Patent Application
20240415462
The present technology relates to a biopotential measurement device, an information processing device, and a biopotential measurement method, and more particularly to a biopotential measurement device, an information processing device, and a biopotential measurement method capable of improving input-referred noise performance of an amplifier.
In recent years, wearable devices capable of measuring biological signals such as pulse waves and electrocardiograms in daily life are commercially available. By measuring biological signals, it is possible to provide new experience and applications for users.
It is possible to measure electroencephalograms (EEGs) by using substantially the same method as a method for measuring biological signals used for measuring electrocardiograms and electromyograms, and wearable devices capable of measuring EEGs in daily life have also started to appear on the market. For example, a device that measures an EEG of a user during sleep and that determines a state of the sleep is commercially available.
Non-Patent Document 1 and Non-Patent Document 2 disclose techniques capable of measuring biological signals in a form in which a dynamic range and resolution are secured while using an analog digital (AD) converter with a low bit depth.
In the techniques disclosed in Non-Patent Document 1 and Non-Patent Document 2, large variations in a level of an input signal to be subjected to AD conversion are canceled by inputting an offset potential of a DC component to an amplifier, in order to secure a dynamic range of an AD converter. The AD converter performs AD conversion on the signal for which variations in the level have been canceled in the amplifier.
Normally, a digital analog (DA) converter is used to input an offset potential to an amplifier. The DA converter is a circuit that generates an analog potential in response to specification of a digital value.
In such a configuration, since a noise component of a DA converter is superimposed upon an input signal of an amplifier, input-referred noise performance (input refer noise) of the amplifier in a period in which an offset potential is applied deteriorates, which results in deterioration of resolution of an EEG acquisition level of an entire system.
The present technology has been made in view of such circumstances and aims to improve input-referred noise performance of an amplifier.
A biopotential measurement device according to a first aspect of the present technology includes an amplifier that amplifies a potential that is a difference between a reference potential and a potential measured by an electrode attached to a measurement target position of a biopotential, an AD converter that converts an analog signal according to the potential amplified by the amplifier into a digital signal, a calculation unit that sets a setting value of an offset potential to be applied to an input of the amplifier on a basis of a signal level of the digital signal after AD conversion, a DA converter that converts a digital signal indicating the setting value into an analog signal and that generates an analog potential, a potential holder that holds the analog potential generated by the DA converter and that applies the held analog potential to the input of the amplifier, a switch provided between the DA converter and the potential holder, and a controller that switches a connected state and a separated state of the switch.
An information processing apparatus according to a second aspect of the present technology includes a biopotential measurement device including an amplifier that amplifies a potential that is a difference between a reference potential and a potential measured by an electrode attached to a measurement target position of a biopotential, an AD converter that converts an analog signal according to the potential amplified by the amplifier into a digital signal, a calculation unit that sets a setting value of an offset potential to be applied to an input of the amplifier on a basis of a signal level of the digital signal after AD conversion, a DA converter that converts a digital signal indicating the setting value into an analog signal and that generates an analog potential, a potential holder that holds the analog potential generated by the DA converter and that applies the held analog potential to the input of the amplifier, a switch provided between the DA converter and the potential holder, and a controller that switches a connected state and a separated state of the switch.
In the present technology, a setting value of an offset potential to be applied to an input of an amplifier is set on the basis of a signal level of a digital signal after AD conversion, and a connected state and a separated state of a switch are switched.
A mode for carrying out the present technology will be described hereinafter. The description will be given in the following order.
A wearable device D illustrated in
As schematically indicated by a hatched circle, a biosensor module 1 is mounted on the wearable device D. The biosensor module 1 measures a user's EEG at a predetermined timing such as during watching of video content or during playing of a game. The biosensor module 1 is not limited to a position indicated by the circle, and may be mounted at another position in the wearable device D.
Here, the measurement of an EEG will be described.
EEG signals are classified into θ waves (4 to 8 Hz), a waves (8 to 12 Hz), and B waves (12 Hz or higher) on the basis of frequency. Amplitude of an EEG signal when an a wave is dominant is about tens of μV.
As performance required for an electric circuit used to measure EEGs, it is specified by a standard that a frequency band of an analog signal be 0.5 Hz to 100 Hz and a value of input-referred noise be 1 μVrms or smaller in the frequency range. Input-referred noise performance is synonymous with resolution of a circuit. The smaller the value of the input-referred noise, the higher the performance.
