JP2002207022A - Biosensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reagent layer capable of suppressing a background current (noise) rising with the elapse of time especially in the presence of heat or moisture, in a biosensor for analyzing a specific component in a liquid specimen. SOLUTION: Sugar alcohol or a metal salt is added to the reagent layer 5 provided on an insulating substrate 1 as an additive for suppressing rise with the elapse of time of the background current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biosensor for analyzing a specific component in a liquid sample, and more particularly, to a reagent configuration for forming a reagent layer of the biosensor.

[0002]

2. Description of the Related Art A biosensor is a sensor that utilizes a biological material such as a microorganism, an enzyme, an antibody and the like to recognize a molecule and applies the biological material as a molecular identification element. That is, the reaction that occurs when the immobilized biological material recognizes the target specific substance, the consumption of oxygen by respiration of microorganisms, the enzymatic reaction,
It utilizes light emission and the like.

[0003] Among biosensors, enzyme sensors have been put into practical use. For example, enzyme sensors for glucose, lactic acid, cholesterol, lactose, urea, and amino acids have been developed.
Used for medical measurement and food industry. Enzyme sensors
Quantitative analysis of the sample by reducing the electron acceptor with the electrons generated by the reaction between the substrate and the enzyme contained in the sample solution and the measuring device electrochemically measures the amount of reduction of the electron acceptor I do. As an example of such a biosensor, for example, a sensor proposed in Japanese Patent Application No. 11-324511 is known.

FIG. 1 is an exploded perspective view showing an example of a three-electrode type biosensor. In this method, a measurement electrode 2 (also called a working electrode), a counter electrode 3 (also called a counter electrode), and a detection electrode 4 made of an electrically conductive substance are formed on an insulating substrate 1 such as polyethylene terephthalate. A reagent layer 5 containing an enzyme that specifically reacts with a specific component in a sample solution, an electron carrier, and a hydrophilic polymer is formed on the electrode.

The current value generated by the reaction between the specific component in the sample solution and the reagent in the reagent layer 5 is applied to the electrodes 2, 3,
In order to form a cavity for detection in step 4, a spacer 6 having an elongated notch 7 in a portion on the electrode and the reagent layer, and a cover 8 in which an air hole 9 is formed are bonded on an insulating substrate. .

In the biosensor having such a configuration,
The sample liquid is supplied into the cavity from the entrance (sample liquid suction port) of the cavity by capillary action, and is guided to a position where the electrode and the reagent layer are present. Then, a specific component in the sample solution reacts with the reagent in the reagent layer to generate a current, and the generated current is read by an external measuring device through the lead of the biosensor, whereby quantitative analysis of the sample is performed.

[0007]

However, in the biosensor having the above-described reagent configuration, the presence of heat or moisture causes
In particular, in a high-temperature and high-humidity environment where the temperature is 30 ° C. or higher and the humidity is 80% or higher, a reduction reaction between the enzyme protein and a part of the hydrophilic polymer contained in the reagent layer 5 and the electron carrier occurs. In addition, a background current (noise current) is generated, and the background current value increases with time.

Further, as means for solving this,
It is possible to remove moisture by enclosing a desiccant such as silica gel or activated alumina in a biosensor storage container that uses a molded container such as an aluminum seal or resin to prevent deterioration of sensor performance. However, such a desiccant alone cannot completely remove even water at the molecular level remaining in the reagent contained in the biosensor.

[0009] Even in the above-mentioned storage container, it is extremely difficult to eliminate (zero) the invasion of water for a long period of time, and the reduction reaction between the electron carrier and a part of the enzyme protein or the hydrophilic polymer is difficult. However, since the process proceeds only with a very small amount of moisture, there is a problem that it is extremely difficult to effectively suppress the temporal rise of the background current. The present invention has been made in view of the above problems, and an object of the present invention is to provide a biosensor that can efficiently prevent performance degradation of a biosensor due to contact with moisture.

[0010]

According to a first aspect of the present invention, there is provided a biosensor for measuring the concentration of a specific substance in a sample solution, the biosensor being dissolved in the sample solution and being specific to the specific substance in the sample solution. Wherein a sugar alcohol is contained in a reagent layer provided in advance so as to react in a specific manner.

