Sensor

Abstract

To provide a sensor having improved selectivity while securing sufficient sensitivity.SOLUTION: The sensor 1 has at least a working electrode 3. The working electrode 3 is provided with a complex 13 comprising a carbon nanotube 5, oxide semiconductor fine particles 7 supporting a catalyst, and a molecular template layer 11 having pores 9 that selectively transmit a molecule to be detected. In the complex 13, the oxide semiconductor microparticles 7 are supported on the surface of the carbon nanotube 5, and the molecular template layer 11 is further provided thereon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to sensors. [Background technology]

[0002] A sensor using carbon nanotubes as a sensing material has been disclosed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-162431 Summary of the Invention [Problem to be solved by the invention]

[0004] However, this sensor had low sensitivity to the target molecules, and also had insufficient selectivity to the target molecules. The present disclosure has been made in view of the above-described circumstances, and aims to provide a sensor that improves selectivity while ensuring sufficient sensitivity. The present disclosure can be realized in the following forms. [Means for solving the problem]

[0005] [1] A sensor having at least a working electrode, The working electrode has Carbon nanotubes and oxide semiconductor particles carrying a catalyst; a molecular template layer having pores that selectively transmit target molecules; The composite sensor comprises the oxide semiconductor particles carried on the surface of the carbon nanotube, and the molecular template layer further provided thereon.

[0006] [2] In the carbon nanotube, a portion where the oxide semiconductor fine particles exist overlaps with a portion where the hole in the molecular template layer exists; The sensor according to [1], wherein the target molecules that selectively pass through the holes in the molecular template layer are capable of contacting the oxide semiconductor particles on the carbon nanotubes.

[0007] [3] The sensor according to [1] or [2], wherein the molecular template layer contains a conductive polymer. [Effects of the Invention]

[0008] The sensors of the present disclosure are highly sensitive and selective. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic explanatory diagram of a cross section of a composite body. [Figure 2] FIG. 2 is a top view of an example of a sensor. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is an explanatory diagram schematically illustrating a verification method using the sensor of the first embodiment. [Figure 5] 1 is a graph showing the evaluation results of output versus geosmin concentration. [Figure 6] 1 is a graph showing the S / N ratio (S: sensitivity of geosmin 1 μg / L, N: sensitivity of quinoclamine 1 μg / L). DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "to" it is intended to include both the lower and upper limits unless otherwise specified. For example, the expression "10 to 20" includes both the lower limit "10" and the upper limit "20". In other words, "10 to 20" has the same meaning as "10 or more and 20 or less". In this specification, the upper and lower limits of each numerical range can be arbitrarily combined. In addition, the drawings are conceptual diagrams for explaining the disclosed contents and do not accurately depict actual dimensions.

[0011] 1. Sensor 1 The sensor 1 of the present disclosure is also referred to as a chemical sensor. The working electrode 6 is provided with a composite 13 including carbon nanotubes 5, oxide semiconductor microparticles 7 supporting a catalyst, and a molecular template layer 11 having pores 9 that selectively transmit target molecules. In the composite 13, the oxide semiconductor microparticles 7 are supported on the surface of the carbon nanotubes 5, and the molecular template layer 11 is further provided thereon. The overall configuration of the sensor 1 will be described later. Here, the composite 13 will first be described.

[0012] (1) Complex 13 As shown schematically in FIG. 1, the composite 13 comprises a carbon nanotube 5, oxide semiconductor microparticles 7 carrying a catalyst, and a molecular template layer 11 having pores 9 that selectively transmit target molecules.

[0013] (1.1) Carbon nanotubes 5 There is no particular limitation on the carbon nanotubes 5. For example, single-walled carbon nanotubes (SWCN), double-walled carbon nanotubes (DWCN), multi-walled carbon nanotubes (MWCN), etc. can be used as the carbon nanotubes 5. These carbon nanotubes 5 can be used alone or in combination of two or more types. The carbon nanotubes may be produced by an arc discharge method, a laser ablation method, a chemical vapor deposition method, or the like.

