JP5306886B2 - Bioelectric signal measuring sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a bioelectric signal measuring sensor that can be suitably used for measuring an electroencephalogram or the like.

  In brain surgery, it is desirable to perform the operation while constantly monitoring the morphological information and functional information of the brain for the safety of the operation and the execution of an appropriate operation plan. Brain morphological information can be obtained from images taken by X-ray CT, MRI, etc., and brain functional information is generated with brain nerve cell activity using electroencephalogram electrodes. It can be obtained by measuring electrical fluctuations (electroencephalogram).

  Conventionally, a silver dish electrode is used as an electroencephalogram electrode, but since silver has the property of disturbing X-rays and magnetism, imaging by X-ray CT or MRI is performed in parallel with the electroencephalogram measurement using the silver dish electrode. If this is done, artifacts (false images) will appear in the CT image and MRI image. For example, in the case of imaging by X-ray CT, the X-ray transmittance is lowered around the silver plate electrode, and the shadowed portion of the silver plate electrode appears radially white as shown in FIG. It becomes impossible (Patent Document 1). For this reason, the conventional silver plate electrode is prohibited from being used together with an X-ray CT apparatus or an MRI apparatus.

  In addition, since the silver plate electrode is hard, if it is worn on the head for a long time, the scalp may be physically stimulated to cause inflammation.

  In addition, many silver pan electrodes are used in brain surgery, but these are expensive, so they may not be discarded in a single use and may be used by multiple patients, and there is concern about the risk of infection. .

JP 2002-51999 A

  Therefore, the present invention can obtain a clear image in which artifacts do not appear even if imaging by X-ray CT or MRI is performed in parallel with the electroencephalogram measurement, and can be disposable at low cost. The present invention is intended to provide a bioelectric signal measuring sensor with less physical burden.

  That is, the bioelectric signal measurement sensor according to the present invention is a sensor including an electrode element for detecting an electric signal emitted from a living body, and the electrode element is a resin in which carbon nanotubes are dispersed in a matrix resin. It consists of a composition.

  If this is the case, the X-rays and magnetism will not be disturbed even if the X-ray CT or MRI is performed while detecting the electroencephalogram using the bioelectric signal measurement sensor according to the present invention, so that artifacts will not occur. A clear CT image or MRI image that does not appear can be obtained. For this reason, for example, during brain surgery, while acquiring functional information of the brain using the bioelectric signal measurement sensor according to the present invention, in parallel, morphological information of the brain by X-ray CT or MRI And can perform highly safe surgery.

  Further, the bioelectric signal measuring sensor according to the present invention can be made inexpensive and disposable because the raw material is inexpensive. For this reason, the risk of the infectious disease by reuse can be reduced.

  Furthermore, since the electrode element of the bioelectric signal measurement sensor according to the present invention is formed from a flexible resin composition, it is easy to follow the surface shape of the skin and easily adhere to it. For this reason, the bioelectric signal measuring sensor according to the present invention has less physical irritation to the skin and is less prone to irritation even when worn for a long time, so that the physical burden on the subject can be reduced.

  The carbon nanotube is preferably a multi-walled carbon nanotube. Multi-walled carbon nanotubes have higher strength, heat resistance, and chemical resistance than semiconductor single-walled carbon nanotubes, and are superior in electrical conductivity, so that the detection sensitivity of bioelectric signals can be improved.

  The carbon nanotubes preferably form a laminate in which a plurality of carbon nanotube particles are laminated. When a large number of carbon nanotube particle laminates are formed in the matrix resin, the conductivity of the resin composition is improved. Accordingly, the detection sensitivity of bioelectric signals can be further improved.

  The resin composition is preferably formed into a sheet shape. By making the resin composition into a sheet shape, the electrode element can be more easily adhered to the skin, so that physical irritation to the skin can be further reduced.

  The bioelectric signal measuring sensor according to the present invention preferably further comprises a lead wire made of carbon fiber and electrically connected to the electrode element. If the lead wire connected to the electrode element is made of carbon fiber, the flexibility of the electrode element formed from the resin composition is not impaired. Instead of using carbon fiber as a lead wire, the electrode element may be extended to form a lead wire.

  The use of the bioelectric signal measurement sensor according to the present invention is not particularly limited. For example, the bioelectric signal measurement sensor can be suitably used as an electroencephalogram measurement sensor by wearing it on the subject's head.

