JP2012005640A - Electrode unit for electroencephalography - Google Patents

Abstract

An electroencephalogram measurement electrode device capable of measuring an electroencephalogram signal without directly contacting the electrode with the scalp is provided.
An electrode 2 attached to a human scalp 10 via a hair 11, an operational amplifier 30 connected to the electrode 2 and detecting a voltage change due to capacitive coupling between the electrode 2 and the scalp 10; A capacitor formed between the electrode 2 and the scalp 10 when the electrode 2 is attached to the scalp 10 via the scalp 11 with a resistance element 4 having one end connected to the electrode 2 and the other end grounded The resistance value of the resistance element 4 is determined so that the cut-off frequency of the high-pass filter formed by the resistance element 4 can be approximated to 0 as much as possible. The electrode 2 is mounted on one surface of the substrate, the operational amplifier 30 is mounted on the other surface of the substrate, and the substrate is molded with resin so that only the electrode 2 is exposed.
[Selection] Figure 1

Description

  The present invention relates to an electrode device for electroencephalogram measurement that enables highly accurate electroencephalogram examination even from above the hair without directly contacting the electrode with the scalp.

  In recent years, human sensibility has been objectively evaluated from brain waves, and research is being conducted on techniques for analyzing, for example, evaluation of products and evaluation of ride comfort of vehicles using brain waves. In order to accurately evaluate such an electroencephalogram, it is indispensable to accurately measure an electroencephalogram signal.

  The electroencephalogram signal is measured by, for example, contacting a plurality of electrodes made of silver-silver chloride plate electrodes with the subject's scalp. In order to achieve the contact state, it is common practice to perform a scalp treatment such as wiping away fat and dirt on the subject's scalp before measurement, and then using a paste to bring the electrode into contact with the scalp. It has been broken. However, in the case of using the paste, there is a problem that the subject feels uncomfortable because the paste contacts the scalp, and it is necessary to scrape the hair and bring the electrode into contact with the scalp. It takes a lot of time to complete the test. Moreover, when attaching an electrode to a scalp, expertise is requested | required and the problem of being unsuitable for daily use easily also arises.

  Thus, a pasteless EEG signal detection method that does not use paste has also been proposed (see, for example, Patent Document 1). The detection method described in Patent Document 1 uses a method in which an elastic member that has absorbed physiological saline as an electrolytic solution is brought into contact with the scalp as an electrode, and does not use paste, so that the subject's discomfort is reduced. Is possible.

JP 2006-34429 A

  However, even in the detection method described in Patent Document 1 described above, since it is necessary to directly contact the electrode with the scalp, it is necessary to scrape the hair and expose the scalp. This causes a problem that the burden on the subject is large.

  The present invention has been made paying attention to the above-described problems, and an object thereof is to provide an electroencephalogram measurement electrode device capable of measuring an electroencephalogram signal without directly contacting the electrode with the scalp.

  The object of the present invention is an electrode device for electroencephalogram measurement used for detecting an electroencephalogram signal of a person, which is connected to the electroconductive electrode attached to the human scalp via the hair, and the electrode. An amplification circuit for detecting a voltage change due to capacitive coupling between the electrode and the scalp, and a resistance element having one end connected to the electrode and the other end grounded, and the electrode on the human scalp When mounted through the hair, the resistance of the resistive element is such that the cut-off frequency of the high-pass filter formed by the capacitor and the resistive element formed between the electrode and the scalp is close to zero. This is achieved by an electroencephalogram measuring electrode device characterized in that a resistance value is determined.

  In a preferred embodiment of the present invention, the electrode is mounted on one surface of the substrate, the amplifier circuit is mounted on the other surface of the substrate, and the electrode is inserted through a through hole provided in the substrate. And the amplifier circuit is connected.

  In a further preferred aspect of the present invention, the substrate is molded with a resin so that only the electrodes are exposed.

  In still another preferred embodiment of the present invention, the substrate is entirely molded of resin including the electrodes and the amplifier circuit.

