JP7835966B2 - Electromyography sensor system - Google Patents

Description

This invention relates to an electromyography (EMG) sensor system, and more particularly to a waterproof EMG sensor system.

In electromyographic prosthetics, the 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.

A highly biocompatible conductive polymer material has been proposed for the electrodes of electromyography sensors, and electrodes with layers of conductive polymers having different conductivity have been laminated (see, for example, Patent Document 1). In this electrode, the contact portion with the skin is formed of conductive silicone with added carbon, resulting in fewer electrode marks after prosthetic use and providing a comfortable fit.

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 (EMG) sensors come into contact with conductive materials such as water, the internal impedance fluctuates, causing a decrease in output voltage. Therefore, 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 EMG electrode and increasing the pressure that ensures the electrode is in close contact with the skin (see, for example, Non-Patent Document 2).

Japanese Patent Publication No. 2019-213857

A. Rainoldi, et al., "Surface EMG alterations induced by underwater recording", Journal of Electromyography and Kinesiology, Vo. 14, pp. 325-331, 2004 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.

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 under low and high pressure in water, and does not disclose any peripheral structures for ensuring the sensor adheres to the skin. Since electromyography sensors are generally susceptible to external forces, concretizing a configuration for ensuring the sensor adheres to the skin requires addressing the issue of noise reduction caused by fluctuations in contact pressure between the sensor and the skin.

The present invention aims to provide a waterproof electromyography sensor system that is easy to attach and has suppressed noise.

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.

The above configuration enables the realization of an easy-to-install, noise-suppressed, waterproof electromyography (EMG) sensor system.

This is a schematic diagram of an electromyography sensor system according to an embodiment. Figure 1 shows the bottom and side views of the electromyography sensor. This diagram shows the substrate before the waterproof chip was installed. This is an external view of the manufactured electromyography sensor system. This diagram shows the signal input and output of an electromyography (EMG) sensor. This diagram shows the attachment of an electromyography sensor system. This diagram shows the load acting due to the string-like arrangement of electromyography sensors. This is a simulation diagram showing the relationship between the elongation of the electromyography sensor substrate and the load. This is measured data showing the relationship between the elongation of the electromyography sensor substrate and the load. This is an electromyography waveform diagram measured by the electromyography sensor system of the embodiment. This is an electromyography waveform diagram measured by the electromyography sensor system of the embodiment. This is an electromyography waveform diagram measured by the electromyography sensor system of the embodiment.

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, EMG sensors acquire electrical signals from a pair of electrodes attached to the skin at a predetermined distance apart, and output these signals through differential amplification. If water is present between the electrodes and the skin, the internal impedance fluctuates, causing a decrease in output voltage. 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.

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, making it challenging to extract only the differential component, the electromyogram (EMG).

In this embodiment, the following configuration is employed to satisfy both the need for electrode adhesion to the skin and noise suppression. By embedding the electrodes in a waterproof substrate that can be stretched in one direction, the electromyography (EMG) sensor itself functions as a waterproof seal. Simultaneously, by fixing the substrate to the arc-shaped mounting belt like a string, pressure fluctuations on the EMG sensor are minimized, thereby suppressing noise. The string-like arrangement of the EMG sensors also enhances the adhesion between the EMG sensors and the skin when the user wears the EMG sensor system, thereby strengthening the waterproof function. This results in an easy-to-wear, noise-suppressed, waterproof EMG sensor system.

<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 can be stretched in the longitudinal direction, as indicated by the bidirectional arrow A.

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 relative 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 described later, a belt in which part is made of plastic or a waterproof polymer. The mounting belt 12 may be provided with a belt fastener such as a buckle 121.

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 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, thereby suppressing noise.

The base material 17 of the electromyography sensor 11 has two sets of measuring electrodes 140 and 150, and a reference electrode 131 that provides a reference potential embedded within it. 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 facing the arc-shaped mounting belt 12, and is the surface that comes into contact with the skin.

Figure 2 is a schematic diagram of the electromyography sensor 11. Figure 2(A) is a bottom view, and (B) is a side view. The coordinate system is defined as the X-direction for the length (l) of the electromyography sensor 11, the Y-direction for the width (W), and the Z-direction for the height.

The electromyography sensor 11 comprises 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.

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

The base material 17 is formed from a material with sufficient elasticity and waterproof or water-repellent properties. 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 to the mounting belt 12 using only the short-side (width) end.