  The bioelectric signal measuring sensor according to the present invention is manufactured using, for example, a method including the steps of adding the carbon nanotubes to the matrix resin and applying ultrasonic vibration to disperse the carbon nanotubes in the matrix resin. be able to. Such a manufacturing method is also one aspect of the present invention.

  As described above, according to the present invention, a weak bioelectric signal can be detected with high sensitivity, and X-rays and magnetism are not disturbed. Even if it performs, it is possible to obtain a clear image without artifacts. The bioelectric signal measurement sensor according to the present invention can be disposable at low cost because the raw material is inexpensive. Furthermore, since the electrode element of the bioelectric signal measurement sensor according to the present invention is formed of a flexible resin composition, the physical burden on the subject wearing the electrode element is small.

It is an external view of the sensor for electroencephalogram measurement concerning one embodiment of the present invention. It is a longitudinal cross-sectional view of the electroencephalogram measurement sensor according to the same embodiment. It is a graph which shows the influence which the dispersion degree of a carbon nanotube has on the electroconductivity of a resin composition. It is the X-ray CT image of the brain imaged using the electroencephalogram measurement sensor according to the embodiment. It is the MRI image of the brain imaged using the sensor for electroencephalogram measurement concerning the embodiment. It is the electroencephalogram chart measured using the sensor for electroencephalogram measurement or silver plate electrode concerning the embodiment. It is the X-ray CT image of the brain imaged using the conventional silver plate electrode.

  An embodiment of the present invention will be described below with reference to the drawings.

  An electroencephalogram measurement sensor 1 according to the present embodiment is for mounting on the head of a subject to detect an electroencephalogram, and as shown in FIGS. 1 and 2, an electrode portion 2 and a lead wire portion 3. And.

  Each part is described in detail below.

  The electrode portion 2 is a thin disk having a diameter of about 1 cm and a thickness of about 0.9 mm. From the scalp contact surface 211 side, an electrode layer 21, an adhesive layer 22, and a cover layer 23, which are electrode elements, are laminated. It will be. On the other hand, the lead wire part 3 includes a carbon fiber part 31 connected to the electrode part 2 and a vinyl wire part 32 extended from the carbon fiber part 31. The electrode layer 21 and the cover layer 23 are bonded to each other with the adhesive layer 22 so that the free end of the carbon fiber portion 31 is sandwiched therebetween.

  The electrode layer 21 is made of a resin composition obtained by dispersing carbon nanotubes in a matrix resin and formed into a sheet shape, and has a thickness of about 0.4 mm.

  The carbon nanotube production method is not particularly limited, and examples thereof include chemical vapor deposition methods (CVD methods) such as an arc discharge method, a laser ablation method, a HiPCO method, and the like, and are produced using these various methods. Carbon nanotubes can be used.

  As the carbon nanotube, for example, one having a diameter of 1 to 140 nm and a length of 7 μm is used.

  The carbon nanotube may have a single-layer structure or a multi-layer structure, but a multi-wall carbon nanotube is preferably used. Multi-walled carbon nanotubes have higher strength, heat resistance, and chemical resistance than semiconductor single-walled carbon nanotubes, and are excellent in electrical conductivity. Therefore, it is possible to improve brain wave detection sensitivity. The carbon nanotubes include metal single-walled carbon nanotubes and those whose diameters expand toward one side, usually called carbon nanohorns.

  The matrix resin for dispersing the carbon nanotubes is selected in consideration of irritation to the living body, dispersibility of the carbon nanotubes, moldability, etc., for example, an acrylic resin such as polymethyl methacrylate, polyurethane, polypropylene, Polyethylene, polyvinyl carbazole, polycarbonate and the like are used. Of these, polyurethane, which is an artificial organ material, is preferable because of its excellent biocompatibility.

  The addition amount of the carbon nanotubes to the matrix resin is preferably 20 to 64% by weight in the resin composition. If the amount is less than 20% by weight, sufficient conductivity cannot be obtained, and thus the electroencephalogram detection sensitivity becomes insufficient. If the amount exceeds 64% by weight, it becomes difficult to form a sheet.

  In order to prepare the resin composition by dispersing the carbon nanotubes in the matrix resin, the carbon nanotubes may be directly kneaded in the matrix resin, but after dissolving the matrix resin in a solvent. It is preferable to add the carbon nanotubes thereto to prepare a liquid resin composition. By preparing a liquid resin composition in this manner, the dispersion state of the carbon nanotubes can be easily adjusted, and the resin composition can be easily formed into a sheet.