[0014] (1.2) Oxide semiconductor particles 7 The oxide semiconductor particles 7 support a catalyst. The catalyst metal used for the catalyst is not particularly limited. The catalyst metal is one or more selected from the group consisting of palladium (Pd), platinum (Pt), rhodium (Rh), gold (Au), and iridium (Ir). For example, palladium is preferably used from the viewpoint of reducing costs while ensuring sufficient sensitivity of the sensor 1. The shape of the catalyst is not particularly limited. The catalyst may be in a particulate form (for example, nanoparticle form). There is no particular limitation on the oxide semiconductor particles 7. From the viewpoint of ensuring sufficient sensitivity of the sensor 1 while reducing costs, the oxide semiconductor is preferably one or more selected from the group consisting of cobalt oxide (Co3O4), tin oxide (SnO2), tungsten oxide (WO3), and indium oxide (In2O3). From the viewpoint of reducing costs while ensuring sufficient sensitivity of the sensor 1, the amount of catalytic metal is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 1% by mass or more and 3% by mass or less, when the entire oxide semiconductor microparticles 7 carrying the catalytic metal are taken as 100% by mass.

[0015] (1.3) Ratio of carbon nanotubes 5 to oxide semiconductor particles 7 The ratio of the carbon nanotubes 5 (A) to the oxide semiconductor particles 7 (B) is not particularly limited. From the viewpoint of sensor sensitivity, the ratio between the two is preferably A:B=20:1 to 0.1:1, more preferably 10:1 to 0.5:1, and even more preferably 5:1 to 1:1, on a mass basis.

[0016] (1.4) Molecular template layer 11 The molecular template layer 11 has holes 9 that selectively allow the target molecules to pass through. The material of the molecular template layer 11 is not particularly limited. The molecular template layer 11 is a layer of a molecular imprinted polymer (MIP). A "molecular template" having a structure complementary to the molecular structure of the target molecules is formed on the surface or within the polymer. Only the target molecules can pass through this molecular template. The molecular template layer 11 preferably contains a conductive polymer from the viewpoints of preventing the resistance between the working electrode 6 and the counter electrode 8 from becoming high and reducing noise. The conductive polymer is not particularly limited. The conductive polymer is preferably one or more selected from the group consisting of polypyrrole, polyaniline, and polythiophene. Polypyrrole is preferred from the viewpoint of relatively easy formation of holes 9 that selectively transmit target molecules.

[0017] There are no particular limitations on the thickness of the molecular template layer 11. From the viewpoints of ensuring high selectivity by selectively transmitting target molecules and detecting target molecules with high sensitivity, the thickness of the molecular template layer 11 is preferably 5 nm to 100 nm, more preferably 10 nm to 80 nm, and even more preferably 20 nm to 50 nm.

[0018] The molecules to be detected are not particularly limited and may be in a liquid, solid, or gaseous state at room temperature and normal pressure (25°C, 1 atm). The size of the detection target molecule is not particularly limited, and is preferably 0.1 nm to 100 nm, more preferably 0.3 nm to 80 nm, and even more preferably 0.5 nm to 50 nm. The molecule to be detected is not particularly limited as long as it is an organic compound capable of forming a template, but is preferably selected from the group consisting of geosmin, 2-MTB, and proteins.

[0019] (1.5) Preparation of Complex 13 Oxide semiconductor particles 7 carrying a catalyst are supported on the carbon nanotubes 5. There are no particular limitations on the method for supporting the oxide semiconductor particles 7 on the carbon nanotubes 5. For example, the oxide semiconductor particles can be supported by impregnating them with a solution in which the catalyst is dissolved, followed by baking. The method for forming the molecular template layer 11 is not particularly limited. Various methods known to those skilled in the art can be used to form a molecular template polymer. Specifically, the molecular template layer 11 can be produced by polymerizing a monomer solution containing target molecules (target substances) to be detected to form a polymer, and then removing the target molecules from the polymer. Alternatively, for example, a polymer layer can be formed by depositing a mixture of a conductive polymer and target molecules, and then removing the target molecules from the polymer layer, thereby forming a molecular template layer 11 having a pore structure complementary to the molecular structure of the target molecules in the polymer layer.