Therefore, in order to increase the strength of the base material 17 and make it easier to process, a base material 17 is prepared 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.

Powernet is a mesh material using elastic yarns such as polyester, polyurethane, and nylon-polyester polymers. 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).

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 to which the electromyography sensor system 10 is applied (e.g., the forearm).

The measuring electrodes 140 and 150, and the reference electrode 131, embedded in the base material 17, are 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.

The measuring electrode 140 includes a pair of electrodes 141 and 142 positioned at a distance d apart. The measuring electrode 150 includes a pair of electrodes 151 and 152 positioned 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 x 30 mm.

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 amplifier 145 are all housed within 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 amplifier 155 are all housed within a waterproofed, waterproof chip 15.

The waterproof chip 14 may be manufactured by the following procedure: The amplifier 145, with its input/output cords connected, is placed in a waterproofing mold along with a pair of electrodes 141 and 142, and wiring 146. Liquid silicone is then 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.

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 then solidifying the injected liquid silicone. Here, the term "chip" is used literally to mean "small piece," regardless of whether or not it encapsulates an electronic circuit.

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

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, openings 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.

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 its corresponding opening, and then allow the silicone to cure. After curing, sew the ends of the base material 17 to positions P1 and P2 of the mounting belt 12.

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 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 acting on the EMG sensor 11 is at the fixing points at both ends. The external force acting on the measurement electrodes 140, 150, and the reference electrode 131 is minimal, which reduces noise introduced into the EMG signal.

Figure 3C shows the connection status of the cords and wiring 133 connected to amplifiers 145 and 155. The wiring 133 of the reference electrode 131 is connected to the reference potential V _REF of amplifier 145 and the reference potential V _REF of amplifier 155. The GND of amplifiers 145 and 155 are connected to the ground potential, respectively. The voltage driving amplifiers 145 and 155 is connected to their respective V _IN . The current signals obtained from measuring electrodes 140 and 150 are differentially amplified by amplifiers 145 and 155, respectively, and output from V _SIG .

<Attachment of electromyography sensor system>
Figure 4 shows the attachment of the electromyography sensor system 10A. Consider an example in which 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.

The mounting belt 12A has an arc portion 123, a belt 122, and a fastener 121. The arc portion 123 may be molded from plastic or the like 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.

The electromyography (EMG) 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, exposed on the back surface 17b of the base material 17, contact the forearm 20. The base material 17 is extendable in the longitudinal direction. When the user presses their forearm 20 against the back surface 17b of the EMG sensor 11 and fits it into the arc portion 123, the EMG sensor 11 extends longitudinally and curves along the arc portion 123.

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 one being worn, 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 stretched in the longitudinal direction, the electromyography sensor 11 itself functions as a seal. Simultaneously, 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. Because the base material 17 is fixed to the wearing 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.

Figure 5 illustrates the load acting on the electromyography sensor 11 due to its chordal arrangement. The natural length of the electromyography sensor 11 is l [m], the cross-sectional area perpendicular to the extension direction is _S0 [ ^m² ], and the rubber elasticity of the base material 17 is E [N/ ^m² ]. The radius of the forearm 20 is R [m], and the arc length when the electromyography sensor 11 is bent along the forearm 20 is L [m].

When the electromyography sensor 11 undergoes tensile deformation from its natural length l to its arc length L, the strain ε of the electromyography sensor 11 is expressed by equation (1).

ε=(L-l)/l (1)
Therefore, the tensile strength F in the longitudinal direction of the electromyography sensor 11 is expressed by equation (2).

F=εES ₀ = {(L-l)/l}×ES ₀ (2)
Here, (L-1) is the elongation length Δl.

Since the tensile strength F is the same even for small lengths, if we consider that the electromyograph sensor 11 makes contact at a small angle dθ as shown in Figure 5, the resultant of the forces normal to the tensile strength F is equal to the centripetal force acting in the direction of the arrow in Figure 5. The normal component _Fn of the tensile strength F is,
F _n =F sin (dθ/2)
Therefore, as dθ→0, sin(dθ/2) ≈ dθ/2, so the centripetal force, that is, the load _N0 directed towards the center of the forearm 20, is
N ₀ =2F _n =Fdθ={L(L-l)}ES ₀ dθ (3)
This is the result.

