JP2001137193A - Sensor for living body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable measurement of the concentration of gases or ions in living body. SOLUTION: A sensing part of sensor is clipped in biological tissue together with a circular protection part 23, which is arranged around the sensing part of sensor and thicker than the thickness of the sensor part of sensor, to prevent the gate section 7 from outer pressure by contacting biological tissue. Outside of the sensing part of sensor is covered with a plastic member 24 of cylindrically knitted metallic wire such as stainless steel and grounded together with the metallic protection part to avoid induction noise. The plastic member 24 is bent to maintain sensing part of sensor at a suitable angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for a living body capable of stably measuring the concentration of gas or ions in a living tissue.

[0002]

2. Description of the Related Art It is needless to say that measurement of gas concentrations of carbon dioxide gas, ammonia gas, etc. is important in industrial applications, but in recent years, in the fields of medicine and physiology, measurement of gas concentrations and ion concentrations in living organisms has been required. Is considered important.
This measurement requires an extremely small biological sensor that can be inserted into cells or blood vessels.

As this type of sensor, sensors having various structures have been proposed. For example, a gas sensor proposed by the present applicant and described in Japanese Patent Publication No. 4-32985 is known. FIG. 3 is a sectional view showing a configuration of an example of the gas sensor according to this proposal. In FIG. 3, an ion sensor having a gate insulating field effect transistor structure (hereinafter referred to as ISF)
The lead wire 4 connected to the reference electrode 2 (referred to as ET), the reference electrode 2, and the electrode portion 3 of the ISFET 1 is embedded in an insulating resin 6 in a tube 5. A part of the gate portion 7 and the comparative electrode 2 which are the ion-sensitive portions of the ISFET 1 are inserted into the hollow portion of one porous hollow fiber 8 and are covered with the porous hollow fiber 8. The porous hollow fiber 8 and the gap between the porous hollow fiber 8 and the ISFET 1
Is satisfied by The porous hollow fiber 8 is further covered by a gas-permeable homogeneous membrane 10.

According to the gas sensor configured as described above, since the porous hollow fiber 8 is manufactured in advance by a spinning technique, it is easy to make the shape and the pore distribution uniform. For this reason, variations in the characteristics of the gas sensor can be reduced. Further, since the porous hollow fiber 8 has no fluidity and can maintain a substantially constant shape, the characteristics of the sensor hardly change. Further, the porous hollow fiber 8 is
By covering the tip of T1, breaking of the homogeneous film 10 at the tip of ISFET 1 can be suppressed to some extent.

FIG. 4 is a sectional view showing the structure of another conventional example of this type of sensor. This sensor is disclosed in Japanese Patent Application Laid-Open No. 58-973.
No. 46, No. 46. 4, portions corresponding to those of the conventional example shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The feature of this conventional example is that the needle 11 is provided at the tip of the tube 5 and the ISFET 1 and the reference electrode 2 are accommodated in the opening 5 a formed in the side wall of the tube 5 so as to be in contact with the gas absorbing liquid 9. The point is that the aperture 5a is covered with the permeable homogeneous membrane 10. Tube 5
At the rear end, a connector pin 12 is provided, and the lead wire 4 is connected to the connector pin 12. Reference numeral 13 denotes a reinforcing core embedded between the distal end of the tube 5 and the connector 14.

According to the gas sensor configured as described above, by inserting the tube 5 into the tissue of the living body via the needle 11, the adhesion between the ISFET 1 and the tissue is improved,
The gas concentration in the tissue can be measured with good reproducibility.

[0007]

[Problems to be solved by the invention]
According to the gas sensor described in JP-A-329895, the porous hollow fiber 8 has flexibility and is easily deformed by an external pressure, and the gate 7 of the ISFET 1 is
, The pressure from the living tissue is received, and the output of the sensor becomes unstable. Further, since the ISFET 1 and the reference electrode 2 are made of a hard material, they may be broken or break through the gas permeable membrane 10 when subjected to an external force, which may cause damage to the sensor structure.

On the other hand, according to the gas sensor described in Japanese Patent Application Laid-Open No. 58-97346, since the tube 5 is punctured into the tissue of the living body through the needle 11, there is a defect that the living tissue is damaged.

Further, in the above two conventional examples, there is a problem that the sensor is easily detached because no special consideration is given to fixing the sensor to the living body.

