Electromyography sensor system

Abstract

To provide a waterproof-type myoelectric sensor system that is easy to be worn and in which noise is suppressed.SOLUTION: A myoelectric sensor system includes a myoelectric sensor, and an attachment belt that supports the myoelectric sensor. The myoelectric sensor includes a waterproof base material that can extend in a first direction, and an electrode exposed in a first surface of the base material. The myoelectric sensor is fixed to the attachment belt so as to form a string with respect to an arc shape portion of the attachment belt.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electromyography (EMG) sensor system, and more particularly to a waterproof EMG sensor system. [Background technology]

[0002] In myoelectric prosthetics, weak electrical currents (surface electromyography) generated by muscle contractions are collected by electrodes to control the movement of artificial fingers, arms, and legs. Since the electrodes are in direct contact with the skin of the limbs, the electrodes of the sensors that detect electromyography (EMG) signals must be comfortable to wear.

[0003] A highly biocompatible conductive polymer material has been used for the electrodes of electromyography sensors, and electrodes have been proposed in which layers of conductive polymers with different conductivity are stacked (see, for example, Patent Document 1). In this electrode, the contact portion with the skin is formed of conductive silicone with carbon added, resulting in fewer electrode marks after prosthetic use and providing a good wearing comfort.

[0004] To live independently with a prosthetic limb, it is desirable to be able to perform water-related activities such as bathing, washing one's face, and cooking. When electrodes used in electromyography sensors come into contact with conductive materials such as water, the internal impedance fluctuates and the output voltage decreases, so in addition to comfort, high waterproof functionality is required. Research has shown that protecting the conductive path between electrodes that acquire EMG signals with water-resistant tape can suppress the decrease in EMG signal amplitude (see, for example, Non-Patent Document 1). It has also been reported that performance can be improved by waterproofing the differential amplifier circuit of the active electrode for electromyography and increasing the pressure that makes the electrode adhere to the skin (see, for example, Non-Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-213857 [Non-patent literature]

[0006] [Non-Patent Document 1] A. Rainoldi, et al., "Surface EMG alterations induced by underwater recording", Journal of Electromyography and Kinesiology, Vo. 14, pp. 325-331, 2004 [Non-Patent Document 2] Yasuharu Koike, "Development of a welfare device that allows people to take baths," Research Results Report of the Grant-in-Aid for Scientific Research, 2014. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The waterproof configurations described in Non-Patent Documents 1 and 2 above are experimental and do not disclose specific configurations for actual application to prosthetic limbs. In fact, Non-Patent Document 2 only compares output signals at low and high pressures in water, and does not disclose any peripheral structures for ensuring the sensor is in close contact with the skin. Since electromyography sensors are generally susceptible to external forces, when realizing a configuration for ensuring the sensor is in close contact with the skin, it is necessary to solve the problem of noise reduction caused by fluctuations in contact pressure between the sensor and the skin.

[0008] The present invention aims to provide a waterproof electromyography sensor system that is easy to attach and has suppressed noise. [Means for solving the problem]

[0009] In one embodiment, the electromyography sensor system comprises an electromyography sensor and a mounting belt that supports the electromyography sensor. The electromyography sensor comprises a waterproof substrate that can be stretched in a first direction, and electrodes exposed on a first surface of the substrate. The electromyography sensor is fixed to the mounting belt so as to form a string with respect to the arc-shaped portion of the mounting belt.

Advantages of the Invention

[0010] With the above configuration, a waterproof electromyogram sensor system that is easy to wear and has noise suppression is realized.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic diagram of the electromyogram sensor system of the embodiment. [Figure 2] It is a bottom view and a side view of the electromyogram sensor of FIG. 1. [Figure 3A] It is a diagram showing a base material before mounting a waterproof chip. [Figure 3B] It is an external view of the fabricated electromyogram sensor system. [Figure 3C] It is a diagram showing signal input / output of the electromyogram sensor. [Figure 4] It is a diagram showing the wearing of the electromyogram sensor system. [Figure 5] It is a diagram showing the load acting due to the string-like arrangement of the electromyogram sensors. [Figure 6] It is a simulation diagram showing the relationship between the elongation amount of the base material of the electromyogram sensor and the load. [Figure 7] It is measured data showing the relationship between the elongation amount of the base material of the electromyogram sensor and the load. [Figure 8A] It is an electromyogram waveform diagram measured by the electromyogram sensor system of the embodiment. [Figure 8B] It is an electromyogram waveform diagram measured by the electromyogram sensor system of the embodiment. [Figure 8C] It is an electromyogram waveform diagram measured by the electromyogram sensor system of the embodiment.

