JP2011156215A - Electrode for biological signal and biological information measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for a biological signal which combines the high conductivity with the easiness of manufacturing, and to provide a biological information measuring system using the electrode. <P>SOLUTION: Each of the electrodes 3 and 5 for biological signals contains plastic, a metallic piece, and a carbon fiber. Stainless steel chip is suitable as the metallic piece, and three-dimensional curled fiber made of coal is suitable as the carbon fiber. The biological information measuring system 1 includes: the electrodes 3 and 5 for biological signals; and measuring means 9 for measuring biological information, based on the biological signals acquired by the electrodes 3 and 5 for biological signals. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a biological signal electrode and a biological information measurement system.

  It is reported that 15% of 18175 single traffic fatalities per year are caused by a heart attack while driving (US2003, Source: Bureau of Transportation Statistics). In Japan, 12.3% (16/130) of fatalities in traffic accidents examined were reported as “sudden death while driving” due to ischemic heart disease (Source: Dokkyo University School of Medicine).

  In Japan, in the aging society where the average age of driver's license exceeds 60 years old, as mentioned above, “sudden death while driving” has become a significant part of traffic accident death, Furthermore, considering that it is expected that the number of elderly driving will increase and the ratio will increase in the future, physical condition monitoring of passengers (including drivers) while driving will not only help passengers but also prevent harm accidents. It has become extremely important from the viewpoint of In particular, detection of abnormalities in the cardiovascular system, which is said to account for about 70% of sudden death, is an urgent task.

  For this purpose, it is necessary to measure the occupant's biological signals while driving and to monitor the physical condition (health condition). However, general medical devices for monitoring are basically resting in hospitals or homes. Since it is made on the premise of measuring in a state, it is not suitable for use in a vehicle. For example, it is not preferable to attach an adhesive electrode or a gel electrode used in a general medical device to an occupant in terms of influence on driving or comfort.

  Therefore, various in-vehicle systems that measure biological signals such as electrocardiograms without causing the occupant to be aware have been proposed (see Patent Document 1). In this in-vehicle system, an electrode is provided at a position such as a steering wheel where an occupant contacts. Examples of the electrode include a metal electrode, a metal plating electrode, and a conductive cloth electrode.

JP-A-6-22914

  The metal electrode and the metal plating electrode have a problem in terms of the feeling (thermal feeling) related to the temperature at the moment when the occupant touches the electrode when the temperature is low or high. Furthermore, it cannot be used in places where passengers are in constant contact due to metal allergy problems. In addition, the conductive cloth electrode has a problem in terms of durability.

  Therefore, it is conceivable to use a plastic imparted with conductivity by mixing a metal piece or the like as the electrode. This is because the plastic itself has no problems of thermal sensation and metal allergy.

  However, it has been difficult to obtain a conductive plastic electrode that can achieve both conductivity sufficient for use as an electrode and ease of manufacture. For example, if the conductivity is increased to a level sufficient for use as an electrode by increasing the mixing ratio of metal pieces into plastic, the fluidity of the material becomes extremely poor, and it is difficult to manufacture the electrode by a method such as injection molding. turn into. In addition, the tactile sensation and thermal sensation approach the metal electrode and deteriorate. On the other hand, if the mixing rate of the metal pieces is suppressed to such an extent that the fluidity of the material does not deteriorate, the conductivity becomes insufficient for use as an electrode.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a biological signal electrode that can achieve both high conductivity and ease of manufacture, and a biological information measurement system using the same.

  The biosignal electrode of the present invention includes plastic, a metal piece, and carbon fiber. The biosignal electrode of the present invention can achieve both conductivity sufficient for use as an electrode and ease of manufacture. Moreover, the biosignal electrode of the present invention is excellent in tactile sensation without being sticky when touched. Furthermore, the biosignal electrode of the present invention is excellent in thermal sensation.