Furthermore, since there is no shield structure for protecting a lead portion (not shown) for guiding the signal detected by the ISFET 1 to the outside from induction noise, there is also a problem that the signal output is changed by the influence of an electric knife or the like. there were.

The present invention has been made in view of such a situation, and has as its object to provide a biological sensor capable of stably measuring gas and ion concentrations in a living tissue without damaging the living tissue. I do. It is another object of the present invention to provide a living body sensor that can be easily fixed to a measurement site of a living body.

[0012]

In order to achieve the above object, the present invention according to the first aspect of the present invention is directed to a sensor responsive section for detecting a gas concentration or an ion concentration of a living tissue by contacting the living tissue. And a derivation unit for deriving a signal of the gas concentration or the ion concentration detected by the sensor response unit to the outside, wherein the protection unit having a thickness greater than that of the sensor response unit includes the sensor response unit. It is characterized by being surrounded and fixed to the lead-out section.

According to a second aspect of the present invention, there is provided the biological sensor, wherein the protective portion is made of a resin or metal having high hardness which does not easily absorb gas and ions.

According to a third aspect of the present invention, the sensor for a living body is characterized in that an outer periphery of the lead-out portion on the sensor sensitive portion side is covered with a plastic member.

According to a fourth aspect of the present invention, in the biosensor, the plastic member includes a metal member that covers the lead-out portion.

According to a fifth aspect of the present invention, in the biological sensor, the metal member is electrically grounded.

According to a sixth aspect of the present invention, in the biological sensor, the protection portion is made of a metal, and the metal member is further electrically connected to the protection portion.

According to a seventh aspect of the present invention, the biosensor is characterized in that the protection portion is made of metal and is electrically grounded.

In the biosensor according to the present invention, the plastic member is composed of a metal wire having plasticity and a synthetic resin tube having flexibility, and the metal wire is covered with the synthetic resin tube. It is characterized by.

According to a ninth aspect of the present invention, there is provided a sensor for a living body, the sensor being sensitive to a living tissue to detect at least a gas concentration or an ion concentration of the living tissue, and a gas concentration detected by the sensor sensing portion. Or a deriving unit for deriving a signal of ion concentration to the outside, and a protection unit for preventing excessive pressure from being applied to the sensor sensitive unit when the biological sensor is placed in a living tissue, wherein the protection unit is Gas from living tissue is diffused from at least two directions toward the sensor responsive part.

In the biological sensor according to the first and second aspects, the sensor sensitive portion for detecting the concentration of gas and ions from the biological tissue is surrounded by the protective portion having a greater thickness. By inserting the part between the living tissues, a signal such as the gas concentration of the living tissue can be stably output without the living tissue coming into direct contact with the sensitive part.

In the biosensor according to the third and fourth aspects, since the outer periphery of the lead-out portion is covered with a plastic member having plasticity, the lead-out portion is curved and stably fixed at an angle corresponding to the measurement site. be able to.

In the biosensor according to any one of claims 4 to 7, by electrically grounding the metallic protection portion and the metal member, induction noise due to high frequency from the electric scalpel and the like received by the lead-out portion is reduced. And a stable signal output can be obtained. That is, since the induction noise of the electric scalpel is easily received from the sensor signal deriving unit, grounding the metal member of the plastic member has a great effect. When a metal member is not included, an effect is obtained by guiding the ground wire of the protection unit together with the lead-out unit. In order to obtain the effect, a metal member is included in the plastic member, and the metal protection member and the plastic member are formed. It is desirable to ground both of the members.

In the sensor for a living body according to the eighth aspect, by covering the metal wire with a flexible synthetic resin tube, it is possible to prevent the danger of elution of metal ions into the living body and leakage current. Can be.

In the biosensor according to the ninth aspect, when the biosensor is indwelled in the living tissue, the protection portion prevents the sensor sensitive portion from being applied with excessive pressure, and the sensor is provided from at least two directions. The gas is configured to diffuse to the sensitive part.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a living body sensor according to an embodiment of the present invention. FIG. 1 is a perspective view showing a first configuration example of an embodiment of the present invention.
In FIG. 1, portions corresponding to those of the conventional example shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

Although not shown, the ISFET 1 is provided with a comparison electrode 2 and an electrode portion 3 as in the conventional example shown in FIG. 3, and a lead wire 4 is connected to the electrode portion 3. ISF
The gate 7 at the end of the ET 1 and a part of the outer periphery of the comparative electrode 2 are covered with a gas-permeable silicone film 10. The tubular body 5 serving as a lead-out portion containing the lead wire 4 is covered with a cable cover 21, and the lead wire 4 is connected to a connector 22 provided at a base end of the cable cover 21.