[0020] From the viewpoint of ensuring high selectivity by selectively transmitting target molecules and detecting target molecules with high sensitivity, it is preferable that the locations of oxide semiconductor particles 7 in carbon nanotubes 5 overlap with the locations of holes 9 in molecular template layer 11. In such a configuration, it is presumed that target molecules that selectively pass through holes 9 in molecular template layer 11 can come into contact with oxide semiconductor particles 7 on carbon nanotubes 5.

[0021] (2) Overall configuration of sensor 1 The overall configuration of one example of the sensor 1 will be described with reference to Figures 2 and 3. Figure 2 is a top view of the sensor 1. Figure 3 is a cross-sectional view taken along line AA in Figure 2. The sensor 1 is a device for detecting target molecules contained in a liquid sample, and is used to determine the concentration of geosmin, for example.

[0022] The sensor 1 is generally in the shape of a plate extending in the left-right direction in Figures 2 and 3. In this specification, the right side of Figure 2 is referred to as the front end side of the sensor 1, and the left side of Figure 2 is referred to as the rear end side of the sensor 1.

[0023] The sensor 1 mainly comprises a main body 2, a housing 4, a working electrode 6, a counter electrode 8, and a reference electrode 10.

[0024] The main body 2 is made of a plurality of ceramic green sheets (three in this embodiment) that are stacked and sintered (ceramic substrate), and has an overall plate shape. For ease of explanation, the portion of the main body 2 where the ceramic green sheet arranged at the bottom is sintered will be referred to as the "first layer 21," the portion where the ceramic green sheet stacked on top of that will be sintered will be referred to as the "second layer 22," and the portion where the ceramic green sheet stacked on top of that (i.e., the ceramic green sheet arranged at the top) will be sintered will be referred to as the "third layer 23."

[0025] The ceramic green sheet used for the main body 2 is not particularly limited as long as the surface (particularly the bottom surface 41) of the housing portion 4 described later exhibits hydrophilicity, and any known ceramic green sheet can be used.

[0026] For example, ceramic powder such as aluminum oxide (Al2O3), aluminum nitride (AlN), or yttrium oxide (Y2O3) may be mixed with a sintering aid, a binder (such as an organic binder), or a plasticizer using a solvent, and the resulting slurry mixture may be formed into a thin plate using a known method such as a doctor blade method, which may then be used as a ceramic green sheet.

[0027] The thickness of the ceramic green sheets is not particularly limited and may be set to, for example, 0.1 mm or more and 0.7 mm or less. The thicknesses of the ceramic green sheets used in the main body 2 may be the same or different from each other. In this embodiment, the main body 2 uses ceramic green sheets all having the same thickness.

[0028] The storage section 4 is a portion into which a liquid sample is placed, and is formed as a recess on the upper surface 1a side of the sensor 1. The upper surface 1a of the sensor 1 is made up of the upper surface of the third layer 23. The storage section 4 is arranged so as to be biased toward the front end side (right side in FIG. 2) of the rectangular upper surface 1a that extends in the front-to-rear direction in a plan view. Note that a terminal section is arranged on the rear end side (left side in FIG. 2), as will be described later.

[0029] The storage section 4 has a bottom surface 41 and a wall surface 42 arranged to surround the bottom surface 41. The bottom surface 41 is made up of part of the upper surface of the second layer 22 of the main body section 2 and has a flat (planar) surface shape. An opening 23a is formed in the third layer 23 of the main body section 2 so as to penetrate through in the thickness direction, and the upper surface of the second layer 22 exposed through the opening 23a forms the bottom surface 41 of the storage section 4. As shown in FIG. 2, the opening 23a has a square shape in a plan view.