Examples of the plastic include polyurethane, vinyl chloride, and polypropylene. Moreover, the mixture of 2 or more types of them may be sufficient.
Although the said metal piece is not specifically limited, For example, a stainless steel chip | tip etc. are mentioned. An example of the stainless steel chip is SUSECEC (product name). The size of the metal piece is preferably in the range of 10 to 100 μm. Examples of the shape of the metal piece include a granular shape and a foil shape, but a foil shape is preferable. In particular, a foil shape elongated in one direction is preferable. The SUSECEC (product name) has a foil shape elongated in one direction.

As the carbon fiber, for example, a three-dimensional curled fiber manufactured from coal is preferable. An example of this three-dimensional curled fiber is Donna Carbon (product name).
The surface of the biosignal electrode is preferably subjected to mesh processing, blast processing, knurling processing, or dimple processing. By doing so, the contact resistance with the skin of the subject is reduced, and the electrical performance (conductivity, S / N, etc.) is further improved.

  The composition ratio of the biosignal electrode of the present invention is that the metal piece content is 25 to 50 parts by weight and the carbon fiber content is 2 to 10 parts by weight with respect to 100 parts by weight of the biosignal electrode. It is preferable. By being within this range, it is possible to achieve both high conductivity sufficient for use as an electrode and ease of manufacture at a high level.

The resistance value between two points 10 mm apart on the surface of the biosignal electrode of the present invention is preferably 200 kΩ or less. By doing so, the performance as an electrode is enhanced.
The biosignal electrode of the present invention can appropriately contain various additives in addition to plastics, metal pieces, and carbon fibers.

  The living body information measuring system of the present invention includes the living body signal electrode described above and measuring means for measuring living body information based on the living body signal acquired by the living body signal electrode. The biosignal electrode in the present invention has sufficiently high conductivity and is easy to manufacture. As a result, the biological information measuring system of the present invention has high performance and is easy to manufacture.

  The biological information measuring system of the present invention is mounted on a vehicle, for example, and the biological signal electrode is one type selected from the group consisting of a vehicle steering, a seat, a seat belt, a headrest, a shift knob, a handle, and an operation switch. The thing provided above is mentioned. The living body information measuring system of the present invention can measure various kinds of living body information (for example, electrocardiogram) based on the living body signal acquired by the living body signal electrode.

1 is a block diagram illustrating a configuration of a biological information measurement system 1. FIG. It is explanatory drawing showing the measuring method of resistance value. It is explanatory drawing showing the measuring method of an electrocardiogram. It is a graph showing the measured value of resistance value and S / N in an Example and a comparative example. It is a graph showing the measurement result of the electrocardiogram in Example W3. It is a graph showing the measurement result of the electrocardiogram in Example W4. It is a graph showing the measurement result of the electrocardiogram in Comparative Example R3. It is explanatory drawing showing the arrangement | positioning location of the electrode for biological signals. FIG. 4 is an explanatory diagram showing the arrangement of biological signal electrodes in a steering wheel.

An embodiment of the present invention will be described.
1. Configuration and Action of Biological Information Measurement System 1 The configuration of the biological information measurement system 1 will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the biological information measurement system 1.

  The biological information measurement system 1 is an in-vehicle system mounted on a vehicle, and includes a right electrode part (biological signal electrode) 3, a left electrode part (biological signal electrode) 5, a differential amplifier 7, and an arithmetic circuit (measurement). Means) 9.

  The right electrode portion 3 is attached to a portion of the vehicle steering 101 that is gripped with the right hand. The right electrode part 3 includes a first electrode 3A and a second electrode 3B. The first electrode 3 </ b> A is located on the front side of the steering 101, and the second electrode 3 </ b> B is located on the outer peripheral side of the steering 101.

  The left electrode portion 5 is attached to a portion of the steering 101 that is gripped with the left hand. The left electrode part 5 includes a first electrode 5A and a second electrode 5B. The first electrode 5A is located on the front side of the steering 101, and the second electrode 5B is located on the outer peripheral side of the steering 101.

