Biological signal measurement system

Abstract

This biological signal measurement system comprises two first electrode devices (100a), a second electrode device (100b), and a biological signal generation device (130). The first electrode device (100a)' comprises an electrode (101a), a non-inverting amplification circuit (102a), a quantization circuit (103a), a wireless transmitter (104a), an FM transmitter (105a), an FM receiver (106a), an adjustment circuit (107a), and a power source (108a). Additionally, the second electrode device (100b) comprises an electrode (101b), a non-inverting amplification circuit (102b), a quantization circuit (103b), a wireless transmitter (104b), an FM transmitter (105b), an FM receiver (106b), an adjustment circuit (107b), and a power source (108b). Additionally, the biological signal generation device (130) comprises a wireless receiver (131), a computing circuit (132), and a memory (133).

Description

Biosignal Measurement System

[0001] The present invention relates to a biological signal measurement system.

[0002] In measuring an electrocardiogram, which is one type of bioelectric potential measurement, the potential difference between electrodes placed on the left and right sides of the human body is measured. For example, as shown in Fig. 6, a measurement system has been proposed in which a device 301 is worn around the center of the torso, and electrodes 304 are attached to the left and right waist areas by wiring 303 that run through compression wear 302 (Non-Patent Document 1).

[0003] Naoko Kasai et al., "Development and Practical Application of Functional Material Hitoe, which Enables Biometric Measurement Simply by Wearing It," Institute of Electronics, Information and Communication Engineers, Communications Society Magazine, Vol. 11, No. 1, pp. 17-23, 2017.

[0004] However, wearing the device on the torso can be uncomfortable due to the pressure and the laborious process of wearing it, leading to a feeling of aversion. Other locations besides the torso include the limbs. However, in this case, the wiring connecting the left and right electrodes forms a loop like handcuffs, which strongly restricts body movement. These issues could be resolved if the device could be divided into two by cutting the wiring between the left and right electrodes, but dividing the device would make it difficult to determine the standard for potential measurement, making biopotential measurement difficult.

[0005] The present invention has been made to solve the above problems, and aims to make it possible to easily measure bioelectric potentials even if the wiring between the two electrodes is cut and the device is divided into two devices.

[0006] The biosignal measurement system according to the present invention comprises two electrode devices and a biosignal generating device, each of which includes an electrode for measuring a biopotential in a human body of interest, a non-inverting amplifier circuit for inputting the measured biopotential to a non-inverting amplifier terminal, amplifying the amplified signal, and outputting the amplified signal from an output terminal, a quantization circuit for converting the amplified signal output from the output terminal of the non-inverting amplifier circuit into digital data to generate biopotential information, a wireless transmitter for transmitting the biopotential information to the biosignal generating device, an FM transmitter for converting the voltage signal output from the output terminal of the non-inverting amplifier circuit into an FM signal and transmitting the FM signal to the other electrode device, and a quantization circuit for converting the FM signal transmitted from the other electrode device to the own electrode device. the FM signal transmitted from one of the two electrode devices to the other and the FM signal transmitted from the other to the one have different frequencies, and the biosignal generating device has a wireless receiver that receives biopotential information transmitted from each of the two electrode devices and an arithmetic circuit that generates a biosignal waveform using the biopotential information received by the wireless receiver.

[0007] As described above, according to the present invention, two electrode devices are connected to a biosignal generating device via wireless communication, and the two electrode devices are connected via FM communication, so that even if the wiring between the two electrodes is cut and the device is divided into two devices, bioelectric potentials can be easily measured.

[0008] FIG. 1A is a configuration diagram showing the configuration of a biosignal measurement system according to a first embodiment of the present invention. FIG. 1B is a configuration diagram showing a partial configuration of a biosignal measurement system according to the first embodiment of the present invention. FIG. 2 is an explanatory diagram showing the concept of a biosignal measurement system according to the first embodiment of the present invention. FIG. 3 is a configuration diagram showing the configuration of a biosignal measurement system according to a second embodiment of the present invention. FIG. 4 is a configuration diagram showing the configuration of a biosignal measurement system according to a third embodiment of the present invention. FIG. 5 is a configuration diagram showing the configuration of a biosignal measurement system according to a fourth embodiment of the present invention. FIG. 6 is a configuration diagram showing the configuration of a conventional biosignal measurement system.