Modes for Carrying Out the Invention

[0012] In this embodiment, the electromyography (EMG) sensor itself, which detects EMG signals, is made waterproof, providing an easy-to-attach and noise-suppressed EMG sensor system. Generally, an EMG sensor acquires electrical signals from a pair of electrodes attached to the skin at a predetermined distance apart, and outputs these signals after differential amplification. If water is present between the electrodes and the skin, the internal impedance fluctuates, causing the output voltage to decrease. To realize a waterproof EMG sensor, it is necessary to waterproof electronic components such as the differential amplifier circuit, as well as the interface between the skin and the electrodes.

[0013] The electrical impedance between an electrode and the skin tends to be inversely proportional to the contact pressure between the electrode and the skin. To lower the electrical impedance between the electrode and the skin (called skin impedance) and increase the detection sensitivity of the EMG signal, it is necessary to maintain high contact pressure. On the other hand, the contact pressure between the electrode and the skin is strongly affected by external forces, and skin impedance also changes sensitively due to these external forces. If the impedance between the electrode and the skin changes and the skin impedance differs between the two electrodes, it becomes difficult to remove common-phase noise and to extract only the differential component, the electromyogram.

[0014] In this embodiment, the following configuration is adopted to satisfy both the adhesion of the electrodes to the skin and noise suppression. By embedding the electrodes in a waterproof substrate that can be stretched in one direction, the electromyography sensor itself functions as a waterproof seal. At the same time, by fixing the substrate to the arc-shaped mounting belt like a string, pressure fluctuations on the electromyography sensor are minimized, thereby suppressing noise. The string-like arrangement of the electromyography sensors also has the effect of strengthening the adhesion between the electromyography sensors and the skin when the user wears the electromyography sensor system, thereby enhancing the waterproof function. This results in a waterproof electromyography sensor system that is easy to wear and has suppressed noise.

[0015] <Configuration of the electromyography sensor system> Figure 1 is a schematic diagram of an electromyography (EMG) sensor system 10 according to an embodiment. The EMG sensor system 10 includes an EMG sensor 11 and a mounting belt 12 that supports the EMG sensor 11. The EMG sensor 11 has a waterproof base material 17 that is stretchable in the longitudinal direction, as indicated by the bidirectional arrow A.

[0016] The base material 17 is fixed to the mounting belt 12 at two points, P1 and P2. The mounting belt 12 forms an arc between P1 and P2. By fixing both ends of the base material 17 in the longitudinal direction to the mounting belt 12 at P1 and P2 in the state shown in Figure 1, the electromyography sensor 11 forms a chord with respect to the arc of the mounting belt 12. The mounting belt 12 may be a belt made of fiber, synthetic fiber, or other fabric, or, as will be described later, a belt in which part is made of plastic or waterproof polymer. The mounting belt 12 may be provided with a belt fastener such as a buckle 121.

[0017] The electromyography (EMG) sensor 11 is connected to the mounting belt 12 at positions P1 and P2, but the area between P1 and P2 is not fixed to the mounting belt 12. By minimizing the connection points between the EMG sensor 11 and the mounting belt 12 and holding the EMG sensor 11 in a suspended state, the influence of external forces on the EMG sensor 11 can be minimized. Generally, simply moving the arms or legs while wearing the mounting belt that secures the EMG sensor applies a significant external force to the mounting belt. In a configuration where the entire EMG sensor is attached to the mounting belt, the EMG sensor itself vibrates due to the generation of external forces, resulting in increased noise. By using the configuration shown in Figure 1, pressure fluctuations on the EMG sensor 11 can be minimized, and noise can be suppressed.

[0018] Two sets of measuring electrodes 140 and 150 and a reference electrode 131 that provides a reference potential are embedded in the base material 17 of the electromyography sensor 11. The measuring electrodes 140, 150, and the reference electrode 131 are exposed at the bottom surface 17b of the base material 17. The bottom surface 17b of the base material 17 is the surface opposite to the surface of the electromyography sensor 11 that faces the arc-shaped mounting belt 12, and is the surface that comes into contact with the skin.

