JPH04324351A - Sensor - Google Patents

Abstract

PURPOSE:To improve orienting property and endurance while enabling a non- electrolytic measurement by arranging a group of hydrophobic groups each bonded chemically to a substrate electrode to cover the entire surface thereof contacting a solution to be measured of the substrate electrode. CONSTITUTION:A functional group is introduced into the surface of a substrate electrode 1 comprising a carbon-based electrode and a metal electrode or a metal oxide semiconductor electrode. A hydrophobic group 2 of an amphipathic substance or a bitter substance for various sensors is modified using a normal organic chemical reaction so that the group of hydrophobic groups 2 is bonded 3 chemically to the substrate electrode 1 immediately. This enables the producing of a taste sensor using a monomolecular film made of the group of hydrophobic groups 2, amphipathic substance or the like having endurance, excellent orienting propery and limited variations in quality and moreover, a sensor highly sensitive to non-electrolyte such as sugar.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates primarily to a concentration sensor for non-electrolyte aqueous solutions. It is intended to be used as a sensor for the five human senses, especially taste.

0002

[Prior Art] The same applicant previously filed a patent application for the invention of "taste sensor and method for manufacturing the same" (Japanese Patent Application No.
No. 90819 (hereinafter referred to as the earlier invention A of the same applicant)
, its specification and drawings show that a so-called lipid molecule group housed in a specific molecular arrangement within the surface matrix of a certain kind of high molecular weight polymer produces a salty taste called a basic taste.
It was shown that the sensor can be sensitive to sour, bitter, and sweet tastes. Moreover, this type of sensor has been shown to be able to measure taste in place of taste, which is one of the five human senses.

[0003] To explain this in more detail, in the prior invention A of the same applicant, for example, polyvinyl chloride (PVC) is used as a polymer, and a plasticizer such as dioctyl phthalate (DOP) is used. The agent and lipid are approximately 2:
Tetrahydrofuran (mixed at a weight ratio of 3:1)
THF), transferred to a flat-bottomed container, and held at approximately 30°C for 2 hours on a uniformly heated plate to volatilize the THF and remove the lipids housed within the lipid membrane, i.e., the surface matrix of PVC. A molecular membrane was obtained. Experiments have confirmed that this lipid membrane serves as a taste sensor. In addition, when a lipid membrane is immersed in an aqueous solution of potassium chloride (KCl), the hydrophilic groups of lipid molecules appear to be arranged on the surface of the lipid membrane, and the sensor (membrane potential) It was shown that the sensitivity and stability of
issue).

[0004] However, although it is possible to obtain some measurement results by using the lipid membrane produced in this way as a sensor, the production method of placing lipid molecules within the surface matrix of a high molecular weight polymer does not allow measurement at the molecular level. The structure is not constant,
In other words, it is not always possible to obtain a constant surface matrix, and it is difficult to guarantee that the lipid membrane in which lipid molecules are housed will always be of a constant quality. The orientation of the sexual molecules is also poor, and therefore, it is unavoidable that measurements of membrane potential and electrical resistance tend to have data that fluctuate and have insufficient sensitivity.

[0005] Furthermore, the types of lipid molecules that can be relatively easily accommodated within the surface matrix of high molecular weight polymers have been limited. For example, phosphatidylcholine (P
Lipids constituting biological membranes such as C) have poor compatibility with polymeric materials such as polyvinyl chloride (PVC), so it has been difficult to form lipid membranes for use in taste sensors. As a means of solving the above problem, the same applicant previously filed a patent application for the invention of "taste sensor and its manufacturing method" (Japanese Patent Application No. 3-20450; hereinafter referred to as the earlier invention B of the same applicant). ), its specification and drawings show a new method for forming a single layer of amphiphilic molecules and a bitter substance, and this single layer provides increased sensitivity compared to the earlier invention A of the same applicant. It was shown that a sensor with improved measurement stability, less variation in measured values from sensor to sensor, and logarithmic linearity could be obtained.