It is difficult to achieve performance in which the input-referred noise is 1 μVrms or smaller in the frequency band of 0.5 Hz to 100 Hz unless parts of each of components are appropriately selected.
In addition, since EEG signals are weak, configuration of a first stage of the circuit needs to be a high-impedance configuration in order to represent an EEG as a signal. There are many circuits in which the configuration of the first stage has an impedance of 1 GΩ or higher.
Furthermore, a range of potential of EEG signals is very wide. In addition, the potential of EEG signals varies in a range of several hundred mV due to body movement or the like.
In general, in a medical electroencephalograph, impedance between an electrode and a living body is lowered and a phenomenon called “polarization”, which occurs at an interface between the electrode and the living body, is prevented by using a dedicated paste, gel, or the like. Polarization is a phenomenon caused by a chemical reaction at an interface, and corresponds to presence of a direct-current battery. A polarization voltage depends on a material of an electrode. The polarization voltage reaches several tens of mV and also fluctuates due to body motion.
In the case of various wearable devices including the wearable device D, a dry electrode is used to ensure comfortable wearability. That is, since a paste or gel for EEG measurement is not used, polarization tends to increase. A range of an input level of an EEG measurement circuit, therefore, is desirably wide, and a range of about ±300 mV is required.
As described above, the value of the input-referred noise required in the EEG measurement circuit is 1 μVrms. In a case where an AD converter converts a signal on this μV level into a digital signal, necessary resolution of the AD converter is provisionally set as resolution represented by the following Expression 1.
A required bit depth of the AD converter at this time is obtained as 24 bits by the following Expressions 2 and 3 when a required dynamic range is a range of ±300 mV.
Normally, the lower the bit depth of the AD converter, the more the options for implementation. For example, in a case where an analog circuit and an AD converter are mounted on one semiconductor chip, selection of a 12-bit AD converter or a 16-bit AD converter can expand options of a semiconductor process, rather than selection of a 24-bit AD converter.
In order to lower the required bit depth of the AD converter, it is substantially difficult to lower the resolution, and it is therefore necessary to make the dynamic range of the input level narrower than the range of ±300 mV.
The biosensor module 1 mounted on the wearable device D is a biopotential measurement circuit that achieves low cost and low noise while securing a wide dynamic range and high resolution.
Note that a wearable device on which the biosensor module 1 is mounted is not limited to the wearable device D worn on the head. The biosensor module 1 can be mounted on a wearable device attached to other parts such as a wrist, a foot, or a torso.
In addition, biological signals measured by the biosensor module 1 are not limited to EEG signals. The biosensor module 1 can be used to measure signals representing various biological reactions appearing as changes in potential, such as electrocardiograms and electromyograms.
The biosensor module 1 includes a bioelectrode 11, a bioelectrode 12, a signal reception unit 13, and a controller 14. The biosensor module 1 is a biopotential measurement device used to measure biological signals such as EEG signals.
The signal reception unit 13 includes a buffer 21, a capacitor 22, a buffer 23, a differential amplifier 24, an AD converter 25, a DA converter 26, a switch 27, and a capacitor 28. As described later, an analog signal output from the DA converter 26 is supplied to the capacitor 28 via the switch 27. The capacitor 28 functions as a potential holder that holds a potential according to the analog signal output from the DA converter 26. The capacitor 28 will be described hereinafter as a potential holder 28 as appropriate.
A signal of a reference potential obtained by the bioelectrode 11 attached to a body surface is supplied to the buffer 21. The buffer 21 performs impedance conversion (current enhancement) on the signal obtained by the bioelectrode 11 and outputs the signal. The signal output from the buffer 21 is supplied to the differential amplifier 24 via the capacitor 22.
A signal of a certain potential obtained by the bioelectrode 12 attached to the body surface at a measurement target position is supplied to the buffer 23 as a signal of a first channel. The buffer 23 performs impedance conversion (current enhancement) on the signal obtained by the bioelectrode 12 and outputs the signal to the differential amplifier 24.
The differential amplifier 24 amplifies a potential that is a difference between the potential at the measurement target position represented by the signal supplied from the buffer 23 and the reference potential, which is the potential held by the potential holder 28 and applied as the offset potential, and outputs a signal according to the amplified potential. The signal output from the differential amplifier 24 is supplied to the AD converter 25.