According to a second aspect of the present invention, there is provided the biosensor according to the first aspect, wherein the concentration of the specific substance is determined by using an electrode comprising at least a working electrode and a counter electrode provided on an insulating substrate. It is characterized in that the measurement is performed by using.

According to a third aspect of the present invention, in the biosensor according to the second aspect, the reagent layer is diffused by dissolving a reagent on the electrode or the reagent layer in a sample solution. The electrode is formed so as to be arranged in the diffusion area, and the reagent layer contains at least an enzyme and an electron carrier.

According to a fourth aspect of the present invention, in the biosensor according to any one of the first to third aspects, the sugar alcohol is a linear polyhydric alcohol or a cyclic alcohol. It is a sugar alcohol or a substituted or derivative thereof.

According to a fifth aspect of the present invention, there is provided the biosensor according to any one of the first to third aspects, wherein the sugar alcohol is maltitol,
Characterized in that it is either or both of lactitol.

A biosensor according to claim 6 of the present invention is a biosensor for measuring the concentration of a specific substance in a sample solution, which is dissolved in the sample solution and reacts specifically with the specific substance in the sample solution. Thus, a metal salt is contained in a reagent layer provided in advance as described above.

According to a seventh aspect of the present invention, there is provided the biosensor according to the sixth aspect, wherein the concentration of the specific substance is controlled by an electrode comprising at least a working electrode and a counter electrode provided on an insulating substrate. It is characterized in that the measurement is performed by using.

[0017] In the biosensor according to claim 8 of the present invention, in the biosensor according to claim 7, the reagent layer is diffused by dissolving the reagent on the electrode or the reagent layer in a sample solution. The electrode is formed so as to be arranged in the diffusion area, and the reagent layer contains at least an enzyme and an electron carrier.

According to a ninth aspect of the present invention, in the biosensor according to any one of the sixth to eighth aspects, the metal salt is a metal sulfate, a metal hydrogensulfate, or a metal sulfite. , Metal bisulfite or metal hyposulfite.

The biosensor according to claim 10 of the present invention is the biosensor according to any one of claims 6 to 8, wherein the metal salt is one or both of magnesium sulfate and calcium sulfate. It is characterized by having.

The biosensor according to claim 11 of the present invention is the biosensor according to any one of claims 6 to 8, wherein the metal salt is a metal nitrate, a metal hydrogen nitrate, or a metal nitrite. Salt, metal hydrogen nitrite or metal nitrite.

According to a twelfth aspect of the present invention, in the biosensor according to any one of the sixth to eighth aspects, the metal salt is one or both of magnesium nitrate and calcium nitrate. It is characterized by having.

According to a thirteenth aspect of the present invention, in the biosensor according to any one of the first to twelfth aspects, the reagent layer further contains a hydrophilic polymer. Is what you do.

[0023]

(Embodiment 1) A biosensor according to Embodiment 1 of the present invention will be described below.
In each embodiment of the present invention described below, an enzyme sensor using an enzyme as a molecular identification element that specifically reacts with a specific substance in a sample solution will be described.

FIG. 1 is an example of an exploded perspective view of a three-electrode type biosensor. In FIG. 1, reference numeral 1 denotes an insulating substrate. On the insulating substrate 1, a measurement electrode 2, a counter electrode 3, and a detection electrode 4 made of an electrically conductive substance are formed at predetermined positions and shapes, respectively. Thus, the detection electrode 4 can be used not only as an electrode for detecting a shortage of a sample amount but also as a part of a reference electrode or a counter electrode.

The preferred material of the insulating substrate 1 includes polyethylene terephthalate, polycarbonate, polyimide and the like. In addition, examples of the electrically conductive substance constituting each electrode include a simple material such as a noble metal such as gold, platinum and palladium and carbon, and a composite material such as a carbon paste and a noble metal paste.

Simple materials such as noble metals such as gold, platinum and palladium and carbon are easily formed by sputtering deposition, and composite materials such as carbon paste and noble metal paste are easily formed by screen printing. The insulating layer can be formed on the insulating substrate 1.

