JPH0933532A - Apparatus for measuring biochemical substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small, portable, efficient and noninvasive apparatus for measuring biochemical substance. SOLUTION: The apparatus 10 for measuring biochemical substance comprises an electrode 12 mounted on the upper surface of a basic material 11, and a protective electrode 13 mounted on the upper surface of the electrode 12. A protective film 14 is provided at a part on the upper surface of the electrode 12 where the protective electrode 13 is not mounted. An enzyme film 15 is provided on the upper surface of protective electrode 13 and covered with a separation film 16 for preventing the aging. The apparatus 10 is held to abut against the surface of an organism 40 by means of a cover 22 and the surface of enzyme film 15 (separation film 16) is prevented from touching the surface of organism 40 directly prior to measurement by means of a separation sheet 23. After sufficient perspiration, the separation sheet 23 is removed and the quantity of substance contained in sweat 30 is detected.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-invasive biochemical substance measuring apparatus.

[0002]

2. Description of the Related Art Conventionally, various biochemical substance measuring devices have been devised which skillfully utilize the strict molecular discrimination function of an enzyme. By using these biochemical substance measuring devices,
It is being applied to the analysis of biologically active substances in the living body.

For example, in the field of diabetes treatment, biochemical substance measuring devices have brought about a great revolution in blood glucose measuring technology. In the 1970s, a blood glucose sensor using an enzyme membrane in which glucose oxidoreductase (glucose oxidase) was immobilized on a polymer was developed, and blood glucose measurement that took tens of minutes to more than one hour until now was measured in minutes. Now you can measure.

However, since these biochemical substance measuring devices use blood, there is a problem that the patient has to take a blood sample each time the measurement is performed, which causes physical pain. Also,
There has been a problem that a virus (hepatitis B, AIDS, etc.) is transmitted through blood as a medium, and the patient and the nurse always have a feeling of mental anxiety.

In order to solve these problems, a non-invasive method for measuring a physiologically active substance using an optical method has been proposed. For example, Motoaki Nanri et al. -Development of optical glucose sensor, BME, Vol.5, N
8-8, pp. 16-21, 1991 "and the like are reported.

[0006]

However, in the case of measuring blood glucose, for example, by measuring the blood glucose level by a non-invasive physiologically active substance measuring method using an optical method, the blood glucose level is estimated based on the absorbance of glucose. Absorbed light wavelength is 9 to 1
Since it is as long as 1 μm, infrared rays are required as its light source. However, the current infrared laser is very large,
Further, since the cooling device is required, there is a problem that the measuring device becomes very large. In addition, this type of device is generally desired to be small and portable, which cannot be realized by a device using an optical method.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a non-invasive biochemical substance measuring device which is small in size, portable, and capable of efficient measurement. Has an aim.

[0008]

In the biochemical substance measuring apparatus according to claim 1 for achieving this object, the catalyst body contains an enzyme or a chemical substance that functions in the same manner as the enzyme. The increase or decrease in the amount of substance that can be detected by an electrode that is generated by the reaction of the substance to be measured contained in the secretion from the living body in the presence of the enzyme contained in the catalytic body or the chemical substance that functions similarly to the enzyme The electrodes measure electrically. The detection means detects the amount or concentration of the substance to be measured contained in the secretion based on the measurement value measured by the electrode section. The separating member keeps the catalyst body and the living body surface in a non-contact state when the electrode portion is not measured, and keeps the catalyst body and the living body surface in a contact state when measuring the electrode portion. .

Further, in the biochemical substance measuring apparatus according to a second aspect, the separating member is a separating sheet capable of closely covering the catalyst body and the surface of the living body, and separating the electrode portion when measuring the electrode portion. By pulling out the sheet in the specified direction,
Since the catalyst body and the surface of the living body are in contact with each other, the measurement can be easily started.

Further, in the biochemical substance measuring apparatus according to the third aspect, the holding member holds the catalyst body and the electrode portion on one side, and the catalyst body is directly or directly attached to the living body surface. Hold so that it indirectly contacts.

Further, in the biochemical substance measuring apparatus according to a fourth aspect of the present invention, the holding member is formed of a sheet capable of closely covering the surface of the living body in order to promote the secretion of secretions from the living body. Therefore, the measurement can be performed efficiently.

Further, in the biochemical substance measuring device according to the fifth aspect, when an oxidoreductase is used as the enzyme or a chemical substance having a function equivalent to that of the enzyme, the reaction of the substance to be measured contained in the secretion product from the living body. Can be simplified and accurate measurement can be performed.

