WO2024052977A1

WO2024052977A1 - Biological signal measurement system

Info

Publication number: WO2024052977A1
Application number: PCT/JP2022/033384
Authority: WO
Inventors: 健斗渡辺; 賢一松永
Original assignee: 日本電信電話株式会社
Priority date: 2022-09-06
Filing date: 2022-09-06
Publication date: 2024-03-14

Abstract

This biological signal measurement system comprises: electrodes (1-1, 1-2) which come into contact with a portion of the skin on the limbs of a measurement subject; an electrocardiogram sensor control unit (2) for acquiring cardiogram signals of the measurement subject on the basis of the biological potential detected through the electrodes (1-1, 1-2); a perspiration sensor (3) for measuring electrical characteristics derived from the perspiration of a portion of the limbs of the measurement subject; and a perspiration sensor control unit (4) for calculating the psychological perspiration amount of the measurement target on the basis of the electrical characteristics measured through the perspiration sensor (3).

Description

Biosignal measurement system

The present invention relates to a biological signal measurement system used for monitoring human stress and emotions.

In recent years, monitoring of human stress and emotions has been studied as an applied field of biological signal measurement. A variety of biological signals have been proposed as effective for monitoring, including electroencephalograms, electrocardiograms, and psychological sweating. Among biological signals, electrocardiograms and psychological sweating are relatively easy to measure, and simultaneous measurement of these is expected to improve the accuracy of monitoring.

Non-Patent Document 1 discloses a sensor system that measures an electrocardiogram using an electrocardiogram sensor device attached to a person's chest and measures perspiration using a sweat sensor device attached to the palm of the hand.

When monitoring stress and emotions, attaching sensor devices with numerous wires to the wearer's body, or attaching measurement devices connected to these sensor devices, can interfere with the monitoring results and have a negative impact. There is sex. In particular, stick-on sensor devices such as electrocardiographs are viewed as problematic due to the discomfort caused by sticking electrodes to the chest.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a biological signal measurement system that can measure electrocardiogram signals and mental sweat rate in a part of the measurement subject that causes less discomfort. shall be.

The biosignal measurement system of the present invention obtains an electrocardiogram signal of the measurement subject based on an electrode configured to be in contact with the skin of a part of the limb of the measurement subject and a bioelectrical potential detected by the electrode. a first control unit configured as shown in FIG. The method is characterized by comprising a second control section configured to calculate the amount of mental perspiration of the person to be measured based on the characteristics.

According to the present invention, measurement can be carried out by providing electrodes that come into contact with the skin of some of the limbs of the measurement subject and a sweat sensor that measures electrical characteristics derived from sweating of some of the limbs of the measurement subject. The electrocardiogram signal and the amount of mental sweating can be measured at a site where the subject feels less discomfort. As a result, the present invention can reduce the negative impact on applications that utilize measurement results.

FIG. 1 is a block diagram showing the configuration of a biological signal measurement system according to a first embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the electrocardiographic sensor control section according to the first embodiment of the present invention. FIG. 3 is a block diagram showing another configuration of the electrocardiographic sensor control section according to the first embodiment of the present invention. FIG. 4 is a block diagram showing another configuration of the biological signal measurement system according to the first embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of a biological signal measurement system according to a second embodiment of the present invention. FIG. 6 is a block diagram showing the configuration of an electrocardiographic sensor control section according to a second embodiment of the present invention. FIG. 7 is a circuit diagram showing the configuration of an amplifier section according to a second embodiment of the present invention. FIG. 8 is a block diagram showing the configuration of an electrocardiographic sensor control section according to a second embodiment of the present invention. FIG. 9 is a block diagram showing another configuration of the biological signal measurement system according to the second embodiment of the present invention. FIG. 10 is a block diagram showing an example of the configuration of a computer that implements the biological signal measurement system according to the first and second embodiments of the present invention.

[First example]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a biological signal measurement system according to a first embodiment of the present invention. The biosignal measurement system is based on two or more electrodes 1-1, 1-2 that are in contact with the skin of some of the limbs of the measurement subject, and bioelectrical potentials detected by the electrodes 1-1, 1-2. An electrocardiogram sensor control unit 2 (first control unit) that obtains an electrocardiogram signal of a measurement subject, a sweat sensor 3 that measures electrical characteristics derived from sweating in a part of the limbs of the measurement subject, and a sweat sensor 3. a sweat sensor control unit 4 (second control unit) that calculates the amount of mental sweat of the subject based on the electrical characteristics measured by the sensor, and wirelessly transmits the electrocardiogram signal and information on the amount of mental sweat to the outside. It includes a wireless communication section 5 , a power source 6 that supplies power to the electrocardiographic sensor control section 2 , the sweat sensor 3 , the sweat sensor control section 4 , and the wireless communication section 5 .

The interval between R waves, which are the peaks of an electrocardiogram waveform, is dually controlled by a person's sympathetic and parasympathetic nerves, and changes in the time domain and frequency domain depending on the person's mental state. Additionally, mental sweating is controlled by the sympathetic nervous system. Mental stress causes sweating in the palms and soles of the feet. By measuring these biological signals such as electrocardiograms and mental sweating in a multimodal manner, we can expect more accurate mental monitoring.