  The first electrode 3A of the right electrode portion 3 is connected to the minus side terminal 11 of the differential amplifier 7, and the first electrode 5A of the left electrode portion 5 is connected to the plus side terminal 13. Further, the second electrode 3B of the right electrode part 3 and the second electrode 5B of the left electrode part 5 are connected to the ground electrode (intermediate electrode) G of the differential amplifier 7, respectively.

  The arithmetic circuit 9 is connected to the output terminal 15 of the differential amplifier 7. The arithmetic circuit 9 includes an A / D converter 17 that performs A / D conversion on the signal output from the differential amplifier 7 and a CPU 19 that executes a measurement process described later. The arithmetic circuit 9 can output display, alarm, and vehicle control signals.

  Measurement of biological information by the biological information measuring system 1 is performed as follows. The right electrode unit 3 and the left electrode unit 5 acquire the driver's electrocardiographic waveform. The acquired electrocardiogram waveform is amplified by the differential amplifier 7 and sent to the arithmetic circuit 9. The arithmetic circuit 9 performs A / D conversion on the electrocardiographic waveform by the A / D converter 17, performs arithmetic processing by the CPU 19, and sends it to a display (not shown). The display device displays an electrocardiogram waveform. The arithmetic circuit 9 calculates the ECG peak interval from the ECG waveform, and compares the peak interval with a reference value to determine whether the ECG waveform is abnormal. If it is determined that the peak interval is abnormal, a warning signal is output. The vehicle navigation screen, meter, CAN, etc. (all not shown) display warnings (alarms) in response to the warning signals to alert the driver. A vehicle control unit (not shown) of the vehicle controls the vehicle (for example, reduces the speed) according to the warning signal. Further, when the arithmetic circuit 9 determines that the electrocardiographic waveform is abnormal, the arithmetic circuit 9 communicates with an external engine (for example, a help net) by communication means (not shown).

2. Manufacturing method of the right electrode part 3 and the left electrode part 5 The right electrode part 3 and the left electrode part 5 were manufactured as follows. That is, plastic (polyurethane), stainless steel chips (micro-chip chips), and carbon fibers (micro-fragment fiber materials) were mixed with a mixer, poured into a mold of an injection molding machine, and manufactured by an injection molding method.

  Table 1 shows the compounding ratio of plastic, stainless steel chip, and carbon fiber in Examples W1 to W4. The right electrode portion 3 and the left electrode portion 5 were manufactured under the conditions of Examples W1 to W4. The stainless steel chip in Table 1 is SUSECEC (product name). Moreover, the carbon fiber in Table 1 is Donna carbon (product name).

In Examples W2 and W3, the surface of the electrode was blasted. In Example W4, mesh processing was performed on the surface of the electrode.

3. Measurement of electrode resistance value and S / N In order to evaluate the performance of the right electrode part 3 and the left electrode part 5, the evaluation electrode manufactured in the same manner as each of Examples W1 to W4 and having the same shape Prepared. For this evaluation electrode, the resistance value and the electrocardiogram (ECG) were measured. In addition, as a comparative example, an evaluation electrode having the same shape as that of the comparative examples R1 to R4 in Table 1 described above was manufactured, and this evaluation electrode was similarly measured.

  The resistance value is measured as follows. As shown in FIG. 2, the two metal cylinders 103 and 105 are pressed against the surface of the evaluation electrode 21, respectively. The diameters of the metal cylinders 103 and 105 are 2 mm, respectively, and the distance between them is 10 mm. Since the evaluation electrode 21 is processed in accordance with the surface shape of the steering 101 and the surface thereof is a curved surface, the contact between the evaluation electrode 21 and the metal cylinders 103 and 105 is a point contact. In this state, the resistance value between the metal cylinders 103 and 105 is measured.