Further, in the biochemical substance measuring apparatus according to the sixth aspect, the enzyme or the chemical substance having a function equivalent to that of the enzyme is held in a solid state in the catalyst body. Alternatively, a chemical substance that functions similarly to an enzyme can be retained in a stable state.

Further, the biochemical substance measuring device according to claim 7 uses glucose oxidase as the enzyme or a chemical substance having a function equivalent to that of the enzyme.
When sweat is used as the secretion, the detecting means detects the amount or concentration of glucose contained in the sweat, so that the blood glucose level can be easily measured.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of a biochemical substance measuring apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of the sensor section 10 of the biochemical substance measuring apparatus of this embodiment. As shown in FIG. 1, the sensor unit 10 includes a sensor body 10a and a cover 22 described later. In the sensor body 10a, an electrode 12 made of a highly conductive material is attached to an upper surface of a base material 11, and a protective electrode 13 made of a water resistant material is attached to an upper surface of the electrode 12. The highly conductive material of the electrode 12 may be a noble metal such as gold, silver and platinum, or a metal material such as copper and aluminum. This electrode 12 constitutes the electrode portion of the present invention.

The protective electrode 13 is provided in order to prevent water from adhering to and corroding the electrode 12, and the water-resistant material of the protective electrode 13 itself contributes to a chemical reaction. It is desirable not to do so, and carbon or the like is considered. However, when the biochemical substance measuring device is used as a disposable device, it is not necessary to purposely provide the protective electrode 13.

On the upper surface of the electrode 12, the protective electrode 1
A protective film 14 made of a polymer or the like is provided on a portion where 3 is not attached. Further, an enzyme film 15 is provided on the upper surface of the protective electrode 13. The surface of the enzyme membrane 15 is covered with a separation membrane 16 in order to prevent the change over time. This enzyme film 15 constitutes the catalyst body of the present invention.

As a method of forming the electrode 12, the protective electrode 13 and the protective film 14 described above, for example, a method such as screen printing, etching and thermal spraying can be used. As the material of the base material 11, the base material of the enzyme membrane 15, and the separation membrane 16, for example, the materials shown in FIG. 2 can be used.

Next, a method of forming the enzyme membrane 15 and the separation membrane 16 will be described. 1. Preparation of electrodes 1) 1 [g] of carboxymethylcellulose (hereinafter, abbreviated as CMC) is added little by little to 1 [L] of pure water while adding 1 to 1
After stirring for 2 hours, the mixture was left to stand overnight to obtain 0.1% by weight of CMC.
Make a solution.

2) 0.1 per unit area on the protective electrode 13.
Apply 8 [μL / mm ² ] of CMC.

3) In order to prevent the deterioration of the electrode, the CMC layer is formed by drying at a temperature as low as possible, for example, 40 ° C. for 1 hour. 2. Dissolution of enzyme For example, when making a biochemical substance measuring device for measuring blood glucose level, 10 [mg] of glucose oxidase is mixed with 67 [mL] of pure water and 10 [μM] of Make an enzyme solution. At this time, in order to prevent the inactivation of the enzyme, it is preferable that the magnetic stirrer or the like is not used and the mixture is slowly stirred by hand.

3. Immobilization of enzyme 1) 16.463 [g] potassium ferricyanide (potassium hexacyanoferrate (3), K ₃ [Fe (CN) ₆ ])
Is mixed with 1 [L] of pure water to prepare a 50 [mM] potassium ferricyanide solution.

2) A CMC solution, an enzyme solution, and a potassium ferricyanide solution (10 mL each) were added at a ratio of 1: 1: 1 to prepare a mixed aqueous solution.

3) 1.0 [μL / mm ² ] per unit area of the mixed aqueous solution was dropped on the CMC layer, and then 1 at 40 ° C.
After drying for an hour, the enzyme film 15 is formed. 4. Preparation of Separation Membrane (If Necessary) 1) 1 [g] of polyvinylpyrrolidone (hereinafter abbreviated as PVP) is mixed with 100 [g] of ethanol, and stirred for about 1 hour to prepare 1% by weight. Make a PVP solution.

2) The PVP solution is spread on the enzyme membrane 15 by 0.4 [μL / mm ² ] per unit area and dried at 40 ° C. for 20 minutes to form the separation membrane 16.

According to this method, since the enzyme (glucose oxidase) in the enzyme film 15 is retained in a solid state, it is possible to obtain the enzyme film 15 with little change over time. The enzyme retained in the enzyme membrane 15 of the present invention is not limited to the above glucose oxidase,
It is possible to use various enzymes including oxidoreductase and hydrolase, and as a result, biobiochemical substances other than glucose (glucose), for example, ethanol, lactic acid, uric acid, urea, neutral fat, It is possible to realize a biochemical substance measuring device that measures total cholesterol, pyruvic acid, or the like. When an oxidoreductase is used, the reaction of the substance to be measured becomes simple and accurate measurement can be performed.