[0009] A biological signal measurement system according to an embodiment of the present invention will be described below.

[0010] 1A and 1B, a biosignal measurement system according to a first embodiment of the present invention will be described. The system includes two first electrode devices 100a, a second electrode device 100b, and a biosignal generating device 130.

[0011] The first electrode device 100a first comprises an electrode 101a for measuring the biopotential of a target human body, a non-inverting amplifier circuit 102a for inputting the measured biopotential to a non-inverting amplifier terminal, amplifying the signal, and outputting the signal from an output terminal, a quantization circuit 103a for converting the amplified signal output from the output terminal of the non-inverting amplifier circuit 102a into digital data to generate biopotential information, and a wireless transmitter 104a for transmitting the biopotential information to a biosignal generating device 130.

[0012] The first electrode device 100a also includes an FM transmitter 105a, an FM receiver 106a, and an adjustment circuit 107a. The FM transmitter 105a converts a voltage signal output from the output terminal of the non-inverting amplifier circuit 102a into an FM signal and transmits the converted FM signal to the second electrode device 100b via a transmitting antenna 109a. The FM receiver 106a converts an FM signal transmitted from the second electrode device 100b to the first electrode device 100a and received by a receiving antenna 110a into a voltage signal and outputs the voltage signal. The adjustment circuit 107a adjusts the voltage signal output from the FM receiver 106a according to preset conditions and outputs the adjusted signal to the inverting input terminal of the non-inverting amplifier circuit 102a.

[0013] The output of the non-inverting amplifier circuit 102a is also input to the inverting input terminal. For example, as shown in FIG. 1B, if the signal input to the inverting input terminal of the non-inverting amplifier circuit 102a from the adjustment circuit 107a is Vdev2 at the negative terminal input Vin- of the operational amplifier of the non-inverting amplifier circuit 102a and the output of the non-inverting amplifier circuit 102a is Vout1, the signals are mixed in a ratio of "Vin- = (R + RG) / (2R + RG) Vout + (R) / (2R + RG) Vdev2" and input to the inverting input terminal of the non-inverting amplifier circuit 102a. The same applies to the non-inverting amplifier circuit 102b described below.

[0014] The first electrode device 100a also includes a power supply 108a that supplies power to the non-inverting amplifier circuit 102a, the quantizer circuit 103a, the radio transmitter 104a, the FM transmitter 105a, the FM receiver 106a, and the adjustment circuit 107a.

[0015] The second electrode device 100b first comprises an electrode 101b for measuring the biopotential of the target human body, a non-inverting amplifier circuit 102b for inputting the measured biopotential to a non-inverting amplifier terminal, amplifying the signal, and outputting the signal from an output terminal, a quantization circuit 103b for converting the amplified signal output from the output terminal of the non-inverting amplifier circuit 102b into digital data to generate biopotential information, and a wireless transmitter 104b for transmitting the biopotential information to the biosignal generating device 130.

[0016] The second electrode device 100b also includes an FM transmitter 105b, an FM receiver 106b, and an adjustment circuit 107b. The FM transmitter 105b converts a voltage signal output from the output terminal of the non-inverting amplifier circuit 102b into an FM signal and transmits the converted FM signal to the first electrode device 100a via a transmitting antenna 109b. The FM receiver 106b converts an FM signal transmitted from the first electrode device 100a to the second electrode device 100b and received by a receiving antenna 110b into a voltage signal and outputs the voltage signal. The adjustment circuit 107b adjusts the voltage signal output from the FM receiver 106b according to preset conditions and outputs the adjusted signal to the inverting input terminal of the non-inverting amplifier circuit 102b.

[0017] The second electrode device 100b also includes a power supply 108b that supplies power to the non-inverting amplifier circuit 102b, the quantizer circuit 103b, the radio transmitter 104b, the FM transmitter 105b, the FM receiver 106b, and the adjustment circuit 107b.