In the technique disclosed in Non-Patent Document 1, an electrocardiographic sensor is attached to the chest of a person to be measured, and a sweat sensor is attached to the palm of the hand. However, although it is convenient to wear each sensor independently, depending on where and how it is worn, it may cause strong discomfort to the person to be measured, which may affect mental monitoring.

On the other hand, in the configuration shown in FIG. 1, the electrodes 1-1, 1-2, the electrocardiographic sensor control unit 2, the sweat sensor 3, and the sweat sensor control unit are installed inside the mat-like sensor device 7 on which the person to be measured stands barefoot. A section 4, a wireless communication section 5, and a power source 6 are provided. When measuring an electrocardiogram signal as a biological signal, it is necessary to place multiple electrodes 1-1 and 1-2 at positions sandwiching the heart of the person to be measured. Electrodes 1-1 and 1-2 are arranged so as to contact at least one of each of the electrodes 1-1 and 1-2. The sweat sensor 3 may contact at least one of the right sole and the left sole.

In this way, in this example, the discomfort of wearing the biological signal measurement system can be reduced by making it a form that the measurement subject can use on a daily basis, so it is possible to measure the degree of tension and stress of the measurement subject. , suitable for mental monitoring such as emotion estimation.

FIG. 2 is a block diagram showing the configuration of the electrocardiographic sensor control section 2. The electrocardiogram sensor control unit 2 includes amplification units 20-1 and 20-2 that amplify the biopotentials detected by the electrodes 1-1 and 1-2 that are in contact with the skin of the measurement subject, and AD conversion units 21-1 and 21-2 that convert electric potential into digital data, and calculation that calculates the difference between the biopotential detected by electrode 1-1 and the biopotential detected by electrode 1-2 as an electrocardiogram signal. 22.

Since the biopotentials detected by the electrodes 1-1 and 1-2 are very weak signals, signal amplification by the amplification sections 20-1 and 20-2 is required. The amplifier sections 20-1 and 20-2 require high input impedance in order to reduce loss of biopotential. In the inverting amplifier circuit, the resistance that determines the input impedance also affects the gain setting and further contributes as thermal noise, resulting in a decrease in the S/N ratio of the biopotential. On the other hand, a non-inverting amplifier circuit has a characteristic that noise does not easily increase even if it has a high input impedance configuration. Therefore, it is effective to use non-inverting amplifier circuits as the amplifier sections 20-1 and 20-2. Further, a low-pass filter may be provided in the amplifier sections 20-1 and 20-2.

The calculation unit 22 calculates the difference between the biopotential detected by the electrode 1-1 and amplified by the amplification unit 20-1 and the biopotential detected by the electrode 1-2 and amplified by the amplification unit 20-2 as an electrocardiogram signal. calculate.

As the sweat sensor 3, there is a skin electrometer that applies current or voltage to an electrode in contact with the skin of the person to be measured to measure changes in impedance of the skin of the person to be measured due to sweating. When using a skin electrometer, the sweat sensor control unit 4 estimates the amount of mental perspiration of the person to be measured based on the measured change in skin impedance.

Further, as the perspiration sensor 3, a sensor having a structure that collects moisture from the skin of the person to be measured and outputs an electrical signal derived from the collected moisture may be used. When using such a sensor, the sweat sensor control unit 4 estimates the amount of mental sweat of the person to be measured based on the electrical signal output from the sensor.

When a skin electrometer is used as the sweat sensor 3, miniaturization is possible. On the other hand, in the case of the sweat sensor 3 that requires a structure for collecting moisture from the skin of the person to be measured, it is bulky and may interfere with the activities of the person to be measured.

When a skin electrometer is used as the sweat sensor 3, the electrodes for measuring skin impedance and the electrodes 1-1 and 1-2 for measuring electrocardiogram signals are shared, thereby eliminating the need to prepare separate electrodes. When sharing electrodes, if the signal applied to the electrode for skin impedance measurement is in the same frequency band as the biopotential, it will be difficult to separate the signal applied to the electrode from the biopotential. It is impossible to perform impedance measurement and electrocardiogram signal measurement at the same time.

In order to perform skin impedance measurement and electrocardiogram signal measurement at the same time, the signal applied to the electrodes for skin impedance measurement may be an AC signal with a frequency different from that of the biopotential. In this case, the potentials of the electrodes 1-1 and 1-2 include various frequency components. The electrocardiographic sensor control unit 2 can extract the bioelectrical potential by frequency filtering processing that removes the signal applied by the sweat sensor 3. The frequency filtering process of the electrocardiographic sensor control section 2 can be realized by the low-pass filters of the amplification sections 20-1 and 20-2. Furthermore, the sweat sensor 3 can measure skin impedance through frequency filtering processing that removes biopotential.

The frequency of biopotential is approximately 50Hz or less. The cutoff frequency of the low-pass filter provided in the amplifier sections 20-1 and 20-2 is, for example, 50 Hz or 100 Hz. Therefore, by setting the frequency of the AC signal applied to the electrode by the sweat sensor 3 for skin impedance measurement to 100 Hz or more, the signal applied to the electrode and the biopotential can be separated.

