Device for detecting brain activity in mammal and related method

Abstract

The invention relates to a device for brain activity in a mammal, the device comprising at least one earpiece comprising:-a body (3) comprising an elongate portion extending along an elongate axis, and-an ear mold (4) configured to be inserted into an ear canal of a mammal and comprising at least one electrode assembly, the invention relates to an ear mold (4) for a brain, comprising:-an electrode assembly comprising a measuring electrode arranged on the outer surface of the ear mold (4) and configured to transmit an electrical signal representative of brain activity,-a processing unit wherein the electrode assembly comprises at least one preamplifier positioned upstream of the processing unit in the propagation direction of the electrical signal.

Description

[0001] Invention Field This invention relates to the field of devices for detecting brain activity in mammals. The invention is particularly applicable to determining the physiological or psychological state of mammals based on detected brain activity, and especially relates to methods and devices for determining such a state by measuring electroencephalogram (EEG) signals. Background of the Invention An in-ear device for measuring human biological data (such as the device described in US 2018 / 0235540) is known, which includes an interchangeable part intended to be inserted into the ear canal, the interchangeable part having electrodes disposed on its outer surface intended to detect electrical signals from the heart.

[0003] The detection of electrical signals by electrodes may lack accuracy. In fact, this type of in-ear device is sensitive to both external and internal noise.

[0004] The object of the present invention is to provide a solution in this regard, and more specifically, to overcome the above-mentioned disadvantages and to provide a biological data measurement device that can provide more accurate signals and has a simple, inexpensive and compact structure.

[0005] Overview Therefore, the present invention relates to a device for detecting brain activity in mammals, the device comprising at least one earpiece configured to be worn on the ear of a mammal, the earpiece comprising: - A main body comprising a shell portion and an elongated portion extending from the shell portion along an elongation axis, the elongated portion being configured to insert into the ear canal of a mammalian ear, and - An earmold configured for insertion into the ear canal of a mammal, the earmold having a channel extending along an axis of the earmold and a skirt surrounding the channel, the channel being adapted to receive an elongated portion for removably mounting the earmold onto a body, at least the skirt of the earmold being made of an elastically deformable material, the earmold including at least one electrode assembly, the electrode assembly including measuring electrodes disposed on the outer surface of the skirt of the earmold to contact the ear canal and configured to transmit an electrical signal representing brain activity in a mammal, the electrical signal having an electrical intensity; - A processing unit, disposed within the housing portion of the main body, the earpiece including at least one first electrical track and at least one second electrical track, the at least one first electrical track disposed in the channel of the earmold and connected to the measuring electrodes, the at least one second electrical track disposed in the elongated portion of the main body and configured to transmit electrical signals transmitted by the measuring electrodes to the processing unit, wherein the electrode assembly includes a preamplifier having an intensity gain adapted to adjust the measuring electrodes (42) of the electrode assembly. kThe preamplifier is positioned upstream of the processing unit in the propagation direction of the electrical signal transmitted by the measuring electrode of the electrode assembly, such that the processing unit is configured to process the intensity-adjusted electrical signal from the electrode assembly.

[0006] Therefore, the preamplifier can amplify the electrical strength of the electrical signal transmitted by the device's measuring electrodes, making the electrical signal stand out more relative to the external and internal noise that the device also measures when it is in use.

[0007] A preamplifier can be adapted to amplify the intensity of an electrical signal detected by the measuring electrodes of an electrode assembly.

[0008] In some implementations, the preamplifier of the electrode assembly is housed in the elongated portion.

[0009] In some implementations, the preamplifier exhibits an operating frequency range extending from 0.1 Hz to 1 kHz.

[0010] Therefore, this position of at least one preamplifier allows amplification of the electrical signals detected by the measuring electrodes, which are close to the location where those electrical signals are captured, thus minimizing the capture of unwanted signals.

[0011] In some embodiments, the preamplifier is coupled to an ESD (electrostatic discharge) circuit. Therefore, advantageously, the ESD circuit protects the device according to the invention from electrostatic discharge (which may occur, for example, when a user touches the device).

[0012] In some implementations, the preamplifier includes a follower circuit. The follower circuit is also called a buffer or unity-gain amplifier and is based on an operational amplifier. Advantageously, the operational amplifier provides an output with the same voltage as the input but with a higher current capability. Therefore, the follower circuit advantageously provides low output impedance to minimize signal loss when the follower circuit is connected to a load.