[0018] Here, the FM signal transmitted from the first electrode device 100a to the second electrode device 100b and the FM signal transmitted from the second electrode device 100b to the first electrode device 100a have different frequencies.

[0019] The biosignal generating device 130 includes a wireless receiver 131 that receives biopotential information transmitted from each of the first and second electrode devices 100b and 100b, and an arithmetic circuit 132 that generates a biosignal waveform using the biopotential information received by the wireless receiver 131. The arithmetic circuit 132 can generate an electrocardiogram signal waveform using, for example, two pieces of biopotential information transmitted from each of the first and second electrode devices 100b attached to any two of the limbs of the human body. The biosignal generating device 130 also includes a memory 133 that stores the biosignal waveform generated by the arithmetic circuit 132.

[0020] The concept of the biosignal measurement system according to the first embodiment is shown in FIG. 2 . For example, when measuring electrocardiograms as biosignals, multiple electrodes must be positioned so as to sandwich the heart. Therefore, a measurement site that is comfortable for the human body 140 is considered to be wearing the first electrode device 100a and the second electrode device 100b at at least two locations on the limbs, such as the hands and feet. By adopting such a wearing configuration for the first electrode device 100a and the second electrode device 100b, it is possible to significantly reduce the sense of pressure and discomfort associated with wearing clothing. This biosignal measurement system is not limited to measuring electrocardiograms; it can also be used to measure myoelectrical signals and electroencephalograms. This application is expected to eliminate the discomfort of wiring, increase the flexibility of electrode placement, and broaden the range of devices that can be implemented.

[0021] In this example, the non-inverting amplifier circuit 102a of the first electrode device 100a and the non-inverting amplifier circuit 102b of the second electrode device 100b are mutually coupled. Since this configuration is similar to that of an oscillator circuit, oscillation occurs when the phase rotation and amplification caused by delays in the mutually coupled signals reach 180 degrees and 1 or greater.

[0022] For example, when constructing a non-inverting amplifier circuit with a bandwidth of DC to 1 kHz, which is typical for biosignals, a 0.1 ms delay results in a 36-degree phase rotation for a 1 kHz signal. In other words, a 0.5 ms delay results in a 180-degree phase rotation, making oscillation undeniable. Therefore, when mutually coupling the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b described above, it is necessary to minimize the delay in the portion where the voltage signals are coupled.

[0023] Next, electrodes 101a and 101b will be described. Various electrodes can be used for these electrodes, including Ag / AgCl electrodes, which are also used in medical applications, conductive cloth electrodes, metal electrodes, and other electrodes. In particular, usability can be further enhanced by using a non-contact electrode configuration in which the sensor device is worn over clothing using cloth or metal electrodes that do not need to be attached to the human body. In particular, non-contact electrode configurations based on capacitive coupling are preferable because they allow high-frequency communication to pass through more easily.

[0024] Next, adjustment circuits 107a and 107b will be described. These circuits adjust the received FM signal by a constant factor, and can therefore be configured with operational amplifiers. Although it is possible to configure them by connecting operational amplifiers in multiple stages, the more stages connected, the greater the accumulation of delay, making them more susceptible to instability. For this reason, it is preferable that each of adjustment circuits 107a and 107b be configured with a minimum of one stage of operational amplifier.

[0025] Next, the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b will be described. Because bioelectric potentials are very weak signals, signal amplification is required by the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b, which are configured with a filter circuit and an amplifier circuit using an operational amplifier. In particular, by using a non-inverting amplifier circuit, it is possible to realize a system configuration equivalent to that of an instrumentation amplifier with high common-mode suppression capabilities.

[0026] Furthermore, the amplification stages of the non-inverting amplifier circuits 102a and 102b require high input impedance to reduce bioelectric potential loss, but the non-inverting amplifier circuits 102a and 102b are less likely to increase noise even when configured with a high input impedance. On the other hand, in an inverting amplifier circuit, the resistor that determines the input impedance also affects the gain setting and contributes directly to thermal noise, lowering the S / N ratio. For this reason, a non-inverting amplifier circuit is effective.