The AD converter 25 performs AD conversion on the signal supplied from the differential amplifier 24 and outputs a signal (digital signal) obtained through the AD conversion at a certain cycle in accordance with an AD conversion timing signal ADCcap supplied from a control timing determination unit 33 of the controller 14. As described later, a signal after the AD conversion in a period in which the AD conversion timing signal ADCcap is “H”, for example, is output from the AD converter 25. The signal output from the AD converter 25 is supplied to a potential measurement unit 31 of the controller 14.
The DA converter 26 performs DA conversion on a signal supplied from an offset setting value calculation unit 32 of the controller 14 and outputs a potential (analog signal) generated through the DA conversion. A digital signal indicating a value (offset setting value) of an offset potential set by the offset setting value calculation unit 32 is supplied from the offset setting value calculation unit 32. The signal output from the DA converter 26 is supplied to the switch 27. As described above, the DA converter 26 is a circuit or a functional block that generates an analog potential in response specification of the offset setting value, which is a digital value, by the offset setting value calculation unit 32.
The switch 27 switches on and off in accordance with a switching signal SWdac supplied from the control timing determination unit 33. As described later, the switch 27 turns on in a period different from one in which the AD converter 25 supplies a signal after the AD conversion to the potential measurement unit 31 in response to the AD conversion timing signal ADCcap supplied from the control timing determination unit 33 to the AD converter 25 becoming “H”. In a case where the switch 27 is on, a potential generated by the DA converter 26 is supplied to the potential holder 28.
The potential holder 28 holds the potential generated by the DA converter 26 via the switch 27. The potential held by the potential holder 28 is applied to the reference potential as an offset potential.
The potential generated by the DA converter 26 (a potential corresponding to a signal subjected to DA conversion output from the DA converter 26) is held as a charge by the potential holder 28. When the potential generated by the DA converter 26 is updated, the switch 27 turns on. In addition, after the potential generated by the DA converter 26 is updated, the switch 27 turns off.
As a result, it becomes possible to maintain a state in which the offset potential is applied to the differential amplifier 24 even in a state in which a connection from the DA converter 26 is off.
The DA converter 26 is a circuit or a functional block that generates an analog potential from any digital value and mainly generates noise caused by thermal noise. In particular, the larger the potential generated by the DA converter 26, that is, the larger the potential applied to the differential amplifier 24 as the offset potential, the larger the noise generated by the DA converter 26.
Since the differential amplifier 24 and the DA converter 26 can be appropriately disconnected from each other by the switch 27 and a desired potential can be held by the potential holder 28, an effect of noise caused by the DA converter 26 can be eliminated even in a case where a desired offset potential is continuously applied. By turning off the switch 27 during a period in which the signal after the AD conversion is supplied from the AD converter 25 to the potential measurement unit 31, it is possible to prevent the effect of noise caused by the DA converter 26 upon a result of the AD conversion performed by the AD converter 25.
The controller 14 includes the potential measurement unit 31, the offset setting value calculation unit 32, and the control timing determination unit 33.
The potential measuring unit 31 includes a reception signal obtaining section 41, a threshold holding section 42, and a reception signal threshold determination section 43.
The reception signal obtaining section 41 receives a signal output from the AD converter 25 and obtains a digital signal value of an output signal of the differential amplifier 24. The digital signal value obtained by the reception signal obtaining section 41 is appropriately output to the outside of the biosensor module 1 as a measurement result in the biosensor module 1. The signal received by the reception signal obtaining section 41 is also output to the reception signal threshold determination section 43 and the like.
The threshold holding section 42 holds a threshold used to make a determination as to offset potential control. Two thresholds, namely an offset control threshold Th-H and an offset control threshold Th-L, which are thresholds used to make a determination as to the offset potential control, are set in advance. The two thresholds, namely the offset control threshold Th-H and the offset control threshold Th-L, held by the threshold holding section 42 are used by the reception signal threshold determination section 43.
The reception signal threshold determination section 43 compares a digital signal value Vadc of a reception signal with the thresholds held by the threshold holding section 42 and outputs a comparison result to the offset setting value calculation unit 32.
The offset setting value calculation unit 32 calculates an offset potential to be applied to the differential amplifier 24 on the basis of the comparison result obtained by the reception signal threshold determination section 43 and outputs a signal indicating an offset setting value to the DA converter 26.
The control timing determination unit 33 outputs the AD conversion timing signal ADCcap to the AD converter 25 and the switching signal SWdac to the switch 27. The control timing determination unit 33 controls an AD conversion timing of the AD converter 25 and the connected state and separated state (ON/OFF) of the switch 27. The control timing determination unit 33 controls both timings.
As described above, for example, the control timing determination unit 33 generates the switching signal SWdac such that the switch 27 turns on at a timing different from the AD conversion timing signal ADCcap. In addition, the control timing determination unit 33 controls the switch 27 such that the switch 27 turns off after the potential held by the potential holder 28 is updated.
A waveform W illustrated in an upper part of
A lower part of
As illustrated in
Similarly, in a case where the potential of the input signal exceeds the offset control threshold Th-H, a potential higher than a previous potential is set as a new offset potential. In response to an update of the offset potential, the dynamic range of the AD converter 25 is switched to a higher range.
The threshold holding section 42 holds the offset control threshold Th-H and the offset control threshold Th-L used for the comparison with the potential of the input signal. The offset control threshold Th-H is a threshold that is set within the dynamic range and that is an upper limit of the potential of the input signal. In addition, the offset control threshold Th-H is a threshold that is set within the dynamic range and that is a lower limit of the potential of the input signal.
Here, a process for switching an offset potential performed by the biosensor module 1 will be described with reference to a flowchart of
In step S1, the control timing determination unit 33 determines whether or not a counter value Tcnt managed thereby is equal to a value Tadc, and waits until determining that these values are equal. For example, the value Tadc is an AD conversion sampling frequency, and a value Tadc corresponding to a certain period of time such as 1 ms is set in advance.
In a case where the control timing determination unit 33 determines in step S1 that the counter value Tcnt is equal to the value Tadc since the certain period of time such as 1 ms has elapsed, the control timing determination unit 33 outputs the AD conversion timing signal ADCcap to the AD converter 25 in step S2. As the AD conversion timing signal ADCcap is output from the control timing determination unit 33, the signal after the AD conversion is output from the AD converter 25 to the potential measurement unit 31 and obtained as a reception signal.
In step S3, the reception signal threshold determination section 43 determines whether or not a digital signal value Vadc of the reception signal is larger than the offset control threshold Th-H.
In a case where the reception signal threshold determination section 43 determines in step S3 that the digital signal value Vadc is larger than the offset control threshold Th-H, the offset setting value calculation unit 32 calculates, in step S4, a new offset setting value Vdac by adding an offset potential ΔVoffset to a current offset setting value Vdac. For example, a potential according to how greatly the digital signal value Vadc exceeds the offset control threshold Th-H is added as the offset potential ΔVoffset. The offset setting value calculation unit 32 outputs a signal indicating the newly obtained offset setting value Vdac to the DA converter 26.
In step S5, the control timing determination unit 33 outputs a switching signal SWdac “H” to the switch 27. The switch 27 turns on, and an offset potential according to the new offset setting value Vdac generated by the DA converter 26 is supplied to the potential holder 28.
In step S6, the control timing determination unit 33 waits until a period of time Tsw, which is a certain period of time, elapses.
When the certain period of time Tsw has elapsed, the control timing determination unit 33 outputs, in step S7, the switching signal SWdac “L” to the switch 27. The switch 27 turns off, and the potential holder 28 holds a potential according to the new offset setting value Vdac. In addition, an offset potential according to the new offset setting value Vdac is applied to the differential amplifier 24.
In a case where the reception signal threshold determination section 43 determines in step S3 that the digital signal value Vadc is not larger than the offset control threshold Th-H, the reception signal threshold determination section 43 determines, in step S8, whether or not the digital signal value Vadc is smaller than the offset control threshold Th-L.
In a case where the reception signal threshold determination section 43 determines in step S8 that the digital signal value Vadc is smaller than the offset control threshold Th-L, the offset setting value calculation unit 32 calculates, in step S9, a new offset setting value Vdac by subtracting an offset potential ΔVoffset from the current offset setting value Vdac. The offset setting value calculation unit 32 outputs a signal indicating the newly obtained offset setting value Vdac to the DA converter 26.
After the new offset setting value Vdac is set in step S9, the process proceeds to step S5, and processing similar to the above-described processing is performed. The potential holder 28 is in a state of holding the potential according to the new offset setting value Vdac, and an offset potential according to the new offset setting value Vdac is applied to the differential amplifier 24.
After the switch 27 turns off in step S7, or in a case where the reception signal threshold determination section 43 determines in step S8 that the digital signal value Vadc is not smaller than the offset control threshold Th-L, the process returns to step S1, and the above process is repeated.
As illustrated in an uppermost part of
In the example illustrated in
As illustrated in a third part, at a time t3 after the offset setting value Vdac is updated, the switching signal SWdac becomes “H”, and the switch 27 turns on. In addition, as illustrated in a fourth part, immediately after the switch 27 turns on, the potential held by the potential holder 28 is updated from the value Vdac #0 to the value Vdac #1. After the potential held by the potential holder 28 is updated, the switching signal SWdac becomes “L”, and the switch 27 turns off. The switching signal SWdac becomes “H” for the period of time Tsw.
A similar process is performed after a time t4. That is, the AD conversion timing signal ADCcap becomes “H” at the time t4, and the offset setting value is updated from the offset setting value Vdac #1 to an offset setting value Vdac #2 at a time t5.
At a time to, the switching signal SWdac becomes “H”, and immediately after that, the potential held by the potential holder 28 is updated from the value Vdac #1 to the value Vdac #2, and the switch 27 turns off.
As illustrated in
As described above, by changing the dynamic range of the input of the AD converter 25 in accordance with a signal level of a reception signal, a wide dynamic range and high resolution can be achieved. In addition, choices of the AD converter 25 can be increased, and cost can be reduced.
Furthermore, the offset potential applied to change the dynamic range is updated in a period different from one in which a signal after AD conversion is output from the AD converter 25, and after the offset potential is updated, the AD converter 25 and the DA converter 26 are disconnected. This makes it possible to prevent noise caused by the DA converter 26 from affecting the input-referred noise of the amplifier.
That is, with the biosensor module 1, it is possible to achieve cost reduction and noise reduction while securing a wide dynamic range and high resolution.
Among components illustrated in
The signal reception unit 13 is provided with a configuration for processing the signal of the second channel in addition to a configuration for processing the signal of the first channel. A capacitor 22-1, a buffer 23-1, a differential amplifier 24-1, a switch 27-1, and a potential holder 28-1 are provided for the signal of the first channel, and a capacitor 22-2, a buffer 23-2, a differential amplifier 24-2, a switch 27-2, and a potential holder 28-2 are provided for the signal of the second channel.
A signal output from the buffer 21 is supplied to the differential amplifier 24-1 and the differential amplifier 24-2 through the capacitor 22-1 and the capacitor 22-2, respectively.
The buffer 23-1 amplifies the signal supplied from the bioelectrode 12-1 and outputs the amplified signal to the differential amplifier 24-1.
The differential amplifier 24-1 amplifies a potential that is a difference between a potential at a measurement target position represented by the signal supplied from the buffer 23-1 and a reference potential, which is a potential held by the potential holder 28-1 and applied as an offset potential, and outputs a signal according to the amplified potential. The signal output from the differential amplifier 24-1 is supplied to a selector 29.
The buffer 23-1 amplifies the signal supplied from the bioelectrode 12-2 and outputs the amplified signal to the differential amplifier 24-2.
The differential amplifier 24-2 amplifies a potential that is a difference between a potential at a measurement target position represented by the signal supplied from the buffer 23-2 and a reference potential, which is a potential held by the potential holder 28-2 and applied as an offset potential, and outputs a signal according to the amplified potential. The signal output from the differential amplifier 24-2 is supplied to the selector 29.
The selector 29 selects the signal of the first channel supplied from the differential amplifier 24-1 or the signal of the second channel supplied from the differential amplifier 24-2 and outputs the selected signal to the AD converter 25. The output of the selector 29 is switched at a certain timing.
The switch 27-1 switches on and off in accordance with a switching signal SWdac #1 supplied from the control timing determination unit 33.
The potential holder 28-1 holds a potential according to a signal output from the DA converter 26 and supplied through the switch 27-1.
The switch 27-2 switches on and off in accordance with a switching signal SWdac #2 supplied from the control timing determination unit 33.
The potential holder 28-2 holds a potential according to a signal output from the DA converter 26 and supplied through the switch 27-2.
The control timing determination unit 33 outputs the switching signal SWdac #1 to the switch unit 27-1 to control on and off of the switch 27-1. In addition, the control timing determination unit 33 outputs the switching signal SWdac #2 to the switch unit 27-2 to control on and off of the switch 27-2. The control timing determination unit 33 controls the switch 27-1 and the switch 27-2 such that a connected state is established in different periods.
As illustrated in an uppermost part of
In an example illustrated in
As illustrated in a third part, at a time t13 after the offset setting value Vdac of the first channel is updated, the switching signal SWdac #1 becomes “H”, and the switch 27-1 turns on. In addition, as illustrated in a fifth part, immediately after the switch 27-1 turns on, the potential held by the potential holder 28-1 is updated to the value Vdac #1.
After the offset potential of the first channel held by the potential holder 28-1 is updated, the switch 27-1 turns off. The switching signal SWdac #1 becomes “H” for a period of time Tsw1. Thereafter, the update of the offset potential of the second channel is started.
As illustrated in the uppermost part, the AD conversion timing signal ADCcap becomes “H” at a time t14, and as illustrated in the second part, the offset setting value Vdac according to the digital signal value Vadc of a reception signal of the second channel is updated from a certain offset setting value to the offset setting value Vdac #2 at a time tis. The DA converter 26 performs DA conversion on a digital signal according to the offset setting value Vdac #2 and outputs a signal obtained through the DA conversion.
As illustrated in a fourth part, at a time tis after the offset setting value Vdac of the second channel is updated, the switching signal SWdac #2 becomes “H”, and the switch 27-2 turns on. In addition, as illustrated in a sixth part, immediately after the switch 27-2 turns on, the potential held by the potential holder 28-2 is updated to the value Vdac #2.
After the offset potential of the second channel held by the potential holder 28-2 is updated, the switch 27-2 turns off. The switching signal SWdac #2 becomes “H” for a period of time Tsw2. Thereafter, the update of the offset set value Vdac of the first channel and the update of the offset set value Vdac of the second channel are sequentially performed.
As described above, the control of the switch 27-1 and the switch 27-2 is performed in a period different from the period in which the digital signal value is obtained. Even in a case where signals input to the signal reception unit 13 are signals of a plurality of channels, the offset potential is updated for the AD converter 25 in a state where the AD converter 25 and the DA converter 26 are separated from each other, so that it is possible to prevent noise caused by the DA converter 26 from affecting a result of the AD conversion performed by the AD converter 25.
For example, in a case where attention is paid to the first channel, the switch 27-1 is controlled to update the offset set value Vdac of the first channel at a cycle twice as long as a cycle according to the value Tadc, which is a cycle for obtaining the digital signal value with the AD conversion timing signal ADCcap set to “H”. For example, in a case where attention is paid to the second channel, the switch 27-2 is controlled to update the offset set value Vdac of the second channel at a cycle twice as long as the cycle according to the value Tadc, which is the cycle for obtaining the digital signal value with the AD conversion timing signal ADCcap set to “H”.
As described above, a control cycle of a switch corresponding to one channel is variable in accordance with the number of channels of a biopotential signal. In the example described with reference to
The switch 27-1 and the switch 27-2 may be controlled so as not to be turned on at different timings but to be turned on at the same time. In this case, the control timing determination unit 33 synchronously controls the switch 27-1 and the switch 27-2. The update of the potential held by the potential holder 28-1 and the update of the potential held by the potential holder 28-2 are performed in synchronization.
The signal input to the signal reception unit 13 may be signals of three or more channels.
The effects described herein are merely examples and are not restrictive, and other effects may also be produced.
An embodiment of the present technology is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present technology.
In addition, each step described in the above flowchart can be executed by one device or shared and performed by a plurality of devices.
Moreover, in a case where a plurality of processing steps is included in one step, the plurality of processing included in the one step can be performed by one device or shared and performed by a plurality of devices.
The present technology may also have the following configurations.
(1)
A biopotential measurement device including:
The biopotential measurement device according to (1), further including:
The biopotential measurement device according to (2), further including:
The biopotential measurement device according to any one of (1) to (3), further including:
The biopotential measurement device according to (4),
The biopotential measurement device according to (5),
The biopotential measurement device according to (7),
The biopotential measurement device according to (8),
The biopotential measurement device according to any one of (1) to (9),
The biopotential measurement device according to (4),
The biopotential measurement device according to (11),
The biopotential measurement device according to (11) or (12),
A biopotential measurement method used by a biopotential measurement device including
An information processing apparatus including:
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-180768 | Nov 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/039461 | 10/24/2022 | WO |