  In still another preferred embodiment of the present invention, the electroencephalogram measurement electrode device is incorporated in a cap.

  ADVANTAGE OF THE INVENTION According to this invention, the electrode apparatus for electroencephalogram measurement which can detect an electroencephalogram signal even from the top of hair without making an electrode contact a scalp directly can be provided.

It is a circuit diagram which shows schematic structure of the electrode apparatus for electroencephalogram measurement which concerns on one Embodiment of this invention. FIG. 2 is an equivalent circuit diagram of FIG. 1. It is sectional drawing of the electrode apparatus for electroencephalogram measurement. It is explanatory drawing explaining the mounting position of an electrode. It is a photograph which shows the state which mounted | wore the test subject's head and the electrode used for experiment. In Example 1, it is a graph which shows a part of measurement waveform of the electroencephalogram signal measured at the time of eye opening and closing eyes. It is a graph which shows the result of having performed frequency analysis about the measurement waveform of FIG. In Example 2, it is a graph which shows a part of measurement waveform of the electroencephalogram signal measured at the time of sleep. It is a graph which shows the result of having performed frequency analysis about the measurement waveform of FIG. It is a block diagram which shows schematic structure of the measurement system of Example 3. FIG. In Example 3, it is a graph which shows a part of measurement waveform of the electroencephalogram signal measured at the time of sleep. It is a graph which shows the result of having performed frequency analysis about the measurement waveform of FIG. It is a perspective view which shows the state which incorporated the electrode apparatus for electroencephalogram measurement into the balaclava. In Example 4, it is a graph which shows the measurement waveform part of the electroencephalogram signal measured at the time of sleep. It is a graph which shows the result of having performed frequency analysis about the measurement waveform of FIG. In Example 4, it is a graph which shows the measurement waveform part of the electroencephalogram signal measured at the time of sleep. It is sectional drawing of other embodiment of the electrode apparatus for electroencephalogram measurement.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a schematic configuration of an electroencephalogram measurement electrode device 1 according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing an equivalent circuit of FIG. 1, and FIG. 3 is a cross-sectional view showing the configuration of the electroencephalogram measurement electrode device 1 Each figure is shown. As shown in FIGS. 1 to 3, the electroencephalogram measurement electrode device 1 includes a conductive electrode 2, an amplifier circuit 3, and a resistance element 4 as main components. The electric signal generated from the brain can be detected even from above the hair 11 without directly contacting the electrode 2.

The electrode 2 is not attached to the surface of the human scalp 10 directly, but is attached to the scalp 10 using the human hair 11 as a dielectric and sandwiching the hair 11 as the dielectric. The electrode 2 forms a virtual capacitor 5 (see FIG. 2) with the human scalp 10, and the generated potential (brain potential) V _{vivo of the} brain by capacitive coupling between the electrode 2 and the scalp 10. It functions as a capacitively coupled electrode for detecting.

The material constituting the electrode 2 is not particularly limited as long as it has conductivity, but has a softness that does not give a strange feeling to the human head when worn on the human hair 11. In this embodiment, it is constituted by a flat copper plate. The electrode 2 is connected to the amplifier circuit 3 and transmits the potential (electric signal) of the electrode 2 that fluctuates according to the fluctuation of the brain potential V _vivo to the amplifier circuit 3.

The amplifier circuit 3 detects a brain potential V _vivo by detecting a voltage change due to capacitive coupling between the electrode 2 and the human scalp 10, and in this embodiment, a high input impedance (low Output impedance) operational amplifier 30. The electrode 2 is connected to the input terminal (+ side) 30A of the operational amplifier 30, and the potential of the electrode 2 (brain potential V _VIVO ) is input as an electric signal. Also, feedback from the output terminal 30C of the operational amplifier 30 is input to the input terminal (− side) 30B of the operational amplifier 30. The operational amplifier 30 can transmit the electric signal from the electrode 2 to the output terminal 32 </ b> C while suppressing the input of current with the above-described configuration. The amplifier circuit 3 is connected to a measuring device (not shown) via a signal line 12 (shown in FIG. 3), and an output voltage _VOUT of the amplifier circuit 3 is input to the measuring device as an electric signal, and an electroencephalogram signal Used for measurement.