In the formation of each electrode, the above-mentioned electrically conductive layer is formed on the entire surface or a part of the insulating substrate 1 by the above-described sputtering deposition method or screen printing method, and then slit by using a laser or the like. The electrodes can be divided and formed. Further, the electrodes can be similarly formed by a screen printing method, a sputtering deposition method, or the like using a printing plate or a mask plate on which an electrode pattern is formed in advance. On the electrode thus formed, a reagent layer 5 containing an enzyme, an electron carrier, a hydrophilic polymer, and a sugar alcohol is formed.

The first embodiment of the present invention is characterized in that a sugar alcohol is contained in the reagent layer 5, and the sugar alcohol is oxidized in the reagent layer 5 formed on the electrode. When the electron carrier comes into contact with some of the reactive functional groups present in the enzyme proteins and hydrophilic polymers contained in the reagent, the electron carrier changes from the oxidized form to the reduced form. (Reduced).

For this reason, in the biosensor having the above-described reagent configuration, the enzyme protein contained in the reagent layer 5 under the presence of heat or moisture, especially in a high-temperature and high-humidity environment where the temperature is 30 ° C. or more and the humidity is 80% or more. And some of the hydrophilic polymers,
Since a background current (noise current) that occurs due to a reduction reaction with the electron carrier and increases with time can be suppressed, it is possible to prevent the performance of the biosensor from deteriorating.

Furthermore, by including a sugar alcohol in the reagent layer, unnecessary reactions with various contaminants present in blood, especially in blood cells, can be suppressed together. Good linearity (the slope of the regression equation is large and the intercept is small), and the variation of each sensor is small.
A high-performance biosensor can be provided.

The sugar alcohol contained in the reagent layer 5 includes sorbitol, maltitol, xylitol, mannitol, lactitol, reduced palatinose, arabinitol, glycerol, ribitol, galactitol, sedheptitol, perseitol, bolemitol, styritol Chain polyhydric alcohols and cyclic sugar alcohols such as polygalitol, iditol, talitol, allitol, isilitol, reduced starch saccharified product, and isilitol.

The same effect can be obtained even with the stereoisomers, substituted products or derivatives of these sugar alcohols. Also, among these sugar alcohols, maltitol and lactitol are relatively inexpensive materials, can be easily obtained, and are the most suitable materials because the effect of suppressing the background current is remarkably high. I can say.

The amount of the sugar alcohol to be added is suitably from 0.1 to 500 mM, more preferably from 1 to 100 mM, as the concentration of the reagent solution.

The biosensor shown in FIG. 1 is thereafter equipped with the reagent layer 5 and the electrodes 2, 3, 4
A cavity to which the sample liquid is supplied is formed by laminating the cover 6 and the spacer 6 having the notch 7 thereon.

Suitable materials for the spacer 6 and the cover 8 include polyethylene terephthalate, polycarbonate, polyimide, polybutylene terephthalate, polyamide, polyvinyl chloride, polyvinylidene chloride, and nylon.

The supply of the sample liquid to the biosensor constituted by such a cavity is realized by the capillary phenomenon. However, in order to realize the smooth supply of the sample liquid, air is supplied to the outside of the biosensor in the cavity. An air hole 9 for escape is required. The arrangement of the air holes 9 is as follows.
Any position in the cavity may be used as long as the supply of the sample liquid is not hindered.

In the biosensor formed as described above, the current value obtained by the reaction between the specific component in the sample solution and the reagent layer 5 containing the enzyme and the like is measured by the measuring electrode 2, the counter electrode 3, and the detecting electrode. 4, the respective lead portions 10, 11, 12
It is read by an external measuring device connected through.

(Embodiment 2) A biosensor according to Embodiment 2 of the present invention will be described below. In the biosensor according to the second embodiment of the present invention, the reagent layer 5 of the biosensor shown in FIG. 1 is formed of an enzyme, an electron carrier, a hydrophilic polymer, and a metal salt. The other components are the same as those of the biosensor according to the first embodiment, and thus the description will be omitted.

The second embodiment of the present invention is characterized in that the reagent layer 5 contains a metal salt, and this metal salt is oxidized in the reagent layer 5 formed on the electrode. The electron carrier comes into contact with the enzyme protein contained in the reagent and some highly reactive functional groups present in the hydrophilic polymer, etc., and the electron carrier changes from an oxidized form to a reduced form. It acts to suppress denaturation (reduction).