[0019] Figure 2 is a schematic diagram of the electromyography sensor 11. Figure 2(A) is a bottom view, and (B) is a side view. In the coordinate system, the length (l) direction of the electromyography sensor 11 is the X direction, the width (W) direction is the Y direction, and the height direction is the Z direction.

[0020] The electromyography sensor 11 includes a base material 17, measuring electrodes 140 and 150 exposed on the bottom surface 17b of the base material, and a reference electrode 131. In this example, two sets of measuring electrodes 140 and 150 are provided with the reference electrode 131 to create a two-channel sensor, but the sensor is not limited to this example. One set of measuring electrodes may be used with the reference electrode, or four sets of measuring electrodes may be used to create a four-channel sensor.

[0021] The base material 17 is stretchable in the X direction. Even if the base material 17 is slightly stretchable in the Y direction, the stretching in the Y direction is negligible because the base material 17 is fixed to the mounting belt 12 along the width direction. The base material 17 can be evaluated as being stretchable in one direction.

[0022] The base material 17 is formed from a material that has sufficient elasticity and is waterproof or water-repellent. Such materials can include silicone, polyurethane rubber polymers, and ethylene propylene rubber, with highly elongated silicone being particularly desirable. However, silicone is prone to tearing, making it difficult to secure it to the mounting belt 12 using only the short (width) end.

[0023] Therefore, in order to increase the strength of the base material 17 and make it easier to process, a base material 17 is made by filling a stretchable fabric with an elastic material such as silicone. As the stretchable fabric, power net, stretchable bandage, spandex® bandage, etc., can be used. In this embodiment, a power net with few surface irregularities and an appropriate mesh size is used.

[0024] Powernet is a mesh material made using elastic yarns such as polyester, polyurethane, and a polymer of nylon and polyester. By applying silicone (TSG-E30, manufactured by Tanac Co., Ltd.) to the powernet and filling the mesh with silicone, a waterproof and elastic base material 17 is obtained. In this embodiment, a powernet woven in a honeycomb shape is used so that it stretches predominantly in only one direction (for example, the X direction).

[0025] The thickness t of the base material 17 is, for example, 0.45 mm, and the width W is, for example, 50 mm. The natural length l of the base material 17 can be determined by the thickness or diameter of the area (such as the forearm) to which the electromyography sensor system 10 is applied.

[0026] Each of the measuring electrodes 140 and 150 and the reference electrode 131 embedded in the base material 17 is waterproofed. The measuring electrodes 140 and 150 and the reference electrode 131 may be formed from silicone rubber containing a predetermined amount of carbon, as described in Patent Document 1. Alternatively, these electrodes may be formed from a material obtained by adding a binder resin to a conductive polymer such as polyphenylene vinylene, or from a relatively soft metal with excellent corrosion resistance such as gold or platinum.

[0027] The measuring electrode 140 includes a pair of electrodes 141 and 142 arranged at a distance d apart. The measuring electrode 150 includes a pair of electrodes 151 and 152 arranged at a distance d apart. The distance d is, for example, about 10 mm. The length l2 of electrodes 141, 142, 151, and 152 is, for example, 20 mm, and the width w2 is, for example, 10 mm. The reference electrode 131 may be, for example, a square shape of 30 mm × 30 mm.

[0028] The measuring electrode 140 is connected to the amplifier 145 by wiring 146. Except for the bottom surfaces of electrodes 141 and 142, the measuring electrode 140, wiring 146, and the amplifier 145 are all housed in a waterproofed, waterproof chip 14. Similarly, the measuring electrode 150 is connected to the amplifier 155 by wiring 156. Except for the bottom surfaces of electrodes 151 and 152, the measuring electrode 150, wiring 156, and the amplifier 155 are all housed in a waterproofed, waterproof chip 15.

[0029] The waterproof chip 14 may be manufactured by the following procedure: The amplifier 145, with the input and output cords connected, is placed in a waterproofing mold along with a pair of electrodes 141 and 142 and wiring 146, and liquid silicone is injected. After the liquid silicone dries and solidifies, it is removed from the mold to obtain the waterproof chip 14. The waterproof chip 15 is manufactured in the same manner.