The resistance element 4 is a resistor provided to discharge the charge in order to prevent the output voltage _VOUT of the amplifier circuit 3 from being saturated by the charge accumulated in the electrode 2. The resistance element 4 has one end connected to the electrode 2 and the other end connected to the ground terminal 6, and this configuration, that is, the capacitor 5 and the resistance element 4 formed by the electrode 2 and the scalp 10, A virtual circuit having the potential V _vivo as an input is formed. This circuitry functions as a high-pass filter 7, cut-off frequency f _c of the high-pass filter 7 is represented by two parameters R _g, with C _b the following formula (1). R _g is a resistance value of the resistance element 4 provided between the input terminal (+ side) of the operational amplifier 30 and the ground terminal 6. _Cb is a capacitance value of the capacitor 5 formed by the electrode 2 and the human scalp 10.

Here, the electrical signal of the brain potential V _vivo output from the electrode 2 passes through the high-pass filter 7 and is input to the amplifier circuit 3 with a predetermined frequency component cut by the high-pass filter 7. Therefore, in order to output an electric signal of brain potentials V _vivo more accurately the amplifier circuit 3, to reduce the influence of the high-pass filter 7, i.e., so that the cut-off frequency f _c is a small value, the resistance value _Rg needs to be set. Therefore, in this embodiment, as cut-off frequency f _c of the high-pass filter 7 is approximated to zero as possible, the resistance R _g is set as large as possible, and configured to ignore the influence of the high-pass filter 7 Yes.

The resistance value R _g can be appropriately set in consideration of the capacitance value C _b (C _b << R _g ). However, if an example of a desirable value is shown, R _g = 2.2 [MΩ] is there. Incidentally, the greater the value of the resistance R _g is greater, electrical signals in the brain potentials V _vivo output by the electrode 2, it is considered that hardly affected by the high-pass filter 7, the value of the resistance R _g is 2 It may be larger than 2 [MΩ]. By substituting this resistance value _Rg into the above equation (1), the cutoff frequency f _c can be approximated as f _c ≈0 [Hz], so that the influence of the high-pass filter 7 can be ignored. .

  The electroencephalogram measurement electrode device 1 of the present embodiment is composed of an active electrode in which an electrode 2 and an operational amplifier 30 are integrally formed, and the operational amplifier 30 is mounted on one surface of the substrate 8 as shown in FIG. In addition, the electrode 2 is mounted on the other surface of the substrate 8 opposite to the operational amplifier 30. The electrode 2 and the operational amplifier 30 are connected by a leading wire (not shown) inserted into a through hole (not shown) formed in the substrate 8. Further, the substrate 8 is covered with an insulating resin such as an epoxy resin, for example, and most of the substrate 8 is sealed in the mold resin 9 so that troubles such as a short circuit do not occur in other parts other than the electrode 2. It has become. Note that at least the surface 20 of the electrode 2 is not resin-molded and is exposed to the outside.

Next, the measurement principle by the electroencephalogram measurement electrode device 1 having the above-described configuration will be described. As shown in FIG. 2, the electrode 2 is mounted on a human scalp 10 with a dielectric (hair 11) sandwiched therebetween. The electrode 2 corresponds to one electrode of the capacitor 5 in the region surrounded by the broken line in FIG. 2 and is grounded via the resistance element 4. As shown in FIG. 2, the capacitance value between the scalp 10 and the electrode 2 is C _b , the resistance value of the resistance element 4 is R _g , and the resistance value and capacitance value of the input stage of the operational amplifier 30 are R _op. , C _op , the brain potential is V _vivo , and the output voltage of the operational amplifier 30 is V _out , the transfer function of this virtual circuit configuration is expressed by the following formula (2).

In the above equation (2), the resistance value R _op of the operational amplifier 30 is sufficiently large due to the characteristics of the operational amplifier 30, and thus can be approximated as the following equation (3).