[0030] The wall surface 42 surrounds the bottom surface 41 and extends in the thickness direction of the main body 2. The wall surface 42 is a frame-shaped end surface of the opening 23a formed in the third layer 23.

[0031] 2, when the bottom surface 41 of the storage section 4 is viewed from above, the bottom surface 41 has a square shape. In other words, the bottom surface 41 has a square shape in a plan view, and the wall surfaces 42 surrounding the bottom surface 41 are also arranged to have a square shape.

[0032] The surfaces of the storage unit 4 (i.e., the bottom surface 41 and the wall surfaces 42) are hydrophilic. In this specification, "hydrophilic" refers to a contact angle with water of less than 90°. The contact angles of the bottom surface 41 and the wall surfaces 42 are preferably 60° or less, more preferably 55° or less, and even more preferably 50° or less. If the bottom surface 41 and the wall surfaces 42 are hydrophilic, when a liquid sample is placed in the storage unit 4, the liquid sample will easily spread out in a planar shape within the storage unit 4 and will easily come into contact with electrodes such as the working electrode 6 described below.

[0033] Cylindrical electrode holes 31a, 31b, and 31c are formed in the bottom surface 41 of the housing 4, and are filled with the working electrode 6, the counter electrode 8, and the reference electrode 10. The electrode holes 31a, 31b, and 31c are provided so as to penetrate the second layer 22 of the main body 2 in the thickness direction.

[0034] The working electrode 6, counter electrode 8, and reference electrode 10 constitute a so-called three-electrode electrochemical cell. The working electrode 6 is formed by filling the electrode hole 31a with an electrode material for the working electrode 6. The working electrode 6 has a cylindrical shape extending along the thickness direction (vertical direction) of the main body 2, and an upper surface 6a is exposed from the upper side (bottom surface 41 side) of the electrode hole 31a. The upper surface 6a is circular and is disposed so as to be flush with the bottom surface 41. A composite 13 is used as the electrode material for the working electrode 6. Because the redox current at the working electrode 6 depends on the concentration of the target molecule, the target molecule can be quantitatively measured by measuring the current.

[0035] The counter electrode 8 has a cylindrical shape extending in the vertical direction, and an upper surface 8a is exposed from the upper side (bottom surface 41 side) of the electrode hole 31b. The upper surface 8a is circular and is disposed so as to be flush with the bottom surface 41. The electrode material for the counter electrode 8 is, for example, platinum paste.

[0036] The reference electrode 10 has a cylindrical shape extending in the vertical direction, and an upper surface 10a is exposed from the upper side (bottom surface 41 side) of the electrode hole 31c. The upper surface 10a is circular and is disposed so as to be flush with the bottom surface 41. The electrode material for the reference electrode 10 is, for example, a mixed paste of silver (Ag) and silver chloride (AgCl).

[0037] 2, the working electrode 6, the counter electrode 8, and the reference electrode 10 are arranged to form a triangle while maintaining a distance between them on the bottom surface 41 of the housing part 4. In this example, the counter electrode 8 is arranged at the most distal end, and the working electrode 6 and the reference electrode 10 are arranged further rearward than the counter electrode 8.

[0038] The sensor 1 further includes a first conductive path 40, a second conductive path 50, a third conductive path 60, a first terminal portion 45 (working electrode terminal portion), a second terminal portion 55 (counter electrode terminal portion), and a third terminal portion 65 (reference electrode terminal portion).

[0039] The first conductive path 40, the second conductive path 50, and the third conductive path 60 are formed independently of one another inside the main body 2 of the sensor 1. As shown in FIG. 2, the first conductive path 40, the second conductive path 50, and the third conductive path 60 extend generally in the front-to-rear direction.