The enzyme immobilization method has been described by taking the physical adsorption method as an example, but the enzyme immobilization method is not limited to this. For example, Suzuki Shuichi ed .: Ion electrode and enzyme electrode, Kodansha Scientific, 1981. As disclosed in November, a carrier binding method such as an ionic bonding method or a covalent bonding method, a crosslinking method, an encapsulation method, or the like can also be used.

Here, the electrode 1 of the sensor body 10a
2. The two-dimensional shape of the protective electrode 13 is shown in FIG.
The one shown in (b) is considered. 3 (a) and 3 (b), in order to clarify the shapes of the electrode 12 and the protective electrode 13, the enzyme membrane 15 and the separation membrane 16 are omitted. In addition, the electrode 12 and the protective electrode 13
Is composed of two parts, an anode 12a, 13a and a cathode 12b, 13b, respectively. Then, the enzyme film 15 is formed inside the portions indicated by the dotted lines B and C.
The electrode shape is not limited to these, and may be a circular shape, an elliptical shape, a rectangular shape, a zigzag shape, or the like. The portions of the enzyme membrane 15 and the separation membrane 16 are referred to as a detection section.

The side surface (lower surface) of the base material 11 on which the electrodes 12 and 13 are not formed is fixed to the inner surface of the cover 22 in the sensor main body 10a having the above-described structure. The cover 22 is composed of a flexible sheet that is impermeable to water and has a bottomed structure having a jawed opening 22a. An adhesive layer is provided on the end surface of the jawed opening 22a. ing. When the adhesive layer is attached to the skin of the living body of the sword recipient, the cover 22 bends according to the shape of the skin and the inside of the cover 22 is sealed.

It is necessary to use, for a part or all of the cover 22, a material that has a strong adhesive force, is excellent in sweat resistance, and is less likely to cause a rash even on a weak part of the skin. For example, a fluid paste or gel is used like an electrode used in an electrocardiograph and is configured to be attached to the skin of the living body 40. Further, it is desirable that the cover 22 is formed in a sheet shape capable of closely contacting and covering the surface of the living body 40 in order to promote perspiration of the living body.

By providing such a cover 22, the detecting portion can be easily held on the surface of the living body 40.

On the other hand, the protective film 1 of the sensor body 10a
4, one end of the separation sheet 23 is detachably adhered, and the other end of the separation sheet 23 extends to the opposite side across the detection part and is a notch formed in the end surface of the jawed opening 22a. It protrudes to the outside of the cover 22 through the recess 22b. Therefore, the detection unit is in a state of being covered with the separation sheet 23. This separation sheet 23 constitutes the separation member of the present invention.

Next, a case where a substance contained in sweat, which is a secretory substance of a living body, is measured as a substance to be measured by using the sensor unit 10 as described above will be described with reference to FIGS. 4 and 5.

Before the measurement of the sensor section 10, the cover 22 is attached to the living body 40 with the separation sheet 23 still attached. Therefore, the separation sheet 23 keeps the surface of the detection unit and the surface of the living body 40 from directly contacting each other. In the state where the cover 22 is held by the living body 40, the separation sheet 23 is
As shown in FIG. 3, one end of the cover 22 extends outward from the end of the cover 22. The other end of the separation sheet 23 is
Since it is lightly adhered to the protective film 14, by pulling one end of the separation sheet 23 in the direction of the arrow B, the adhesion at the other end is peeled off, and the separation sheet 23 can be easily removed. When the sensor unit 10 is reusable, the separation sheet 23 needs to be detachable and reusable.

Further, as shown in FIG. 5, in the biochemical substance measuring apparatus according to this embodiment, a CPU 50 for performing various arithmetic processes based on the signal from the electrode 12 of the sensor section 10 as described above is connected. In addition, the CPU 50 includes a storage unit 51 that stores data referred to when the CPU 50 performs arithmetic processing, and a CPU.
Output units 52 for outputting the calculation result of 50, that is, the amount, concentration, etc. of the substance to be measured are respectively connected. The CPU 50 constitutes the detecting means of the present invention.