  In order to disperse the carbon nanotubes in the matrix resin, for example, a method of applying ultrasonic vibration to the matrix resin to which the carbon nanotubes are added, or using a supercritical fluid such as carbon dioxide, the carbon nanotubes are dispersed in the matrix resin. Although the method etc. to disperse | distribute in resin can be used, It is preferable to disperse | distribute using ultrasonic vibration especially. When high-amplitude ultrasonic vibration is applied to the matrix resin to which the carbon nanotubes are added, the carbon nanotubes are cut to form carbon nanotube particles, and a plurality of laminates in which a plurality of the carbon nanotube particles are stacked are formed. A resin composition is obtained. Thus, when many laminated bodies of carbon nanotube particles are formed in the matrix resin, the conductivity of the resin composition is improved, and accordingly, the electroencephalogram detection sensitivity is also improved. The average particle diameter of the carbon nanotube particles is preferably 536 to 584 nm.

  The obtained resin composition can be formed into a sheet by, for example, a method in which a liquid resin composition is applied on a glass plate and dried and solidified.

  In order to verify the effect of ultrasonic treatment, polymethyl methacrylate was dissolved in methyl ethyl ketone, and then a multi-walled carbon nanotube was added thereto, and then the ultrasonic treatment was performed using a 600 W homogenizer. (0 to 60 minutes), then the methyl ethyl ketone is volatilized to form a thin film (measured in dry air, sample dimensions: width 0.9 mm, thickness 0.1 mm, length 0.9 mm). The current / voltage characteristics were measured. The obtained results are shown in the graph of FIG. As shown in FIG. 3, it was confirmed that the conductivity of the resin composition was improved as the treatment time by ultrasonic vibration was longer.

  The adhesive layer 22 is for bonding the electrode layer 21 and the cover layer 23 together. The material of the adhesive layer 22 is not particularly limited as long as it has both adhesiveness and conductivity. For example, a conductive adhesive in which carbon nanotubes are dispersed in a synthetic resin adhesive, or itself The adhesive layer 22 can be formed by applying an adhesive made of a conductive resin having conductivity to the electrode layer 21 or the cover layer 23.

  The cover layer 23 is for protecting the carbon fiber portion 31 and reinforcing the electrode layer 21, and has a thickness of about 250 μm. Like the electrode layer 21, the cover layer 23 may be formed from a resin composition formed by dispersing a conductive material such as carbon nanotubes in a matrix resin into a sheet shape. What was created from the resin sheet which does not contain a carbon nanotube may be used.

  The carbon fiber portion 31 is made of a carbon fiber bundle, is fixed between the electrode layer 21 and the cover layer 23, and is electrically connected to the electrode layer 21.

  The vinyl wire portion 32 is made of a copper wire or the like coated with a resin, and is connected to the carbon fiber portion 31 via a pair of connectors 322 that can be attached to and detached from each other. It is configured to be connected to an electroencephalograph (not shown) via a connector 321 provided in the above.

  In order to measure a subject's brain waves using the brain wave measuring sensor 1 according to the present embodiment, the brain wave measuring sensor 1 is mounted so that the scalp contact surface 211 of the electrode layer 21 is in close contact with the scalp of the subject. Then, the electroencephalogram detected by the electroencephalogram measurement sensor 1 is recorded by an electroencephalograph connected to the electroencephalogram measurement sensor 1.

  An X-ray CT image of the brain imaged using the electroencephalogram measurement sensor 1 according to the present embodiment is shown in FIG. 4, and an MRI image is shown in FIG. The arrows shown in FIGS. 4 and 5 indicate where the electroencephalogram measurement sensor 1 is attached. FIG. 6 shows an electroencephalogram chart comparing an example of an electroencephalogram detected using the electroencephalogram measurement sensor 1 according to this embodiment with an electroencephalogram detected using a conventional silver plate electrode.

  As shown in FIGS. 4 and 5, even if X-ray CT imaging or MRI imaging is performed in parallel with the electroencephalogram measurement using the electroencephalogram measurement sensor 1 according to the present embodiment, the obtained image has no artifact. I was not able to admit. In addition, as shown in FIG. 6, the brain wave detected using the electroencephalogram measurement sensor 1 according to the present embodiment has a clear peak compared to the electroencephalogram detected using a conventional silver plate electrode, It was confirmed that it was detected with high sensitivity.