[0040] The working electrode 6 is connected to one end of the first conductive path 40, and the first terminal 45 is connected to the other end. The counter electrode 8 is connected to one end of the second conductive path 50, and the second terminal 55 is connected to the other end. The reference electrode 10 is connected to one end of the third conductive path 60, and the third terminal 65 is connected to the other end.

[0041] The first conductive path 40, the second conductive path 50, and the third conductive path 60 each have a basic configuration in common, with multiple vias and multiple layered (thin film) wiring portions electrically connected to each other.

[0042] The second terminal portion 55 is made of a layered conductive material having a rectangular shape in a plan view, and is formed on the upper surface of the third layer 23 (i.e., the upper surface 1a of the sensor 1). As shown in Fig. 2 and other figures, the second terminal portion 55 is formed on the rear end portion of the upper surface 1a. The second terminal portion 55 is formed on the upper surface 1a of the sensor 1 so that its longitudinal direction is along the front-to-rear direction of the sensor 1 and is disposed approximately in the center in a direction perpendicular to the front-to-rear direction (i.e., the short-side direction of the sensor 1).

[0043] The first terminal 45 and the third terminal 65 are each made of a layered conductive material having a rectangular shape in a plan view, and are formed on the top surface 1a of the sensor 1 further forward (towards the accommodation section 4) than the second terminal 55. The first terminal 45 and the third terminal 65 are formed on the top surface 1a of the sensor 1 so that their longitudinal directions are aligned with the short-side direction of the sensor 1 and so that they face each other while maintaining a gap between them in the short-side direction of the sensor 1.

[0044] The sensor 1 configured as described above is manufactured, for example, by the following method. First, three ceramic green sheets are prepared and processed to form the first layer 21, the second layer 22, and the third layer 23. For example, the ceramic green sheet for the first layer 21 is subjected to a process such as printing a metallization paste to form the wiring portion of the second conductive path 50. The ceramic green sheet for the second layer 22 is subjected to a process such as forming (punching) electrode holes 31a and the like, drilling holes to form vias and the like of the second conductive path 50 and filling the holes with metallization paste, and printing a metallization paste to form the wiring portion of the second conductive path 50. The ceramic green sheet for the third layer 23 is subjected to a process such as drilling holes to form openings 23a, drilling holes to form vias and the like of the second conductive path 50 and filling the holes with metallization paste, and printing a metallization paste to form the first terminal 45, the second terminal 55, and the like.

[0045] These ceramic green sheets are then stacked and thermocompressed together, followed by cutting and other processing to obtain a ceramic green sheet laminate. The resulting laminate is fired to sinter the ceramic green sheets, thereby obtaining the main body 2 of the sensor 1. Finally, the electrode holes 31a, 31b, and 31c provided in the main body 2 are filled with electrode materials for the working electrode 6, counter electrode 8, and reference electrode 10, respectively, and dried at a temperature of 150°C to obtain the sensor 1. The electrode material for the working electrode 6 is the composite 13 described above.

[0046] For example, when detecting target molecules in a liquid sample, the liquid sample is placed on the bottom surface 41 of the storage section 4. The main body 2 of the sensor 1 is arranged so that the bottom surface 41 of the storage section 4 is approximately horizontal. The amount of the liquid sample is set, for example, so that the upper surface 6a of the working electrode 6, the upper surface 8a of the counter electrode 8, and the upper surface 10a of the reference electrode 10, which are arranged on the bottom surface 41, are all sufficiently covered with the liquid sample and so that the liquid sample does not overflow from the storage section 4.

[0047] A predetermined voltage is applied between the reference electrode 10 and working electrode 6 of the sensor 1 (i.e., a predetermined voltage is applied between the third terminal 65 and the first terminal 45). In this state, when a liquid sample is supplied into the container 4, a current corresponding to a predetermined amount of target molecules contained in the liquid sample flows between the working electrode 6 and the counter electrode 8 (i.e., between the first terminal 45 and the second terminal 55). By detecting this current, the target molecules in the liquid sample can be detected.