[0013] In some implementations, the preamplifier includes an impedance matching circuit. This impedance matching circuit modifies the impedance of the electrical signal source (in this case, the mammal's body) to match the impedance of the connected load (in this case, the processing unit, which will be described further). In this way, the impedance matching circuit optimizes power transfer between the mammal's body and the load by minimizing losses due to impedance mismatch. Typically, when the mammal is a human, the input impedance is in the terahertz range (T0). The impedance is within the range of 1000 ohms (kΩ), while at the output of the impedance matching circuit, the impedance is within 1000 ohms (kΩ). Within the range of ).

[0014] In some implementations, the preamplifier is mounted on a printed circuit board with a maximum size of 3 mm.

[0015] In some implementations, the printed circuit board is made of a flexible material that allows it to fold. In this way, at least one preamplifier can be integrated, for example, in a simple and compact manner within the extended portion of the body.

[0016] For example, flexible materials can be selected from polyimides (such as Kevlar Kapton), polyetheretherketone (PEEK), polymers, and PTFE (Teflon).

[0017] In some implementations, the printed circuit board includes a U-shape to surround additional components embedded in the elongated portion. Also in this way, at least one preamplifier can be integrated, for example, in a simple and compact manner within the elongated portion of the body.

[0018] In some embodiments, the earpiece is also configured to transmit sound signals into the ear canal via at least one electroacoustic transducer housed in the elongated portion, with a preamplifier attached to the electroacoustic transducer in the circumferential direction along the elongation axis. Therefore, the device according to the invention can be multifunctional while remaining compact.

[0019] In some implementations, the elongated portion of the body is embedded with a signal LED, and at least one preamplifier is mounted on the signal LED.

[0020] The earmold can be arranged to be rotatable about an elongation axis on the elongated portion so as to allow measuring electrodes to be guided to a region of the mammalian brain. A second rail extends circumferentially about the elongation axis on at least a portion of the outer surface of the elongated portion, and a first rail presents an end that extends radially relative to the elongation axis to contact the second rail.

[0021] The shell portion can be configured to receive or be housed within the concha of a mammal's ear.

[0022] At least one electrode assembly may include multiple electrode assemblies, each of which includes a measuring electrode and a preamplifier.

[0023] The plurality of electrode assemblies may include at least a first electrode assembly and a second electrode assembly, wherein at least a first measuring electrode of the first electrode assembly is configured to transmit a first electrical signal, and a second measuring electrode of the second electrode assembly is configured to detect a second electrical signal, the at least first electrical rail including at least two first electrical rails, and the at least second electrical rail including at least two second electrical rails, the at least two first electrical rails being electrically insulated from each other, the at least two second electrical rails being electrically insulated from each other, and the processing unit being configured to detect brain activity based on the first electrical signal transmitted by the first measuring electrode and whose intensity is adjusted by a first preamplifier of the first electrode assembly, and the second electrical signal transmitted by the second measuring electrode and whose intensity is adjusted by a second preamplifier of the second electrode assembly, particularly based on the difference between the first electrical signal and the second electrical signal.

[0024] In some embodiments, referred to as single-ear device implementations, a first electrode assembly and a second electrode assembly are arranged on a single ear device, a first measuring electrode and a second measuring electrode are spaced apart along the ear mold axis, two first electrical rails are spaced apart along the ear mold axis, and two second electrical rails are spaced apart along the elongation axis. These single-ear device implementations are based on using a device employing only one ear device.

[0025] In other embodiments, referred to as binaural implementations, the device includes two earpieces configured to be disposed in a mammal's first ear canal and a mammal's second ear canal, respectively, and configured to transmit corresponding electrical signals to a processing unit, with a first electrode assembly and a second electrode assembly disposed on the two earpieces. These binaural implementations are based on the use of a device employing two earpieces.

[0026] The processing unit can also be configured to determine a physiological or psychological state based on detected brain activity.

[0027] Another aspect of the invention relates to a computer-implemented method for determining the physiological or mental state of a mammal by means of a previously described device, the method comprising: - Determine the electroencephalogram (EEG) signals of mammals based on the transmitted electrical signals. - Determine the amplitude of at least one brain wave within a predefined frequency range based on the electroencephalogram (EEG) signal, and - Mental state is determined based on the amplitude of at least one brainwave by comparing the amplitude with a preset threshold.

[0028] In some implementations, the method further includes the step of calculating the quality index of the electrical signal transmitted by the measuring electrode based on the correlation calculation between the common-mode measurement and the difference between the first electrical signal and the second electrical signal (or the difference between the two electrical signals).