A base of an annular protective portion 23 surrounding the gate portion 7 is fixed to one end of the ISFET 1 on the side of the electrode portion 3 shown in FIG. The thickness of the protection portion 23 is larger than the thickness of the ISFET 1 covered with the silicone film 10, and when the protection portion 23 is inserted into the tissue of a living body as described later, external pressure from the tissue is not directly applied to the silicone film 10. It has become. Sensor sensitive part and protective part 23
Are placed from both sides so as to be sandwiched between the living tissues (FIG. 5 shows a view placed below the tongue), and the change in the gas concentration in the space around the sensor sensitive part is the gas concentration of the living tissue. The gas is configured to diffuse from both sides of the living tissue so as to follow the change well. FIG.
FIG. As shown in FIG. 6, the space 103 between the sensor sensitive part and the protection part 23 is provided so as not to hinder the diffusion of gas, and the protection part is provided so that the sensor sensitive part does not receive excessive pressure from the living tissue. 23 is configured to support the living tissue. The protection portion 23 is made of a polymer that hardly absorbs gas, ions, etc., has high hardness, a resin such as polycarbonate, Teflon (registered trademark), polypropylene, epoxy, or the like, or a metal such as stainless steel or a material obtained by coating the surface thereof with a resin. ing.

As shown in the BB sectional view of FIG.
The lead wire 4 for deriving the output of the ISFET 1 is covered with a tube 5 made of a synthetic resin tube that is difficult to expand and contract, such as a nylon tube or a Teflon tube. The plastic member 24 is formed by being braided into a tubular shape or spirally wound with a flexible synthetic resin tube 102 such as a silicone tube or a vinyl chloride tube. The plastic member 24 may be molded by kneading a metal wire in advance when molding the synthetic resin tube 102, or the synthetic resin tube 10
It can also be manufactured by bonding a metal wire to the inner side of 2 with an adhesive. To one end of the plastic member 24, a part of the protection part 23 is pushed into the inner periphery and adhered with an adhesive.

When the protection part 23 is made of metal, the protection part 23
An electric connection portion 26 is provided by welding or soldering one end of the metal wire 25 inside the base portion. The metal wire 25 passes through the cable cover 21 together with the tube 5, and the other end is connected to a connector 22 provided at the base end of the cable cover 21 and grounded. The connection portion 26 may be electrically connected to the metal member 101 constituting the plastic member 24 and installed via the metal wire 25.

Next, a description will be given of a method of using the living body sensor configured as described above. The protective part 23 is sandwiched between the organ tissue and the sublingual tissue in the oral cavity at the time of the laparotomy, the plastic member 24 is bent at an angle at which the sensor can be easily fixed, and is adhered and fixed to the nearby skin with an adhesive tape. In this state, the gas and the body fluid of the living tissue are guided to the gate unit 7 through the opening at the center of the protection unit 23, and the concentration of gas such as CO ₂ and the concentration of ion such as PH are detected.

According to the present embodiment, since the living tissue does not directly contact the ISFET 1 including the gate portion 7 serving as the sensor sensitive portion, a signal such as gas concentration can be stably output without an external pressure acting. . Further, since the ISFET 1 can be easily fixed in a form conforming to the measurement site, the sensor can be stably held without damaging the living tissue, and the signal output can be further stabilized.

Since the induction noise of the electric scalpel is easily received from the sensor signal output portion, grounding the metal member of the plastic member 24 has a great effect. In order to further enhance this effect, it is preferable that both the metallic protection portion 23 and the metal member of the plastic member 24 are grounded. When the plastic member 24 does not include a metal member,
The effect can be improved by guiding the grounding wire together with the pipe 5 as the lead-out portion.

In the above embodiment, the case where the protection portion 23 is formed in an annular shape has been described. However, the shape of the protection portion 23 is not limited to this, and for example, the second configuration example shown in FIG. As shown in FIG. FIG.
Thus, the magnitude relationship between the thickness of the protection portion 23 and the thickness of the sensor sensitive portion can be understood. Further, the configuration of the ISFET 1 is not limited to the configuration shown in FIG. 1, but may be another configuration as long as it has a similar function. Further, when the sensor is easily and stably attached to the living tissue, the plastic member 24 may be omitted, or alternatively, may be formed of a flexible synthetic resin tube. The sensor is ISFET
It can also be applied to cases other than 1, such as a micro PH sensor using a glass electrode, a Severinghouse CO2 electrode,
The present invention can be applied to ion sensors and gas sensors using optical fibers, oxygen sensors using the principle of Clark-type electrodes, and the like.

[0035]

As described above, according to the first and second aspects of the present invention, since the protection portion having a greater thickness than the sensor-sensitive portion is provided so as to surround the sensor-sensitive portion, the sensor can be used as a living tissue. Since the living tissue is not in direct contact with the sensitive portion by being interposed therebetween, external pressure is not applied, and a signal such as a gas concentration of the living tissue can be output stably.

According to the third and fourth aspects of the present invention, since the outer periphery of the lead-out portion is covered with the plastic member, the lead-out portion is bent at an angle corresponding to the measurement site and stably fixed to the living body. The signal output can be stabilized without damaging the living tissue.

According to the present invention described in claims 4 to 7,
By grounding the metal protection part and the metal member, induction noise due to high frequency from an electric knife or the like received by the lead-out part can be reduced, and the signal output can be further stabilized.

According to the present invention, by covering the metal wire with a flexible synthetic resin tube, it is possible to prevent the danger of elution of metal ions into the living body and leakage current. it can.

According to the ninth aspect of the present invention, since both sides of the sensor sensitive portion and the protective portion are opposed to the living tissue, gas diffusion from the living tissue occurs in both directions. The change in gas concentration around the part follows the change in gas concentration in the living tissue well, and furthermore, the space between the sensor sensitive part and the protection part is configured so that gas diffusion is not hindered, and Since the living tissue is configured to be supported by the protection unit so that excessive pressure is not applied to the sensor sensitive unit, the responsiveness of the sensor is improved.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a biological sensor according to the present invention.
FIG.

FIG. 2 shows a second embodiment of the biological sensor according to the present invention.
FIG.

FIG. 3 is a cross-sectional view showing a configuration of an example of a conventional biological sensor.

FIG. 4 is a cross-sectional view showing the configuration of another example of a conventional biological sensor.

FIG. 5 is a diagram showing a state in which a protection unit and a sensor response unit are placed under a tongue.

FIG. 6 is a sectional view taken along line AA of FIG. 1;

FIG. 7 is a sectional view taken along the line BB of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ISFET 5 Tube (lead-out part) 23 Protection part 24 Plastic member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 27/46 353A 376

Claims (9)

[Claims] 1. A sensor responsive unit for detecting a gas concentration or an ion concentration of a living tissue by contacting the living tissue, and a signal of the gas concentration or the ionic concentration detected by the sensor sensitive unit is derived to the outside. A sensor for a living body, comprising: a lead-out part; a protection part having a thickness greater than that of the sensor sensitive part is fixed to the lead-out part around the sensor sensitive part. 2. The living body sensor according to claim 1, wherein the protection portion is made of a resin or a metal having high hardness, which hardly absorbs gas or ions. 3. The biosensor according to claim 1, wherein an outer periphery of the lead-out section on the sensor sensitive section side is covered with a plastic member. 4. The biosensor according to claim 3, wherein the plastic member has a metal member that covers the lead-out portion. 5. The biological sensor according to claim 4, wherein the metal member is electrically grounded. 6. The biological sensor according to claim 1, wherein the protection section is made of metal, and the metal member is further electrically connected to the protection section. 7. The biological sensor according to claim 1, wherein the protection section is made of metal and is electrically grounded. 8. The plastic member is composed of a metal wire having plasticity and a synthetic resin tube having flexibility,
The biological sensor according to claim 3, wherein the metal wire is covered with the synthetic resin tube. 9. A sensor for a living body, comprising: a sensor-sensitive part for detecting at least a gas concentration or an ion concentration of the living tissue by contacting the living tissue; and a sensor for detecting a gas concentration or an ion concentration detected by the sensor-sensitive part. A deriving unit that derives a signal to the outside, and a protection unit that prevents an excessive pressure from being applied to the sensor sensitive unit when the biological sensor is placed in a living tissue. A biological sensor, wherein gas is diffused from at least two directions toward the sensor sensitive portion.