[0030] The reference electrode 131 is connected to wiring 133 for supplying a reference potential to amplifiers 145 and 155. The waterproof chip 13 is manufactured by placing the reference electrode 131 in a mold with the wiring 133 exposed and allowing the injected liquid silicone to solidify. Here, the term "chip" is used literally to mean "small piece," regardless of whether or not it encapsulates an electronic circuit.

[0031] The waterproof chips 13, 14, and 15 are embedded in the substrate 17 such that the reference electrode 131 and electrodes 141, 142, 151, and 152 are exposed on the bottom surface 17b of the substrate 17. The manufacturing method is not particularly limited as long as each electrode is exposed on the bottom surface 17b of the substrate 17b. In this embodiment, an opening for electrode exposure is formed in the prepared substrate 17, and the waterproof chips 13, 14, and 15 are fitted into the opening and sealed.

[0032] Figure 3A shows the substrate 17 before the waterproof chips 13, 14, and 15 are mounted. The substrate 17, which is a power net filled with silicone, has openings formed for mounting the waterproof chips. Specifically, an opening 171 for exposing the reference electrode 131, openings 173 and 174 for exposing electrodes 141 and 142 respectively, and openings 175 and 176 for exposing electrodes 151 and 152 respectively are formed in the substrate 17.

[0033] Apply uncured silicone to the periphery of openings 171, 173, 174, 175, and 176, attach waterproof tips 13, 14, and 15 so that each electrode is positioned within the corresponding opening, and then cure the silicone. After curing, sew the ends of the base material 17 to positions P1 and P2 of the mounting belt 12.

[0034] Figure 3B shows the appearance of the actually fabricated electromyography (EMG) sensor system 10. The mounting belt 12 is bent into an arc shape, and the EMG sensor 11 is attached to the mounting belt 12 so that it forms a string. Even when external force is applied to the EMG sensor system 10 during use, the only external force applied to the EMG sensor 11 is to the fixing parts at both ends. The external force acting on the measuring electrodes 140, 150 and the reference electrode 131 is small, which reduces noise mixed into the EMG signal.

[0035] Figure 3C shows the connection status of the cords and wiring 133 connected to amplifiers 145 and 155. Wiring 133 of the reference electrode 131 is connected to the reference potential V of amplifier 145. REF And the reference potential V of amplifier 155 REF It is connected to the following. The GND of amplifiers 145 and 155 are each connected to ground potential. The voltage driving amplifiers 145 and 155 is V IN It is connected to the current signals obtained from measuring electrodes 140 and 150, which are differentially amplified by amplifiers 145 and 155, respectively, and V SIG Output from here.

[0036] <Attachment of electromyography sensor system> Figure 4 shows the attachment of the electromyography sensor system 10A. Consider an example where the electromyography sensor system 10A is attached to the forearm 20. Figure 4(A) shows the state before attachment, and (B) shows the state after attachment. The electromyography sensor system 10A has an attachment belt 12A and an electromyography sensor 11 attached to the attachment belt 12A in a string-like manner.

[0037] The mounting belt 12A has an arc portion 123, a belt 122, and a fastener 121. The arc portion 123 may be made of plastic or the like and molded to fit the outer circumference of the forearm 20. The belt 122 is made of any material that can be wrapped around the forearm 20, for example, a Velcro belt. The fastener 121 is a fastener that secures the belt 122 in a predetermined position, for example, a buckle.

[0038] The electromyography sensor 11 is fixed to the mounting belt 12A at positions P1 and P2 such that the measuring electrodes 140, 150 and the reference electrode 131, which are exposed on the back surface 17b of the base material 17, are in contact with the forearm 20. The base material 17 is extendable in the longitudinal direction. When the user presses the forearm 20 against the back surface 17b of the electromyography sensor 11 and fits it into the arc portion 123, the electromyography sensor 11 extends in the longitudinal direction and curves along the arc portion 123.

[0039] As shown in Figure 4(B), when the belt 122 is wrapped around the outer circumference of the forearm 20 with the hand opposite to the arm to be fitted, the measuring electrodes 140, 150 and the reference electrode 131 make tight contact with the forearm 20. Since the base material 17 covers the forearm 20 while being pulled in the longitudinal direction, the electromyography sensor 11 itself functions as a seal. At the same time, the measuring electrodes 140, 150 and the reference electrode 131 are pressed against the surface of the forearm 20, preventing water from entering between the skin and the electrodes. Since the base material 17 is fixed to the fitting belt 12 only at both ends, impedance fluctuations caused by pressure fluctuations are suppressed in each of the measuring electrodes 140, 150 and the reference electrode 131, thereby reducing noise.

[0040] FIG. 5 is a diagram for explaining the load acting due to the string-like arrangement of the electromyographic sensor 11. The natural length of the electromyographic sensor 11 is l [m], and the cross-sectional area perpendicular to the extension direction is S0 [m 2 , and the rubber elasticity of the base material 17 is E [N / m 2 . Let the radius of the forearm 20 be R [m], and the arc length when the electromyographic sensor 11 is bent along the forearm 20 be L [m].

[0041] When the electromyographic sensor 11 is elastically deformed from the natural length l to the arc length L, the strain ε of the electromyographic sensor 11 is expressed by Equation (1).

[0042] ε = (L - l) / l (1) Therefore, the tensile strength F in the longitudinal direction of the electromyographic sensor 11 is expressed by Equation (2).

[0043] F = εES0 = {(L - l) / l} × ES0 (2) Here, (L - 1) is the elongation length Δl.

[0044] Since the tensile strength F is the same even for a minute length, considering that the electromyographic sensor 11 contacts as shown in FIG. 5 at a minute angle dθ, the synthesis of the forces in the normal direction of the tensile strength F is equal to the centripetal force acting in the direction of the arrow in FIG. 5. The normal component F n of the tensile strength F is F n = Fsin(dθ / 2) When dθ → 0, since sin(dθ / 2) ≒ dθ / 2, the centripetal force, that is, the load N0 acting in the direction of the center of the forearm 20 is N0 = 2F n = Fdθ = {L(L―l)}ES0dθ (3) becomes.

[0045] In the model of FIG. 5, when considering θ0 that satisfies L = Rθ0, the load N acting in the direction of the center of the forearm 20, which acts on the region where the electromyographic sensor 11 is in contact, is

[0046]

Equation

[0047] This value N is a theoretical value. Below, we will verify the correspondence between the theoretical value based on the mechanical model in Figure 5 and the actual value by measuring the actual value with a force sensor.

[0048] <Relationship between elongation length Δl and load N> Figure 6 is a simulation diagram showing the relationship between the elongation of the base material 17 of the electromyography sensor 11 and the load. The simulation in Figure 6 is based on the model in Figure 5. N = {L(L - l) / RL} × ES0 This plots the theoretical values ​​represented by for different circumferences L. The natural length l of the electromyography sensor 11 is 14 cm (0.14 m), and the cross-sectional area S0 is 50 mm × 0.45 mm = 22.5 mm. 2 (22.5 × 10 -6 m 2 Set the circumference L to 19cm, 24cm, and 29.4cm, and plot the relationship between the elongation length Δl and the load N.

[0049] Regardless of the value of the circumference L, the load N increases monotonically with respect to the elongation length Δl. To increase the load acting from the electromyography sensor 11 toward the center of the attachment site, the elongation length Δl from the natural length l should be increased. Also, the smaller the circumference L, the greater the change in load due to the increase in elongation length Δl.

[0050] Figure 7 shows the measured data illustrating the relationship between the elongation of the fabricated electromyography sensor 11 and the load. The measurement is performed using the following procedure: The force sensor is fixed to the surface of a tapered cylinder that simulates the forearm 20. With the electromyography sensor 11 extended by Δl in the longitudinal direction, the center of the reference electrode 131 is brought into contact with the force sensor and the mounting belt 12 is tightened.

[0051] Similar to Figure 6, the circumference L was varied to 19 cm, 24 cm, and 29.4 cm, and the load was measured for each circumference L. An Interlink Electronics, Inc. pressure sensor FSR(registered trademark)400 was used as the force sensor, and the voltage displacement obtained via serial communication was measured.

[0052] In Figure 7, the horizontal axis represents the elongation length Δl, similar to Figure 6, while the vertical axis represents the exponential function exp(Vout) of the force sensor's output voltage value Vout. exp(Vout) is used as the value corresponding to the load.

