Biosignal measurement system

Abstract

This biosignal measurement system is provided with two first electrode device (100a) and second electrode device (100b), a right foot drive device (120), and a biosignal generation device (130). The biosignal generation device (130) is provided with a midpoint potential calculation circuit (134) that uses biopotential information that has been transmitted respectively from the two first electrode device (100a) and second electrode device (100b) and received by a first wireless receiver (131) to determine a midpoint potential and a second wireless transmitter (135) that wirelessly transmits the midpoint potential to the right foot drive device (120), wherein the right foot drive device (120) includes: a second wireless receiver (121) that receives the midpoint potential transmitted from the second wireless transmitter (135); an amplification circuit (122) that amplifies the midpoint potential received by the second wireless receiver (121); and a second electrode (123) that applies to a human body the midpoint potential amplified by the amplification circuit (122).

Description

Technical Field

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

Background Art

[0002] In the measurement of an electrocardiogram, which is one of the measurements of bioelectric potential, the potential difference between electrodes arranged on both the left and right sides of the human body is measured. For example, as shown in FIG. 5, a measurement system has been proposed in which a device 301 is attached to the central part of the body, and wiring 303 is allowed to crawl on compression wear 302 to provide electrodes 304 that contact the left and right waist parts (Non-Patent Document 1).

[0003] In addition, in bioelectric potential measurement, the removal of common-mode noise is an important factor for stable operation. As shown in FIG. 6, a Right Leg Drive (RLD) circuit that feeds back the midpoint potential 401 of the differential voltage and controls it to an arbitrary voltage is often implemented (Non-Patent Document 2).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, attaching the device to the torso causes discomfort due to pressure and is cumbersome to attach, leading to aversion. Attaching it to the limbs, for example, is another possibility. However, in this case, the wiring connecting the left and right electrodes forms a handcuff-like loop, resulting in a strong restriction on body movement. These problems could be solved by cutting the wiring between the left and right electrodes and splitting the device into two, but this would make it difficult to establish a reference point for potential measurement, thus hindering bioelectric potential measurement. Furthermore, right-foot drive devices, as the name suggests, are often attached to the right foot, further increasing the amount of wiring that runs along the body, inducing discomfort.

[0006] This invention was made to solve the above-mentioned problems, and aims to enable easy measurement of biopotential even when the wiring between the two electrodes and the right foot drive device is cut and the device is divided into three devices. [Means for solving the problem]

[0007] The biosignal measurement system according to the present invention comprises two electrode devices, a right foot drive device, and a biosignal generation device. Each of the two electrode devices includes a first electrode for measuring the biopotential in the target human body, a non-inverting amplifier circuit that inputs the measured biopotential to a non-inverting amplifier terminal, amplifies it, and outputs it from an output terminal, a quantization circuit that converts the amplified signal output from the output terminal of the non-inverting amplifier circuit into digital data to generate biopotential information, a first wireless transmitter that transmits the biopotential information to the biosignal generation device, an FM transmitter that converts the voltage signal output from the output terminal of the non-inverting amplifier circuit into an FM signal and transmits it to the other electrode device, an FM receiver that receives the FM signal transmitted from the other electrode device to its own electrode device, converts it into a voltage signal, and outputs it, and an adjustment circuit that outputs the voltage signal output from the FM receiver as an adjustment signal adjusted under set conditions to the inverting input terminal of the non-inverting amplifier circuit, and non-inverting The biosignal generation device comprises a power supply that provides power to an amplification circuit, a quantization circuit, a first wireless transmitter, an FM transmitter, an FM receiver, and an adjustment circuit, wherein the FM signals transmitted from one of the two electrode devices to the other and the FM signals transmitted from the other to the first each have different frequencies, and the biosignal generation device comprises a first wireless receiver that receives biopotential information transmitted from each of the two electrode devices, a calculation circuit that generates a biosignal waveform using the biopotential information received by the first wireless receiver, a midpoint potential calculation circuit that determines the midpoint potential from the biopotential information transmitted from each of the two electrode devices received by the first wireless receiver, and a second wireless transmitter that wirelessly transmits the midpoint potential to a right foot drive device, and the right foot drive device comprises a second wireless receiver that receives the midpoint potential transmitted from the second wireless transmitter, an amplification circuit that amplifies the midpoint potential received by the second wireless receiver, and a second electrode that applies the midpoint potential amplified by the amplification circuit to the human body. [Effects of the Invention]