For this reason, in the biosensor having the above-described reagent configuration, the enzyme protein contained in the reagent layer 5 under the presence of heat or moisture, particularly in a high-temperature and high-humidity environment where the temperature is 30 ° C. or more and the humidity is 80% or more. And some of the hydrophilic polymers,
Since a background current (noise current) that occurs due to a reduction reaction with the electron carrier and increases with time can be suppressed, it is possible to prevent the performance of the biosensor from deteriorating.

As the metal salt contained in the reagent layer 5, metal sulfates and metal nitrates are particularly effective.
For example, metal sulfate, metal hydrogen sulfate, metal sulfite,
As a metal bisulfite or a metal hyposulfite,
Aluminum sulfate, magnesium sulfate, zinc sulfate, antimony sulfate, indium sulfate, uranyl sulfate, uranium sulfate, cadmium sulfate, potassium sulfate, gallium sulfate, calcium sulfate, silver sulfate, chromium sulfate, cobalt sulfate, potassium hydrogen sulfate, zirconium sulfate, sulfuric acid Mercury, tin sulfate, strontium sulfate, cesium sulfate, cerium sulfate, thallium sulfate, titanium sulfate, iron sulfate, copper sulfate, sodium sulfate, lead sulfate, nickel sulfate, neodymium sulfate, vanadium sulfate, palladium sulfate, barium sulfate, bismuth sulfate, Praseodymium sulfate, beryllium sulfate, manganese sulfate, lanthanum sulfate, lithium sulfate, rubidium sulfate,
Potassium aluminum sulfate, sodium aluminum sulfate, uranyl potassium sulfate, chromium potassium sulfate, disodium magnesium sulfate, dipotassium magnesium sulfate, cesium manganese sulfate, rubidium aluminum sulfate, potassium hydrogen sulfate, sodium hydrogen sulfate, potassium sulfite, calcium sulfite, sodium sulfite , Barium sulfite, bismuth sulfite, sodium hyposulfite, potassium bisulfite, sodium bisulfite, etc.,
Metal nitrate, hydrogen nitrate, metal nitrite, metal nitrite, or metal nitrite include aluminum nitrate, magnesium nitrate, zinc nitrate, antimony sulfate, ytterbium nitrate, yttrium nitrate, indium nitrate, Uranyl nitrate, erbium nitrate, cadmium nitrate, gadolinium nitrate, potassium nitrate, calcium nitrate, silver nitrate, chromium nitrate, cobalt nitrate, samarium nitrate, zirconium nitrate, dysprosium nitrate, mercury nitrate, tin nitrate, strontium nitrate, cesium nitrate, cerium nitrate, nitric acid Thallium, iron nitrate, terbium nitrate,
Copper nitrate, thorium nitrate, sodium nitrate, lead nitrate, nickel nitrate, neodymium nitrate, palladium nitrate, barium nitrate, bismuth nitrate, praseodymium nitrate, beryllium nitrate, holmium nitrate, manganese nitrate, europium nitrate, lanthanum nitrate, lithium nitrate, ruthenium nitrate , Rubidium nitrate, rhodium nitrate, mercury nitrate, potassium nitrite, silver nitrite, calcium nitrite, sodium nitrite, potassium potassium nitrite, sodium cobalt nitrite, sodium hyponitrite and the like.

Of these metal salts, magnesium sulfate, calcium sulfate, magnesium nitrate, and calcium nitrate are particularly preferred because of their high moisture absorption preventing effect. In addition,
The addition amount of these metal salts is 0.1 to
500 mM is suitable, more preferably 1-50 mM.

In the first and second embodiments of the present invention, an example in which a sugar alcohol and a metal salt are added to the reagent layer 5 has been described. However, a similar effect can be obtained by combining them. Can be The enzymes contained in the reagents of Embodiments 1 and 2 include glucose oxidase, lactate oxidase, cholesterol oxidase, cholesterol esterase, uricase, ascorbate oxidase, bilirubin oxidase, glucose dehydrogenase, and lactate dehydrogenase, and the like. Examples of the body include potassium ferricyanide, p-benzoquinone and its derivatives, phenazine methosulfate, methylene blue, ferrocene and its derivatives.