As shown in FIG. 4, when the sensor unit 10 is attached to the surface of the living body 40 with the cover 22, the surface of the living body 40 is covered with the cover 22 and the separation sheet 23 in a sealed state. As shown by arrow A, the sweating phenomenon is promoted, and the living body 4 is placed under the separation sheet 23.
Sweat 30, which is a secretion from 0, accumulates. At this time, if one end of the separation sheet 23 is pulled out in the direction of the arrow B in the drawing and removed, the sweat 30 comes into direct contact with the detection unit. At this time, the sweat 30 becomes an electrolyte, and the enzyme membrane 1
The enzyme retained in 5 such as glucose oxidase will be dissolved in sweat. As a result, the following chemical reaction is catalyzed by the enzyme (glucose oxidase).

[0038]

[Equation 1]

At this time, when a predetermined voltage is applied between the anode 12a and the cathode 12b of the electrode 12 from a power source (not shown), it is generated by the above chemical reaction and constitutes the electrode detectable substance of the present invention. Electrolysis is generated in the electrode 12 by H ₂ O ₂ , and the following chemical reaction is performed.

[0040]

[Equation 2]

Then, the temporal change of the current flowing between the anode 12a and the cathode 12b is sent to the CPU 50, and the characteristics shown in FIG. 6 are obtained. The change indicated by arrow C in FIG. 6 is that the chemical substance contained in the enzyme film 15 is sweat 3
It is considered to be a transient phenomenon based on a diffusion phenomenon that melts into zero.

When the initial current value I ₀ is calculated based on the current values at the predetermined times t ₁ and t _{2 in} FIG. 6, a current value proportional to the amount of H ₂ O ₂ generated is obtained. To be As estimated from the above formula (1), the amount of H ₂ O ₂ generated is proportional to the amount of β-D-glucose, that is, glucose, so that the current value I ₀ is glucose contained in the sweat 30. It turns out that it is proportional to the amount of. Then, using this current value I ₀ ,
In the CPU 50, arithmetic processing is performed based on the data stored in the storage unit 51, the glucose amount in the sweat 30 is obtained, and further the blood glucose level is calculated. The calculation is performed based on the correspondence relationship between the current value I ₀ , the glucose amount in the sweat 30 and the blood glucose level stored in the storage unit 51. Further, the blood glucose level converted by the CPU 50 is output by the output unit 52. As the output unit 52, for example, a display device or the like that can be visually confirmed is used.

As described above, according to the biochemical substance detection apparatus of this embodiment, the secreted substance naturally secreted from the living body 40,
For example, sweat can be used to detect the amount of the substance to be measured (eg, glucose) contained in the secretion, so that the substance to be measured can be hygienically hygiene-free without the pain of blood sampling as in the past. Can be measured.

Since the separation sheet 23 is provided,
Secretion of the secretory substance from the living body 40 is promoted, and the separation sheet 23 is removed in a state where the secretory substance is sufficiently secreted, and the secretory substance and the enzyme membrane 15 (separating membrane 16) are brought into contact with each other to detect the amount of the substance to be measured. Since the measurement can be started, the measurement can be performed efficiently in a short time.

Further, the size and weight of the device can be reduced and the device can be carried.

The present invention is not limited to the above embodiment, but various modifications can be added. For example, the chemical substance used for the enzyme membrane and contributing to electrolysis is not limited to potassium ferricyanide, but various ionized substances, that is, metals and complex salts can be used. For example, benzoquinone / hydroquinone, and the literature “Electrochemical-Enzymatic Analysis of Blood Gl” by David LW, Alfred RD Jr, Alexander K, et al.
ucose and Lactate, Analytical Chemistry, Vol.42, N
O.1, pp.118-121, 1970 ”, potassium ferrocyanide and its derivatives may be used.

In this embodiment, the amount of the substance to be measured contained in the secretory substance from the living body is detected, but the concentration may be detected. In this case,
It is necessary to detect the volume of the secreted substance used for detection, and it is possible to calculate the concentration by performing arithmetic processing depending on how much the substance to be measured is contained in the predetermined volume.

[0048]

As is clear from the above description,
The biochemical substance measuring device according to claim 1, wherein the substance to be measured contained in the secretion from the living body causes a reaction in the presence of an enzyme contained in the catalytic body or a chemical substance having a function equivalent to that of the enzyme. The electrode part electrically measures the increase or decrease of the electrode detectable substance generated by the, based on the measurement value measured by this electrode part, the detection means, the amount of the substance to be measured contained in the secretion, Alternatively, for detecting the concentration, the separation member keeps the catalyst body and the living body surface in a non-contact state when the electrode portion is not measured, and when the electrode portion is measured, the catalyst body and the living body surface are not in contact with each other. Since the surface is kept in contact with each other, a small, lightweight, portable non-invasive biochemical substance measuring device can be realized, and the secretion product and the enzyme membrane are sufficiently secreted. To detect the amount of substance to be measured. It is possible to start in a short time, efficiently measurement can be performed.