[0053] According to the datasheet of the pressure sensor used, the output voltage Vout of the pressure sensor changes with respect to the load N according to Vout = C × logN. The constant C is a value determined by individual differences in the pressure sensor, and its exact value is unknown, so we set C = 1 here. The value obtained by N = exp(Vout) is recorded as the value corresponding to the load. Five measurements are taken for the same elongation length Δl, and the average value and standard deviation of the five records are calculated.

[0054] According to the measured data, in the region where the elongation length Δl is 2 cm or more, the trend of change in Figure 7 is the same as in Figure 6. That is, regardless of the circumference L, the load increases monotonically with respect to the elongation length Δl, and linear approximation is possible. Also, the smaller the circumference L, the larger the rate of change in the value on the vertical axis with respect to the change in elongation length Δl. The reason why the same trend as in Figure 6 is not observed in the region where the elongation length Δl is less than 2 cm is thought to be because the output voltage acquired by the pressure sensor increases logarithmically with respect to the load, so the error becomes larger in the region where Δl is small and the load is small.

[0055] Figures 6 and 7 show that the electromyography sensor system 10 of the embodiment exhibits the same trend as the theoretical value, and that the load that satisfies the condition of preventing water from entering between the skin and the electrode can be designed based on the natural length l of the electromyography sensor 11, the elongation length Δl, and the circumference L of the attachment site.

[0056] <Effect Confirmation> Figures 8A to 8C show electromyography waveforms measured by the electromyography sensor system 10 of the embodiment. The electromyography sensor system 10 is intended to enable daily living activities involving water while using a prosthetic limb. We will verify that there is no difference in the EMG signal when the electromyography sensor system 10 is used in air and when it is used in water.

[0057] The experiment will be conducted according to the following procedure. For three subjects, the electromyography sensor system 10 will be fixed to the same position on their forearms. A pair of electrodes 141 and 142 will be placed at a predetermined distance apart along the length of the arm. The forearm circumferences of the three subjects, measured at the center line along the long axis of the base material 17, will be 23.0 cm, 24.8 cm, and 26.6 cm, respectively.

[0058] A tank of water is placed on a table, and each subject maintains the same posture both when using the device in air and when using it in water. In both air and water, the subject performs a grasping motion, clenching their fist and applying force for 5 seconds, followed by an offset, and then a relaxing motion for 5 seconds, and the signal is recorded. This is repeated 20 times. The output of the electromyography sensor 11 is connected to an A / D converter, and the digitally converted data is input to a personal computer to obtain the EMG waveform.

[0059] For each of the three subjects, the extension length Δl of the electromyography sensor 11 was varied to 1 cm, 3 cm, and 5 cm. Under the same conditions, 20 measurements were taken in three sets, for a total of 60 measurements. The RMS (root mean square) and MDF (median frequency) were calculated for each measurement, and the values ​​for use in water and air were compared.

[0060] Figure 8A shows the EMG waveform when the extension length Δl is 1 cm, Figure 8B shows the EMG waveform when the extension length Δl is 3 cm, and Figure 8C shows the EMG waveform when the extension length Δl is 5 cm. At rest, the hand is relaxed, so the EMG signal caused by muscle contraction is almost constant. When gripping, an EMG signal is obtained due to muscle contraction. Regardless of the subject, i.e., the extension length Δl, equivalent EMG signals are obtained in air (labeled "Land" in the figure) and water (labeled "Water" in the figure). In this configuration example, the amplitude of the EMG waveform is approximately 0.5V in both water and air for all subjects, indicating that noise is suppressed.

[0061] The results in Figures 8A to 8C show that the electromyography sensor system 10 of the embodiment ensures waterproofing of the electronic components and waterproofing between the electrodes and the skin. As mentioned above, the larger the elongation length Δl, the greater the load N acting in the direction of the forearm center, and the greater the degree of contact with the skin. When the condition of the back surface 17b of the substrate 17 of the electromyography sensor 11 was observed after measurement in water, no evidence of water entering the electrode exposure area of ​​the electromyography sensor 11 was found when the elongation length Δl was 3 cm and 5 cm.

[0062] When the elongation length Δl was 1 cm, slight water intrusion was observed between the skin and the back surface 17b of the substrate 17, but this did not have a visually noticeable effect on the EMG signal measurement. This is likely because the configuration, in which the electromyography sensor 11 is fixed to the mounting belt 12 only at its ends, minimizing pressure fluctuations on the electrode surface, is working effectively.