[0006] To explain this in a little more detail, in the prior invention B of the same applicant, for example, a compound is coated with a substance that has a property of being friendly to the hydrophobic part of an amphiphilic molecule group or a bitter substance molecule group. Using the LB method or modification method, a monolayer (single molecule) is formed on a substrate with hydrophilic groups of amphiphilic molecules or bitter substance molecules exposed on the surface. A film) was formed. In this way, we experimentally demonstrated that by creating a uniform monolayer on the sensor surface, we can more closely mimic human taste characteristics. Considering this result and the fact that the taste receptor membrane of living organisms is a uniform bilayer membrane, it can be said that this membrane is ideal as a taste sensor.

[0007]

[Problem to be solved by the invention] However, by making the sensor surface into a uniform monolayer, the characteristics have become ideal, but the film of the earlier invention B of the same applicant has problems in terms of durability. . It is fixed to the base membrane only by the attraction force between the hydrophobic group of the amphipathic substance or the bitter substance and the part that is familiar with the hydrophobic group of the base membrane, and the repulsive force between the hydrophobic group of the amphipathic substance or bitter substance and water. This is because the lipid membrane and base membrane are likely to separate. In reality, the lifespan of a human taste receptor is one day, and its metabolism is extremely rapid, so it would be good to consider a disposable type of taste sensor, but this is extremely inconvenient from a practical standpoint.

[0008] Furthermore, when detecting non-electrolytes such as sweet substances in foods, even with an ideal lipid monolayer membrane, sweet substances only affect the charge density of the monolayer membrane. Potential changes are extremely small compared to electrolytes. As shown in the earlier invention B of the same applicant, an output of about 150 to 200 mV can be obtained for four basic tastes other than sweetness, whereas an output of only about 20mV can be obtained for sweetness. This small output can be presumed to be the result of the sweet substance affecting the orientation of lipids. However, such effects on lipid orientation are thought to change membrane resistance and membrane capacitance more than membrane potential. In order to measure the concentration of non-electrolyte, it is better to measure changes in membrane resistance and membrane capacitance of a membrane with excellent orientation, but in this case as well, the durability of the membrane becomes an issue. Since it is a monolayer, even partial destruction makes it impossible to measure membrane resistance and membrane capacitance.

In addition, in conventional membranes with hydrophilic groups exposed on the surface, substances that are adsorbed to hydrophobic groups, such as bitter substances, are hindered by the hydrophilic groups on the surface and are absorbed into the membrane. Because it is difficult to bond with hydrophobic groups, there is not much difference in the response of the membrane to substances that adsorb to hydrophobic groups and substances that do not.

[0010] A taste sensor using a conventional lipid membrane (or a membrane using amphiphilic molecules or molecules of a bitter substance) has durability, that is, a lipid membrane with excellent lipid orientation. The object of this invention is to focus on and improve membrane immobilization.

[0011] As a result, it is an object of the present invention to make it possible to measure non-electrolytes such as sweetness, which could not be measured using conventional potentials, by stably measuring the resistance and capacitance of the membrane.

[0012] Furthermore, the structure of conventional lipid membranes (or membranes using amphiphilic molecules or molecules of bitter substances) has been changed to increase the response to substances adsorbed to hydrophobic groups such as bitter substances.
It lowers the response to substances that do not adsorb to hydrophobic groups, gives the sensor selectivity, and increases the amount of information.

[0013]

[Means for Solving the Problems] In this invention, in order to obtain a sensor film with excellent orientation and excellent durability, the manufacturing method is changed, and thereby a highly durable and uniform film is formed on the electrode. It is said that it forms a layer of lipids. In other words, in the earlier invention B of the same applicant, a uniform lipid film with excellent orientation was obtained, but the fixation was only due to the weak forces of attraction between hydrophobic groups and repulsion between hydrophobic groups and water. Because of this, there was a problem with durability. This fixation is done by strong bonding and devised to increase durability. The following four methods can be considered for the connection.

(2) A functional group is introduced onto the electrode surface, and an amphipathic substance or a bitter substance for various sensors is modified using a conventional organic chemical reaction. Figures 2 and 3
shows a systematic diagram of chemical modification. Flowcharts of the manufacturing procedure of each system are shown in FIGS. 26 to 46. Further, Table 1 shows examples of electrodes that will become the substrate electrode 1.