  Moreover, when the above formulas (1) and (3) are used, they can be approximated as the following formula (4).

Furthermore, the characteristics of the operational amplifier 30, the capacitance value C _op of the operational amplifier 30 in order C _b to be sufficiently smaller than the other electrostatic capacitance values can be approximated by the following expression (5), the equation (2 ), Assuming that the above equations (3), (4), and (5) are satisfied, V _out ≈V _vivo is derived.

Thus, according to the electroencephalogram measurement electrode device 1 of the present embodiment, the electrode 2 is not directly brought into contact with the human scalp 10 and is mounted and measured with the hair 11 sandwiched between the scalp 10. In addition, the brain potential V _vivo can be detected without changing the voltage value.

  Examples of electroencephalogram measurement using an electroencephalogram measurement electrode device (hereinafter referred to as “capacitive coupling electrode”) 1 according to the present invention will be described below. The basic rhythm of brain waves is named for each frequency. The main frequency bands are δ waves (0.5 Hz to 4 Hz), θ waves (4 Hz to 8 Hz), α waves (8 Hz to 13 Hz), and β waves. (13 Hz to 40 Hz). Therefore, in this embodiment, in order to confirm whether or not the α wave, β wave, and δ wave, which are characteristic brain waves that appear during awakening and sleep, can be measured using the capacitively coupled electrode 1, The following four experiments (Examples 1 to 4) were conducted. The measurement was performed in a shielded room for one healthy adult male.

  The capacitively coupled electrode 1 uses a disk-shaped copper plate having a diameter of about 5 mm and a thickness of about 0.65 mm for the electrode 2, and the substrate 8 is epoxy-coated so that the surface of the copper plate is exposed as shown in FIG. 3. What was covered and molded with resin was used. The operational amplifier 30 was a low noise type (“OPA124U” manufactured by BURR-BROWN).

<Example 1>
It is known that α waves appear relatively predominantly in the occipital region when the eyes are closed in a resting state when awake. Further, it is known that β waves appear in a relatively large amount at the center of the head when the eyes are opened in a resting state when awake. Therefore, in Example 1, in order to confirm whether or not the α-wave and the β-wave can be measured using the capacitively coupled electrode 1, brain waves were measured when the eyes were opened and when the eyes were closed. As for the electrode mounting position, the electrode was mounted at one point of O 2 according to the 10-20 method, which is the standard method of the International Electroencephalographic Society shown in FIG. The output voltage _Vout output from the capacitively coupled electrode 1 mounted on the subject's head is input to a measuring device (not shown) via the signal line 12 (shown in FIG. 3). Further, according to the reference electrode derivation method, an electrode (reference electrode) is attached to the subject's earlobe (left earlobe A1 in this embodiment), the potential of the left earlobe A1 is taken as the reference voltage V ₀ and similarly input to the measuring device. Thus, the measurement device performs differential amplification of V _out and V ₀ and band-pass filtering of the electric signal, obtains a target electroencephalogram signal, and stores it in a PC (not shown) as time series data. It was. As a comparative example, a conventional silver-silver chloride dish electrode (hereinafter referred to as “reference electrode”) is mounted at the same position on the subject's head, and an electroencephalogram is simultaneously measured in the same manner as the capacitively coupled electrode 1. Went. As a measuring instrument, a portable versatile biological amplifier ("Polymate" manufactured by TEAC) was used. The set value of the bandpass filter was set to 5.0 to 60 [Hz] (in the other examples described later, it was set to 0.5 to 30 [Hz]).

  As shown in FIG. 5 (a), the reference electrode 100 was placed side by side with the capacitively coupled electrode 1, and the hair at the measurement site was scraped off and mounted using a paste. On the other hand, the capacitively coupled electrode 1 was only fixed on the hair with a tape or the like. Further, in order to improve the adhesion between each electrode and the head, a seal was applied to the hair from the top of each electrode and fixed with a net or the like (see FIG. 5B).

  The measurement results are shown in FIGS. FIG. 6 shows a measurement waveform of an electroencephalogram signal 10 seconds after the start of measurement, among the measurement waveforms of the electroencephalogram signal when the eye is opened and closed by the capacitive coupling electrode 1 and the reference electrode 100. From the top, the electroencephalogram measurement waveform when the eye is opened by the capacitive coupling electrode 1, the electroencephalogram measurement waveform when the eye is opened by the reference electrode 100, the electroencephalogram measurement waveform when the eye is closed by the capacitive coupling electrode 1, and the electroencephalogram when the eye is closed by the reference electrode 100 Each of the measurement waveforms is shown. FIG. 7 shows the result of frequency analysis (FFT) using the frequency analysis software (“OriginPro 7J” manufactured by Light Stone) for the measurement waveform of the electroencephalogram signal 60 seconds after the start of measurement.

  Referring to FIG. 6, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 shows a variation very close to the electroencephalogram measurement waveform by the reference electrode 100, and the electroencephalogram measurement waveform by the capacitively coupled electrode 1 also depends on the reference electrode 100. As with the electroencephalogram measurement waveform, the α wave can be confirmed when the eye is closed, and the α wave is suppressed and the β wave (fast wave) is increased when the eye is opened.

  In addition, referring to FIG. 7, in the electroencephalogram measurement waveform by the capacitively coupled electrode 1, as can be seen from FIGS. 7A and 7B, the spectrum is dispersed over a wide frequency band when the eye is opened. It was confirmed that the spectrum was maximum at 10 Hz when the eyes were closed. Further, comparing (a) and (c) of FIG. 7 and (b) and (d) of FIG. 7, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 and the electroencephalogram measurement waveform by the reference electrode 100 are equivalent. It was confirmed that the frequency analysis result of the level was obtained.

  From these results, by using the capacitively coupled electrode 1, it is possible to measure α waves and β waves, which are main brain waves, even if they are worn on the hair without directly contacting the scalp. It was confirmed that.

<Example 2>
The δ wave generally appears during deep sleep (sleep depth 3 or 4), and when it appears at rest awakening, it can be immediately judged as an abnormal decrease in brain function (a wave having a smaller frequency than the α wave) It is. Thus, in Example 2, in order to confirm whether or not the δ wave, which is a characteristic brain wave during sleep, can be measured using the capacitively coupled electrode 1, an electroencephalogram measurement during overnight sleep was performed. The electrodes were mounted at four points C3, C4, O1, and O2 according to the 10-20 method, which is a standard method of the International Electroencephalogram Society shown in FIG. In the second embodiment, the reference electrode is attached to the left earlobe A1 and right earlobe A2 of the subject, and the potential of the left earlobe A1 and right earlobe A2 is taken as the reference voltage V ₀ to reduce the influence due to the activation of the reference electrode. In order to achieve this, a reference electrode derivation method in which the exploration electrode and the reference electrode are combined, such as C3-A2, O1-A2, C4-A1, and O2-A1, was used. Further, the capacitively coupled electrode 1 and the reference electrode 100 were mounted on the subject's head in the same manner as in Example 1 described above for each electrode position.

  The measurement results are shown in FIGS. FIG. 8 shows a measurement waveform of an electroencephalogram signal for 20 seconds during deep sleep (sleep depth 3, 4) by the capacitively coupled electrode 1 and the reference electrode 100. From the top, the electroencephalogram measurement waveform at the C3 position by the capacitive coupling electrode 1, the electroencephalogram measurement waveform at the C3 position by the reference electrode 100, the electroencephalogram measurement waveform at the C4 position by the capacitive coupling electrode 1, and the electroencephalogram at the C4 position by the reference electrode 100. Measurement waveform, electroencephalogram measurement waveform at O1 position by capacitively coupled electrode 1, electroencephalogram measurement waveform at O1 position by reference electrode 100, electroencephalogram measurement waveform at O2 position by capacitively coupled electrode 1, and electroencephalogram measurement waveform at O2 position by reference electrode 100 , Respectively. FIG. 9 shows the result of frequency analysis (FFT) of the measurement waveform of the electroencephalogram signal of FIG. 8 using frequency analysis software (“OriginPro 7J” manufactured by Light Stone).

  Referring to FIG. 8, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 shows a variation that is very close to the electroencephalogram measurement waveform by the reference electrode 100. For example, in the electroencephalogram measurement waveforms at the C3 position and the C4 position, the reference electrode 100 As in the case of the electroencephalogram measurement waveform, the δ wave was remarkably confirmed between 2.5 seconds and 5 seconds and between 8 seconds and 15 seconds.

  Referring to FIG. 9, as can be seen from FIGS. 9A, 9 </ b> C, 9 </ b> E, and 9 </ b> G, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 is the same as the electroencephalogram measurement waveform by the reference electrode 100. Similarly, it was confirmed that the spectrum was maximized in the frequency band of δ wave of 0.5 to 4.0 [Hz].

  From these results, by using the capacitively coupled electrode 1, it is possible to measure the δ wave, which is the main brain wave, even if it is worn on the hair without directly contacting the scalp. Was confirmed.

<Example 3>
In the third embodiment, in the first and second embodiments, the same electric signal as the electric signal output from the reference electrode 100 to the measuring device is measured by the cross-talk from the reference electrode 100. This is in consideration of the possibility of output to the device. In the third embodiment, as shown in FIG. 10, two measuring devices and two PCs are prepared, and the output voltage output from the capacitively coupled electrode 1 mounted on the subject's head for electroencephalogram measurement. While outputting the electrical signal of V _out to the measurement device 14A and the PC 15A, the electrical signal output from the reference electrode 100 is output to the measurement device 15B and the PC 15B different from the capacitive coupling type electrode 1, and the capacitive coupling type electrode 1 and the reference electrode 100 were completely separated electrically, and then electroencephalogram measurement was performed in the same manner as in Example 2 above.

  The measurement results are shown in FIGS. FIG. 11 shows a measurement waveform of an electroencephalogram signal for 40 seconds during deep sleep (sleep depth 4) by the capacitively coupled electrode 1 and the reference electrode 100. From the top, the electroencephalogram measurement waveform at the C3 position by the capacitive coupling electrode 1, the electroencephalogram measurement waveform at the C3 position by the reference electrode 100, the electroencephalogram measurement waveform at the C4 position by the capacitive coupling electrode 1, and the electroencephalogram at the C4 position by the reference electrode 100. Measurement waveform, electroencephalogram measurement waveform at O1 position by capacitively coupled electrode 1, electroencephalogram measurement waveform at O1 position by reference electrode 100, electroencephalogram measurement waveform at O2 position by capacitively coupled electrode 1, and electroencephalogram measurement waveform at O2 position by reference electrode 100 , Respectively. FIG. 12 shows the result of frequency analysis (FFT) on the measurement waveform of the electroencephalogram signal of FIG. 11 using frequency analysis software (“OriginPro 7J” manufactured by Light Stone).

  Referring to FIG. 11, even if the capacitively coupled electrode 1 and the reference electrode 100 are electrically completely separated, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 fluctuates very closely to the electroencephalogram measurement waveform by the reference electrode 100. For example, in the electroencephalogram measurement waveform at the O2 position, similarly to the electroencephalogram measurement waveform by the reference electrode 100, it is 0 second to 8 seconds, 10 seconds to 20 seconds, and 22 seconds to 38 seconds. In the meantime, the δ wave was remarkably confirmed.

  Referring to FIG. 12, as can be seen from FIGS. 12A, 12 </ b> C, 12 </ b> E, and 12 </ b> G, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 is the same as the electroencephalogram measurement waveform by the reference electrode 100. Similarly, it was confirmed that the spectrum was maximum at 1 Hz which is the frequency band of the δ wave.

  From these results, it was confirmed that the measurement result by the capacitive coupling electrode 1 of Example 1 and Example 2 was not due to the crosstalk from the reference electrode 100. By using the capacitive coupling electrode 1, It was confirmed that the main brain waves, α wave, β wave, and δ wave can be measured even if it is worn on the hair without directly contacting the scalp.