[0029] definition In this invention, the following terms have the following meanings: The terms “adaptation” and “configuration” are used extensively in this disclosure to cover the initial configuration, subsequent adaptation or supplementation, or any similar combination thereof, of the device, whether implemented by material or software means (including firmware).

[0030] The term "reference electrode" refers to a point in EEG used to establish a baseline voltage or reference point for measuring the potentials recorded by the measuring electrodes. It serves as a comparison point against which electrical activity from other electrodes is measured. The reference electrode does not directly measure brain activity; instead, it provides a stable voltage reference that helps in interpreting electrical signals from other electrodes.

[0031] The term "measuring electrode" (also known as a measuring electrode or recording electrode) refers to an electrode configured to directly measure the electrical activity generated by the brain. It detects voltage fluctuations caused by electrical signals generated by neural activity in the brain. Measuring electrodes are the primary electrodes used to capture EEG signals.

[0032] Brief description of the attached figures Figure 1 This is a side view of a device for detecting brain activity in mammals, according to some implementations.

[0033] Figure 2 express Figure 1 The equipment in Figure 1 An internal view in a plane.

[0034] Figure 3A and Figure 3B It is based on some implementation methods, in Figure 1 and Figure 2 A three-dimensional perspective view of a printed circuit board with an embedded preamplifier used in the device, the preamplifier being in an unfolded configuration (3A) and a folded configuration embedded in a channel (3B).

[0035] Figure 4 It is configured to be in such Figure 1 and Figure 2 A schematic diagram of the processing unit used in the device shown.

[0036] Figure 5 Indicates that it is different from Figure 1 and Figure 2 Some embodiments of a device for detecting brain activity in mammals.

[0037] Figure 6 This is an example of a flowchart illustrating the use of, for example, a flowchart for... Figure 1 , Figure 2 and Figure 5The apparatus shown is used to perform steps of a method for determining the physiological or psychological state of a mammal.

[0038] Detailed explanation The present invention relates to devices 1a and 1b for detecting brain activity in mammals, the devices including at least one earpiece 2 and 2', and to a computer-implemented method 100 for determining the physiological or mental state of a mammal by means of at least one processor of device 1. Preferably, the mammal is a human.

[0039] A single earpiece 2 configured to be worn on the ear of a mammal and including at least two measuring electrodes can be used. Alternatively, two earpieces 2, 2' can be used, configured to be worn on the respective ears of a mammal, each earpiece including at least one measuring electrode, and the two earpieces 2, 2' may be the same as or different from each other. The computer-implemented method 100 will be further explained and described how it relies on the use of at least two measuring electrodes, either included in a single earpiece 2 or each of the two electrodes included in one of two separate earpieces 2, 2'.

[0040] More specifically, devices 1a and 1b are used to determine a person’s electroencephalogram (EEG) data as brain activity.

[0041] Now we will describe the earpieces 2 and 2', and Figure 1 Examples of earpieces 2 and 2' are shown. For example, earpieces 2 and 2' are similar in shape and size to headphones and include a body 3 and a removable ear mold 4.

[0042] The main body 3 includes a housing portion 30 and an elongated portion 31 extending from the housing portion 30 along an elongation axis 32. In one example, the elongated portion 31 may be a body of revolution, wherein the elongation axis is the axis of revolution. The housing portion 30 may be configured to be received in the concha of a person's ear, while the elongated portion 31 may be configured to be inserted into the ear canal 10, 10' of a person's ear.

[0043] The earmold 4 is configured to fit onto the elongated portion 31 of the body 3 and be inserted into the ear canal 10, 10' of a person. The earmold 4 includes a channel 41 extending along the earmold axis 45 and a skirt 40 surrounding the channel 41. The channel 41 is adapted to receive the elongated portion 31 of the body 3 to detachably mount the earmold 4 onto the body 3. At least the skirt 40 of the earmold 4, and possibly the entire earmold 4, is made of an elastically deformable material. The earmold 4 includes N (or more) electrode assemblies. Each electrode assembly includes measuring electrodes (421, 42...). k ……42 N The measuring electrodes (421, 42) are arranged on the outer surface of the skirt 40 of the earmold 4 to contact the ear canals 10, 10'.k ……42 N The measuring electrodes extend along the entire length of the earmold 4 in the direction of the earmold axis 45. For example, the measuring electrodes are spaced apart in the circumferential direction around the earmold axis 45. Other arrangements of the measuring electrodes are also possible. Figure 1 Above, two measuring electrodes 421 and 422 can be seen.