[0048] 2. Effects of Sensor 1 The sensor 1 of the present disclosure has sufficient sensitivity and high selectivity for the target molecules. The reason for this is presumed to be as follows. In the above-described composite 13, a large number of oxide semiconductor particles are supported on carbon nanotubes with a large specific surface area, and it is believed that a structure exists in which holes 9 complementary to the target molecules in the molecular template layer 11 overlap with the oxide semiconductor particles 7. With this structure, only the target molecules can selectively pass through the holes 9 in the molecular template layer 11, and the passing target molecules can come into contact with the catalyst of the oxide semiconductor particles 7 on the carbon nanotubes 5. It is therefore presumed that the sensor 1 has high sensitivity and high selectivity for the target molecules. [Example]

[0049] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples in any way.

[0050] Experimental Examples 1, 2, and 3 correspond to working examples, and Experimental Examples 4, 5, and 6 are reference examples. 1. Fabrication and evaluation of sensor 1 (1) Experimental Example 1 Particles (oxide semiconductor particles 7) in which Pd was supported on cobalt oxide were prepared. The above-mentioned particles (oxide semiconductor particles 7) were supported on carbon nanotubes 5. A molecular template layer 11 was formed thereon. Polypyrrole was used as the material for forming the molecular template layer 11. Geosmin was used as the template material (molecules to be detected). A film was formed using a mixture of polypyrrole and geosmin. After the film formation, the geosmin was removed using ethanol, and the molecular template layer 11 (molecular template film) was formed. In this way, a composite 13 was produced. This composite 13 was used as the electrode material for the working electrode 6. The sensor 1 was composed of three electrodes: a reference electrode 10, and a counter electrode 8 in addition to the working electrode 6 (see FIG. 2). The mass ratio of the carbon nanotubes 5 to the cobalt oxide (oxide semiconductor fine particles 7) was 1:1. Geosmin in water was measured using the sensor 1 thus fabricated, with concentrations ranging from 0 μg / L to 5 μg / L.

[0051] Here, a verification method using sensor 1 of Experimental Example 1 will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram that schematically illustrates the verification method using sensor 1 of Experimental Example 1. As shown in FIG. 4, an electrochemical analysis device 100 (potentiostat) was prepared that was electrically connected to sensor 1. This electrochemical analysis device 100 includes a voltage application unit 110 and a current detection unit 120. The voltage application unit 110 applies a predetermined voltage between the reference electrode 10 and working electrode 6 of sensor 1 (between the third terminal 65 and the first terminal 45). The current detection unit 120 detects the value of the current flowing between the working electrode 6 and the counter electrode 8 (the value of the current flowing between the first terminal 45 and the second terminal 55) while the voltage is applied.

[0052] (2) Experimental Example 2 The evaluation was carried out in the same manner as in Experimental Example 1, except that the mass ratio of carbon nanotubes 5 to cobalt oxide was set to 5:1. (3) Experimental Example 3 The evaluation was carried out in the same manner as in Experimental Example 1, except that the mass ratio of carbon nanotubes 5 to cobalt oxide was set to 10:1. (4) Experimental Example 4 The evaluation was carried out in the same manner as in Experimental Example 1, except that the mass ratio of carbon nanotubes 5 to cobalt oxide was 1:1 and no molecular template layer 11 was formed. (5) Experimental Example 5 The evaluation was carried out in the same manner as in Experimental Example 1, except that the mass ratio of carbon nanotubes 5 to cobalt oxide was set to 5:1 and no molecular template layer 11 was formed. (6) Experimental Example 6 The weight ratio of carbon nanotubes 5 to cobalt oxide was set to 10:1, and evaluation was carried out in the same manner as in Experimental Example 1, except that molecular template layer 11 was not formed. (7) Comparative Example 1 The evaluation was carried out in the same manner as in Experimental Example 1, except that the composite 13 was not used and only the carbon nanotubes 5 were used.