[0063] The electromyography sensor system 10 of this embodiment is applicable to myoelectric prosthetic arms, myoelectric prosthetic legs, etc. Until now, poor wearability and degradation of EMG signal quality due to noise interference have been serious problems, especially for children and users with short stumps. By using the waterproof electromyography sensor system 10, which is easy to wear and has suppressed noise, the convenience of prosthetic limbs is improved and rehabilitation can proceed more smoothly.

[0064] In the electromyography sensor system 10, not only are electronic components such as amplifiers 145 and 155 waterproofed, but the electromyography sensor 11 itself exhibits tight adhesion due to tensile force, functioning as a waterproof seal between the skin and the electrodes. As mentioned above, noise is suppressed by the string-like arrangement of the electromyography sensors 11.

[0065] Although the present invention has been described above based on specific configuration examples, the present invention is not limited to the above configuration examples and various modifications are possible. Any material that is waterproof or water-repellent and stretches predominantly in one direction can be used as the base material 17 of the electromyography sensor 11. The attachment of the end of the base material 17 to the mounting belt 12 is not limited to sewing, but may be fixed with staples, or the end of the base material 17 may be inserted into a slit formed in the mounting belt and fixed from the opposite side of the insertion side with a hardened resin or the like.

[0066] The attachment belt is not limited to a Velcro belt; it may be made of foamed propylene rubber for dry suits in whole or in part, or the electromyography sensor may be fixed in a string-like manner to the arc-shaped part of a socket that fits onto the stump. The amplifiers 145 and 155 connected to the measuring electrodes 140 and 150 may be integrated with electronic components that perform filtering, current / voltage conversion, amplification, etc., of the EMG signal. [Explanation of Symbols]

[0067] 10, 10A electromyography sensor system 11. Electromyography Sensors 12, 12A mounting belt 13, 14, 15 Waterproof chip 17 Base material 17b Reverse side (first side) 131 Reference electrode Wiring 133, 146, 156 140, 150 measurement electrode 141, 142, 151, 152 electrode 145, 155 amplifier 171, 173, 174, 175, 176 aperture

Claims

1. electromyography sensor, A mounting belt that supports the electromyography sensor and is attached to the hand, arm, or leg, It has, The electromyography sensor comprises a waterproof substrate that can be stretched in a first direction, and electrodes exposed on a first surface of the substrate. The electromyography sensor is fixed to the mounting belt so as to form a string with respect to the arc-shaped portion of the mounting belt. The first direction is the longitudinal direction of the substrate, The electromyography sensor is fixed to the mounting belt at its first and second ends in the longitudinal direction, and the region between the first and second ends is not fixed to the mounting belt. The electromyography sensor has elasticity that allows it to bend along the hand, arm, or leg when attached to the hand, arm, or leg. The mounting belt is made of a flexible material, such as fiber, synthetic fiber, or fabric, and is configured to be flexible so that the electromyography sensor is fixed to form the string, and to be able to adjust and maintain the length of the circumference of the mounting belt along the hand, arm, or leg until it contacts the electromyography sensor. Electromyography (EMG) sensor system.

2. The first surface is the surface opposite to the surface on which the electromyography sensor faces the arc-shaped portion of the mounting belt. The electromyography sensor system according to claim 1.

3. The base material is formed from a material in which a stretchable fabric that extends in the first direction is filled with silicone rubber. The electromyography sensor system according to claim 1 or 2.

4. The electrode includes a pair of electrodes and a reference electrode. The pair of electrodes, except for the first exposed surface exposed on the first surface, are waterproofed together with the electronic components that process the electromyographic signals. The reference electrode is waterproofed except for the second exposed surface which is exposed on the first surface, with the wiring that supplies the reference potential to the electronic component drawn out. The electromyography sensor system according to any one of claims 1 to 3.

5. The electromyography sensor has elasticity such that, when the electromyography sensor system is attached, it stretches in the first direction and curves toward the arc-shaped portion of the attachment belt, so that the exposed surface of the electrode exposed on the first surface is in close contact with the hand, arm, or leg. The electromyography sensor system according to any one of claims 1 to 4.

6. As the electromyography sensor extends in the first direction, the load directed toward the center of the arc increases monotonically. The electromyography sensor system according to claim 5.

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