[0044] 42 per measuring electrode k It is configured to transmit electrical signals representing brain activity in mammals. The earmold 4 can be arranged to rotate about an elongation axis 32 to allow measurement electrodes 42 to be used. k At least one of them points to a region of the human brain. For example, the earmold 4 is made of an insulating material (such as silicone), and the measuring electrodes 42 k For example, a conductive fabric sheet is embedded in silicone resin in the ear mold 4 by adhesive bonding. The size of the skirt 40 of the ear mold 4 is set to ensure that the walls of the ear canal are aligned with the measuring electrodes 42. k Contact between them.

[0045] like Figure 2 As shown, the earpieces 2 and 2' include a first electrical rail 43 that is electrically insulated from each other. k It is arranged in the channel 41 of the ear mold 4 and connected to the measuring electrode 42. k For example, each of the first rails has 43... k It may include an end in the form of a contact pin, which extends radially relative to the elongation axis 32 and is connected to the measuring electrode 42 via an electrically insulated wire. k The contact pin is embedded in the inner surface of the channel 41 of the ear mold 4.

[0046] The housing portion 30 of the main body 3 houses the processing unit 5, which is configured to receive the measuring electrodes 42 from the earmold 4. k The picked-up electrical signals are processed and converted into digital signals. Accordingly, the earpieces 2, 2' include second electrical rails 33 that are electrically insulated from each other. k It is arranged in the extended portion 31 of the main body 3 and configured to be measured by the measuring electrode 42. k The transmitted electrical signals are sent to processing unit 5. Each second rail 33 k It can extend in the circumferential direction around the elongation axis 32 on at least a portion of the outer surface of the elongation portion 31 to connect with the first electric rail 43. k Contact. For example, such as Figure 2 As shown, the second electric rail 33 k It is a circular electric track, with its axis of extension 32 as its axis, and the tracks are arranged at a certain distance from each other along the direction of extension axis 32. Each circular track is connected to a corresponding first electric track 43. kMeasurement electrode 42 connected to ear mold 4 k The contact pins can be arranged opposite the ring-shaped electrical rails to maintain electrical contact.

[0047] In some embodiments, the elongated portion 31 is made of insulating material, and the second rail 33 k Formed by metal deposits on the elongated portion 31. Second electric rail 33 k It is connected to the processing unit 5 by wires arranged in the extension portion 31.

[0048] Each electrode assembly includes a preamplifier 6, also known as a buffer, which is connected to the measuring electrodes 42. k The propagation direction of the transmitted electrical signal is positioned upstream of the processing unit 5. There are N preamplifiers 6, each configured to receive signals from N measurement electrodes 42. k One of the measuring electrodes receives the corresponding electrical signal.

[0049] Each electrode assembly's preamplifier 6 has an intensity gain that is adapted to adjust, and in particular amplify, the electrical intensity of the electrical signal transmitted by the measuring electrode of the same electrode assembly. Therefore, the processing unit 5 receives and processes the intensity-adjusted (and in particular amplified) electrical signal from each electrode assembly.

[0050] Each of the N preamplifiers 6 is configured to perform impedance matching. In other words, the impedance at the input of one preamplifier 6 is higher than the impedance at its output. For example, each of the N preamplifiers 6 includes a differential amplifier-based follower circuit.

[0051] Advantageously, the intensity gain of each of the N preamplifiers 6 is adjustable, thus allowing for flexibility in the distribution of intensity gain permitted by the N preamplifiers. In other words, the intensity gain of the measurement electrodes 42 is adjustable. kIn the transmitted electrical signals, the electrical intensity of some signals can be amplified to be stronger than that of others, in order to emphasize the differential measurement between the strongly amplified electrical signal (i.e., the signal representing neural or brain activity obtained from the electrode used as the measuring electrode) and the lower-intensity electrical signal from the other electrode (i.e., the baseline voltage obtained from the electrode used as the reference electrode). As will be explained below, devices 1a and 1b are configured to perform and process such differential measurements. Therefore, the independent adjustability of the intensity gain of one or more of the N preamplifiers 6 advantageously makes it possible to increase the signal-to-noise ratio of the different transmitted electrical signals. In other words, since neural recording is performed using differential measurements, the possibility of strongly amplifying the electrical signals from the measuring electrodes using these N preamplifiers 6 increases the noise immunity of devices 1a and 1b and allows for the recovery of neural signals with improved dynamics, i.e., neural signals carrying more information. Simultaneously, the N preamplifiers 6 enable the measurement electrodes 42... k The electrical strength of the transmitted electrical signal is adjustable, thus allowing for a reduction in the power consumption of devices 1a and 1b. Compared to other alternative methods (which improve the difference between the baseline voltage and the measured signal by numerically applying weighting factors to the electrical signal during signal processing), this implementation allows for direct analog amplification of the desired electrical signal, providing a better signal-to-noise ratio while also reducing energy consumption.

