (for example, from the top of the head downwards, if the device is to be worn on the back of the skull). In practice, for better contact and comfort, the movement is preferably along the direction of the hair.

[0062] As shown in Figures 1A-1E and 2A-2C, the various branches of the support supporting the sensor may be substantially parallel to each other and to the line of the conductive blades. This provides aesthetic, mechanical and ergonomic effects. In fact, the parallel branches allow the pressure to be applied precisely to sensors that are equipped with a headband and do not completely cover the support. The headband is placed on the parallel branches and presses against the electrodes at the ends. The branches that are parallel to the conductive blades minimize the visible part of the support when worn. The movement movements required for the placement of the device are easier to understand.

[0063] FIG. 4 shows an example of an electrical architecture for acquiring and processing EEG signals using a portable device according to the present invention.

[0064] As mentioned above, the portable device according to the present invention comprises a predetermined number of active electrodes 41 (e.g., 2 to 128, preferably 2 to 64, more preferably 4 to 16). Each of the active electrodes 41 comprises a sensor 411 for detecting electrical signals generated by the neural activity of the user 100, and an electrical circuit 412 for filtering and amplifying. For example, the electrical circuit 412 comprises a first-order high-pass analog filter, an amplifier, and a first-order low-pass analog filter. The filter allows removing frequency domain components from the detected signal that are not relevant for the intended application. The amplifier allows the signal strength to be adapted to the characteristics of the ADC, so as to obtain the maximum resolution of the conversion. As shown in FIG. 4, the portable device also comprises one or more reference electrodes 41R and a so-called "bias" or ground electrode 41B. The active electrodes are connected to one or more analog-to-digital converters 42 (ADC). Each ADC is capable of converting signals from a predetermined number of active electrodes (e.g., 1 to 128). The reference electrodes are connected to all the converters. The reference electrode(s) is preferably placed in contact with the user's head, at a distance from the other electrodes. The reference electrode may be connected using a connection port, such as port 123 shown in FIG. 1C, and placed in contact with the ear. Alternatively, the reference electrode may be fixed to a garment or accessory to which the portable device is attached. The transducers 42 are controlled by a microcontroller 43 and communicate with each other, for example by SPI (Serial Peripheral Interface) protocol. The microprocessor encapsulates the received data and transmits it to an external processing unit 44, such as a computer, a mobile phone, an on-board computer of a car or an airplane, for example, by technology such as Bluetooth, Wi-Fi, Li-Fi, etc. All parts of the acquisition system are powered by a battery (not shown in FIG. 4) contained within the housing.

[0065] Depending on the operating mode of the portable device according to the invention, each active electrode measures a value of its electric potential, from which the potential measured by the reference electrode is subtracted (Ei=Vi-Vref). The result of this subtraction is digitized using ADC 42 and transmitted by microcontroller 43. To achieve this, as shown in Fig. 4, the device comprises a predefined number of active measurement electrodes (for example 2 to 64, preferably 4 to 16) and one or two reference electrodes 41R and a further ground electrode 41B ("bias" electrode).

[0066] 5A and 5B show two views of an example of a sensor according to the present invention.

[0067] In this example, the sensor 50 comprises a base 51 housed in a flexible support (not shown) by means of a fixing device 52, and a number of conductive blades 53, 54. When worn by a user, the conductive blades form a line contact with the scalp. The line contact offers the advantage of a larger contact area with the scalp, which improves the sensitivity of the signal reception and improves the user's comfort. Moreover, when the conductive blades are arranged substantially parallel, the line contact formed is equivalent to a movement movement, which parts the hair when the device is worn.

[0068] The application showed that the number of conductive blades is optimally two. With only one blade per sensor, the contact formed by the blades on the scalp may become unstable and the pressure distribution on only one blade may cause discomfort to the user. The application showed that two blades are optimal to cover a small enough surface area of ​​the skull and provide a good signal accuracy. The spacing between the blades is a compromise between the requirements of the ability to pass hair, the signal observations and the pressure distribution in terms of user comfort. The spacing between the two blades is preferably large enough to allow the passage of hair. For example, the end-to-end distance between the two blades is greater than 2 mm. The maximum spacing between the two blades depends on the total surface area to be covered and the number of sensors. However, it is preferable that it is less than 50 mm, advantageously less than 10 mm, to avoid a loss of accuracy. For example, the spacing XL is greater than 2 mm and less than 6 mm.

[0069] 5A and 5B, the sensor 50 comprises a metal structure 510 housed in a plastic part 520. The metal structure forms contacts 511 at the base 51. This ensures that current flows through the filter and amplifier circuitry. The metal structure forms electrical contact areas 512 with the scalp at each blade 53, 54.

[0070] At the point of contact with the scalp, a metal treatment (eg, silver / silver chloride plating) may be applied.

[0071] In the example shown in Figures 5A and 5B, the blade is slightly concave in the area where it comes into contact with the scalp, allowing it to more naturally fit the shape of the scalp.

[0072] As shown in Figures 5A and 5B, the blade has one or two points (541, 542 in Figure 5B) on either side of the sensor. This maintains symmetry and allows the sensor to rotate relative to the support. The points on the bottom side of the sensor also help the sensor to penetrate the hair to reach the scalp. The points do not have to be conductive.

[0073] As shown in Figures 5A and 5B, the blades can be solid, which provides more rigidity.

[0074] In Fig. 5C, another example of a sensor according to the invention is shown. In this example, a conductive polymer (for example of the PEDOT:PSS type) forms the flexible layer 543, which when pressure is applied flattens on the scalp, increasing the contact surface area. The pressure is then better distributed on the skull. This improves the comfort of the device. Also, the increased contact surface area reduces the electrical resistance at the interface between the skull and the sensor, which increases the EEG signal flowing to the sensor. Furthermore, the flexible polymer absorbs the micro-movements of the device relative to the user's scalp, making the electrical properties at the interface more stable. This reduces noise, i.e. fluctuations in the measurements that are not related to brain activity. Finally, these polymers have the advantage that they are biocompatible.

[0075] It will be appreciated that other configurations and / or coatings may be used to form the sensors of the present invention, for example, the metal portions of the sensor may be eliminated by using conductive materials other than metals (e.g., conductive polymers) in the construction of the sensor.

[0076] FIG. 6 shows an example of the sensor 50 according to FIGS. 5A and 5B fixed to a flexible support 61. As shown in FIG. 6A, the base 51 of the sensor can be removably fixed in a recess 65 formed between two plates 62, 63 of the support. The sensor 50 is movably fixed with respect to the flexible support 61. This allows the device to be adapted to different skull shapes. A metal blade 66 with a spring effect ensures electrical contact between the conductive area 511 of the base and the filter and amplifier circuits arranged in a circuit 64 printed inside the flexible support. Thanks to the contact point with the base of the sensor, the blade 66 ensures a translational movement in the vertical axis (axis perpendicular to the support) and a rotational movement around two horizontal axes. Such mobility is essential for the formation of the sensor and its support.

[0077] Although the present invention has been described through some detailed embodiments, the portable electroencephalogram signal acquiring device of the present invention includes various modifications, variations, improvements and modifications, which are obvious to those skilled in the art and fall within the scope of the present invention as defined in the following claims.

Claims

1. 1. A portable device for acquiring electroencephalogram (EEG) signals from a user, comprising: a flexible support adapted to conform to a localized area of ​​the user's skull; at least one sensor disposed on the flexible support such that contact is made with a scalp when the user wears the portable device; an electrical circuit for filtering and amplifying an electrical signal detected by the at least one sensor; a housing including an electrical system for processing signals from the electrical circuit; the at least one sensor comprises a plurality of conductive blades deformable by pressure on the scalp of the user and at least one point for parting the user's hair when the portable device is worn; The electrical circuitry is contained within the flexible support and forms an active electrode together with the sensor.

2. 2. The portable device of claim 1, wherein the flexible support is openwork.

3. 10. The portable device of claim 1, wherein the at least one sensor is movably fixed to a flexible support.

4. 2. The portable device of claim 1, wherein the at least one sensor is disposed in a recess in the flexible support and comprises a base in electrical contact with the electrical circuit.

5. said electrical contact being achieved by spring fingers; The portable device of claim 4 , wherein the spring fingers form contact points with the base.

6. The portable device of claim 1 , wherein the conductive blades are arranged parallel to one another.

7. the flexible support comprises a central portion and a set of parallel branches; 2. The portable device of claim 1, wherein the set of parallel branches are connected to the central section by means of flexible lateral branches.

8. 2. The portable device of claim 1, wherein the end-to-end distance between two of the conductive blades is greater than or equal to 2 mm and less than 6 mm.

9. The portable device of claim 1 , wherein the conductive blade comprises a conductive polymer coating.

10. 10. The portable device of claim 1, wherein the housing contains an electrical system including at least one analog-to-digital converter (ADC) and a microprocessor for processing signals from the electrical circuitry.

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