[0027] In biopotential measurement, the potential difference between two electrodes is detected, so the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b require the same reference potential. Therefore, by using the potentials generated by the adjustment circuits 107a and 107b, balanced signal amplification between the first electrode device 100a and the second electrode device 100b is possible, and good biosignal information can ultimately be obtained.

[0028] Furthermore, the FM communication frequencies used when mutually coupling the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b must be different. This is because using the same frequency will cause mutual interference and the desired coupling will not be achieved. This is equivalent to dividing the band in communication, and by increasing the frequency used, the present invention can be used not only in configurations where electrode devices are paired, but also between a larger number of electrode devices.

[0029] Next, the wireless transmitters 104a and 104b will be described. For example, the wireless transmitter 104a can be configured as one communication module, and it is sufficient if it can establish a connection that allows it to receive the measured potential output from the quantization circuit 103a and transmit it to the biological signal generating device 130.

[0030] The wireless communication network 150 between the wireless transmitter 104a, wireless transmitter 104b, and wireless receiver 131 can be based on any standard, such as carrier communication, Wi-Fi (registered trademark), or Bluetooth (registered trademark) (Figure 2). It is necessary to select a transmitter and receiver that matches the communication standard. In the case of a short-range communication standard such as Bluetooth, a smartphone or other device close to the user (the human body being measured) can serve as the biosignal generating device 130. Furthermore, if Wi-Fi or other standards are used, a server or other device can serve as the biosignal generating device 130.

[0031] Furthermore, the function required for the biosignal generating device 130 is to receive signals from multiple electrode devices and calculate the target biopotential. These functions can be implemented (built-in) in one of the electrode devices without using the biosignal generating device 130 (FIG. 3). In this case, as shown in FIG. 3, the second electrode device 100b includes a wireless receiver 104b', and a biosignal generating device 130a including a calculation circuit 132 and a memory 133 is added.

[0032] The wireless receiver 104b' of the second electrode device 100b receives the biopotential information transmitted from the first electrode device 100a and calculates it together with the biopotential information of the second electrode device 100b to determine the biopotential. The determined biopotential is stored in the memory 133 of the second electrode device 100b, enabling the same functions and effects as described above to be achieved. In addition, this configuration does not require a separate biosignal generating device 130, so there is no need to carry a smartphone or other device, allowing for more flexible measurement by the user.

[0033] [Embodiment 2] Next, a biosignal measurement system according to embodiment 2 of the present invention will be described with reference to Fig. 4. This system includes two first electrode devices 100a', a second electrode device 100b', and a biosignal generating device 130.

[0034] The first electrode device 100a' includes an electrode 101a, a non-inverting amplifier circuit 102a, a quantization circuit 103a, a wireless transmitter 104a, an FM transmitter 105a, an FM receiver 106a, an adjustment circuit 107a, and a power supply 108a. The second electrode device 100b includes an electrode 101b, a non-inverting amplifier circuit 102b, a quantization circuit 103b, a wireless transmitter 104b, an FM transmitter 105b, an FM receiver 106b, an adjustment circuit 107b, and a power supply 108b. The biosignal generating device 130 includes a wireless receiver 131, an arithmetic circuit 132, and a memory 133. These configurations are the same as those in the first embodiment.

[0035] In the second embodiment, FM communication is performed using the human body as a communication channel. The FM transmitter 105a converts the voltage signal output from the output terminal of the non-inverting amplifier circuit 102a into an FM signal and transmits the converted FM signal to the second electrode device 100b via the transmitting electrode 109a', using the human body as a channel. The FM receiver 106a converts the FM signal, which is transmitted from the second electrode device 100b to the first electrode device 100a using the human body as a channel and received by the receiving electrode 110a', into a voltage signal and outputs it.

[0036] The FM transmitter 105b converts the voltage signal output from the output terminal of the non-inverting amplifier circuit 102b into an FM signal and transmits the converted FM signal to the first electrode device 100a via the transmitting electrode 109b', using the human body as a channel. The FM receiver 106b converts the FM signal, which is transmitted from the first electrode device 100a to the second electrode device 100b using the human body as a channel and received by the receiving electrode 110b', into a voltage signal and outputs it.

[0037] As described above, FM communication via the human body has the advantages of reducing delay and power consumption, and since the human body functions as a waveguide, it is possible to confine radio waves, making them resistant to external interference and reducing the risk of causing external interference. Even when transmitting through the human body, the FM signal transmitted from the first electrode device 100a to the second electrode device 100b and the FM signal transmitted from the second electrode device 100b to the first electrode device 100a have different frequencies. By using a frequency band ranging from several MHz to 100 MHz, loss can be reduced due to the electrical properties of the human body.

[0038] In this example, for example, the first electrode device 100a' uses three electrodes: electrode 101a, transmitting electrode 109a', and receiving electrode 110a'. However, since each electrode has a different frequency, it is possible to configure it with a single electrode by providing a bandpass filter, which has the effect of improving user comfort by reducing the number of parts that come into contact with the human body.

[0039] [Embodiment 3] Next, a biosignal measurement system according to embodiment 3 of the present invention will be described with reference to Fig. 5. This system includes two first electrode devices 100a'', a second electrode device 100b'', and a biosignal generating device 130.

[0040] In the third embodiment, the FM transmitter is configured with voltage-controlled oscillators (VCO 105a', VCO 105b'), and the FM receiver is configured with phase-locked loops (PLL 106a', PLL 106b'). The other configurations are the same as those in the second embodiment.

[0041] As shown in the second embodiment, in a configuration where FM communication is performed using the human body as a communication channel, delay-related parameters may fluctuate significantly. Therefore, it is necessary to use a device that has minimal delay during transmission and reception, especially in FM communication. As an example, the FM transmitter is configured with a voltage-controlled oscillator, and the output frequency is directly modulated by voltage. The FM receiver is configured with a phase-locked loop circuit and employs a direct detection method.

[0042] When using the human body as a communication channel, a high signal-to-noise ratio can be expected due to the radio wave confinement effect. Therefore, when using the human body as a channel, a configuration with low delay is more effective than high-precision demodulation. Delay can be effectively reduced by configuring the FM transmitter with a voltage-controlled oscillator and the FM receiver with a phase-locked loop.

[0043] By configuring an FM transmitter from a voltage-controlled oscillator and an FM receiver from a phase-locked loop, delay can be reduced. However, when using direct detection and direct modulation, matching the voltage-to-frequency conversion characteristics between the voltage-controlled oscillator in the FM transmitter and the voltage-controlled oscillator in the phase-locked loop in the FM receiver is essential for error-free communication. However, voltage-controlled oscillators generally use LC resonance with variable capacitance diodes called varactors, or oscillation by ring oscillators. Due to manufacturing variations in these elements, there are cases where the voltage-to-frequency conversion characteristics do not match between the voltage-controlled oscillator in the FM transmitter and the voltage-controlled oscillator in the phase-locked loop in the FM receiver.

[0044] As an example of a case where the voltage-to-frequency conversion characteristics do not match, such as when the center frequencies do not match, adjustment can be made by adding an offset to the operational amplifier in the adjustment circuit so that the voltage-frequency characteristics of the voltage-controlled oscillator constituting the FM transmitter of the other electrode device and the voltage-controlled oscillator of the phase-locked loop circuit of the own electrode device match. For example, the offset can be determined by the input voltage to the operational amplifier. In this way, when FM communication is employed, adjustment is possible without increasing delay.

[0045] In addition, as an example of a case where the voltage-frequency conversion characteristics do not match, if the slopes of the voltage-frequency characteristics do not match, the respective oscillation frequency characteristics can be monitored, and the amplification conditions of the operational amplifier in the adjustment circuit can be adjusted so that the voltage-frequency characteristics of the voltage-controlled oscillator constituting the FM transmitter of the other electrode device and the voltage-controlled oscillator of the phase-locked loop circuit of the own electrode device match, thereby making it possible to adjust the voltage-frequency characteristics without increasing the delay. For example, the amplification conditions of the operational amplifier can be adjusted by making the resistance value of the operational amplifier variable.