[0052] The preamplifier 6, located upstream of the processing unit 5, also offers the following advantages: It corresponds to biosignals from the human body and is controlled by the measuring electrodes 42. k The detected electrical signal has an intensity on the order of picoamperes, which is comparable in magnitude to external noise generated by an external induction circuit (e.g., main power supply) and internal noise also detected by the measuring electrodes. Internal noise refers to noise generated by noise sources present in the mammalian body. These noise sources include, for example, contractions of facial muscles, eyelid or eye movements.

[0053] Therefore, the preamplifier 6 allows for the maintenance of the electrode 42 while increasing the electrical intensity. k The input voltage of the transmitted electrical signal. Typically, the impedance at the input of preamplifier 6 roughly corresponds to the impedance of mammalian skin and is in the megaohm range, while the impedance at the output of preamplifier 6 is in the kiloohm range. In practice, the mammalian brain can be modeled as a voltage generator with internal impedance. This internal impedance includes the resistance of the mammalian head and the resistance of the mammalian skin.

[0054] Another advantage is that the preamplifier 6 and the second rail 33 kThe preamplifier 6 is located within the extended portion 31 of the main body 3. This allows for amplification of the corresponding electrical signal near the location where the signal of interest is captured, and thus minimizes the capture of unwanted signals.

[0055] Furthermore, the presence of the intensity-gain adjustable preamplifier 6 reduces the need for downstream digital amplification, which helps to reduce power consumption.

[0056] In some implementations, each of the N preamplifiers 6 is coupled to an ESD protection circuit.

[0057] In some preferred embodiments, the size of each of the N preamplifiers 6 is configured such that the earpieces 2, 2' can be used when the person is a child. For example, the size of the preamplifier / earpiece is less than a few millimeters, such as less than 3 mm.

[0058] Advantageously, N preamplifiers 6 are mounted on a printed circuit board 61.

[0059] In some preferred embodiments, the printed circuit board 61 is flexible so that it can be folded. For example, the printed circuit board may be made of polyimide (such as Kapton), polyetheretherketone (PEEK), polymer, PTFE (Teflon).

[0060] In an alternative embodiment, the printed circuit board is U-shaped or C-shaped, or can be folded into a U-shape or C-shape to surround other components in the extended portion 31 embedded in the body 3.

[0061] Figure 3A and Figure 3B This is an example of a three-dimensional perspective view of one of N preamplifiers (6) mounted on a printed circuit board. Figure 3A The visible electrode 34 is designed to connect to the first track 43 of the ear mold 4. k one of the. Figure 3B An example of a printed circuit board 61 is shown, on which one of the N preamplifiers 6 is mounted and in a folded configuration for integration within the device 1. The corresponding electrodes 34 and the earmold 4 are visible. Because the earmold 4 is made of a flexible material, it is compressed when the device 1 is inserted into the ear canal of a mammal for use. In this configuration, the distance between the surface of the ear canal and the end of the electrode 34 is less than 1.5 mm.

[0062] For example, in some embodiments, the earpieces 2, 2' are also configured to transmit sound signals into the ear canal via at least one electroacoustic transducer housed in the elongated portion 31 of the body 3. In these embodiments, a U-shaped or C-shaped printed circuit board with a preamplifier 6 mounted thereon may be positioned around at least one electroacoustic transducer and, optionally, for example, attached to at least one electroacoustic transducer by adhesive.

[0063] In other embodiments, the earpieces 2, 2' may include additional functional components, such as signal LEDs, that can be positioned within the extended portion 31 of the body 3. Similarly, in these embodiments, a printed circuit board on which the preamplifier 6 is mounted may be attached to the additional functional components.

[0064] In this way, the preamplifier 6 can be easily included in the earpieces 2, 2' while keeping the earpieces 2, 2' compact in size. Other arrangements of the preamplifier 6 within the extension 31 are also possible. The positioning of the printed circuit board (i.e., the preamplifier 6) within the extension 31 is advantageous because it allows the amplifier 6 to be placed closer to the measuring electrode 42. k In order to reduce parasitic noise.