[0015]

[Table 1]

(2) Produced by modifying the thiol group of a molecular group having a thiol group (SH group) and a hydrophobic group on an electrode such as gold or platinum. (2) Produced by modifying the thiol group of a molecular group having a thiol group (SH group), a hydrophobic group, and a functional group on an electrode such as gold or platinum. ■Using a compound that has both a thiol group (SH group) and another functional group, the thiol is modified on an electrode such as gold or platinum, and the above functional group and the functional group of the taste sensor lipid are chemically bonded to each other. Manufactured by

The configuration of each sensor is shown in FIG. 1 and FIGS. 4 to 6. 7 to 9 show the structure of the sensor using chemical formulas. In particular, the thiol group (SH group)
It combines very strongly with gold and platinum.

However, in the structures of (1), (2), and (3) above, it is thought that the hydrophobic groups are firmly fixed on the surface of the sensor with good orientation, and by measuring the membrane resistance against non-electrolytes such as sugar, Taste can be clearly detected. Naturally, for substances that adsorb to hydrophobic groups, such as bitter substances, the adsorption is intense and the response sensitivity increases; conversely, substances that do not adsorb to hydrophobic groups respond because they do not affect the membrane potential even if they have a charge. Sensitivity decreases, resulting in increased selectivity and information content.

[0019] Furthermore, in the above structure (2), an amphiphilic substance with a hydrophilic group on the surface of the sensor and a hydrophobic group on the inside is firmly fixed with good orientation via a thiol group (SH group). it is conceivable that. Structurally, this is an ideal lipid monolayer similar to the prior patent B, and has very excellent characteristics as a sensor. In addition, thiol group (SH
It is fixed to the electrode via a group (group) and does not come off even when washed with an organic solvent.

[0020]

EXAMPLE FIGS. 8 and 9 are schematic diagrams (cross-sectional views) of sensors manufactured for experiments. Figure 8 shows a configuration of gold electrodes, mercaptosulfonic acid, and dioctadecylmethylammonium bromide (hereinafter referred to as A membrane), and Figure 9 shows a configuration of gold electrodes and n-octadecyl mercaptan (hereinafter referred to as B membrane). call).

The manufacturing procedure of the sensor will be described below. The electrode is φ1
．． An acrylic plate with holes made and stuffed with 5 mm gold electrodes was used. Production procedure 1. Wash the electrode with distilled water. 2. The surface of the electrode is polished with emery paper (roughness 0.3 μm). 3. Wash the electrode with distilled water. 4. Step 2. and 3. Repeat 3 times. 5. Absorb the water from the surface of the electrode, being careful not to touch it. 6. Clean the electrode with ethanol.

The following procedure is different for A film and B film. First, the procedure for film A will be shown. 7A. Mercaptosulfonic acid in ethanol solution
Dissolve 00mM. This is referred to as solution A1. 8A. Soak the electrode in solution A1 for 12 hours. 9A. Dissolve 20mM of dioctadecylmethylammonium bromide in the ethanol solution. Add this to solution A2
shall be. 10A. Soak the electrode in solution A1 for 12 hours. 11A. Clean the electrode with ethanol.

Next, the procedure for the B film will be described. 7B. Dissolve 1mM of n-octadecyl mercaptan in the ethanol solution. This will be referred to as solution B1. 8B. Soak the electrode in solution B1 for 24 hours. 9B. Clean the electrode with ethanol.

The response of the sensor manufactured by the above procedure to the four basic tastes will be described. FIG. 10 is a diagram showing a measurement system for measuring the response of a sensor to four basic tastes. A solution to be measured is placed in a container, and a sensor 4, a reference electrode 6, and a platinum electrode 5 for passing a current through the sensor are placed in the solution to be measured. The sensor is connected via a 22 MΩ resistor 7 to the movable point of a variable resistor 8 to which a voltage of 1.5 volts is applied by a dry battery 9 to both ends. The platinum electrode 5 is connected to the connection point between the negative side of the dry battery 9 and the variable resistor 8. The reference electrode 6 is connected to ground. V0 and V1 in the figure are potentials at respective points with reference to the reference electrode 6. Further, R0 is the resistance value of the resistor 7.