[0046] As described above, by appropriately adjusting the conditions of the operational amplifier in the adjustment circuit, it is possible to cover the weaknesses of FM communication using a voltage-controlled oscillator and a phase-locked loop, and the above-mentioned configuration is particularly preferable when using the human body as a communication channel.

[0047] As described above, according to the present invention, two electrode devices are connected to a biosignal generating device via wireless communication, and the two electrode devices are connected via FM communication, so that even if the wiring between the two electrodes is cut and the device is divided into two devices, bioelectric potentials can be easily measured.

[0048] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention.

[0049] 100a...first electrode device, 100b...second electrode device, 101a, 101b...electrodes, 102a, 102b...non-inverting amplifier circuit, 103a, 103b...quantization circuit, 104a, 104b...wireless transmitter, 105a, 105b...FM transmitter, 106a, 106b...FM receiver, 107a, 107b...adjustment circuit, 108a, 108b...power supply, 109a, 109b...transmitting antenna, 110a, 110b...receiving antenna, 130...biological signal generating device, 131...wireless receiver, 132...arithmetic circuit, 133...memory.

Claims

1. Comprising two electrode devices and a biological signal generating device, Each of the two electrode devices An electrode for measuring the bioelectric potential in the human body to be targeted, Comprising a non-inverting input terminal, an inverting input terminal, and an output terminal, and an amplifier circuit that amplifies the bioelectric potential input to the non-inverting input terminal via the electrode and outputs an amplified signal from the output terminal, A quantization circuit that converts the amplified signal output from the output terminal of the amplifier circuit into digital data to generate bioelectric potential information, A wireless transmitter that transmits the bioelectric potential information to the biological signal generating device, An FM transmitter that converts the amplified signal output from the output terminal of the amplifier circuit into an FM signal and transmits it to the other electrode device, An FM receiver that receives the other FM signal transmitted from the other electrode device, converts the received other FM signal into a voltage signal, and outputs it, An adjustment circuit that adjusts the voltage signal output from the FM receiver under set conditions and outputs the voltage signal adjusted under the set conditions as an adjustment signal to the inverting input terminal of the amplifier circuit, And a power supply that supplies power to the amplifier circuit, the quantization circuit, the wireless transmitter, the FM transmitter, the FM receiver, and the adjustment circuit Comprising, The FM signals transmitted from one of the two electrode devices to the other and the FM signals transmitted from the other to one have different frequencies respectively, The biological signal generating device A wireless receiver that receives the bioelectric potential information transmitted from each of the two electrode devices, And an arithmetic circuit that generates a biological signal waveform using the bioelectric potential information received by the wireless receiver A biological signal measurement system characterized by having.

2. In the biological signal measurement system according to Claim 1, The FM communication between the FM transmitter and the FM receiver is performed using the human body as a communication channel. A biological signal measurement system characterized by this.

3. In the biological signal measurement system according to Claim 1, One of the two electrode devices incorporates the biological signal generating device A biological signal measurement system characterized by this.

4. In the biological signal measurement system according to Claim 1, The arithmetic circuit generates an electrocardiogram signal waveform using the two pieces of bioelectric potential information transmitted from each of the two electrode devices attached to any two locations of the limbs of the human body A biological signal measurement system characterized by this.

5. In the biological signal measurement system according to any one of claims 1 to 4, the FM transmitter is composed of a voltage-controlled oscillator, and the FM receiver is composed of a phase-locked loop circuit characterizing the biological signal measurement system.

6. In the biological signal measurement system according to claim 5, the adjustment circuit has an operational amplifier, and at least one of changing the amplification condition of the operational amplifier and adding an offset is performed so that the voltage-frequency characteristics of the voltage-controlled oscillator of the other electrode device and the voltage-frequency characteristics of the voltage-controlled oscillation unit of the phase-locked loop circuit of the self-electrode device match each other characterizing the biological signal measurement system.