In the first and second embodiments of the present invention, the case where the hydrophilic polymer is contained in the reagent layer 5 has been described. In addition, the reagent solution can be made viscous to easily form a uniform reagent on the electrode, and the effect of increasing the adhesion between the electrode and the reagent can be obtained. Furthermore, the reagent crystal state after drying the reagent is also uniform by containing the hydrophilic polymer,
A highly accurate biosensor can be manufactured.

Examples of the hydrophilic polymer used for the above purposes include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethylethyl cellulose,
Polyamino acids such as polyvinyl alcohol, polyvinylpyrrolidone and polylysine, polystyrenesulfonic acid, gelatin and its derivatives, acrylic acid and its salts, methacrylic acid and its salts, starch and its derivatives, maleic anhydride and its salts, agarose gel and its derivatives And so on.

In the first and second embodiments of the present invention, the above-described reagent layer 5 is described as being provided on the electrode. Specifically, the reagent layer 5 is provided on the entire surface or a part of the electrode. 5 can be arranged, and in addition, an electrode is provided in a range where the performance of the biosensor is not deteriorated, that is, in a diffusion area where the reagent in the reagent layer dissolves and diffuses in the sample solution. The reagent layer 5 may be arranged so as to be provided.

[0047]

(Example 1) A palladium thin film having a thickness of about 10 nm was formed on an insulating substrate made of polyethylene terephthalate over the entire surface of the insulating substrate by sputtering deposition, and then a part of the thin film was formed with a YAG laser. By providing slits, the electrodes were divided into measurement electrodes, counter electrodes, and detection electrodes. An aqueous solution containing an enzyme (glucose oxidase), an electron carrier (potassium ferricyanide), a hydrophilic polymer (carboxymethylcellulose), and a sugar alcohol is further placed on the counter electrode and a part of the detection electrode around the measurement electrode. A reagent layer was formed by dropping in a circle so as to cover and drying. Further, a spacer having a cutout portion made of polyethylene terephthalate and a cover having an air hole also made of polyethylene terephthalate are bonded together to form a three-electrode blood glucose level in which a cavity serving as a capillary through which blood is guided is formed. A measurement sensor was manufactured.

FIG. 2 shows the sensor response characteristics when lactitol is added as a sugar alcohol to the reagent solution, and shows four types of cases where the sample solution is whole blood and the lactitol concentration is changed. FIG. 3 shows the response characteristics of a sensor in which maltitol was added as a sugar alcohol and the maltitol concentration was changed to four types. Here, a sensor in which the addition concentration of sugar alcohol (concentration as a reagent aqueous solution) was 0 was treated as a conventional sensor, and a sensor in which the concentration was 5, 10, 25, and 50 mM was used as the sensor of the present invention.

FIG. 4 shows the measurement of the change over time in the background current under a severe environment (exposure at a temperature of 30 ° C. and a humidity of 80%) using the sensor thus manufactured. Purified water containing no glucose was used as the sample liquid. FIG. 5 shows a change in the sensor response value over time when whole blood whose glucose concentration is adjusted to 80 mg / dL is used as the sample solution. In each case, the measurement was performed immediately after the sensor was manufactured (0 hour), 6 hours after the sensor was manufactured,
A total of 4 points after 12 hours and 24 hours.

The current measurement conditions were as follows: after confirming that the sample solution was filled in the cavity, the enzymatic reaction was promoted for 25 seconds, and then 0.1 mm was applied between the measurement electrode, the counter electrode and the detection electrode.
A voltage of 2 V was applied, and a current value obtained 5 seconds later was measured. Here, the detection electrode was also used as a part of the counter electrode. The number of measurements n is n = 10 for each concentration and measurement period, and the average value is plotted in the figure.

As is clear from FIG. 2 shown above, the sensor response characteristic to which lactitol as a sugar alcohol was added was higher than that of a conventional sensor not containing a sugar alcohol, especially in a high concentration region where the glucose concentration was 400 mg / dL or more. Indicates a high response value tendency, indicating that excellent response characteristics with a good regression equation (small intercept and large slope) are obtained.