Membrane resistance measurements were carried out as follows. Figure 1
0 measurement system, the current I (0.005
(using a range from μA to 0.015 μA), and measure V0 and V1 at that time. For measurement, an electrometer with an input impedance of several hundred MΩ or more is used. It is assumed that the current flowing through the electrometer is sufficiently smaller than the current I.

The following equation holds true for V0, V1, I, R0, R (membrane resistance) and VAu (interfacial potential with respect to the reference electrode of the sensor electrode). V0=VAu+RI

(1) I =
(V1-V0)/R0
(2) Here, the current I is forcibly varied by a minute amount ΔI (approximately 0.01 μA). At this time, assuming that VAu does not change, V0 +ΔV0 = VAu+R(I+
ΔI)
(3) I +ΔI=[(V1
+ΔV1)−(V0+ΔV0)]/R0(
4), and from equations (1) to (4), R=R0 /[(ΔV1 /ΔV0
)-1]
(5), so by changing the current I by a small amount ΔI, ΔV
1, ΔV0 was measured to determine the membrane resistance R.

FIG. 11 shows the measurement system described above, in which an unmodified gold electrode (hereinafter referred to as an unmodified gold electrode) is used in place of the sensor, and the current is varied from 0.007 μA to 0.00 μA.
The results are shown in which V0 and V1 were measured while changing the current to 0.08 μA. The slope ΔV1 /ΔV0 is almost constant. Table 2 shows the results of repeated resistance measurement experiments. The standard deviation of the variation in output is 2%, which is sufficiently reliable data.

[0028]

[Table 2]

Using this, changes in membrane resistance of membrane A and membrane B to taste substances are investigated. The taste substances used were sucrose for sweetness, quinine hydrochloride for bitterness, sodium chloride for salty taste, and tartaric acid for sourness. The concentration of each solution to be measured was within the range that humans could feel.

The measurement results are shown in FIGS. 12 to 25. The vertical axis represents the ratio with the membrane resistance in the reference solution (1 mM potassium chloride solution) being 1. By the way, the membrane resistance in the standard solution is about 5MΩ for the unmodified gold electrode, and about 10MΩ~2 for the A membrane.
0 MΩ and the B film is also about 10 MΩ to 20 MΩ.

FIG. 12 shows the concentration characteristics of the membrane resistance of membrane A to sucrose. While the membrane resistance change of the unmodified gold electrode is almost zero, the membrane resistance of the A membrane increases as the concentration of sucrose increases, and at 1000 mM, it increases 1.4 times. This number is sufficiently significant even if the error is ±2 to 3%. This is thought to be because sucrose was adsorbed between the hydrophobic group groups on the sensor surface, increasing the density of the hydrophobic group arrangement.

FIG. 13 shows the concentration characteristics of membrane resistance of membrane A to quinine hydrochloride. While the membrane resistance change of the unmodified gold electrode is almost zero, the membrane resistance of the A membrane increases as the concentration of quinine hydrochloride increases, and at 3 mM, it increases about three times. This is because quinine adsorbs to the group of hydrophobic groups on the sensor surface, increasing the density of the arrangement of hydrophobic groups, and the positive charge of the quinine molecules generates a diffuse electric double layer, which creates an electrical barrier. This is thought to be because. In fact, the membrane potential increased by about 80 mV.

FIG. 14 shows the concentration characteristics of the membrane resistance of membrane B to sucrose. Almost the same as A membrane, 1.4 at 1000mM
It's double.

FIG. 15 shows the concentration characteristics of membrane resistance of membrane B to quinine hydrochloride. Although the increase is not as great as that of A membrane, it is 1.7 times greater at 1 mM.

FIG. 16 shows the concentration characteristics of membrane resistance for sodium chloride in membrane B. The membrane resistance of unmodified gold electrode is 50%
The B film has decreased by 20%. This is because the electrical conductivity improved due to the increased concentration of sodium ions and chloride ions. However, since the membrane surface is covered with hydrophobic groups, the change is smaller than that of an unmodified gold electrode.

FIG. 17 shows the concentration characteristics of the film resistance of film B to tartaric acid. Both the unmodified gold electrode and the B film are reduced by 20%. This is due to an increase in hydrogen ions and organic anions.