[0065] Processing unit 5 is configured to transfer the signal from measuring electrode 42 k The electrical signal transmitted and digitized and processed by the preamplifier 6 is output as a processed signal, and the processed information is output to at least one processor 7, which will be further described, and the at least one processor 7 is configured to implement a computer-implemented method 100 for detecting brain activity and possibly determining the physiological or psychological state of a mammal.

[0066] Figure 4 An example of a component chain included in processing unit 5 is shown, which includes preamplifier 6 and other components downstream of preamplifier 6, and will be described below. It should be noted that, as mentioned above, preamplifier 6 has specific independent technical functions and associated advantages within the component chain included in processing unit 5.

[0067] Advantageously, the processing unit 5 is manufactured in a compact manner and can be housed in a limited volume. For example, when the processing unit 5 is embedded inside the body 3, it can be contained within a cylinder with a radius of 6 mm and a thickness of 1 mm, forming a volume of approximately 200 mm. 3 The volume that can be contained.

[0068] First, amplifier 51 is arranged to amplify the amplitude of each or more electrical signals. The gain of amplifier 51 can be single-stage or multi-stage up to 10,000 times. Amplifier 51 is connected to analog-to-digital converter (ADC) 52, which is configured to digitize each or more electrical signals. ADC 52 is connected to digital signal processing module 53, which is configured to attenuate any stray signals picked up by the electrodes. These stray signals may be caused by head movement, movement of wires connected to device 1, or the environment of device 1. The digital signal processing module 53 specifically includes a bandpass filter, but also includes signal processing functions, particularly allowing the removal of low-frequency (or constant) components of the signal. This low-frequency (or constant) component is present due to the fact that a reference electrode is selected inside the ear canal instead of using a mass block located outside the ear canal. The bandwidth of the bandpass filter is also configured to select electrical signals from a predetermined organ (particularly the brain). For example, the bandwidth of the bandpass filter is between 0.5 Hz and 60 Hz, particularly between 1 Hz and 40 Hz. A bandpass filter is connected to a communication module 54, which is configured to transmit the signal digitized by the ADC 52 and filtered by the bandpass filter to the processor 7 via wired or wireless means.

[0069] Processor 7 includes at least one processor. Processor 7 may be integrated into or separated from the main body 3 to determine EEG data based on processed signals received from processing unit 5.

[0070] In other embodiments, the processing unit 5 may also be arranged outside the main body. In those embodiments, the devices 1a, 1b may include an antenna in the main body 3 or in an extension 31 downstream of at least one preamplifier 6 to transmit electrical signals captured by the measuring electrodes to the processing unit 5.

[0071] As previously mentioned, devices 1a and 1b may include one earpiece 2 (in which case the device is referred to as 1a) or two earpieces 2 and 2' (in which case the device is referred to as 1b).

[0072] In a so-called monoauricular embodiment, where the device is referred to as device 1a, an earpiece 2 configured for insertion into the ear canal of a mammal includes at least two measuring electrodes. The earmold 4 of the earpiece 2 includes measuring electrodes 42. kThe system includes at least a first measuring electrode 421 and a second measuring electrode 422, each configured to transmit a first electrical signal and a second electrical signal, respectively. In these embodiments, at least one processor of the processor 7 is configured to determine a neural signal based on the first and second electrical signals, particularly based on the difference between the first and second electrical signals. More specifically, one of the first measuring electrode 421 and the second measuring electrode 422 is selected as a reference electrode, and a potential is calculated relative to this reference electrode, thereby selecting the other electrode as the measuring electrode. The brain potential is calculated by differentiating the signal picked up by the other electrode with the signal picked up by the reference electrode. Preferably, the first measuring electrode 421 and the second measuring electrode 422 are as identical as possible.

[0073] In alternative so-called binaural implementations, such as Figure 5 As shown, the device, referred to as device 1b, uses two earpieces 2, 2', configured to be inserted into each ear canal of a mammal. Each earpiece 2, 2' includes at least one measuring electrode. In these embodiments, at least one processor of processor 7 is configured to determine a physiological or psychological state based on signals measured by the electrodes of earpiece 2 housed in the first ear canal and signals measured by the electrodes of earpiece 2' housed in the second ear canal (particularly based on the difference between the two signals). Similar to the single earpiece implementation, one electrode of one earpiece 2, 2' is selected as a reference electrode (while the other electrode will act as the measuring electrode), and a potential is calculated relative to this reference electrode. The brain potential is calculated by differentiating the signal picked up by one electrode of the other earpiece with the signal picked up by the reference electrode.