As is apparent from FIG. 3, excellent response characteristics are obtained when maltitol is used as the sugar alcohol, similarly to the case where lactitol is used.

As is clear from FIGS. 4 and 5, in the sensors to which these sugar alcohols are added, the increase in the background current under the exposure environment under high temperature and high humidity is suppressed efficiently. It can be seen that excellent storage stability with little change over time in the sensor response value is obtained.

(Example 2) A blood glucose measurement sensor was manufactured in the same procedure as in Example 1. In addition, here, as an additive for suppressing a temporal increase of the background current, a metal sulfate is used instead of the sugar alcohol.
Magnesium sulfate was added.

FIG. 6 shows the measurement of the change over time of the background current in a harsh environment (exposure at a temperature of 30 ° C. and a humidity of 80%) using the sensor manufactured in this manner. As purified water containing no glucose was used. FIG. 7 shows changes in the sensor response value over time when whole blood whose glucose concentration was adjusted to 80 mg / dL was used as the sample solution. In each case, the measurement is performed at a total of 4 points immediately after the sensor is manufactured (0 hour), 6 hours, 12 hours, and 24 hours after the sensor is manufactured. The current measurement conditions and the number of measurements n are the same as in the first embodiment.

As is clear from FIGS. 6 and 7, in the sensor to which the metal sulfate was added, similarly to the sugar alcohol of Example 1, the background current increased under the exposure environment under high temperature and high humidity. It can be seen that excellent storage stability is obtained with little change over time in the sensor response value.

Although the first and second embodiments show the biosensor for measuring the glucose concentration in blood, the types of the sample liquid, the substance and the biosensor to be measured are not limited to these. For example, besides blood, saliva, interstitial fluid, urine, sweat, and the like, as well as blood, as a target sample liquid, and food and drinking water can also be used. In addition, in addition to glucose, lactic acid, cholesterol, uric acid, ascorbic acid,
Bilirubin and the like can be used. In the first and second embodiments, the three-electrode system including the measurement electrode 2, the counter electrode 3, and the detection electrode 4 shown in FIG. 1 was used as the current measurement system. There is a two-electrode system consisting of only one of them, and any system may be used.
Note that the three-electrode method can measure more accurately than the two-electrode method.

In this embodiment, an enzyme sensor has been described as an example of a biosensor. However, the present invention is not limited to an enzyme, but may be an antibody or a microorganism as a molecular identification element that specifically reacts with a specific substance in a sample solution. It can be similarly applied to biosensors utilizing DNA, RNA, and the like.

[0059]

As described above, according to the biosensor of the present invention, at least the measurement electrode and the counter electrode provided on the insulating substrate are used, and the substance to be measured in the sample solution is separated from the above-mentioned electrode. In a biosensor for measuring the content of the substance to be measured from a current value obtained by a reaction with a reagent layer comprising at least an enzyme formed on or in the vicinity thereof and an electron carrier, a sugar is contained in the reagent layer. Since alcohol is included, it is possible to suppress the increase of the background current with time without inhibiting the enzyme reaction or the like by using a simple method of adding a sugar alcohol to the reagent. In addition, since unnecessary reactions with various contaminants present in blood can be suppressed at the same time, a high-performance biosensor with good linearity and small variations among sensors is provided. Effect that can be.

In addition, according to the biosensor of the present invention, a substance to be measured in a sample solution and a material on or near the electrode are used by using at least an electrode composed of at least a measurement electrode and a counter electrode provided on an insulating substrate. A biosensor for measuring the content of the substance to be measured from a current value obtained by a reaction with a reagent layer comprising at least an enzyme and an electron carrier, wherein a metal salt is contained in the reagent layer. Therefore, by using a simple method of adding a metal salt to the reagent, an effect is obtained in which the increase in the background current with time can be suppressed without inhibiting the enzyme reaction or the like.

According to the biosensor of the present invention, since the reagent layer contains a hydrophilic polymer, the formation of a homogeneous reagent on the electrode surface is facilitated by including the hydrophilic polymer, and Each substance can be promoted to be homogeneously dispersed in the layer. In addition, by realizing uniform reagent formation, there is obtained an effect that a high-performance biosensor with less variation among sensors can be provided.