Membrane potential measurement was carried out as follows. The measurement system was the same as that used for membrane resistance measurement. however,
The current flowing through the sensor was set to the minimum value of about 0.007 μA. Each taste substance was the same as that used in the membrane resistance measurement.

The measurement results are shown in FIGS. 18 to 25. The vertical axis represents the difference in potential from the reference solution. FIG. 18 shows the concentration characteristics of membrane potential for sucrose in membrane A. While the membrane potential change of the unmodified gold electrode is almost zero, the membrane potential of the A membrane increases as the sucrose concentration increases, and increases by about 35 mV at 1000 mM. This means that the membrane resistance is approximately 5MΩ.
This is estimated to be because the current was 0.007 μA. Naturally, it can be assumed that as the current increases, the change in membrane potential also increases accordingly.

FIG. 19 shows the concentration characteristics of the membrane potential of membrane A for quinine hydrochloride. While the membrane potential change of the unmodified gold electrode is almost zero, the membrane resistance of the A membrane increases as the concentration of quinine hydrochloride increases, increasing by about 80 mV at 3 mM. This is thought to be because quinine was adsorbed to the hydrophobic groups on the sensor surface, and an electric double layer was generated due to the positive charge of the quinine molecules. The threshold value is almost the same as that of humans, making it a good sensor for bitterness.

FIG. 20 shows the concentration characteristics of membrane potential for sodium chloride in membrane A. Unmodified gold electrode has a concentration of 1000m
The voltage dropped by about 70 mV at M. This seems to be due to the redox potential caused by chlorine ions. In addition, the voltage decreases by about 30 mV in the A film. This seems to be due to the redox potential caused by chloride ions passing through the lipid.

FIG. 21 shows the concentration characteristics of the membrane potential of membrane A with respect to tartaric acid. The unmodified gold electrode rose approximately 50 mV at a concentration of 30 mM. This seems to be due to the redox potential caused by hydrogen ions. In addition, the voltage has increased by about 40 mV in the A film. This seems to be due to the redox potential caused by hydrogen ions passing through the lipid.

FIG. 22 shows the concentration characteristics of the membrane potential of the B membrane for sucrose. The unmodified gold electrode is the same as that for the A film. Film B does not increase as much as film A, but increases by about 30 mV.

FIG. 23 shows the concentration characteristics of membrane potential for quinine hydrochloride in membrane B. Film B has an increase of about 50% compared to film A.

FIG. 24 shows the concentration characteristics of membrane potential for sodium chloride in membrane B. The B film is almost the same as the A film.

FIG. 25 shows the concentration characteristics of membrane potential for tartaric acid in membrane B. The B film is almost the same as the A film.

As described above, it can be seen that the membrane potential responses of the A membrane and B membrane to each taste substance have specificity to substances having non-electrolytes and hydrophobic parts, compared to conventional taste sensors. By adding a substance that stabilizes the redox potential of gold, such as potassium ferricyanide, to the solution to be measured, it is thought that changes in membrane potential caused by chlorine ions and hydrogen ions can be suppressed to almost zero. It is inferred that the specificity to substances will be further strengthened.

[0047]

As described above, according to the present invention, a sensor having a monolayer structure with excellent orientation and good properties as a taste sensor, for example, but with durability, can be obtained. This means that a practical sensor, particularly for measuring membrane resistance and membrane capacitance, has been obtained, leading to an increase in the amount of information for determining taste and the like. In terms of taste, it has become possible to measure non-electrolytes that could not be measured using sweetness equipotentials. Furthermore, compared to conventional sensors, sensors with hydrophobic groups lined up on the surface have increased responsiveness to substances that adsorb to hydrophobic groups, such as bitter substances, and have decreased responsiveness to substances that do not adsorb to hydrophobic groups. Therefore, the number of types of sensors with selectivity has increased.

[0048]

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a sensor of the present invention.

FIG. 2 is a chemical modification system diagram of the carbon-based electrode of the sensor of the present invention.

FIG. 3 is a chemical modification system diagram of the metal oxide semiconductor electrode and the metal electrode of the sensor of the present invention.