[0008] As described above, according to the present invention, since the two electrode devices and the biosignal generating device are connected by wireless communication, the two electrode devices are connected by FM communication, and the right foot drive device and the biosignal generating device are connected by wireless communication, the biopotential can be easily measured even if the wiring between the two electrodes and the right foot drive device is cut and the device is divided into three devices. [Brief explanation of the drawing]

[0009] [Figure 1A] Figure 1A is a diagram showing the configuration of a biosignal measurement system according to Embodiment 1 of the present invention. [Figure 1B] Figure 1B is a diagram showing a partial configuration of a biosignal measurement system according to Embodiment 1 of the present invention. [Figure 2] Figure 2 is an explanatory diagram illustrating the concept of a biosignal measurement system according to Embodiment 1 of the present invention. [Figure 3] Figure 3 is a configuration diagram showing the configuration of another biosignal measurement system according to Embodiment 1 of the present invention. [Figure 4] Figure 4 is a diagram showing the configuration of a biosignal measurement system according to Embodiment 2 of the present invention. [Figure 5] Figure 5 is a diagram showing the configuration of a conventional biosignal measurement system. [Figure 6] Figure 6 is a diagram showing the configuration of a conventional biosignal measurement system using a right foot drive device. [Modes for carrying out the invention]

[0010] The following describes a biological signal measurement system according to an embodiment of the present invention.

[0011] [Embodiment 1] First, a biosignal measurement system according to Embodiment 1 of the present invention will be described with reference to Figures 1A and 1B. This system comprises two first electrode devices 100a, a second electrode device 100b, a right foot drive device 120, and a biosignal generation device 130.

[0012] The first electrode device 100a comprises an electrode 101a for measuring the biopotential in the target human body, a non-inverting amplifier circuit 102a that inputs the measured biopotential to a non-inverting amplifier terminal, amplifies it, and outputs it from an output terminal, a quantization circuit 103a that converts the amplified signal output from the output terminal of the non-inverting amplifier circuit 102a into digital data to generate biopotential information, and a first wireless transmitter 104a that transmits the biopotential information to a biosignal generation device 130.

[0013] Furthermore, the first electrode device 100a includes an FM transmitter 105a, an FM receiver 106a, and an adjustment circuit 107a. 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 antenna 109a. The FM receiver 106a converts the FM signal transmitted from the second electrode device 100b to the first electrode device 100a and received by the receiving antenna 110a into a voltage signal and outputs it. The adjustment circuit 107a 、F The voltage signal output from the M receiver 106a is adjusted according to the set conditions and output as an adjusted signal to the inverting input terminal of the non-inverting amplifier circuit 102a.

[0014] The output of the non-inverting amplifier circuit 102a is also input to the inverting input terminal. For example, as shown in Figure 1B, if the signal input from the adjustment circuit 107a to the inverting input terminal of the non-inverting amplifier circuit 102a is Vdev2, and the output of the non-inverting amplifier circuit 102a is Vout1, then the signals are mixed in the ratio 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, which will be described later.

[0015] Furthermore, the first electrode device 100a includes a power supply 108a that supplies power to the non-inverting amplifier circuit 102a, the quantization circuit 103a, the first wireless transmitter 104a, the FM transmitter 105a, the FM receiver 106a, and the adjustment circuit 107a.

[0016] The second electrode device 100b first includes an electrode 101b for measuring a bioelectric potential in a target human body, a non-inverting amplifier circuit 102b that inputs the measured bioelectric potential to a non-inverting amplification terminal, amplifies it, and outputs it from an output terminal, and a quantization circuit 103b that converts an amplified signal output from the output terminal of the non-inverting amplifier circuit 102b into digital data to generate bioelectric potential information, and a first wireless transmitter 104b that transmits the bioelectric potential information to the bioelectric signal generation device 130.

[0017] Further, the second electrode device 100b 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 by a transmission 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 reception antenna 110b into a voltage signal and outputs it. The adjustment circuit 107b outputs a voltage signal output from the FM receiver 106b as an adjustment signal adjusted under set conditions to an inverting input terminal of the non-inverting amplifier circuit 102b.

[0018] Further, the second electrode device 100b includes a power supply 108b that supplies power to the non-inverting amplifier circuit 102b, the quantization circuit 103b, the first wireless transmitter 104b, the FM transmitter 105b, the FM receiver 106b, and the adjustment circuit 107b.

[0019] 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 respectively.

[0020] The biosignal generator 130 includes a first wireless receiver 131 that receives biopotential information transmitted from the first electrode device 100a and the second electrode device 100b, and a calculation circuit 132 that generates a biosignal waveform using the biopotential information received by the first wireless receiver 131. The calculation circuit 132 can generate an electrocardiogram waveform using, for example, two pieces of biopotential information transmitted from the first electrode device 100a and the second electrode device 100b, which are attached to any two locations on the limbs of the human body. The biosignal generator 130 also includes a memory 133 that stores the biosignal waveform generated by the calculation circuit 132.

[0021] Furthermore, the biosignal generating device 130 includes a midpoint potential calculation circuit 134 that calculates the midpoint potential from biopotential information transmitted from each of the two first electrode devices 100a and second electrode devices 100b, which is received by the first wireless receiver 131, and a second wireless transmitter 135 that wirelessly transmits the midpoint potential to the right foot drive device 120.

[0022] The right foot drive device 120 includes a second wireless receiver 121 that receives a midpoint potential transmitted from a second wireless transmitter 135, an amplification circuit 122 that amplifies the midpoint potential received by the second wireless receiver 121, and a second electrode 123 that applies the midpoint potential amplified by the amplification circuit 122 to the human body.

[0023] Figure 2 shows the concept of the biosignal measurement system according to Embodiment 1. The biosignal generator 130 determines the midpoint potential from the biopotential information measured by the first electrode device 100a and the second electrode device 100b attached to the human body 140. The determined midpoint potential is fed back by wirelessly transmitting it to the right foot drive device 120 attached to the human body 140. As a result, it is possible to measure biopotential stably while preventing the induction of discomfort due to increased wiring. With this configuration, it is possible to suppress common-mode noise, thus enabling stable biopotential measurement.

[0024] 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 coupled together. Since this configuration is similar to that of an oscillator circuit, the phase rotation and amplification caused by the delay of the coupled signals will cause oscillation if the phase rotation is 180 degrees and the amplification is 1 or greater.

[0025] For example, when constructing a non-inverting amplifier circuit with a bandwidth of DC to 1kHz, which is typical for biological signals, a delay of 0.1ms results in a 36-degree phase rotation for a 1kHz signal. In other words, a delay of 0.5ms results in a 180-degree phase rotation, so the possibility of oscillation cannot be ruled out. For this reason, in the coupling of the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b described above, it is necessary to minimize the delay in the part that couples the voltage signal.

[0026] Next, electrodes 101a and 101b will be described. Various types of electrodes can be used for these electrodes, including Ag / AgCl electrodes used in medical applications, conductive cloth electrodes, metal electrodes, and any other suitable material. In particular, by using cloth or metal electrodes that do not need to adhere to the human body and creating a non-contact electrode configuration in which the sensor device can be attached over clothing, usability can be further enhanced. For non-contact electrode configurations, capacitive coupling is particularly preferable because it allows for easier transmission of high-frequency signals.

[0027] Next, adjustment circuits 107a and 107b will be described. Faith FM signal of Since this section primarily performs adjustments by a constant factor, it can be constructed using operational amplifiers. While it is possible to construct it using multiple operational amplifiers connected in stages, the delay accumulates with each additional stage, making it prone to instability. For this reason, it is preferable to construct each of the adjustment circuits 107a and 107b from a single operational amplifier, which is the minimum configuration.

[0028] Next, we will describe the non-inverting amplifier circuits 102a and 102b. Since bioelectric potential is a very weak signal, signal amplification is necessary using non-inverting amplifier circuits 102a and 102b, which are composed of filter circuits and operational amplifier amplification circuits. In particular, by using non-inverting amplifier circuits, it is possible to achieve a system configuration equivalent to an instrumentation amplifier with high common-mode suppression capability.

[0029] Furthermore, while high input impedance is required in the amplification stages of non-inverting amplifier circuits 102a and 102b to reduce bioelectric potential loss, the noise does not increase significantly even with a high input impedance configuration. On the other hand, in inverting amplifier circuits, the resistor that determines the input impedance also affects the gain setting and contributes directly as thermal noise, thus reducing the signal-to-noise ratio. For this reason, non-inverting amplifier circuits are effective.

[0030] In biopotential measurement, the potential difference between two electrodes is detected, so the same reference potential is required in non-inverting amplifier circuits 102a and 102b. Therefore, by using the potential generated by adjustment circuits 107a and 107b, balanced signal amplification becomes possible between the two first electrode devices 100a and the second electrode device 100b, ultimately yielding good biosignal information.

[0031] Furthermore, the FM communication frequencies used to couple the non-inverting amplifier circuit 102a and the non-inverting amplifier circuit 102b must be different. This is because using the same frequency would cause mutual interference, preventing the desired coupling from being achieved. This is equivalent to dividing the bandwidth in communication, and by increasing the frequency used, the present invention can be used not only with a pair of electrode devices but also with a larger number of electrode devices.

[0032] Next, the first wireless transmitters 104a and 104b will be described. For example, the first wireless transmitter 104a can be composed of a single communication module, and it is sufficient that it can receive the measured potential output from the quantization circuit 103a and transmit it to the biosignal generation device 130.

[0033] The wireless communication network standard between the first wireless transmitters 104a and 104b and the first wireless receiver 131 can be any standard, such as carrier communication, Wi-Fi (registered trademark), or Bluetooth (registered trademark). The transmitter and receiver must be selected according to the communication standard. With short-range communication standards such as Bluetooth, the biosignal generator 130 can be a smartphone or other device close to the user, which is the human body being measured. Alternatively, if Wi-Fi or similar standards are used, a server can be used as the biosignal generator 130.

[0034] Furthermore, the function required of the biosignal generator 130 is to receive signals from multiple electrode devices and calculate the target biopotential. These functions can be implemented (built into) any of the electrode devices without using the biosignal generator 130. In this case, for example, the second electrode device 100b would be equipped with a biosignal generator that includes a calculation circuit, memory, midpoint potential calculation circuit, and second wireless transmitter.

[0035] In this configuration, the second electrode device 100b is equipped with a first wireless receiver instead of the first wireless transmitter. It receives biopotential information transmitted from the first electrode device 100a and calculates the biopotential by combining it with the biopotential information from the second electrode device 100b. The midpoint potential is calculated using a midpoint potential calculation circuit, and the calculated midpoint potential is wirelessly transmitted to the right foot drive device 120 by the second wireless transmitter. The calculated biopotential is stored in the memory 133 of the second electrode device 100b, enabling the same functions and effects as described above. In addition, this configuration does not require a separate biosignal generator 130, eliminating the need to carry a smartphone or other device, thus enabling more user-unrestricted measurements.

[0036] Furthermore, the second wireless transmitter can transmit a midpoint potential to the second wireless receiver via FM communication. This configuration will be explained with reference to Figure 3. As shown in Figure 3, the biosignal generator 130' teeth, The midpoint potential calculated by the midpoint potential calculation circuit 134 is transmitted to the right foot drive device 120' by the FM transmitter 135a, and the right foot drive device 120' receives the transmitted midpoint potential with the FM receiver 121a. The other configurations are the same as described above.

[0037] Furthermore, at least one of the communication between the two electrode devices and the communication between the biosignal generating device and the right foot drive device can use the human body as a communication channel. In this case, in the electrode devices, for example, a transmitting electrode can be used instead of a transmitting antenna, and a receiving electrode can be used instead of a receiving antenna.

[0038] By performing FM communication via the human body, delays and power consumption are reduced, and because the human body functions as a waveguide, radio waves can be confined, making it 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 shall have different frequencies. By using a frequency band of several MHz to approximately 100 MHz, based on the electrical properties of the human body, losses can be minimized.

[0039] Furthermore, when the human body is used as a communication channel, the electrode device uses three electrodes: a first electrode, a transmitting electrode, and a receiving electrode. However, since each electrode has a different frequency, it is possible to use a single electrode by providing a bandpass filter, which reduces the area that comes into contact with the human body and thus improves user comfort.

[0040] Furthermore, when the human body is used as a communication channel, the impedance of the body changes, and the degree of contact between the electrodes and the body also changes. For this reason, methods such as AM and PM modulation cannot escape the generation of noise due to amplitude fluctuations. In contrast, with FM communication, noise related to amplitude does not affect the output. In other words, FM communication is suitable for cases where the human body is used as a communication channel.

[0041] [Embodiment 2] Next, a biosignal measurement system according to Embodiment 2 of the present invention will be described with reference to Figure 4. This system comprises two first electrode devices 100a', a second electrode device 100b', a right foot drive device 120'', and a biosignal generation device 130 ” It is equipped with.

[0042] In Embodiment 2, the FM transmitter is composed of voltage-controlled oscillators (VCO105a', VCO105b', VCO135b), and the FM receiver is composed of phase-locked circuits (PLL106a', PLL106b', PLL121b). The other components are the same as those described above when the human body is used as the channel, and in Embodiment 2, transmitting electrodes 109a', transmitting electrode 109b', receiving electrodes 110a', and receiving electrode 110b' are used.

[0043] In the configuration described in Embodiment 1, which realizes FM communication using the human body as a communication channel, delay parameters may fluctuate significantly. Therefore, it is necessary to use devices with particularly low delay during transmission and reception within FM communication. As an example, first, the FM transmitter is configured from a voltage-controlled oscillator to directly modulate the output frequency with voltage. Furthermore, the FM receiver is configured from a phase-locked circuit and uses a direct detection method.

[0044] When the human body is used as a communication channel, a high signal-to-noise ratio (SNR) can be expected due to the confinement effect of radio waves. Therefore, when using the human body as a channel, it is more effective to use a configuration with low delay than to use highly accurate demodulation. By configuring the FM transmitter from a voltage-controlled oscillator and the FM receiver from a phase-locked circuit, delay can be effectively reduced.

[0045] By the way, by configuring the FM transmitter from a voltage-controlled oscillator and the FM receiver from a phase-locked circuit... 、 While delay can be reduced, when employing direct detection and direct modulation, it is essential for low-error communication that the voltage-to-frequency conversion characteristics of the voltage-controlled oscillator constituting the FM transmitter and the voltage-controlled oscillator included in the phase-locked circuit constituting the FM receiver match. However, voltage-controlled oscillators generally use LC resonance with a variable capacitance diode called a varactor, or oscillation using a ring oscillator. Due to manufacturing variations in these components, it is possible that the voltage-to-frequency conversion characteristics of the voltage-controlled oscillator constituting the FM transmitter and the voltage-controlled oscillator included in the phase-locked circuit constituting the FM receiver do not match.

[0046] 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 is possible 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 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, adjustment can be made without increasing the delay when FM communication is employed.

[0047] Furthermore, in cases where the voltage-to-frequency conversion characteristics do not match, such as when the slopes of the voltage-frequency characteristics do not match, it is possible to adjust the voltage-frequency characteristics of the operational amplifier in the adjustment circuit without increasing the delay by monitoring the respective oscillation frequency characteristics and adjusting the amplification conditions of 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 circuit of the own electrode device match. For example, the amplification conditions of the operational amplifier can be adjusted by making the resistance value of the operational amplifier variable.

[0048] As described above, by appropriately adjusting the conditions of the operational amplifier in the adjustment circuit, it is possible to overcome the weaknesses of FM communication using a voltage-controlled oscillator and a phase-locked circuit. In particular, when using the human body as a communication channel, the above configuration is preferable.

[0049] As described above, according to the present invention, since the two electrode devices and the biosignal generating device are connected by wireless communication, the two electrode devices are connected by FM communication, and the right foot drive device and the biosignal generating device are connected by wireless communication, even if the wiring between the two electrodes and the right foot drive device is cut and the device is divided into three devices, the biopotential can be easily measured.

[0050] 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 implemented within the technical concept of the present invention by those with ordinary skill in the art. [Explanation of Symbols]

[0051] 100a...First electrode device, 100b...Second electrode device, 101a,101b...Electrodes, 102a,102b...Non-inverting amplifier circuit, 103a,103b...Quantization circuit, 104a,104b...First 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, 120...Right foot drive device, 121...Second wireless receiver, 123...Second electrode, 130...Biosignal generation device, 131...First wireless receiver, 132...Calculation circuit, 133...Memory, 134...Midpoint potential calculation circuit, 135...Second wireless transmitter.

Claims

1. It comprises two electrode devices, a right foot drive device, and a biosignal generation device. Each of the two electrode devices is A first electrode for measuring the bioelectric potential in the target human body, A non-inverting amplifier circuit that inputs the measured biopotential to a non-inverting amplifier terminal, amplifies it, and outputs it from the output terminal, A quantization circuit that converts the amplified signal output from the output terminal of the non-inverting amplifier circuit into digital data to generate biopotential information, A first wireless transmitter that transmits the biopotential information to the biosignal generating device, An FM transmitter that converts the voltage signal output from the output terminal of the non-inverting amplifier circuit into an FM signal and transmits it to the other electrode device, An FM receiver that receives an FM signal transmitted from another electrode device to its own electrode device, converts it into a voltage signal, and outputs it, An adjustment circuit outputs to the inverting input terminal of the non-inverting amplifier circuit as an adjustment signal for adjusting the voltage signal output from the FM receiver by a constant multiple under set conditions, A power supply that provides power to the non-inverting amplifier circuit, the quantization circuit, the first wireless transmitter, the FM transmitter, the FM receiver, and the adjustment circuit. Equipped with, The FM signal transmitted from one of the two electrode devices to the other, and the FM signal transmitted from the other to the first, each have different frequencies. The aforementioned biosignal generating device is A first wireless receiver that receives the biopotential information transmitted from each of the two electrode devices, A calculation circuit that generates a biosignal waveform using the biopotential information received by the first wireless receiver, A midpoint potential calculation circuit that calculates the midpoint potential from the biopotential information transmitted from each of the two electrode devices received by the first wireless receiver, A second wireless transmitter wirelessly transmits the midpoint potential to the right foot drive device. Equipped with, The right foot drive device includes a second wireless receiver that receives the midpoint potential transmitted from the second wireless transmitter, An amplification circuit that amplifies the midpoint potential received by the second wireless receiver, A second electrode applies the midpoint potential amplified by the aforementioned amplification circuit to the human body. A biosignal measurement system characterized by having the following features.

2. In the biological signal measurement system according to claim 1, A biosignal measurement system characterized in that the second wireless transmitter transmits the midpoint potential to the second wireless receiver via FM communication.

3. In the biological signal measurement system according to claim 1, One of the two electrode devices incorporates the biosignal generating device. A biosignal measurement system characterized by the following features.

4. In the biological signal measurement system according to claim 1, A biosignal measurement system characterized in that at least one of the communication between the two electrode devices and the communication between the biosignal generating device and the right foot driving device uses the human body as a communication channel.

5. In the biological signal measurement system according to claim 1, The FM transmitter is composed of a voltage-controlled oscillator. The aforementioned FM receiver is composed of a phase-locking circuit. A biosignal measurement system characterized by the following features.

6. In the biosignal measurement system according to claim 5, The adjustment circuit includes an operational amplifier, which modifies the amplification conditions of the operational amplifier and applies an offset to the operational amplifier so that the voltage-frequency characteristics of the voltage-controlled oscillator of the other electrode device and the voltage-controlled oscillator section of the phase-locking circuit of the own electrode device match, based on the voltage signal input by the operational amplifier from the phase-locking circuit. A biosignal measurement system characterized by the following features.

7. In the biosignal measurement system according to any one of claims 1 to 6, The calculation circuit generates an electrocardiogram waveform using two biopotential information signals transmitted from each of the two electrode devices attached to any two locations on the limbs of the human body. A biosignal measurement system characterized by the following features.

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