[0074] Another aspect of the invention relates to a computer-implemented method 100 for determining the physiological or psychological state of a mammal. The computer-implemented method 100 can be implemented by the processor 7 of the previously described devices 1a, 1b. Figure 6 This section demonstrates an example of the steps that can be performed to implement method 100.

[0075] In step S1, at least one processor determines the electroencephalogram (EEG) signal of the mammal based on the detected electrical signal. As previously mentioned in the description of devices 1a, 1b, at least one processor calculates the brain potential based on the difference between the signals from two electrodes, which may be from a single earpiece 2, or one electrode of one earpiece 2 and another electrode of another earpiece 2'.

[0076] In step S2, at least one processor determines the amplitude of at least one brainwave within a predefined frequency range as a function of the electroencephalogram (EEG) signal. For example, a Fourier transform can be applied to determine the frequencies contained in the EEG signal. For instance, if the signal frequency is between 5 Hz and 15 Hz, particularly 10 Hz, the brainwave is of type α, and if the signal frequency is between 15 Hz and 25 Hz, particularly 20 Hz, the brainwave is of type β.

[0077] In step S3, at least one processor determines a mental state based on the amplitude of at least one brainwave compared to a preset threshold. For example, the comparison can be used to determine a person's level of attention.

[0078] Optionally, at least one processor can calculate the quality index of the electrical signal detected by the electrodes by performing a correlation calculation between the common-mode measurement and the differential measurement. The term "differential measurement" in the single-ear embodiment refers to the measurement corresponding to the difference between a first electrical signal (i.e., a reference signal or a measured signal) and a second electrical signal (i.e., a measured signal or a reference signal), and in the dual-ear embodiment, it refers to the measurement corresponding to the difference between a measured signal and a reference signal. This correlation calculation provides an estimate of the system impedance and, therefore, the quality of the measured signal.

[0079] Devices 1a and 1b have many applications, especially in medicine, such as monitoring patients with neuronal diseases (e.g., epilepsy), screening and diagnosing neuronal diseases, screening and monitoring children with attention deficit disorder, and sleep measurement.

Claims

1. A device (1a, 1b) for detecting brain activity in a mammal, said device (1a, 1b) comprising at least one earpiece (2, 2') configured to be worn on the ear of a mammal, said earpiece (2, 2') comprising: - A main body (3) comprising a shell portion (30) and an elongated portion (31) extending from the shell portion (30) along an elongation axis (32), the elongated portion (31) being configured to be inserted into the ear canal (10, 10') of a mammal's ear, and - An earmold (4) configured to be inserted into the ear canal (10, 10') of a mammalian ear, the earmold (4) having a channel (41) extending along an earmold axis (45) and a skirt (40) surrounding the channel (41), the channel (41) being adapted to receive the elongated portion (31) for removably mounting the earmold (4) onto the body (3), at least the skirt (40) of the earmold being made of an elastically deformable material, the earmold (4) including at least one electrode assembly including measuring electrodes (42) k The measuring electrode (42) k The earmold (4) is arranged on the outer surface of the skirt to contact the ear canal (10, 10') and is configured to transmit electrical signals representing brain activity in mammals, the electrical signals having electrical intensity. - Processing unit (5), which is arranged in the housing portion (30) of the main body (3), The earpiece (2, 2') includes at least one first electrical rail (43) k ) and at least one second rail (33 k ), the at least one first rail (43 k The earmold (4) is arranged in the channel (41) and connected to the measuring electrode (42). k ), the at least one second rail (33) k ) is arranged in the elongated portion (31) of the main body (3) and configured to be measured by the at least one measuring electrode (42) k The electrical signal transmitted is sent to the processing unit (5). The electrode assembly includes a preamplifier (6) having a design suitable for adjusting the measuring electrodes (42) of the electrode assembly. k The intensity gain of the electrical signal transmitted by the preamplifier is measured by the electrode assembly (42). k The direction of propagation of the transmitted electrical signal is positioned upstream of the processing unit (5), such that the processing unit (5) is configured to process the intensity-adjusted electrical signal from the electrode assembly.

2. The device (1a, 1b) according to claim 1, wherein, The preamplifier (6) is adapted to amplify the measurement electrodes (42) of the electrode assembly. k The intensity of the detected electrical signal.

3. The device (1a, 1b) according to any one of claims 1 and 2, wherein, The preamplifier (6) of the electrode assembly is housed in the elongated portion (31).

4. The device (1a, 1b) according to any one of the preceding claims, wherein, The preamplifier (6) has an operating frequency range extending from 0.1 Hz to 1 kHz.

5. The device (1a, 1b) according to any one of the preceding claims, wherein, The preamplifier (6) is coupled to the ESD circuit.