Further, in the biochemical substance measuring apparatus according to a second aspect, the separation member is a separation sheet capable of closely covering the catalyst body and the surface of the living body, and the separation is performed when the electrode portion is measured. By pulling out the sheet in the specified direction,
Since the catalyst body and the surface of the living body are in contact with each other, secretion of the secretory substance from the living body can be promoted and the measurement can be easily started.

Further, in the biochemical substance measuring apparatus according to the third aspect, the holding member holds the catalyst body and the electrode portion on one side, and the catalyst body is directly or directly attached to the surface of the living body. Since the catalyst body is held so as to indirectly abut, the catalyst body can be easily held on the surface of the living body.

Further, in the biochemical substance measuring apparatus according to the fourth aspect, the holding member is constituted by a sheet capable of closely covering the surface of the living body in order to promote the secretion of the secretory substance from the living body. Therefore, the measurement can be performed efficiently.

Further, in the biochemical substance measuring device according to the fifth aspect, when an oxidoreductase is used as the enzyme or a chemical substance having a function equivalent to that of the enzyme, the reaction of the substance to be measured contained in the secretion product from the living body. Can be simplified and accurate measurement can be performed.

Further, in the biochemical substance measuring device according to the sixth aspect, the enzyme or the chemical substance having a function equivalent to that of the enzyme is held in a solid state in the catalyst body. Alternatively, a chemical substance that functions similarly to an enzyme can be retained in a stable state.

Further, the biochemical substance measuring apparatus according to claim 7 uses glucose oxidase as the enzyme or a chemical substance having a function equivalent to that of the enzyme.
When sweat is used as the secretion, the detecting means detects the amount or concentration of glucose contained in the sweat, so that the blood glucose level can be easily measured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sensor unit in a biochemical substance measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing materials that can be used as a separation membrane, an enzyme membrane, and a base material of a sensor unit.

FIG. 3 is a top view of a sensor unit.

FIG. 4 is an explanatory diagram of a method of using the biochemical substance measuring apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a biochemical substance measuring apparatus according to an embodiment of the present invention.

FIG. 6 is a diagram showing electrical characteristics of a sensor unit.

[Explanation of symbols]

 10 Biochemical Substance Measuring Device 12 Electrode 15 Enzyme Membrane 22 Holding Member 23 Separation Sheet 30 Sweat 40 Living Body

Claims (7)

[Claims] 1. A catalytic body having an enzyme or a chemical substance having a function equivalent to that of an enzyme, and directly or indirectly contacting the surface of a living body, and a substance to be measured contained in a secretion product from the living body. Is an electrode part for electrically measuring an increase or decrease of an electrode detectable substance generated by causing a reaction in the presence of an enzyme contained in the catalyst body or a chemical substance having a function equivalent to that of the enzyme, and the electrode. A biochemical substance measuring device comprising: a detection unit that detects the amount or concentration of a substance to be measured contained in the secretion based on a measurement value measured by the electrode unit. In the measurement, the catalyst body and the living body surface are kept in a non-contact state, and at the time of the measurement of the electrode section, a separation member for keeping the catalyst body and the living body surface in a contact state is provided. Biochemical substance measuring device 2. The separation member is a separation sheet which is provided between the catalyst body and the surface of a living body and which can closely cover the surface of the living body in order to promote the secretion of secretions from the living body. The biochemical substance measurement according to claim 1, wherein the catalyst body and the surface of the living body are configured to contact each other by pulling out the separation sheet in a predetermined direction when measuring the electrode portion. apparatus. 3. A holding member for holding the catalyst body and the electrode portion on one side and holding the catalyst body so as to directly or indirectly abut on the living body surface. It has provided, Claim 1 or 2 characterized by the above-mentioned.
The biochemical substance measuring device described in. 4. The sheet according to claim 3, wherein the holding member is composed of a sheet capable of closely contacting and covering the surface of the living body in order to promote the secretion of secretions from the living body. Biochemical substance measuring device. 5. The biochemical substance measuring device according to claim 1, wherein the enzyme or a chemical substance that functions similarly to the enzyme is an oxidoreductase. 6. The raw material according to claim 1, wherein the enzyme or a chemical substance having a function equivalent to that of the enzyme is held in a solid state in the catalyst body. Chemical substance measuring device. 7. The enzyme, or a chemical substance that functions similarly to the enzyme is glucose oxidase, and the secretion is sweat, and the detection means is the amount of glucose contained in the sweat, or The density is detected, and the density is detected.
The biochemical substance measuring device according to any one of 1.