<Example 4>
EEG measurement in daily life is useful for health care in daily life, and it is required to perform EEG measurement easily in daily life. Therefore, in the fourth embodiment, in order to confirm whether or not the electroencephalogram measurement can be easily performed using the capacitive coupling electrode 1, the capacitive coupling electrode 1 is used as a cap (a balance cap in this embodiment). The brain wave was measured during the overnight sleep after the subject was wearing this hat.

  As shown in FIG. 13, in the fourth embodiment, the capacitively coupled electrode 1 is placed on the head of the inner surface of the cap 13 so that the electrodes are located at the positions C3, C4, O1, and O2 of the head shown in FIG. Each was attached to the mounting surface. Then, after the reference electrode 100 is attached to a predetermined position (C3, C4, O1, and O2 positions in FIG. 4) of the subject's head, the subject is caused to wear the cap 13, and EEG measurement was performed in the same way. Since the capacitively coupled electrode 1 is attached to the cap 13 with Velcro tape, the electrode position after wearing the cap 13 can be finely adjusted. In FIG. 13, the human hair 11 is not shown.

  The measurement results are shown in FIGS. FIG. 14 shows a measurement waveform of an electroencephalogram signal for 30 seconds during deep sleep (sleep depth 4) by the capacitively coupled electrode 1 and the reference electrode 100. From the top, the electroencephalogram measurement waveform at the C3 position by the capacitive coupling electrode 1, the electroencephalogram measurement waveform at the C3 position by the reference electrode 100, the electroencephalogram measurement waveform at the C4 position by the capacitive coupling electrode 1, and the electroencephalogram at the C4 position by the reference electrode 100. Measurement waveform, electroencephalogram measurement waveform at O1 position by capacitively coupled electrode 1, electroencephalogram measurement waveform at O1 position by reference electrode 100, electroencephalogram measurement waveform at O2 position by capacitively coupled electrode 1, and electroencephalogram measurement waveform at O2 position by reference electrode 100 , Respectively. FIG. 15 shows the result of frequency analysis (FFT) of the measurement waveform of the electroencephalogram signal of FIG. 14 using frequency analysis software (“OriginPro 7J” manufactured by Light Stone).

  Referring to FIG. 14, even if the electroencephalogram is measured by incorporating the capacitively coupled electrode 1 into the cap 13, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 varies very closely to the electroencephalogram measurement waveform by the reference electrode 100. As in the case of the electroencephalogram measurement waveform by the reference electrode 100, the δ wave could be confirmed.

  Referring to FIG. 15, as can be seen from FIGS. 12A, 12 </ b> C, 12 </ b> E, and 12 </ b> G, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 is the same as the electroencephalogram measurement waveform by the reference electrode 100. Similar frequency analysis results were obtained, and it was confirmed that the spectrum was maximized at 1 Hz which is the frequency band of the δ wave, similar to the electroencephalogram measurement waveform by the reference electrode 100.

  From these results, it is confirmed that the capacitively coupled electrode 1 can measure the δ wave, which is one of the characteristic waveforms of the electroencephalogram, by incorporating the capacitively coupled electrode 1 into the cap 13 or the like. It was confirmed that it was possible to perform electroencephalogram measurement by a simple method.

  FIG. 16 shows a measurement waveform of an electroencephalogram signal for 30 seconds by the capacitively coupled electrode 1 and the reference electrode 100 after 5 and a half hours from the start of measurement. From the top, the electroencephalogram measurement waveform at the C3 position by the capacitive coupling electrode 1, the electroencephalogram measurement waveform at the C3 position by the reference electrode 100, the electroencephalogram measurement waveform at the C4 position by the capacitive coupling electrode 1, and the electroencephalogram at the C4 position by the reference electrode 100. Measurement waveform, electroencephalogram measurement waveform at O1 position by capacitively coupled electrode 1, electroencephalogram measurement waveform at O1 position by reference electrode 100, electroencephalogram measurement waveform at O2 position by capacitively coupled electrode 1, and electroencephalogram measurement waveform at O2 position by reference electrode 100 , Respectively.