[0053] 2. Evaluation Results Figure 5 shows the evaluation results of output versus geosmin concentration. Experimental Example 1, which had the molecular template layer 11, as well as Experimental Example 4, which did not have the molecular template layer 11, had a significantly higher output than sensor 1 of Comparative Example 1, which used only carbon nanotubes 5. Experimental Example 2, which had the molecular template layer 11, as well as Experimental Example 5, which did not have the molecular template layer 11, had a significantly higher output than sensor 1 of Comparative Example 1, which used only carbon nanotubes 5. Experimental Example 3, which included the molecular template layer 11, had a significantly higher output than sensor 1 of Comparative Example 1, which used only carbon nanotubes 5, as did Experimental Example 6, which did not include the molecular template layer 11. As described above, compared to the sensor 1 of Comparative Example 1, which used only carbon nanotubes 5, the sensors 1 of Experimental Examples 1 to 3 (Examples) all had significantly higher outputs and higher sensitivities.

[0054] The following experiment was conducted to evaluate selectivity to geosmin. In this experiment, the sensitivity (S) at 1 μg / L of geosmin and the sensitivity (N) at 1 μg / L of quinoclamine, a substance that interferes with the detection of geosmin, were determined using sensors 1 of Comparative Example 1, Experimental Example 4, and Experimental Example 1. The S / N ratio was then calculated. The higher the S / N value, the higher the selectivity can be evaluated. S: Sensitivity of geosmin 1 μg / L N: Sensitivity of quinoclamine 1 μg / L 6 shows the S / N ratios of Comparative Example 1, Experimental Example 4, and Experimental Example 1. For each measurement of the S / N ratio, the number n (number of samples) was set to 2. It was found that the sensor 1 of Comparative Example 1, which used only carbon nanotubes 5, had a low S / N ratio and had no selectivity for geosmin. It was found that the sensor 1 of Experimental Example 4, which did not have the molecular template layer 11, had a low S / N ratio and low selectivity for geosmin. It was found that the sensor 1 of Experimental Example 1, which was provided with the molecular template layer 11, had a high S / N ratio and high selectivity for geosmin.

[0055] 3. Effects of the Example The sensor 1 of this embodiment has sufficient sensitivity and high selectivity for the molecules to be detected.

[0056] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible. [Explanation of symbols]

[0057] 1...Sensor 1a...Top surface 2...Main body 4. Storage area 5...carbon nanotubes 6...Working electrode 6a...Top surface 7. Oxide semiconductor particles 8...opposite 8a...Top surface 9...hole 10...Reference pole 10a...Top surface 11...Molecular template layer 13... Complex 21...1st layer 22…Second layer 23...Third layer 23a...opening 31a...electrode hole 31b...electrode hole 31c...electrode hole 40...First conductive path 41...bottom 42...wall 45...1st terminal section 50...Second conductive path 55...Second terminal section 60...Third conductive path 65...Third terminal section 100...Electrochemical analysis equipment 110...Voltage application section 120...Current detection section

Claims

1. A sensor having at least a working electrode, The working electrode has Carbon nanotubes and oxide semiconductor particles carrying a catalyst; a molecular template layer having pores that selectively transmit target molecules; The composite sensor comprises the oxide semiconductor particles carried on the surface of the carbon nanotube, and the molecular template layer further provided thereon.

2. In the carbon nanotube, a portion where the oxide semiconductor fine particles exist overlaps with a portion where the hole in the molecular template layer exists; 2. The sensor according to claim 1, wherein the detection target molecules that selectively pass through the pores of the molecular template layer are capable of contacting the oxide semiconductor particles on the carbon nanotubes.

3. 3. The sensor according to claim 1, wherein the molecular template layer contains a conductive polymer.

Images