On the other hand, skin impedance measurement and electrocardiogram signal measurement may be performed in a time-sharing manner. FIG. 3 shows the configuration of the electrocardiogram sensor control section 2 when skin impedance measurement and electrocardiogram signal measurement are performed in a time-sharing manner. In the example of FIG. 3, switches 23-1 and 23-2 are added between the electrodes 1-1 and 1-2 and the amplification sections 20-1 and 20-2. An example of the switches 23-1 and 23-2 is a CMOS (Complementary Metal Oxide Semiconductor) switch.

The sampling rate of electrocardiogram signals is usually 1 kHz or less, and the sampling rate of skin impedance is about several Hz. Therefore, it is possible to control the switches 23-1 and 23-2 by the arithmetic unit 22 including an MCU (Micro Controller Unit) or the like. At the timing when the sweat sensor 3 measures skin impedance, the calculation unit 22 turns off the switches 23-1 and 23-2, connects the electrodes 1-1 and 1-2 and the sweat sensor 3, and measures the electrocardiogram signal. At the timing to perform this, the switches 23-1 and 23-2 may be turned on to connect the electrodes 1-1 and 1-2 to the amplifying sections 20-1 and 20-2.

Note that when performing skin impedance measurement, it is desirable to provide multiple electrodes at the same site of the person being measured. For example, two or more electrodes 1-1 are provided to contact the right sole of the person to be measured, and two or more electrodes 1-2 are provided to contact the left sole of the person. The skin impedance of the sole of the right foot may be measured using the electrode 1-1, the skin impedance of the sole of the left foot may be measured using the electrode 1-2, and the skin impedance of the sole of the left foot may be measured using the electrode 1-1. Skin impedance measurement using electrode 1-2 may be performed at the same time.

In the example of FIG. 3, the number of amplifier sections 20-1, 20-2 and AD conversion sections 21-2, 21-2 is matched to the number of electrodes 1-1, 1-2, but the configuration of FIG. This is not a required configuration. Any configuration may be used as long as the calculation unit 22 can calculate the difference between the biopotential detected by at least one electrode 1-1 and the biopotential detected by at least one electrode 1-2.

As the electrodes 1-1, 1-2 and the electrodes of the sweat sensor 3, electrodes made of various materials and configurations can be used. Any electrode can be used, including Ag/AgCl electrodes used in medical applications, conductive cloth electrodes, and metal electrodes. By using cloth or metal electrodes that do not need to be directly attached to the body of the person to be measured, and by creating a non-contact electrode configuration in which the electrodes are worn over clothing, the degree of freedom of the person being measured is further improved. It is also possible.

In the example of FIG. 1, electrodes 1-1, 1-2, an electrocardiographic sensor control section 2, a sweat sensor 3, a sweat sensor control section 4, a wireless communication section 5, and a power source 6 are installed inside a mat-like sensor device 7. Although an example in which the biosignal measurement system is provided has been described, the biosignal measurement system may be separately worn on the right and left hands of the person to be measured, or may be separately worn on the right and left legs of the person to be measured.

When the biosignal measurement system is worn separately on the right and left hands of the person to be measured, for example, the electrodes 1-1, 1-2, the electrocardiographic sensor control unit 2, and the sweat sensor 3 are attached to a glove-shaped or ring-shaped sensor device. An example can be considered in which a sweat sensor control section 4, a wireless communication section 5, and a power source 6 are provided. The person to be measured wears the biosignal measurement system by wearing gloves and rings on each of his right and left hands.

When the biosignal measurement system is separately attached to the right and left legs of a measurement subject, for example, the electrodes 1-1, 1-2 and the electrocardiographic sensor control unit 2 are attached to a sock-type sensor device or a slipper-type sensor device. An example can be considered in which a sweat sensor 3, a sweat sensor control section 4, a wireless communication section 5, and a power source 6 are provided. The person to be measured wears the biological signal measurement system by wearing socks on each of the right and left feet, or slippers on each of the right and left feet.

Although the accuracy is lower because the detection power of psychogenic sweating is weakened, for convenience, a wristband-type sensor device is equipped with electrodes 1-1, 1-2, electrocardiographic sensor control unit 2, sweat sensor 3, and sweat sensor. A control section 4, a wireless communication section 5, and a power source 6 may be provided. The person to be measured wears the biosignal measurement system by wearing a wristband on each of his right and left hands.

FIG. 4 shows the configuration of the biosignal measurement system when the biosignal measurement system is separately attached to the right side and left side of the measurement subject. The biological signal measurement system in the example of FIG. 4 is provided separately into a sensor device 7a that is attached to the right side of the measurement subject and a sensor device 7b that is attached to the left side of the measurement subject.

The sensor device 7a is provided with an electrode 1-1. The sensor device 7b is provided with an electrode 1-2, an electrocardiographic sensor control section 2, a sweat sensor 3, a sweat sensor control section 4, a wireless communication section 5, and a power source 6. The electrode 1-1 and the electrocardiographic sensor control section 2 are electrically connected by a wiring 8. The

sensor devices

7a, 7b are in the form of gloves, rings, socks, slippers or wristbands. When cloth products such as socks and gloves are used as the base material of the

sensor devices

7a and 7b, cloth electrodes using conductive fibers are particularly suitable as the electrodes of the electrodes 1-1 and 1-2 and the sweat sensor 3. . It goes without saying that the sensor device 7a may be attached to the left side of the person to be measured, and the sensor device 7b may be attached to the right side of the person.

In the configuration of FIG. 4 as well, it is possible to share the electrode of the sweat sensor 3 for measuring skin impedance and the electrode 1-2 for measuring the electrocardiogram signal.

Further, as shown in FIGS. 1 and 4, the

sensor devices

7 and 7b are provided with a wireless communication section 5 that wirelessly transmits the electrocardiogram signal and the information on the amount of mental sweating to an external device such as a smartphone or a server device. Good too.

[Second example]
Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of a biological signal measurement system according to a second embodiment of the present invention. In this embodiment, an example will be described in which the biological signal measurement system is separately attached to the right side and left side of the measurement subject, as in FIG. 4. In the configuration of FIG. 4, since the wiring 8 is required to connect the right side part and the left side part, the activities of the person to be measured may be restricted. The present embodiment solves such restrictions on activities.

The sensor device 7a attached to the right side of the person to be measured includes an electrode 1-1, an electrocardiographic sensor control section 2a, a power source 6a, and a standard for generating a reference potential for the amplification section of the electrocardiographic sensor control section 2a. A potential generation section 9a and a wireless communication section 10a that transmits and receives data to and from the sensor device 7b are provided.

The power supply 6a supplies power to the electrocardiographic sensor control section 2a, the reference potential generation section 9a, and the wireless communication section 10a.
FIG. 6 is a block diagram showing the configuration of the electrocardiographic sensor control section 2a. The electrocardiographic sensor control unit 2a includes an amplification unit 20-1, an AD conversion unit 21-1, an AD conversion unit 24a that converts the bioelectrical potential detected by the electrode 1-1 into digital data, and the sensor device 7b. and a DA conversion section 25a that converts the digital data received by the wireless communication section 10a into bioelectrical potential.

The wireless communication unit 10a wirelessly transmits the digital data output from the AD conversion unit 24a to the sensor device 7b, and receives the digital data transmitted from the sensor device 7b. Furthermore, the wireless communication section 10a wirelessly transmits the digital data output from the AD conversion section 21-1 to the sensor device 7b.

When using non-inverting amplifier circuits as the amplifier sections 20-1 and 20-2, it is important that the two amplifier sections 20-1 and 20-2 have a common reference potential. In this embodiment, since the

sensor devices

7a and 7b are not connected by wiring, the reference potentials of the amplifier sections 20-1 and 20-2 may not match, which may deteriorate measurement accuracy.

Therefore, in this embodiment, in order to improve the measurement accuracy of the electrocardiogram, biopotential information is transmitted and received between the

sensor devices

7a and 7b, so that the amplification units 20-1 and 20-2 of each

sensor device

7a and 7b The reference potential Vref is shared.

As will be described later, the biopotential detected by the electrodes 1-2 of the sensor device 7b is converted into digital data by the AD converter 24b, and transmitted from the wireless communication unit 10b of the sensor device 7b. The wireless communication unit 10a receives digital data transmitted from the sensor device 7b. The DA conversion unit 25a converts the digital data received by the wireless communication unit 10a into biopotential.

The reference potential generating unit 9a generates a reference potential by calculating the average of the biopotential detected by the electrode 1-1 and the biopotential output from the DA converter 25a (the biopotential detected by the electrode 1-2). Generate Vref.

FIG. 7 is a circuit diagram showing an example of the configuration of the amplifier section 20-1. The amplifier section 20-1 is composed of an operational amplifier A1 and resistors R1 and R2. The reference potential Vref is supplied from the reference potential generating section 9a to one end of the resistor R1 of the amplifying section 20-1.

On the other hand, the sensor device 7b attached to the left side of the measurement subject includes an electrode 1-2, an electrocardiographic sensor control section 2b, a sweat sensor 3, a sweat sensor control section 4, a wireless communication section 5, A power source 6b, a reference potential generation section 9b that generates a reference potential for the amplification section of the electrocardiographic sensor control section 2b, and a wireless communication section 10b that transmits and receives data to and from the sensor device 7a are provided. The

sensor devices

7a, 7b are shaped like gloves, rings, socks, slippers, or wristbands, similar to the example of FIG.

The power supply 6b supplies power to the electrocardiographic sensor control section 2b, the sweat sensor 3, the sweat sensor control section 4, the wireless communication section 5, the reference potential generation section 9b, and the wireless communication section 10b.
FIG. 8 is a block diagram showing the configuration of the electrocardiographic sensor control section 2b. The electrocardiographic sensor control unit 2b includes an amplification unit 20-2, an AD conversion unit 21-2, a calculation unit 22, and an AD conversion unit 24b that converts the bioelectrical potential detected by the electrode 1-2 into digital data. It is composed of a DA conversion section 25b that converts digital data transmitted from the sensor device 7a and received by the wireless communication section 10b into a biopotential.

The wireless communication unit 10b wirelessly transmits the digital data output from the AD conversion unit 24b to the sensor device 7a. The wireless communication unit 10b also receives data on the biopotential detected by the electrode 1-1 of the sensor device 7a from the sensor device 7a. The DA converter 25b converts the digital data received by the wireless communication unit 10b into biopotential.

The reference potential generation unit 9b generates a reference potential by calculating the average of the biopotential detected by the electrode 1-2 and the biopotential output from the DA converter 25b (the biopotential detected by the electrode 1-1). It generates Vref and supplies the reference potential Vref to the amplifying section 20-2. The configuration of amplifier section 20-2 is similar to amplifier section 20-1.

The wireless communication unit 10a of the sensor device 7a wirelessly transmits not only the biopotential before amplification but also the biopotential that has been amplified by the amplification unit 20-1 and converted into digital data by the AD conversion unit 21-1. The wireless communication unit 10b receives the amplified biopotential data from the sensor device 7a.

The calculation unit 22 calculates the difference between the biopotential amplified by the amplification unit 20-1 of the sensor device 7a and the biopotential amplified by the amplification unit 20-2 of the sensor device 7b as an electrocardiogram signal.
The operations of the sweat sensor 3, sweat sensor control section 4, and wireless communication section 5 are the same as in the first embodiment.

It goes without saying that the sensor device 7a may be attached to the left side of the person to be measured, and the sensor device 7b may be attached to the right side of the person.
As in the first embodiment, also in this embodiment, the electrode of the sweat sensor 3 for measuring skin impedance and the electrode 1-2 for measuring the electrocardiogram signal can be used in common.

As described above, in this embodiment, the wiring connecting the

sensor devices

7a and 7b can be eliminated. As a result, it is possible to reduce the discomfort of the measurement subject caused by the wiring, and it is also possible to eliminate the restraint on the measurement subject's body, so that the measurement subject is not aware that monitoring is in progress. It becomes possible to measure the electrocardiogram signal and the amount of mental sweating. In this embodiment, measurement can be easily performed in daily life without interfering with the walking or exercise of the person to be measured.

Furthermore, in this embodiment, a common reference potential Vref generated by the reference

potential generation units

9a and 9b provided in each

sensor device

7a and 7b is used. This enables signal amplification in which the reference potential Vref of the amplification units 20-1 and 20-2 is shared in the

sensor devices

7a and 7b, and it is possible to improve the measurement accuracy of electrocardiogram signals.

Various methods can be applied as the wireless communication method. For example, modules for radio wave communication are widely available and can be easily implemented at low cost. When performing wireless communication using radio waves, a modulation circuit and a transmitting antenna are provided as the transmitting side circuit of the

wireless communication units

10a and 10b, and a receiving antenna and a demodulating circuit are provided as the receiving side circuit. good.

The modulation circuit on the transmitting side digitally modulates the carrier signal using the data to be transmitted. The modulated signal is transmitted from the transmitting antenna to the receiving sensor device. The demodulation circuit on the receiving side demodulates the signal transmitted from the sensor device on the transmitting side and received by the antenna to extract data.

When performing wireless communication using radio waves, data can be transmitted and received without interfering with each other by setting the carrier frequencies of the radio waves transmitted in each

sensor device

7a, 7b to different frequencies. It goes without saying that the transmitting antenna and the receiving antenna may be shared.

Optical communication may be used as another method for transmitting and receiving data between the

sensor devices

7a and 7b. By using optical communication, it becomes possible to transmit and receive stable data by reducing the influence of existing widely used wireless communication, and it is expected that security will be improved by making communication less likely to be intercepted.

When using optical communication, a modulation circuit and an E/O (Electrical/Optical) converter are provided as the transmitting side circuit of the

wireless communication units

10a and 10b, and an O/E (Optical/Electrical) converter is provided as the receiving side circuit. A converter and a demodulation circuit may be provided.

The modulation circuit on the transmitting side digitally modulates the carrier signal using the data to be transmitted. The E/O converter converts the modulated signal into light and transmits it to a receiving sensor device. The O/E converter on the receiving side receives an optical signal from the sensor device on the transmitting side and converts it into an electrical signal. The demodulation circuit demodulates the signal output from the O/E converter and extracts data.

As in the case of wireless communication using radio waves, by setting the wavelengths of light used in each

sensor device

7a, 7b to be different, data can be transmitted and received without mutual interference.

Magnetic communication used in wireless earphones and the like is also suitable for this embodiment. In magnetic communication, signals are transmitted by mutual induction with another device due to changes in magnetic fields. The magnetic field is permeable to human body components such as moisture. Therefore, since communication can be performed with low interference, stable data transmission and reception is possible even when the

sensor devices

7a and 7b are attached to the measurement subject.

When magnetic communication is used, a modulation circuit, a voltage-current converter such as a transconductance amplifier, and a coil serving as an antenna are provided as a transmitting side circuit of the

wireless communication units

10a and 10b, and a coil and a coil are provided as a receiving side circuit. , a current-voltage converter such as a transimpedance amplifier, and a demodulation circuit may be provided.

The modulation circuit on the transmitting side digitally modulates the carrier signal using the data to be transmitted. A voltage-to-current converter converts the modulated signal into a current and supplies it to the coil. A magnetic field change is caused by the current supplied to the coil of the transmitting sensor device. The current-to-voltage converter on the receiving side converts the current generated in the receiving coil due to the magnetic field change caused by the sensor device on the transmitting side into a voltage. The demodulation circuit demodulates the signal output from the current-voltage converter and extracts data.

As another method for transmitting and receiving data between the

sensor devices

7a and 7b, human body communication using the body of the person to be measured as a transmission path may be used. The configuration of the biological signal measurement system in this case is shown in FIG. When using human body communication, each

sensor device

7a, 7b has electrodes 11-1, 11-2 for performing human body communication in addition to electrodes 1-1, 1-2, as shown in FIG. Be prepared.

The power for communication occupies most of the power consumption of the

sensor devices

7a and 7b. In spatial propagation using radio waves, signal strength attenuates in inverse proportion to the square of the propagation distance. On the other hand, in the case of human body communication, the signal attenuation remains inversely proportional to the propagation distance. Therefore, by using human body communication, it is possible to transmit data with less transmission power. Transmitting and receiving data via the human body can contribute to reducing power consumption.

The

wireless communication units

10a and 10b in FIG. 9 digitally modulate the carrier signal using the data to be transmitted, and send the modulated signal to the measurement target from electrodes 11-1 and 11-2 that are in contact with the skin of the measurement target. through the person's body to other sensor devices. Furthermore, the

wireless communication units

10a and 10b demodulate signals transmitted from other sensor devices and received by the electrodes 11-1 and 11-2 to extract data.

By using human body communication for data transmission and reception, in addition to reducing power consumption, the sampling rate of the biopotential signal for generating the reference potential and the sampling rate of the biopotential signal for generating the biosignal can be set independently. This has the advantage of increasing the degree of freedom in design.

When using the human body as a transmission path, interference can be avoided by using different carrier frequencies for each

sensor device

7a, 7b. By setting the frequency band to be used from several MHz to about 100 MHz based on the electrical properties of the human body, human body communication with low loss can be realized.

As shown in FIG. 9, electrodes 1-1, 1-2 and electrodes 11-1, 11-2 may be provided individually in each

sensor device

7a, 7b. Further, the sensor device 7a may share the electrode 1-1 and the electrode 11-1, and the sensor device 7b may share the electrode 1-2 and the electrode 11-2.

When electrodes are shared, by providing bandpass filters with different passbands, it is possible to separate signals to be transmitted and received from biopotentials to be detected for electrocardiogram signal measurement. By reducing the number of electrodes, the number of parts that come into contact with the person to be measured is reduced, so the comfort of the person to be measured can be improved.

When digitally modulating the carrier signal in the

sensor devices

7a, 7b, multilevel modulation such as QPSK (Quadrature Phase shift Keying) is used, and furthermore, by setting different signal points used by each

sensor device

7a, 7b. , it is possible to separate signals to be transmitted and received in one carrier signal. This makes it possible to use a common device for digital modulation, thereby improving mass productivity and maintainability of the device.

Note that in the analysis of measured data, the electrocardiogram signal is often used only for heart rate variability analysis. The information required for heart rate variability analysis is not the entire electrocardiogram waveform, but only the heartbeat interval can be extracted as a feature. Since the heartbeat interval is the interval between the peaks of the electrocardiogram waveform, it is only necessary to detect the R wave having the sharpest peak among the electrocardiogram waveforms.

When detecting R waves, two electrodes 1-1 and 1-2 are provided, and for example, the potential difference between the two electrodes 1-1 that are in contact with the right palm of the person to be measured, or the two electrodes 1-1 that are in contact with the left palm of the person to be measured is detected. By calculating the potential difference between the two electrodes 1-2, a signal related to the R wave can be obtained, although it is smaller than a normal electrocardiogram signal. In other words, it is possible to detect R waves by attaching a sensor device to only one of the right side and left side of the person to be measured. The reason why R waves can be detected only in either the right side or the left side is thought to be because the electric field distribution in the human body due to the electrical activity of the heart is not uniform and differs slightly depending on the location, so it is possible to detect the potential difference. It will be done.

In this way, R waves can be detected even when the sensor device is attached only to either the right or left side of the person being measured, so it is possible to attach the sensor device only to either the right or left hand of the person being measured. It may be worn on either the right foot or the left foot. In this way, it is possible to eliminate the physical restraint of the measurement subject.

As a technology similar to electrocardiogram measurement, there is a technology that measures pulse intervals using a pulse wave sensor. However, the pulse wave sensor is a mechanism that measures volume changes in blood vessels close to the body surface, such as the radial artery and capillaries, due to heart beats using an optical or physical method. Therefore, there is a delay in the propagation of volume changes in blood vessels, and the volume of blood vessels changes depending on the movement and position of the measurement site, so pulse intervals are less accurate than heartbeat intervals in practice and are not suitable for monitoring. . In the present invention, results suitable for monitoring stress and emotions can be obtained by electrocardiogram measurement.

The calculation unit 22 and sweat sensor control unit 4 described in the first and second embodiments are implemented by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. It can be realized. An example of the configuration of this computer is shown in FIG.

The computer includes a CPU 100, a storage device 101, and an interface device (I/F) 102. The I/F 102 is connected to the sweat sensor 3, the

wireless communication units

5 and 10b, the AD conversion units 21-1 and 21-2, and the like. A program for implementing the method of the present invention is stored in the storage device 101. The CPU 100 executes the processes described in the first and second embodiments according to the program stored in the storage device 101. Further, at least a portion of the calculation unit 22 and the sweat sensor control unit 4 may be configured with hardware logic such as an FPGA (field-programmable gate array).

Part or all of the above embodiments may be described as in the following supplementary notes, but the embodiments are not limited to the following.

(Additional Note 1) The biosignal measurement system of the present invention includes an electrode configured to come into contact with the skin of a part of the extremities of the measurement subject, and a biosignal measurement system based on the bioelectrical potential detected by the electrode. A first control unit configured to obtain an electrocardiogram signal, a sweat sensor configured to measure electrical characteristics derived from sweating of a part of the extremities of the measurement subject, and measurement by the sweat sensor. and a second control section configured to calculate the amount of mental perspiration of the measurement subject based on the electrical characteristics obtained.

(Supplementary Note 2) The biosignal measurement system according to Supplementary Note 1 includes a first sensor device configured to be attached to one of the right side and left side of the measurement subject, and the right side and left side. a second sensor device configured to be attached to the other of the right and left regions, the first sensor device being configured to contact the skin of one of the right and left regions. The second sensor device includes a first of the electrodes, a second of the electrodes configured to contact the skin of the other of the right and left regions, and the first controller. , comprising the sweat sensor and the second control section, the first control section obtaining an electrocardiogram signal of the measurement subject based on the bioelectrical potential detected by the first and second electrodes. .

(Supplementary note 3) In the biosignal measurement system according to supplementary note 1 or 2, the sweat sensor measures a change in the impedance of the skin of the measurement subject as the electrical property, and the second control unit measures the change in impedance of the skin of the measurement subject as the electrical property. The amount of mental perspiration of the measurement subject is calculated based on the change in impedance of the skin.

(Supplementary Note 4) In the biosignal measurement system according to Supplementary Note 2, the electrode for the sweat sensor to measure the electrical characteristics and the second electrode are common, and the sweat sensor has a different biopotential. A frequency signal is applied to the second electrode to measure the electrical characteristic, and the first control section extracts the biopotential by frequency filtering processing.

(Supplementary Note 5) In the biosignal measurement system according to Supplementary Note 2, the electrode for the sweat sensor to measure the electrical characteristic and the second electrode are common, and the sweat sensor measures the electrical characteristic. and measurement of the electrocardiogram signal by the first control unit are performed in a time-sharing manner.

(Supplementary Note 6) In the biological signal measurement system according to Supplementary Note 5, the second sensor device further includes a switch for switching the connection of the second electrode, and the first control unit is configured to control whether the sweat sensor The second electrode and the sweat sensor are connected at a timing when the electrical characteristics are measured, and the second electrode and the first control unit are connected at a timing when the first control unit measures the electrocardiogram signal. The switch is controlled so that the

(Supplementary Note 7) In the biosignal measurement system according to Supplementary Note 2, the first sensor device includes a first amplification section configured to amplify the biopotential detected by the first electrode, and a first amplification section configured to amplify the biopotential detected by the first electrode. a first wireless communication section configured to transmit biopotential data amplified by the first amplification section to the second sensor device, the second sensor device a second amplification unit configured to amplify biopotential detected by the electrode; and a second wireless communication unit configured to receive biopotential data transmitted from the first sensor device. The first control unit generates an electrocardiogram signal of the measurement subject based on the biopotential received by the second wireless communication unit and the biopotential amplified by the second amplification unit. obtain.

(Additional Note 8) In the biological signal measurement system according to Additional Note 7, the first sensor device further includes a first reference potential generation unit configured to generate a reference potential for the first amplification unit, The second sensor device further includes a second reference potential generation section configured to generate a reference potential for the second amplification section, and the first wireless communication section is configured to generate a reference potential for the second amplification section. In addition to the biopotential data amplified by the unit, the biopotential data before being amplified by the first amplification unit is transmitted to the second sensor device, and the biopotential data transmitted from the second sensor device is transmitted to the second sensor device. The second wireless communication unit receives biopotential data before being amplified by the second amplification unit, in addition to the biopotential data amplified by the second amplification unit. data to the first sensor device, and the first reference potential generation section receives the biopotential before being amplified by the second amplification section via the first wireless communication section. , generating a reference potential for the first amplifying section based on the biopotential before being amplified by the first amplifying section and the biopotential before being amplified by the second amplifying section; The reference potential generation unit receives the biopotential before being amplified by the first amplification unit via the second wireless communication unit, and generates the biopotential before being amplified by the second amplification unit. A reference potential for the second amplification section is generated based on the biological potential before being amplified by the first amplification section.

The present invention can be applied to a technique for measuring an electrocardiogram signal and an amount of mental sweating.

1-1, 1-2, 11-1, 11-2...electrode, 2...electrocardiogram sensor control unit, 3...sweat sensor, 4...sweat sensor control unit, 5, 10a, 10b...wireless communication unit, 6, 6a, 6b...Power supply, 7,7a, 7b...Sensor device, 8...Wiring, 9a, 9b...Reference potential generation section, 20-1, 20-2...Amplification section, 21-2, 21-2, 24a, 24b ...AD conversion section, 22... calculation section, 23-1, 23-2... switch, 25a, 25b... DA conversion section.

Claims

an electrode configured to come into contact with the skin of a portion of a limb of a measurement subject;
a first control unit configured to obtain an electrocardiogram signal of the measurement subject based on the biopotential detected by the electrode;
a sweat sensor configured to measure electrical characteristics derived from sweat in a part of the limb of the measurement subject;
A biological signal measurement system comprising: a second control section configured to calculate the amount of psychological sweat of the measurement subject based on the electrical characteristics measured by the sweat sensor.
The biological signal measurement system according to claim 1,
a first sensor device configured to be attached to one of a right side part and a left side part of the measurement subject;
a second sensor device configured to be attached to the other of the right side part and the left side part,
The first sensor device includes a first of the electrodes configured to contact the skin of one of the right side and left side,
The second sensor device includes the second electrode configured to come into contact with the skin of the other of the right side and left side, the first controller, the sweat sensor, and the second electrode configured to contact the skin of the other of the right side and left side, the first control unit, the sweat sensor, and the first control unit. 2 control parts,
The biological signal measurement system, wherein the first control unit obtains an electrocardiogram signal of the measurement subject based on the biological potential detected by the first and second electrodes.
The biological signal measurement system according to claim 1 or 2,
The sweat sensor measures a change in impedance of the skin of the measurement subject as the electrical property,
The biological signal measurement system is characterized in that the second control unit calculates the amount of mental sweat of the measurement subject based on the measured change in skin impedance.
The biological signal measurement system according to claim 2,
The electrode for the sweat sensor to measure the electrical characteristics and the second electrode are common,
The sweat sensor measures the electrical characteristics by applying a signal of a frequency different from the biopotential to the second electrode,
A biological signal measurement system, wherein the first control unit extracts the biological potential by frequency filtering processing.
The biological signal measurement system according to claim 2,
The electrode for the sweat sensor to measure the electrical characteristics and the second electrode are common,
A biological signal measurement system characterized in that the measurement of the electrical characteristics by the sweat sensor and the measurement of the electrocardiogram signal by the first control unit are performed in a time-sharing manner.
The biological signal measurement system according to claim 5,
The second sensor device further includes a switch for switching connection of the second electrode,
The first control unit connects the second electrode and the sweat sensor at a timing when the sweat sensor measures the electrical characteristics, and at a timing when the first control unit measures the electrocardiogram signal. A biosignal measurement system, characterized in that the switch is controlled so that the second electrode and the first control section are connected.
The biological signal measurement system according to claim 2,
The first sensor device includes:
a first amplifying section configured to amplify the biopotential detected by the first electrode;
further comprising a first wireless communication unit configured to transmit biopotential data amplified by the first amplification unit to the second sensor device,
The second sensor device includes:
a second amplification unit configured to amplify the biopotential detected by the second electrode;
further comprising a second wireless communication unit configured to receive biopotential data transmitted from the first sensor device,
The first control unit obtains an electrocardiogram signal of the measurement subject based on the biopotential received by the second wireless communication unit and the biopotential amplified by the second amplification unit. biological signal measurement system.
The biological signal measurement system according to claim 7,
The first sensor device further includes a first reference potential generation section configured to generate a reference potential for the first amplification section,
The second sensor device further includes a second reference potential generation section configured to generate a reference potential for the second amplification section,
The first wireless communication unit transmits the biopotential data before being amplified by the first amplification unit to the second sensor device in addition to the biopotential data amplified by the first amplification unit. and receiving biopotential data transmitted from the second sensor device;
The second wireless communication unit transmits the biopotential data before being amplified by the second amplification unit to the first sensor device in addition to the biopotential data amplified by the second amplification unit. and send it to
The first reference potential generation section receives the biopotential before being amplified by the second amplification section via the first wireless communication section, and receives the biopotential before being amplified by the first amplification section. generating a reference potential for the first amplification unit based on the biopotential and the biopotential before being amplified by the second amplification unit;
The second reference potential generation section receives the biopotential before being amplified by the first amplification section via the second wireless communication section, and receives the biopotential before being amplified by the second amplification section. A biosignal measurement system, characterized in that a reference potential for the second amplification section is generated based on a biopotential and a biopotential before being amplified by the first amplification section.