  Referring to FIG. 16, even after 5 and a half hours have elapsed from the start of measurement, the electroencephalogram measurement waveform by the capacitively coupled electrode 1 is the same as the electroencephalogram measurement waveform by the reference electrode 100, At 5 seconds and 27.5 seconds, a sleep spindle wave, which is a determination index of sleep depth 2, could be confirmed. The sleep spindle wave is a waveform in which the contour of the waveform exhibits a spinning shape and the duration is 0.5 seconds to 1.5 seconds.

  From this result, it was confirmed that the capacitively coupled electrode 1 can be used even for long-time measurement.

  As described above, when the electroencephalogram measurement electrode device 1 of the present invention is used, a good signal level can be obtained even if the scalp is worn with the hair sandwiched over the hair without directly contacting the human scalp. Can be measured. Therefore, when performing electroencephalogram measurement, the scalp treatment such as wiping off the fat and dirt on the scalp, and the need for pre-treatment such as using a paste to bring the electrode into contact with the scalp can be saved. In addition, the subject is not uncomfortable and the burden on the subject can be reduced.

  In addition, it can be used to measure brain waves over a long period of time, and a good brain wave signal can be measured by incorporating it into a hat, etc. Is possible.

As mentioned above, although one Embodiment of this invention was described, the specific aspect of this invention is not limited to the said embodiment. For example, in the present embodiment, as shown in FIG. 3, the substrate 8 is covered and molded with an epoxy resin so that only the electrode 2 is exposed. However, as shown in FIG. The whole including the electrode 2 and the operational amplifier 30 may be molded with an epoxy resin. The electrode apparatus 1 for electroencephalogram measurement of the present invention does not wear the electrode 2 so as to be in direct contact with the surface of the human scalp 10, but interposes a dielectric such as hair between the electrode 2 and the scalp 10. Since the brain potential V _vivo is measured by capacitive coupling between the electrode 2 and the scalp 10, even if the surface 20 of the electrode 2 is covered with resin as shown in the example, Since it functions as a dielectric interposed between the scalp 10 and the electrode 2, it is possible to measure an electroencephalogram signal with a good signal level.

  According to this embodiment, since the electrode 2 is completely encapsulated in the mold resin 9, the electrode 2 is less likely to deteriorate due to aging due to external force, wear, etc., and to affect the measurement accuracy. It can also be obtained.

DESCRIPTION OF SYMBOLS 1 Electrode apparatus for electroencephalogram measurement 2 Electrode 3 Amplifying circuit 4 Resistive element 7 High pass filter 8 Substrate 9 Mold resin 10 Scalp 11 Hair 13 Hat 30 Operational amplifier

Claims (5)

An electroencephalogram measurement electrode device used to measure a human electroencephalogram signal,
Conductive electrodes attached to the human scalp via the hair,
An amplification circuit connected to the electrode and detecting a voltage change due to capacitive coupling between the electrode and the scalp;
A resistance element having one end connected to the electrode and the other end grounded,
When the electrode is attached to a human scalp via scalp, the cut-off frequency of the high-pass filter formed by the capacitor and the resistance element formed between the electrode and the scalp is close to 0 as much as possible. Thus, the resistance value of the resistance element is determined, and the electrode device for electroencephalogram measurement characterized by the above.   The electrode is mounted on one surface of the substrate, the amplifier circuit is mounted on the other surface of the substrate, and the electrode and the amplifier circuit are connected through a through hole provided in the substrate. The electroencephalogram measurement electrode device according to claim 1.   3. The electroencephalogram measurement electrode device according to claim 2, wherein the substrate is molded with a resin so that only the electrode is exposed.   3. The electroencephalogram measurement electrode device according to claim 2, wherein the entire substrate including the electrode and the amplifier circuit is molded with resin.   5. The electroencephalogram measurement electrode device according to claim 2, wherein the electroencephalogram measurement electrode device is incorporated in a cap.

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