6. The device (1a, 1b) according to any one of the preceding claims, wherein, The preamplifier includes a follower circuit.

7. The device (1a, 1b) according to claim 6, wherein, The follower circuit is an active circuit.

8. The device (1a, 1b) according to any one of the preceding claims, wherein, The preamplifier includes an impedance matching circuit.

9. The device (1a, 1b) according to any one of the preceding claims, wherein, The preamplifier (6) is mounted on a printed circuit board (61) with a maximum size of 3 mm.

10. The device (1a, 1b) according to claim 9, wherein, The printed circuit board (61) is made of a flexible material so that it can be folded.

11. The device (1a, 1b) according to claim 9, when subordinate to claim 2, wherein, The printed circuit board includes a U-shape to surround additional components embedded in the elongated portion (31).

12. The device (1a, 1b) according to any one of the preceding claims, wherein, The earpiece (2, 2') is also configured to transmit sound signals into the ear canal by means of at least one electroacoustic transducer housed in the elongation (31), the preamplifier (6) being attached to the electroacoustic transducer in the circumferential direction along the elongation axis (32).

13. The device (1a, 1b) according to any one of the preceding claims, wherein, The ear mold (4) is arranged to rotate about the elongation axis (32) on the elongated portion (31) so that the measuring electrodes (42) k ) points to a region of the mammalian brain, the second electric track (33) k The first electric rail (43) extends in the circumferential direction around the elongation axis (32) on at least a portion of the outer surface of the elongated portion (31). k ) has an end that extends radially relative to the elongation axis (32) to connect with the second electric rail (33). k )touch.

14. The device (1a, 1b) according to any one of the preceding claims, wherein, The shell portion (30) is configured to be received in the concha of a mammal's ear.

15. The device (1a, 1b) according to any one of the preceding claims, wherein, The at least one electrode assembly includes a plurality of electrode assemblies, wherein each electrode assembly includes a measuring electrode and a preamplifier.

16. The device (1a) according to claim 15, wherein, The plurality of electrode assemblies includes at least a first electrode assembly and a second electrode assembly, wherein at least a first measuring electrode (421) of the first electrode assembly is configured to transmit a first electrical signal, and a second measuring electrode (422) of the second electrode assembly is configured to detect a second electrical signal. The at least first electric rail (43) k ) includes at least two first rails, and the at least second rail (33) k This includes at least two second rails. The at least two first rails are electrically insulated from each other. The at least two second rails are electrically insulated from each other. The processing unit (5) is configured to detect brain activity based on the following signals: a first electrical signal transmitted by the first measuring electrode (421) and whose intensity is adjusted by the first preamplifier of the first electrode assembly, and a second electrical signal transmitted by the second measuring electrode (422) and whose intensity is adjusted by the second preamplifier of the second electrode assembly, and in particular, to detect brain activity based on the following signal: the difference between the first electrical signal and the second electrical signal.

17. The device (1b) according to claim 16, wherein, The first electrode assembly and the second electrode assembly are arranged on a single earpiece (2, 2'), the first measuring electrode (421) and the second measuring electrode (422) are spaced apart along the earmold axis, the two first electrical rails are spaced apart along the earmold axis, and the two second electrical rails are spaced apart along the elongation axis.

18. The device (1b) according to claim 16, wherein, The device (1) includes two earpieces (2, 2') configured to be disposed in a first ear canal (10) and a second ear canal (10') of a mammal, respectively, and configured to transmit respective electrical signals to a processing unit (5), wherein the first electrode assembly and the second electrode assembly are disposed on the two earpieces (2, 2').

19. The device (1a, 1b) according to any one of the preceding claims, wherein, The processing unit is also configured to determine a physiological or psychological state based on the detected brain activity.

20. A computer-implemented method (100) for determining a physiological or mental state of a mammal by means of the apparatus (1a, 1b) according to claim 19, the method comprising: - Determining the electroencephalogram (EEG) signals of mammals based on the transmitted electrical signals. - Determine the amplitude of at least one brainwave within a predefined frequency range based on the electroencephalogram (EEG) signal, and - The mental state is determined based on the amplitude of at least one brainwave by comparing the amplitude with a preset threshold.

21. The method of claim 20, further comprising: The quality index of the electrical signal transmitted by the measuring electrode is calculated based on the correlation calculation, which is the correlation calculation between the common-mode measurement and the difference between the first electrical signal and the second electrical signal, or the correlation calculation between the common-mode measurement and the difference between the two electrical signals.

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