  In addition, an electrocardiogram (ECG) measurement method is as follows. Three evaluation electrodes manufactured under the same conditions are prepared. An electrocardiogram measurement subject (the same person throughout the entire experiment) has two evaluation electrodes with the right hand and one evaluation electrode with the left hand. As shown in FIG. 3, one of the two evaluation electrodes held by the right hand is input to the minus terminal of the biological signal amplifier 107, and the other signal is input to the intermediate terminal. Further, the signal of the evaluation electrode held by the left hand is input to the plus terminal of the biological signal amplifier 107. At this time, the electrocardiographic waveform of the measurement subject is input to the biological signal amplifier 107. The biological signal amplifier 107 amplifies the electrocardiographic waveform 1000 times. Then, the amplified electrocardiogram waveform is A / D converted and recorded on the PC. At this time, a band pass filter of 0.5 to 30 Hz is applied. Then, the S / N of the obtained electrocardiogram waveform is measured.

  FIG. 4 shows the measurement result of the resistance value and the measurement result of the electrocardiogram S / N for the electrodes for evaluation corresponding to Examples W1 to W4 and Comparative Examples R1 to R3. FIG. 4 also shows the measurement result of the chromium plating electrode. The evaluation electrodes corresponding to Examples W1 to W4 all had low resistance values (high conductivity) and high S / N in the electrocardiographic waveform. FIG. 5 shows an electrocardiographic waveform at the evaluation electrode corresponding to Example W3. From FIG. 5, it can be seen that the noise (N) is sufficiently smaller than the signal (S). FIG. 6 shows an electrocardiographic waveform at the evaluation electrode corresponding to Example W4. FIG. 6 also shows an electrocardiographic waveform measured using a medical wet electrode. From FIG. 6, the evaluation electrode corresponding to Example W4 has a signal close to the medical wet electrode even in a subject who is difficult to detect the R wave (the R wave is low in the first induction and the same level as the T wave). You can see that

  On the other hand, as shown in FIG. 4, the evaluation electrodes corresponding to Comparative Examples R2 and R3 both had high resistance values and low S / N in the electrocardiographic waveform. FIG. 7 shows an electrocardiographic waveform of the evaluation electrode corresponding to Comparative Example R3. As is clear from FIG. 7, the noise (N) was very large compared to the signal (S).

  The resistance value of the electrode for evaluation corresponding to Comparative Example R4 was 10 MΩ, which was very high. In addition, as in Comparative Example R4, in an electrode that does not include a stainless steel tip and includes only carbon fibers, in order to sufficiently reduce the resistance value, the amount of carbon fibers needs to be 50% by weight or more. Causes problems such as depositing carbon on hands and clothes.

4). Evaluation of tactile sensation, thermal sensation, and ease of production of electrodes The evaluation electrodes corresponding to Examples W1 to W4 and Comparative Examples R1 to R4 were evaluated for tactile sensation, thermal sensation, and ease of injection molding. The tactile sensation and the thermal sensation were evaluated based on the feeling when the surface of the evaluation electrode was touched by hand.

  The electrodes for evaluation corresponding to Examples W1 to W4 were not sticky when touched, and the tactile sensation was good. In addition, the evaluation electrodes corresponding to Examples W1 to W4 had a good thermal feeling because the content of the stainless steel tip was relatively small. Furthermore, since the fluidity of the material is high at the time of manufacture, it can be easily manufactured by an injection molding method.

  On the other hand, the evaluation electrode corresponding to Comparative Example R1 was defective because it had a thermal feeling close to that of a metal. Moreover, the electrode for evaluation corresponding to Comparative Example R1 has a poor fluidity at the time of production due to a large content of the stainless steel tip, and injection molding is very difficult. Table 1 shows an outline of each evaluation result. Table 1 also shows the evaluation results of the conventional chromium plating electrode.

In addition, this invention is not limited to the said embodiment at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
For example, substantially the same effect can be obtained even if the plastic used for manufacturing the right electrode portion 3 and the left electrode portion 5 is vinyl chloride or polypropylene.

Moreover, even if the processing applied to the surfaces of the right electrode portion 3 and the left electrode portion 5 is knurling processing or dimple processing, substantially the same effect can be obtained.
Further, as shown in FIG. 8, the biosignal electrodes may be attached to any or all of the positions 109A, 109B, 109C in contact with the driver in the vehicle seat 109. In addition, the biomedical electrode may be attached to the position 111A of the seat belt 111 that contacts the driver. Furthermore, the biological signal electrode may be provided on a portion (for example, a headrest, a shift knob, a handle, or an operation switch) that the driver can contact in the vehicle.

  Further, the right electrode part 3 may be as shown in FIG. 9A is a left side view of the steering 101, FIG. 9B is a front view of the steering 101, and FIG. 9C is a right side view of the steering 101.

  In FIG. 9, the right electrode part 3 is composed of a first electrode 3A, a second electrode 3B, a third electrode 3C, and a fourth electrode 3D. The first electrode 3A and the third electrode 3C are located on the front side of the steering 101 and are connected to the negative terminal 11 of the differential amplifier 7 (see FIG. 1). The second electrode 3 </ b> B and the fourth electrode 3 </ b> D are located on the outer peripheral side of the steering 101 and are connected to the ground electrode G of the differential amplifier 7. The second electrode 3B and the fourth electrode 3D are indifferent electrodes.

  The left electrode portion 5 is composed of a first electrode 5A, a second electrode 5B, a third electrode 5C, and a fourth electrode 5D. The first electrode 5 </ b> A and the third electrode 5 </ b> C are located on the front side of the steering 101 and are connected to the negative terminal 11 of the differential amplifier 7. The second electrode 5B and the fourth electrode 5D are located on the outer peripheral side of the steering 101 and are connected to the ground electrode G of the differential amplifier 7. The second electrode 5B and the fourth electrode 5D are indifferent electrodes.

  In addition, the biological information measurement system 1 may be mounted on a moving body other than a vehicle (for example, a railway vehicle, an aircraft, a ship, etc.) and measure the biological information of the driver of the moving body.

DESCRIPTION OF SYMBOLS 1 ... Biological information measurement system, 3 ... Right electrode part, 3A ... 1st electrode,
3B ... second electrode,
3C ... 3rd electrode, 3D ... 4th electrode, 5 ... Left electrode part, 5A ... 1st electrode,
5B ... 2nd electrode, 5C ... 3rd electrode, 5D ... 4th electrode, 7 ... Differential amplifier,
9 ... arithmetic circuit, 11 ... minus side terminal, 13 ... plus side terminal,
15 ... Output terminal,
17 ... A / D converter, 19 ... CPU, 21 ... Evaluation electrode,
101 ... steering,
103, 105 ... Metal cylinder, 107 ... Amplifier for biological signal, 109 ... Sheet,
111 ... seat belt, G ... ground electrode

Claims (8)

  An electrode for biosignal, comprising plastic, a metal piece, and carbon fiber.   2. The biosignal electrode according to claim 1, wherein the plastic is at least one selected from the group consisting of polyurethane, vinyl chloride, and polypropylene.   The biological signal electrode according to claim 1, wherein the metal piece is a stainless steel tip.   The biosignal electrode according to any one of claims 1 to 3, wherein the surface is subjected to mesh processing, blast processing, knurling processing, or dimple processing.   The content of the metal piece is 25 to 50 parts by weight and the content of the carbon fiber is 2 to 10 parts by weight with respect to 100 parts by weight of the biosignal electrode. The biological signal electrode according to any one of the above.   The electrode for biosignal according to any one of claims 1 to 5, wherein a resistance value between two points 10 mm apart on the surface is 200 kΩ or less. The biological signal electrode according to any one of claims 1 to 6,
Measurement means for measuring biological information based on the biological signal acquired by the biological signal electrode;
A biological information measurement system comprising: Mounted on the vehicle,
8. The biological signal according to claim 7, wherein the biological signal electrode is provided on at least one selected from the group consisting of a steering wheel, a seat, a seat belt, a headrest, a shift knob, a handle, and an operation switch of the vehicle. Information measurement system.