[Brief description of the drawings]

FIG. 1 is an example of an exploded perspective view of a biosensor.

FIG. 2 is a diagram showing sensor response characteristics when lactitol is added as a sugar alcohol to a reagent solution in Example 1.

FIG. 3 is a graph showing sensor response characteristics when maltitol is added as a sugar alcohol to a reagent solution in Example 1.

FIG. 4 is a diagram showing an increase in background current under a severe environment when purified water is used as a sample liquid in Example 1.

FIG. 5 is a diagram showing an increase in a whole blood response value under a harsh environment when whole blood is used as a sample liquid in Example 1.

FIG. 6 is a diagram showing an increase in background current in a harsh environment when purified water is used as a sample liquid in Example 2.

FIG. 7 is a diagram showing an increase in a whole blood response value under a severe environment when whole blood is used as a sample liquid in Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Measurement electrode 3 Counter electrode 4 Detection electrode 5 Reagent layer 6 Spacer 7 Notch 8 Cover 9 Air hole 10 Lead (measurement electrode) 11 Lead (counter electrode) 12 Lead (detection electrode)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 27/46 336H 336G 338 (72) Inventor Masaki Fujiwara 1 Fukushinmachi, Takamatsu, Kagawa Prefecture Inside the Industrial Co., Ltd. (72) Inventor Junko Nakayama 1 at 8 Koshinmachi, Takamatsu City, Kagawa Prefecture Inside of Matsushita Hisashi Denki Kogyo Co., Ltd. (72) Inventor Nagariko Yamanishi 8 at Koshinmachi, Takamatsu City, Kagawa Prefecture Matsushita Hisako Electric Co., Ltd. F term in the company (reference) 2G045 AA13 CA25 CA26 DA04 DA31 DA53 DA58 DA69 FB01 FB05 GC20

Claims (13)

[Claims] 1. A biosensor for measuring a concentration of a specific substance in a sample solution, wherein a sugar alcohol is dissolved in the sample solution and added to a reagent layer provided in advance so as to specifically react with the specific substance in the sample solution. A biosensor comprising: 2. The biosensor according to claim 1, wherein the concentration of the specific substance is measured using an electrode including at least a working electrode and a counter electrode provided on the insulating substrate. . 3. The biosensor according to claim 2, wherein the reagent layer is disposed on the electrode or in a diffusion area in which a reagent of the reagent layer dissolves in a sample solution and diffuses. A biosensor formed, wherein the reagent layer contains at least an enzyme and an electron carrier. 4. The biosensor according to claim 1, wherein the sugar alcohol is a linear polyhydric alcohol, a cyclic sugar alcohol, or a substituted or derivative thereof. A biosensor characterized in that: 5. The biosensor according to claim 1, wherein the sugar alcohol is maltitol or lactitol, or both. 6. A biosensor for measuring the concentration of a specific substance in a sample solution, wherein the metal salt is dissolved in the sample solution and a metal salt is added to a reagent layer provided in advance to specifically react with the specific substance in the sample solution. A biosensor comprising: 7. The biosensor according to claim 6, wherein the concentration of the specific substance is measured using an electrode including at least a working electrode and a counter electrode provided on the insulating substrate. . 8. The biosensor according to claim 7, wherein the reagent layer is disposed on the electrode or in a diffusion area in which a reagent of the reagent layer dissolves in a sample solution and diffuses. A biosensor formed, wherein the reagent layer contains at least an enzyme and an electron carrier. 9. The biosensor according to claim 6, wherein the metal salt is a metal sulfate, a metal hydrogensulfate, a metal sulfite, a metal bisulfite, or a metal hyposulfite. A biosensor, comprising: 10. The biosensor according to claim 6, wherein the metal salt is one or both of magnesium sulfate and calcium sulfate. 11. The biosensor according to claim 6, wherein the metal salt is a metal nitrate, a metal hydrogen nitrate, a metal nitrite, a metal hydrogen nitrite, or a metal hyponitrite. A biosensor characterized by being a salt. 12. The biosensor according to claim 6, wherein the metal salt is one or both of magnesium nitrate and calcium nitrate. 13. The biosensor according to claim 1, wherein the reagent layer further contains a hydrophilic polymer.