  In the case of the electroencephalogram measurement sensor 1 according to such an embodiment, X-rays and magnetism are not disturbed even when imaging by X-ray CT or MRI is performed while detecting the electroencephalogram using the electroencephalogram measurement sensor 1. It is possible to obtain a clear CT image or MRI image in which artifacts are not captured. Therefore, for example, during brain surgery, while acquiring functional information of the brain using the electroencephalogram measurement sensor 1 according to the present embodiment, in parallel, morphological information of the brain by X-ray CT or MRI. And can perform highly safe surgery.

  Moreover, since the electroencephalogram measurement sensor 1 according to the present embodiment has a low raw material cost, it can be made inexpensive and disposable. For this reason, the risk of infectious diseases caused by reuse can be reduced to zero.

  Furthermore, since the electrode layer 21 (electrode element) of the electroencephalogram measurement sensor 1 according to the present embodiment is made of a flexible resin sheet, it is easy to adhere to the surface shape of the scalp. For this reason, the electroencephalogram measurement sensor 1 according to the present embodiment has less physical stimulation to the scalp and is less prone to inflammation even when worn for a long time, so that the physical burden on the subject can be reduced.

  Further, since the carbon fiber portion 31 and the vinyl wire portion 32 are connected via a pair of connectors 322 that can be attached to and detached from each other, the electrode portion 2 and the carbon fiber portion 31 are used after the use of the electroencephalogram measurement sensor 1. Only the vinyl wire portion 32 can be reused.

  The present invention is not limited to the above embodiment.

  For example, a lead wire made of the same resin composition as that of the electrode element may be provided integrally with the electrode layer 21 (electrode element) without providing the carbon fiber portion 31 separately. Such an electrode element with a lead wire can be obtained, for example, by cutting out an electrode element from a resin composition molded into a sheet shape into a shape with a lead wire attached to the electrode element. In addition, when the lead wire which consists of the same resin composition is integrally provided in the electrode element, the cover layer 23 and the adhesive bond layer 22 do not need to be provided.

  The vinyl wire portion 32 and the lead wire made of the same resin composition as the carbon fiber portion 31 and the electrode element described above are connected by ultrasonic soldering or the like without using a pair of connectors 322 detachable from each other. Also good.

  Since the electroencephalogram measurement sensor 1 according to the present embodiment can also detect electrical signals generated by various living bodies other than the electroencephalogram, it can be used, for example, when recording an electrocardiogram or an electromyogram.

  The size and shape of the bioelectric signal measurement sensor according to the present invention are not limited to the above-described embodiment, and can be appropriately selected according to the application and purpose.

  In addition, the present invention is not limited to the above-described embodiments, and may be configured by appropriately combining some or all of the various configurations described above without departing from the spirit of the present invention.

  The present invention is useful in various medical fields including the field of brain surgery.

1 ... Electroencephalogram measurement sensor (Bioelectric signal measurement sensor)
21 ... Electrode layer (electrode element)

Claims (8)

A sensor that is attached to the head of a subject during brain surgery to measure brain waves,
It consists of a resin composition in which carbon nanotubes are dispersed in a matrix resin, and includes an electrode element for detecting brain waves.
The carbon nanotubes are particles by being cut by ultrasonic vibration ,
The bioelectric signal measurement sensor, wherein the matrix resin is an acrylic resin or polyvinyl carbazole.   The bioelectric signal measuring sensor according to claim 1, wherein the carbon nanotube is a multi-walled carbon nanotube. The particulate carbon nanotubes, 請 Motomeko 1 or 2 bioelectrical signal measuring sensor according that form a laminate formed by stacking a plurality. 4. The bioelectric signal measuring sensor according to claim 1, wherein the acrylic resin is polymethyl methacrylate. The bioelectric signal measurement sensor according to claim 1, 2, 3, or 4, wherein the average particle diameter of the particulate carbon nanotube is 536 to 584 nm. It said resin composition, bioelectrical signal measuring sensor according to claim 1, 2, 3, 4 or 5, wherein it has been formed into a sheet shape. Wherein a resin composition, bioelectrical signal measuring sensor according to claim 2, 3, 4, 5 or 6 wherein and a lead wire which is electrically connected to the electrode element. A method for producing a bioelectric signal measuring sensor according to claim 1, 2, 3, 4, 5, 6, or 7.
The addition of Ca over carbon nanotubes in a matrix resin, bioelectrical signal production method of the measurement sensor, characterized in that the addition of ultrasonic vibrations having a step of cutting the carbon nanotube in the form of particles.