In the model shown in Figure 5, when considering θ ₀ that satisfies L = Rθ ₀ , the load N acting on the region in contact with the electromyography sensor 11, directed towards the center of the forearm 20, is:

It is expressed as follows.

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.

<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}×ES ₀
This plots the theoretical values represented by for different circumferences L. The natural length l of the electromyograph sensor 11 is set to 14 cm (0.14 m), and the cross-sectional area _S0 is set to 50 mm × 0.45 mm = 22.5 ^mm² (22.5 × ^{10⁻⁶ m²} ). The circumference L is set to three different values: 19 cm, 24 cm, and 29.4 cm, and the relationship between the elongation length Δl and the load N is plotted.

Regardless 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 towards the center of the attachment site, the elongation length Δl from the natural length l should be increased. Furthermore, the smaller the circumference L, the greater the change in load due to the increase in elongation length Δl.

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 simulating the forearm 20. With the electromyography sensor 11 extended longitudinally by Δl, the center of the reference electrode 131 is brought into contact with the force sensor, and the mounting belt 12 is tightened.

Similar to Figure 6, the circumference L was varied to 19 cm, 24 cm, and 29.4 cm, and the load was measured at each circumference L. An Interlink Electronics, Inc. pressure sensor FSR® 400 was used as the force sensor, and the voltage displacement obtained via serial communication was measured.

In Figure 7, the horizontal axis represents the extension 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.

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 the formula Vout = C × logN. The constant C is 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 performed for the same elongation length Δl, and the average and standard deviation of the five records are calculated.

According to the measured data, the trend of change in Figure 7 is the same as in Figure 6 in the region where the elongation length Δl is 2 cm or more. That is, regardless of the circumference L, the load increases monotonically with respect to the elongation length Δl, and linear approximation is possible. Furthermore, the smaller the circumference L, the larger the ratio of the 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, resulting in larger errors in the region where Δl is small and the load is small.

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.

<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 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.

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 positioned 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, are 23.0 cm, 24.8 cm, and 26.6 cm, respectively.

A water tank 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 (grasp) for 5 seconds, followed by a 5-second relaxation motion (with an offset in between), 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 acquire the EMG waveform.

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.

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. Holding an object generates an EMG signal due to muscle contraction. Regardless of the subject, i.e., the extension length Δl, similar 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 suppressed noise.

From the results in Figures 8A to 8C, it can be seen that the electromyography sensor system 10 of the embodiment reliably waterproofs both the electronic components and the area 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 observed when the elongation length Δl was 3 cm and 5 cm.

When the elongation length Δl was 1 cm, slight water infiltration 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 due to the advantageous performance of 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.

The electromyography (EMG) sensor system 10 of this embodiment is applicable to MMG prosthetic arms, MMG prosthetic legs, etc. Previously, poor fit and degradation of EMG signal quality due to noise interference were serious problems, especially for children and users with short stumps. By using the easy-to-wear, noise-suppressed, waterproof EMG sensor system 10, the convenience of prosthetic limbs is improved, and rehabilitation progresses more smoothly.

In the electromyography (EMG) sensor system 10, not only are electronic components such as amplifiers 145 and 155 waterproofed, but the EMG 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 EMG sensors 11.

The present invention has been described above based on specific configuration examples, but the present invention is not limited to the above-described examples, and various modifications are possible. Any material that is waterproof or water-repellent and predominantly stretches 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 stitching; it 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 with a hardened resin or the like.

The attachment belt is not limited to a Velcro belt; it may be partially or entirely made of foamed propylene rubber for dry suits, or the electromyography sensor may be fixed in a string-like manner to the arc-shaped portion 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 EMG signal filtering, current/voltage conversion, amplification, etc.

10, 10A Electromyography sensor system 11 Electromyography sensors 12, 12A Mounting belts 13, 14, 15 Waterproof tip 17 Base material 17b Back side (first side)
131 Reference electrode
133, 146, 156 Wiring 140, 150 Measuring electrodes 141, 142, 151, 152 Electrodes 145, 155 Amplifiers 171, 173, 174, 175, 176 Opening

Claims (6)

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 the 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 adjustable and maintainable in circumference along the hand, arm, or leg until it contacts the electromyography sensor.
Electromyography (EMG) sensor system. 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. 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. 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 extended from it.
The electromyography sensor system according to any one of claims 1 to 3. 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. 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.