FIG. 4 is a schematic cross-sectional view of the sensor of the invention.

FIG. 5 is a schematic cross-sectional view of the sensor of the present invention.

FIG. 6 is a schematic cross-sectional view of the sensor of the invention.

FIG. 7 is a schematic cross-sectional view of the membrane of the sensor of the present invention represented by a chemical formula.

FIG. 8 is a schematic cross-sectional view of the membrane of the sensor of the present invention represented by a chemical formula.

FIG. 9 is a schematic cross-sectional view showing the membrane of the sensor of the present invention using a chemical formula.

FIG. 10 is a diagram of a system for measuring membrane potential and membrane resistance of a sensor.

FIG. 11 is a diagram showing ΔV1 /ΔV0 of an unmodified gold electrode.

FIG. 12 is a diagram showing the concentration characteristics of the membrane resistance of membrane A to sucrose.

FIG. 13 is a diagram showing the concentration characteristics of the membrane resistance of Membrane A to quinine hydrochloride.

FIG. 14 is a diagram showing the concentration characteristics of the membrane resistance of membrane B to sucrose.

FIG. 15 is a diagram showing the concentration characteristics of the membrane resistance of Membrane B to quinine hydrochloride.

FIG. 16 is a diagram showing the concentration characteristics of membrane resistance with respect to sodium chloride of membrane B.

FIG. 17 is a diagram showing concentration characteristics of film resistance of film B to tartaric acid.

FIG. 18 is a diagram showing the concentration characteristics of membrane potential for sucrose in membrane A.

FIG. 19 is a diagram showing the concentration characteristics of the membrane potential of Membrane A with respect to quinine hydrochloride.

FIG. 20 is a diagram showing the concentration characteristics of membrane potential with respect to sodium chloride of membrane A.

FIG. 21 is a diagram showing the concentration characteristics of the membrane potential of membrane A with respect to tartaric acid.

FIG. 22 is a diagram showing the concentration characteristics of membrane potential for sucrose in B membrane.

FIG. 23 is a diagram showing the concentration characteristics of membrane potential for quinine hydrochloride in membrane B.

FIG. 24 is a diagram showing the concentration characteristics of membrane potential with respect to sodium chloride in membrane B.

FIG. 25 is a diagram showing the concentration characteristics of membrane potential for tartaric acid in membrane B.

FIG. 26 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 27 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 28 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 29 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 30 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 31 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 32 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 33 is a flow chart showing the manufacturing procedure of the sensor of the present invention.

FIG. 34 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 35 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 36 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 37 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 38 is a flow chart showing the manufacturing procedure of the sensor of the present invention.

FIG. 39 is a flow chart showing the manufacturing procedure of the sensor of the present invention.

FIG. 40 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 41 is a flow chart showing the manufacturing procedure of the sensor of the present invention.

FIG. 42 is a flow chart showing the manufacturing procedure of the sensor of the present invention.

FIG. 43 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 44 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 45 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

FIG. 46 is a flowchart showing the manufacturing procedure of the sensor of the present invention.

[Explanation of symbols]

1　Substrate electrode 2 Hydrophobic group (hydrophobic group) 3 Chemical bonding part 4 Sensor 5 Electrode 6 Reference electrode 7 Resistance 8 Variable resistance 9 Dry battery 10 Thiol part 11 Hydrophobic part 12 Hydrophilic group 13 Hydrocarbon part

Claims (3)

[Claims] 1. Consisting of a substrate electrode (1) and a hydrophobic group group (2) chemically bonded to the substrate electrode, the hydrophobic group group covering the entire surface of the substrate electrode in contact with the solution to be measured. A sensor featuring: 2. The substrate electrode is a carbon-based electrode, and the chemical bond is at least one of an amide bond, an ester bond, an ether bond, a ketone bond, a carbon-carbon bond, or a carbon-nitrogen bond. The sensor according to claim 1, characterized in that: 3. The substrate electrode is either a metal electrode or a metal oxide type semiconductor electrode, and the chemical bond is at least one of an amide bond, an amino bond, an ester bond, or an ether bond. The sensor according to claim 1, characterized in that: