Biosignal Measurement System

Abstract

This biosignal measurement system (10) that is an invention of the present application is provided with: a plurality of electrode devices (20, 30) each including an electrode (21, 31) for measuring a biopotential, an amplifier circuit (22, 32) for amplifying the measured biopotential, a quantization circuit (23, 33) for converting the amplified biopotential to digital data to generate biopotential information, and a radio transmitter (24, 34) for transmitting the biopotential information; and a biosignal generation device (40) for generating a biosignal waveform by using the biopotential information transmitted from each of the electrode devices (20, 30). According to this configuration, it becomes possible to eliminate uncomfortable feeling in a wearer of an electrode device and the restraint of the body of the wearer during the wearing of the electrode device, and therefore it becomes possible to measure a biosignal naturally.

Description

[Technical Field]

[0001] The present invention relates to a biosignal measurement system for measuring biosignals such as electrocardiogram waveforms. [Background technology]

[0002] In recent years, one of the methods for managing personal health is to record biosignals such as electrocardiogram waveforms over a long period of time and analyze the characteristics and changes of the waveforms to detect the activity of the autonomic nervous system and early signs of heart disease.As a method for acquiring biosignals such as electrocardiogram waveforms over a long period of time, wearable electrodes in which bioelectrodes are attached to clothing have been proposed (see, for example, Non-Patent Document 1).

[0003] An electrocardiogram, which is one type of biosignal, requires measuring the potential difference between electrodes placed on both the left and right sides of the heart. As shown in Figure 7, the wearable electrode 100 in Non-Patent Document 1 has a device 400 that measures bioelectric potentials worn around the center of the torso, and electrodes (200, 300) that are wired over compression wear and come into contact with the left and right waist regions. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Naoko Kasai, Takayuki Ogasawara, Hiroshi Nakajima, Shingo Tsukada, "Development and Practical Application of Hitoe, a Functional Material that Enables Biometric Measurement Simply by Wearing It," IEICE Communications Society Magazine, Vol. 11, No. 1, pp. 17-23, Published June 1, 2017 Summary of the Invention [Problem to be solved by the invention]

[0005] When bioelectrodes are attached to the torso through clothing, the effort required for attachment can be irritating to the wearer, and the pressure of the clothing can be uncomfortable for the wearer. When electrodes are attached to a location other than the torso, for example, to the limbs, the wiring connecting the left and right electrodes forms a loop like handcuffs, which restricts the wearer's physical movement and creates a strong constraint.

[0006] The object of the present invention is to solve the above-mentioned problems and to provide a biosignal measurement system that can measure biosignals naturally by eliminating the discomfort and physical constraints that the wearer feels when wearing an electrode device. [Means for solving the problem]

[0007] In order to solve the above problems, the biosignal measurement system of the present invention comprises an electrode for measuring a biopotential, an amplifier circuit for amplifying the measured biopotential, a quantization circuit for converting the amplified biopotential into digital data to generate biopotential information, a wireless transmitter for transmitting the biopotential information, a plurality of electrode devices having a power source for supplying power to the amplifier circuit, the quantization circuit, and the wireless transmitter, a wireless receiver for receiving the biopotential information transmitted from the wireless transmitter of the electrode device, and a biosignal generating device having an arithmetic circuit for generating a biosignal waveform using the biopotential information from at least two of the plurality of electrode devices. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a biosignal measurement system that can measure biosignals naturally by eliminating the discomfort and physical constraints that the wearer feels when wearing an electrode device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a biological signal measurement system according to a first embodiment of the present invention. [Figure 2]FIG. 2 is a conceptual diagram of a biological signal measurement system according to an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of the configuration of a biological signal measurement system according to the second embodiment of the present invention. [Figure 4] FIG. 4 shows an example of a measurement circuit used in a conventional biosignal measurement system. [Figure 5] FIG. 5 is a diagram showing an example of the configuration of a biological signal measurement system according to the third embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing another example of the configuration of the biological signal measurement system according to the third embodiment of the present invention. [Figure 7] FIG. 7 shows an example of the configuration of a conventional biosignal measurement system. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0011] First Embodiment 1 is a diagram showing an example of the configuration of a biosignal measurement system according to a first embodiment of the present invention. The biosignal measurement system 10 of this embodiment includes a plurality of electrode devices (20, 30) that measure biopotentials, and a biosignal generating device 40 that generates a biosignal waveform using biopotential information from the plurality of electrode devices (20, 30).

[0012] The electrode device (20, 30) includes electrodes (21, 31) for measuring biopotentials, amplifier circuits (22, 32) for amplifying the measured biopotentials, quantization circuits (23, 33) for converting the amplified biopotentials into digital data to generate biopotential information, and wireless transmitters (24, 34) for transmitting the biopotential information, and has a power source (35) for supplying power to the amplifier circuits (22, 32), the quantization circuits (23, 33), and the wireless transmitters (24, 34).

[0013] The biosignal generating device 40 has a wireless receiver 41 that receives biopotential information transmitted from the wireless transmitters (24, 34) of the electrode devices (20, 30), an arithmetic circuit 42 that generates a biosignal waveform using the biopotential information from at least two of the multiple electrode devices, and a memory 43 that stores the generated biosignal waveform.

[0014] A conceptual diagram of a biosignal measurement system 10 according to this embodiment is shown in FIG. 2. For example, when generating an electrocardiogram as a biosignal, it is necessary to arrange multiple electrode devices in positions that sandwich the heart. A possible way to wear the electrode devices in a comfortable way for the wearer 1 is to wear the electrode devices in at least two places on the limbs, such as the hands and feet. By adopting such a wearing style of the electrode devices, it is possible to significantly reduce the feeling of pressure and discomfort caused by wearing clothing.

[0015] Each electrode device (20, 30) measures an in-phase component that appears as a noise component and an out-of-phase component that appears as a biopotential. The biopotential signals that can be measured by the electrodes (21, 31) of each electrode device (20, 30) are weak and have an extremely poor signal-to-noise ratio.

[0016] In the biosignal measurement system 10 according to this embodiment, a plurality of measured biopotential signals are transmitted to the biosignal generation device 40 via wireless communication, and a difference calculation is performed on the biopotential signals in the biosignal generation device 40. By performing the difference calculation, common-mode components that appear as noise components are removed to generate a biosignal, thereby improving the S / N ratio.

[0017] In the biosignal measurement system 10 of this embodiment, the transmission of biopotential information from multiple electrode devices (20, 30) that measure biopotentials to a biosignal generating device that generates biosignal waveforms is performed using wireless communication. This makes it possible to provide a biosignal measurement system that can measure biosignals naturally, eliminating the discomfort and physical constraints on the wearer caused by physical wiring when wearing electrode devices.

[0018] 2 illustrates the case where an electrocardiogram, which is one type of biosignal, is measured, but the biosignal measurement system of this embodiment is not limited to electrocardiogram measurement and can also be applied to measurement of other biosignals such as electromyograms and electroencephalograms. By applying the biosignal measurement system of this embodiment, it is possible to eliminate discomfort felt by the wearer due to the physical wiring of the electrode device, and it is also expected to have the effect of increasing the degree of freedom in electrode placement and broadening the range of gadgets that can be implemented.

[0019] The electrodes (21, 31) of the electrode devices (20, 30) can be made of various materials and have various configurations, including Ag / AgCl electrodes used in medical applications, conductive cloth electrodes, and metal electrodes.

[0020] In addition, usability can be further improved by using a non-contact electrode configuration in which electrodes are worn over clothing using cloth or metal electrodes that do not need to be directly attached to the wearer's body.

[0021] Since biopotential information is a very weak signal, it requires signal amplification using a filter circuit and an operational amplifier (22, 32). The amplifier circuits (22, 32) of the electrode devices (20, 30) require high input impedance to reduce loss of biopotential.

[0022] In an inverting amplifier circuit, the resistor that determines the input impedance also affects the gain setting and contributes directly to thermal noise, reducing the signal-to-noise ratio of the biopotential. On the other hand, a non-inverting amplifier circuit has the advantage that noise is less likely to increase even when configured with a high input impedance. It is effective to use a non-inverting amplifier circuit as the amplifier circuit (22, 32). By adopting a non-inverting amplifier circuit, it is possible to achieve a configuration equivalent to that of an instrumentation amplifier, which has a high ability to suppress common-mode components that appear as noise components in the system.

[0023] Any wireless standard can be used in the wireless transmitters (24, 34) of the electrode devices (20, 30), such as carrier communication, Wi-Fi (registered trademark), or Bluetooth (registered trademark). The biosignal generating device 40 that receives the biopotential information transmitted by the electrode devices (20, 30) can be selected according to the communication standard being used. When a short-range communication standard such as Bluetooth is used, a device carried by the wearer, such as a smartphone, can be used, and when a short-range communication standard such as Wi-Fi is used, a device such as a server can also be used.

[0024] One type of biosignal is the electrocardiogram signal waveform, known as the 12-lead electrocardiogram signal waveform, which is used for medical purposes. When measuring a 12-lead electrocardiogram signal waveform, electrodes are attached to 10 locations on the human body around the limbs and ribs, and the potential difference between multiple electrode pairs is measured. With this type of electrode arrangement, numerous cables get tangled around the wearer's body, causing significant discomfort to the wearer, so measurements are rarely taken in positions other than the recumbent position.

[0025] By applying the biosignal measurement system of this embodiment as a system for generating 12-lead electrocardiogram signal waveforms, it is possible to eliminate all of the numerous cables mentioned above. This eliminates the discomfort felt by the wearer due to the numerous cables, and makes it possible to measure 12-lead electrocardiogram signal waveforms at all times in daily life, which is expected to contribute to the advancement of medicine.

[0026] <Second embodiment> 3 is a diagram showing an example of the configuration of a biosignal measurement system according to a second embodiment of the present invention. The function required of the biosignal generating device 40 is to receive biopotential information transmitted from multiple electrode devices (20, 30) and generate a biosignal by arithmetic processing using the received biopotential information. As in the example configuration of FIG. 3, the function of the biosignal generating device 40 may be implemented in any of the electrode devices 30.

[0027] In the following explanation, the electrode device 30 that implements the functions of the biological signal generating device 40 is referred to as the parent device, and the electrode device 20 that transmits a signal of the measured potential to the parent device is referred to as the child device, and the operation of this embodiment is explained.

[0028] A wireless receiver 41 of the parent device receives information on the biopotential measured by the child device, and an arithmetic circuit 42 generates a biosignal using the information on the biopotential measured by the parent device and the information on the biopotential measured by the child device. The generated biosignal is stored in a memory 43 of the parent device and can be used when analyzing the biosignal, thereby achieving the same function as the biosignal generating device 40 of the first embodiment. In this embodiment, the biosignal generating device 40 is not required as a separate device from the electrode device, so there is no need to carry a device such as a smartphone, and biosignal measurement can be achieved with less restrictions on the user.

[0029] <Third embodiment> As explained in the first and second embodiments, usability is improved by using multiple electrode devices (20, 30) without physical wiring. However, since the electrode devices are not connected by physical wiring, a problem occurs in that the reference potentials in the amplifier circuits (22, 32) of each electrode device (20, 30) do not match. An instrumentation amplifier, as shown in Figure 4, is a measurement circuit commonly used in conventional systems that involve physical wiring.

[0030] In biosignal measurement, to detect the potential difference between biopotentials measured by multiple electrodes, it is necessary to amplify the difference between the two input potentials input to the input terminals of the differential amplifier circuit downstream of the instrumentation amplifier in Figure 4 while significantly suppressing the common-mode noise component input to the input terminals.To suppress this common-mode noise component, it is important that the inverting input terminals of the two non-inverting amplifier circuits in the amplification stage upstream of the instrumentation amplifier in Figure 4 are connected to each other, in other words, that the reference potential of the two non-inverting amplifier circuits is shared.

[0031] The potential at the connection point of the inverting input terminals of these two non-inverting amplifier circuits converges to the average value of the two input potentials and becomes the reference potential of the two non-inverting amplifier circuits. In the first embodiment, there is no physical wiring between the electrode devices (20, 30), and the inverting input terminals of the amplifier circuits (22, 32) of the electrode devices (20, 30) are not connected by physical wiring. Therefore, the reference potentials of the amplifier circuits (22, 32) of each electrode device (20, 30) may not match, which may result in a deterioration of measurement accuracy.

[0032] 5 is a diagram showing an example of the configuration of a biosignal measurement system according to a third embodiment of the present invention. In the third embodiment, in order to improve the measurement accuracy of biosignals, information on biopotentials is transmitted and received between other electrode devices, thereby making the reference potentials of the amplifier circuits (22, 32) of the electrode devices (20, 30) common.

[0033] 5 uses a common reference potential generated by a reference potential generating circuit (27, 37) provided in each electrode device (20, 30). This enables signal amplification with a common reference potential for the amplifier circuits (22, 32) between the multiple electrode devices (20, 30), improves the measurement accuracy of the biosignal, and ultimately results in a good biosignal.

[0034] The electrode device (20, 30) of this embodiment has a wireless communication unit (26, 36) for transmitting and receiving information on biopotentials to and from other electrode devices, and a reference potential generating circuit (27, 37) for generating a reference potential for the amplifier circuit (22, 32) using information on a biopotential (first biopotential) measured by its own electrode device and information on a biopotential (second biopotential) measured by the other electrode devices. For example, the reference potential generating circuit (27, 37) may generate the reference potential by using an arithmetic average of the biopotentials it measures itself and the biopotentials received from the other electrode devices.

[0035] In this embodiment, information on the biopotential for generating the reference potential is transmitted and received wirelessly, so that the reference potential of the amplifier circuits (22, 32) in each electrode device (20, 30) can be made common without physical connection. This eliminates the discomfort and physical constraints on the wearer caused by physical wiring when wearing the electrode device, while improving the S / N ratio of the biosignal and improving the measurement accuracy of the biosignal.

[0036] Wireless communication modules are widely available and can be implemented easily and at low cost. For example, the wireless communication devices (26, 36) may have a modulation circuit and an antenna as their transmitting circuit, and a demodulation circuit and an antenna as their receiving circuit. Furthermore, by setting the carrier frequencies of the transmitted radio waves to different frequencies in each electrode device (20, 30), bioelectric potential information can be transmitted and received without interference.

[0037] <Other embodiments> Optical communication may be used as another method for transmitting and receiving biopotentials between electrode devices. By using optical communication, it is possible to reduce the influence of existing wireless communication, which is widely used, and to transmit and receive stable signals, and it is expected to improve security by making communication less susceptible to eavesdropping.

[0038] The method using optical communication can be implemented by providing a modulator and an E / O converter as the transmitter circuit of the communication device, and an O / E converter and a demodulator as the receiver circuit. As with the case of using wireless radio wave communication, by setting the wavelength of light used in each electrode device (20, 30) to be different, bioelectric potentials can be transmitted and received without interference.

[0039] Magnetic communication, such as that used in wireless earphones, is also suitable for this embodiment. In magnetic communication, signals are transmitted through mutual induction with another device due to changes in the magnetic field caused by passing a current through a coil. Magnetic fields are permeable to components of the human body, such as water, and communication can be carried out with low interference, making it possible to stably send and receive bioelectric potential information even when the device is attached to the human body.

[0040] To implement magnetic communication, the transmitter circuit of the communication device must be equipped with a modulator, a voltage-current converter such as a transconductance amplifier, and a coil that serves as an antenna, while the receiver circuit must be equipped with a coil, a current-voltage converter such as a transimpedance amplifier, and a demodulator.

[0041] Another method for transmitting and receiving biopotentials in the electrode devices (20, 30) may be to use human body communication, which uses the human body as a transmission path. When human body communication is used, as shown in Fig. 6, each electrode device (20, 30) has an electrode #2 (28, 38) (second electrode) for performing human body communication in addition to an electrode #1 (21, 31) (first electrode) for measuring biopotentials.

[0042] The power required for communication accounts for a large portion of the power consumption of the electrode device (20, 30). In spatial propagation using radio waves, the signal strength attenuates inversely proportional to the square of the propagation distance. On the other hand, when transmission is performed via the human body, the attenuation is limited to an inverse proportion to the propagation distance, so using intrabody communication enables transmission with less transmission power. Sending and receiving bioelectric potential information via the human body can contribute to reducing power consumption.

[0043] The communicator (26, 36) in Fig. 6 digitally modulates a carrier signal using a sampled signal of the biosignal provided from electrode #1 (21, 31), and transmits the signal from electrode #2 (28, 38) for human body communication to the human body, which is the transmission path. It also receives and demodulates a digitally modulated biosignal transmitted from another electrode device from electrode #2 (28, 38) for human body communication, and provides the demodulated biosignal to the reference potential generating circuit (27, 37).

[0044] The reference potential generating circuit (27, 37) in Figure 6 can generate a common reference potential in each electrode device (20, 30) by averaging the biopotential measured by its own electrode device and the biopotential of other electrode devices obtained through the human body.

[0045] By using human body communication to send and receive biopotential information, in addition to reducing power consumption, it is possible to independently set the sampling rate of the biopotential signal for generating the reference potential and the sampling rate of the biopotential signal for generating the biosignal, which has the advantage of increasing design freedom.

[0046] When using the human body as a transmission path, interference can be avoided by using different carrier frequencies for each electrode device. The frequency band used can be set to a few MHz to around 100 MHz based on the electrical properties of the human body, enabling human body communication with little loss.

[0047] The electrode section of the electrode device (20, 30) may include electrodes for measuring biopotentials, electrodes for transmitting biopotentials, and electrodes for receiving biopotentials. The number of electrodes can also be reduced by providing bandpass filters with different passbands in each electrode. Reducing the number of electrodes reduces the number of contact points with the human body, improving comfort for the wearer.

[0048] When digitally modulating a carrier signal in the electrode devices (20, 30), multi-level modulation such as QPSK is used, and by setting different signal points to be used by each electrode device (20, 30), it is possible to separate the signals to be transmitted and received in one carrier signal. This allows a common device to be used for digital modulation, thereby improving the mass productivity and maintainability of the device. [Industrial Applicability]

[0049] The present invention can be applied to bioelectrodes that are routinely used to acquire biosignals such as electrocardiogram signals, and to biosignal measurement systems that use bioelectrodes. [Explanation of symbols]

[0050] 1...wearer, 2...clothing, 10...biological signal measurement system, 20, 30...electrode device, 21, 31...electrode, 22, 32...amplification circuit, 23, 33...quantization circuit, 24, 34...wireless transmitter, 25, 35...power supply, 40...biological signal generating device, 41...wireless receiver, 42...arithmetic circuit, 43...memory

Claims

1. a plurality of electrode devices including electrodes for measuring biopotentials, an amplifier circuit for amplifying the measured biopotentials, a quantizer circuit for converting the amplified biopotentials into digital data to generate biopotential information, a wireless transmitter for transmitting the biopotential information, and a power source for supplying power to the amplifier circuit, the quantizer circuit, and the wireless transmitter; a biosignal generating device having a wireless receiver that receives the biopotential information transmitted from the wireless transmitter of the electrode device, and an arithmetic circuit that generates a biosignal waveform using the biopotential information of at least two of the plurality of electrode devices; Equipped with The electrode device comprises: a wireless communication device that transmits information about a first bioelectric potential measured by the electrode device via radio waves and receives information about a second bioelectric potential measured by another electrode device via radio waves; a reference potential generating circuit that generates a reference potential in the amplifier circuit using information on the first biopotential and information on the second biopotential; Biosignal measurement system.

2. a plurality of electrode devices including electrodes for measuring biopotentials, an amplifier circuit for amplifying the measured biopotentials, a quantizer circuit for converting the amplified biopotentials into digital data to generate biopotential information, a wireless transmitter for transmitting the biopotential information, and a power source for supplying power to the amplifier circuit, the quantizer circuit, and the wireless transmitter; a biosignal generating device having a wireless receiver that receives the biopotential information transmitted from the wireless transmitter of the electrode device, and an arithmetic circuit that generates a biosignal waveform using the biopotential information of at least two of the plurality of electrode devices; Equipped with The electrode device comprises: a communicator that transmits information about a first bioelectric potential measured by the electrode device via light and receives information about a second bioelectric potential measured by another electrode device via light; a reference potential generating circuit that generates a reference potential in the amplifier circuit using information on the first biopotential and information on the second biopotential; Biosignal measurement system.

3. a plurality of electrode devices including electrodes for measuring biopotentials, an amplifier circuit for amplifying the measured biopotentials, a quantizer circuit for converting the amplified biopotentials into digital data to generate biopotential information, a wireless transmitter for transmitting the biopotential information, and a power source for supplying power to the amplifier circuit, the quantizer circuit, and the wireless transmitter; a biosignal generating device having a wireless receiver that receives the biopotential information transmitted from the wireless transmitter of the electrode device, and an arithmetic circuit that generates a biosignal waveform using the biopotential information of at least two of the plurality of electrode devices; Equipped with The electrode device comprises: a communicator that transmits information about a first bioelectric potential measured by the electrode device via magnetism and receives information about a second bioelectric potential measured by another electrode device via magnetism; a reference potential generating circuit that generates a reference potential in the amplifier circuit using information on the first biopotential and information on the second biopotential; Biosignal measurement system.

4. a plurality of electrode devices including electrodes for measuring biopotentials, an amplifier circuit for amplifying the measured biopotentials, a quantizer circuit for converting the amplified biopotentials into digital data to generate biopotential information, a wireless transmitter for transmitting the biopotential information, and a power source for supplying power to the amplifier circuit, the quantizer circuit, and the wireless transmitter; a biosignal generating device having a wireless receiver that receives the biopotential information transmitted from the wireless transmitter of the electrode device, and an arithmetic circuit that generates a biosignal waveform using the biopotential information of at least two of the plurality of electrode devices; Equipped with The electrode device comprises: a communicator that transmits information about a first bioelectric potential measured by the electrode device via the human body and receives information about a second bioelectric potential measured by another electrode device via the human body, and a second electrode for performing human body communication; a reference potential generating circuit that generates a reference potential in the amplifier circuit using information on the first biopotential and information on the second biopotential; Biosignal measurement system.

5. The electrode device is equipped with the biosignal generating apparatus, and the arithmetic circuit of the electrode device generates the biosignal waveform using the biopotential information measured by the electrode device and the biopotential information measured by another electrode device.

5. The biological signal measurement system according to claim 1, wherein the biological signal measurement system comprises: a first electrode;

6. The biological signal generating device includes: Generating an electrocardiogram signal waveform using the biopotential information transmitted from the electrode devices attached to at least two locations on the limbs of the human body.

5. The biological signal measurement system according to claim 1, wherein the biological signal measurement system comprises: a first electrode;

7. The biological signal generating device includes: A 12-lead electrocardiogram signal waveform is generated using the biopotential information transmitted from the electrode devices attached to 10 locations on the limbs of the human body.

7. The biological signal measuring system according to claim 6.

Images