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 or portable surface electroencephalograph for acquiring electroencephalogram signals (EEG) and a method for acquiring electroencephalogram signals using such an electroencephalograph. [Background technology]

[0002] Surface electroencephalographs measure changes in the diffuse electrical potential on the surface of the skull. These changes in electrical potential 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 devices used to acquire EEG signals. Indeed, given that the observed changes in electrical potential are very low in intensity (on the order of a few microvolts), acquiring EEG signals 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, contact is achieved by a gel or conductive liquid, which penetrates through the user's hair and easily reaches the scalp. The gel reduces electrical impedance and reduces interference with surrounding signals. This solution allows for good electrical conductivity at any location on the scalp. However, this type of device requires technical assistance to position the electrodes. This type of device, in particular, requires a long time (when the gel is placed, the electrical conductivity varies from electrode to electrode). Furthermore, the device can only be used for a few hours (until the gel dries and contact can no longer be guaranteed).

[0006] Recently, dry surface electroencephalographs, so-called "active electrodes," have been developed. Such electrodes are disclosed, for example, in U.S. Patent Application No. US20133066183. The function of dry-active electrodes is to detect, filter, and amplify 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 increased impedance 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, thereby improving the signal-to-noise ratio. However, the main difficulty with this technology is scalp access.

[0008] Current solutions generally use polymer-based sensors and pins that apply high pressure to reach the user's scalp (see, for example, U.S. Patent Application No. 201514788). While this approach can improve contact with the scalp, it has the drawback of being extremely uncomfortable, especially during prolonged use.

[0009] Yet another difficulty in the design of surface EEG equipment is 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 (where 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 (EEG) acquisition devices that do not require the assistance of a professional technician have been proposed. For example, U.S. Patent Application Publication No. 20020029005 discloses a headgear for acquiring EEG signals. The headgear includes electrodes positioned at predetermined locations and adjustable elastic bands, ensuring contact between the electrodes and the scalp. However, such devices are cumbersome to use because they have many separate adjustable components.

[0012] U.S. Patent Application Publication No. 20170027466 also discloses a portable electroencephalogram (EEG) acquisition device that can be used without assistance. This 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 EEG signal acquisition device has a central section positioned on the top of the head and capable of housing all electrical components. Long and short arms extend from the central section to surround the entire head. Sensors are located at the ends of these arms. At least some of these arms have elastic heels or springs. This allows them to grip the head with sufficient force, when applied to the periphery of the device, to ensure the required sensor-to-scalp contact. However, these devices suffer from the drawbacks of lacking delicacy and being very uncomfortable to use. This is because, unless the head is kept vertical and straight, the gripping force is transmitted only through the sensor, which causes significant pressure concentration at one point.

[0013] U.S. Patent Application No. 2016157777 also discloses a portable electroencephalogram acquisition device. The device includes a central section positioned on the top of the head. Long and short arms extend from the central section, encircling the entire head. Sensors are located at the ends of the arms. All electrical components can be housed within the central section or the flexible branches.

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

[0015] Although the above-described 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 sensitivity required, especially for consumer applications (e.g., video games, workouts, sleep aids, etc.).

[0016] This paper proposes a portable surface electroencephalograph with dry-active electrodes that provides excellent signal quality, is very easy to use, comfortable to use, and highly sensitive. Such a portable surface electroencephalograph is suitable for use in hospital environments (e.g., by outpatients) 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 electroencephalogram (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, together with the sensors, forms 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 devices described herein, electrical components responsible for various electrical functions are distributed between a flexible support and a housing, which mechanically cooperate to form a connection means for clothing or accessories. This allows for a more flexible and thinner support that comes into contact with the user's skull. Typically, the support has a thickness of less than 10 mm, and can even be less than 5 mm. Furthermore, the device can be very user-friendly without compromising the quality of the acquired EEG signals. Thus, the portable devices described herein offer performance levels at least comparable to those of 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, which makes it suitable for use in animal research.

[0020] The number of sensors placed on the flexible support depends on the application. For example, this number can be between 2 and 128, or even more. Depending on the envisioned application, the support may cover a limited area of ​​the skull to measure brain activity generated in a specific region of the brain, such as the visual cortex, auditory cortex, motor cortex, somatosensory cortex, or 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, the gap is between 2 mm and 5 mm.

[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 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., accelerometers and / or gyroscopes).

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

[0027] For example, the sensors are distributed among two to six branches.

[0028] In one or more embodiments, the branches are parallel, which allows for 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 how to move the device to properly position it.

[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-like fashion.

[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, spring fingers ensure electrical contact between the sensor and the filter and amplifier circuitry.

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

[0035] In one or more embodiments, the sensor comprises a plurality 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 has two conductive blades, which is a good compromise because it distributes 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, allowing 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 braid comprises 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 this point is to part the hair when the device is worn, thereby exposing the user's skull to the conductive blades.

[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, or headset.

[0044] A third aspect of the present invention relates to a method of acquiring electroencephalogram (EEG) signals emitted by a user using the portable device of the first aspect, the method comprising the steps of: - Measuring electrical signals generated by the user's neural activity with 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, processing the electrical signal includes analog-to-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 explanation of the drawings]

[0046] Other advantages and features of the present invention will become apparent from the following description and the accompanying drawings. [Figure 1A] 1A to 1C are views of the portable EEG signal acquiring device according to the first embodiment of the present invention, viewed from different directions. [Figure 1B] 1A to 1C are views of the portable EEG signal acquiring device according to the first embodiment of the present invention, viewed from different directions. [Figure 1C] 1A to 1C are views of the portable EEG signal acquiring device according to the first embodiment of the present invention, viewed from different directions. [Figure 1D] 1A to 1C are views of the portable EEG signal acquiring device according to the first embodiment of the present invention, viewed from different directions. [Figure 1E] 1A to 1C are views of the portable EEG signal acquiring device according to the first embodiment of the present invention, viewed from different directions. [Figure 2A] 5A and 5B 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 and 5B 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 and 5B are views of a portable EEG signal acquiring device according to a second embodiment of the present invention, viewed from different directions. [Figure 3A]10A and 10B are views of a portable EEG signal acquiring device according to a third embodiment of the present invention, viewed from different directions. [Figure 3B] 10A and 10B 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 illustrates an example of an electrical architecture for EEG signal acquisition and processing using a portable device according to the present invention. [Figure 5A] 1A and 1B are diagrams illustrating examples of sensors according to the present invention. [Figure 5B] 1A and 1B are diagrams illustrating examples of sensors according to the present invention. [Figure 5C] FIG. 10 is a diagram showing another example of a sensor according to the present invention. [Figure 6] 1A and 1B show examples of sensors movably fixed to a flexible support. DETAILED DESCRIPTION OF THE INVENTION

[0047] 1A-1D respectively show a front view, a first side view, a back 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-1D includes 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. A sensor 13 is positioned on the support to detect electrical signals generated by the user's neural activity. Additionally, a ground or "bias" electrode 13B is provided to eliminate common-mode signals from other measured signals. As described in more detail below, each sensor may include multiple conductive blades (e.g., two conductive blades 131, 132). These may be arranged substantially parallel to form 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 includes electrical circuitry that filters and amplifies the electrical signal (not shown in Figures 1A-1D), forming an active electrode. Signals from the filtering and amplifying electrical circuitry are processed by an electrical system. As described below, the electrical system may include, for example, one or more analog-to-digital converters (ADCs) and a microcontroller. This allows, among other things, the storage and / or transmission of processed signals to an external device. The electrical circuitry for filtering and amplifying the active electrodes is housed within the flexible support. Meanwhile, the electrical system is housed within the housing 12. Separating the electrical components within the flexible support (where the sensors are located) and within the housing allows for a variety of designs for the flexible support 11 (particularly its shape, thickness, and mechanical resilience). For example, the thickness Xs of the flexible support may be advantageously less than 10 mm, e.g., between 2 mm and 10 mm, and even more advantageously less than 5 mm, e.g., between 2 mm and 5 mm. The housing may, of course, house other electrical components necessary for the device's operation, such as a battery and / or other types of sensors (e.g., accelerometers and / or gyroscopes). In the example of FIGS. 1A-1D, the housing 12 also includes an on / off switch and a connection port 123 (e.g., a USB port).

[0049] 1A-1E, the support 11 and the housing 12 cooperate to form a connection means for a garment or accessory worn by the user. In this example, the housing 12 is connected to the support 11 using an eccentric attachment 121. This creates a gap (a few millimeters, e.g., 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 and thus forms a clamp or "clip" through which the garment and / or accessory (e.g., 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 housing's electrical system. For example, the attachment point may include a sleeve. The electrical connection can pass through the 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 located on the outer branches and in 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] 1A-1E show two outer branches positioned outside the central portion. These outer branches allow sensors to be placed in the region of interest on the skull. If desired, other branches supporting sensors may be provided (e.g., third and fourth branches positioning sensors on the lateral portions 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 example above). Each sensor includes filter and amplifier circuitry (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 certain number of branches 211-215, all of which are arranged in parallel. In these branches, sensors are arranged. Ground electrodes are not shown in these drawings, but of course these may be provided as in the previous example. In this example again, the branches 211-215 with sensors are connected by transverse branches 216-217, which gives the assembly flexibility.

[0056] In this example, housing 22 and support 21 (housing 22 connected to support 21 using 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 support 21 and housing 22 to secure device 20 to a user's skull 100.

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

[0058] 1A-1E, the central portion 310 of the support is substantially circular. This shape is superimposed on the shape of the housing 32, allowing for easy gripping by the user. The sensor 13 and the ground electrode 13B are located on the central portion and the outer branches 311-314.

[0059] In the examples shown in the aforementioned drawings, particularly 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 readily apparent that the connection means formed by the housing and the support can be applied to any other type of clothing or accessory. Examples of such clothing or accessories include 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 reality or augmented reality headsets, hard hats, bicycle helmets, surgical caps, and protective masks. The connection means formed by the support and the housing can also be applied to clothing or accessories worn by the user. The connection means formed by the flexible support and the housing may be provided with any type of device, such as a scratch tag, a snap fastener, a mechanical or magnetic clip, etc., to ensure fastening to the clothing or accessory.

[0060] The portable device may be "clipped" to clothing or an accessory before it is actually worn by the user, or conversely, the portable device may be "clipped" to clothing or an 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 blade. This provides aesthetic, mechanical and ergonomic benefits. In fact, the parallel branches allow for precise application of pressure 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 their ends. Branches that are parallel to the conductive blade minimize the visible portion of the support when worn. This makes it easier to understand the movement movements required for device placement.

[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 described above, the portable device according to the present invention includes a predetermined number of active electrodes 41 (e.g., 2 to 128, preferably 2 to 64, more preferably 4 to 16). Each active electrode 41 includes 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 may include a first-order high-pass analog filter, an amplifier, and a first-order low-pass analog filter. The filter allows frequency domain components irrelevant to the target application to be removed from the detected signal. The amplifier allows the signal strength to be adapted to the characteristics of the ADC, thereby achieving maximum resolution for the conversion. As shown in FIG. 4, the portable device also includes 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 (ADCs). Each ADC can convert signals from a predetermined number of active electrodes (e.g., 1 to 128). Reference electrodes are connected to all converters. The reference electrode(s) are preferably positioned in contact with the user's head, away from the other electrodes. The reference electrode may be connected using a connection port, such as port 123 shown in FIG. 1C, and positioned in contact with the ear. Alternatively, the reference electrode may be fixed to clothing or an accessory to which the portable device is attached. The transducers 42 are controlled by a microcontroller 43 and communicate with each other, for example, via the 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, or an onboard computer in a car or airplane, via technologies such as Bluetooth, Wi-Fi, or Li-Fi. All components of the acquisition system are powered by a battery (not shown in FIG. 4) housed within the housing.

[0065] Depending on the operating mode of the portable device according to the invention, each active electrode measures the value of its electrical potential. From this value, the potential measured by the reference electrode is subtracted (Ei=Vi-Vref). The result of this subtraction is digitized using an ADC 42 and transmitted by a microcontroller 43. To achieve this, as shown in Figure 4, the device comprises a predetermined number of active measurement electrodes (e.g., between 2 and 64, preferably between 4 and 16), 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 fixation device 52, and a plurality of conductive blades 53, 54. When worn by a user, the conductive blades form a line contact with the scalp. The line contact provides the advantage of a larger contact area with the scalp, which improves signal reception sensitivity and improves user comfort. Furthermore, when the conductive blades are arranged substantially parallel, the line contact formed is equivalent to a movement motion (which separates the hair when the device is worn).

[0068] Applications have shown that two conductive blades is optimal. With only one blade per sensor, the contact formed by the blade on the scalp can be unstable, and the pressure distribution on only one blade can be uncomfortable for the user. Applications have shown that two blades are optimal for covering a small enough surface area of ​​the skull and provide good signal accuracy. The spacing between the blades is a compromise between requirements for hair passage, signal observation, and pressure distribution in terms of user comfort. The spacing between the two blades is preferably large enough to allow hair to pass through. For example, the edge-to-edge 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, to avoid a loss of accuracy, it is desirable for the spacing to be less than 50 mm, preferably less than 10 mm. 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, which ensure current flow to the filter and amplifier circuitry. The metal structure forms electrical contact areas 512 with the scalp at each blade 53, 54.

[0070] The point of contact with the scalp may be metallized (eg, silver / silver chloride plated).

[0071] In the example shown in Figures 5A and 5B, the blades are slightly concave in the area that comes into contact with the scalp, allowing them to fit the shape of the scalp more naturally.

[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 penetrate the hair more easily so that it can reach the scalp. The points do not have to be conductive.

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

[0074] Figure 5C shows another example of a sensor according to the present invention. In this example, a conductive polymer (for example of the PEDOT:PSS type) forms the flexible layer 543. This layer flattens on the scalp when pressure is applied, increasing the contact surface area. Pressure is then better distributed over the skull. This improves the comfort of the device. The increased contact surface area also reduces the electrical resistance at the skull-sensor interface, thereby increasing the EEG signal flow to the sensor. Furthermore, the flexible polymer absorbs small 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 of being biocompatible.

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

[0076] FIG. 6 shows an example of the sensor 50 shown in FIGS. 5A and 5B fixed to a flexible support 61. As shown in FIG. 6A, the sensor's base 51 can be removably fixed in a recess 65 formed between two plates 62 and 63 of the support. The sensor 50 is movably fixed relative to the flexible support 61, allowing the device to adapt to different skull shapes. A spring-loaded metal blade 66 ensures electrical contact between the conductive region 511 of the base and the filter and amplifier circuits located on the printed circuit 64 inside the flexible support. Thanks to the contact points with the sensor's base, the blade 66 is guaranteed to move in translation along a vertical axis (perpendicular to the support) and in rotation around two horizontal axes. This mobility is essential for the formation of the sensor and its support.

[0077] Although the description has been given through several detailed embodiments, it will be apparent to those skilled in the art that the portable electroencephalogram signal acquiring device according to the present invention includes various modifications, variations, improvements and alterations, which are within the scope of the present invention as defined in the following claims.

Claims

1. 1. A portable device for acquiring electroencephalogram (EEG) signals emitted by a user, comprising: a flexible support adapted to fit a localized area of ​​the user's skull; at least one sensor positioned on the flexible support such that contact with the scalp is made when the user wears the portable device; an electrical circuit for filtering and amplifying the electrical signal detected by the at least one sensor; a housing containing 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 user's scalp and at least one point for parting the user's hair when the portable device is worn; the electrical circuit is contained within the flexible support and forms an active electrode with the sensor; 1. A portable device, comprising: a flexible support having a central portion and branches connected to the central portion by flexible lateral branches.

2. The portable device of claim 1 , wherein the flexible support comprises a plurality of branches.

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

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

5. the electrical contact is achieved by spring fingers; 5. 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 using flexible lateral branches.

8. 2. The portable device of claim 1, wherein the edge-to-edge 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.

Images