WO2020166520A1 - Electrical measurement-type surface plasmon resonance sensor, electrical measurement-type surface plasmon resonance sensor chip, and surface plasmon polariton change detection method - Google Patents

Abstract

Provided is an electrical measurement-type surface plasmon resonance sensor provided with: a sensor chip in which a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are disposed in this order; a plasmon polariton enhanced sensor chip in which a prism is disposed in the order of the prism, the transparent electrode, the n-type transparent semiconductor film, the plasmon resonance film electrode, and the reflection resonance film; and an electrical measurement device which directly measures a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode.

Description

Electric measurement type surface plasmon resonance sensor, electric measurement type surface plasmon resonance sensor chip, and surface plasmon polariton change detection method

The present invention relates to an electrical measurement type surface plasmon resonance sensor, an electrical measurement type surface plasmon resonance sensor chip, and a surface plasmon polariton change detection method, and more specifically, an electrical measurement type surface plasmon resonance sensor and an electrical measurement type surface plasmon resonance used therefor. The present invention relates to a sensor chip and a surface plasmon polariton change detection method using the same.

Surface plasmon resonance (SPR: Surface Plasmon Resonance) is a state in which free electrons are causing collective vibrational motion (plasma vibration) on the surface of a metal. Propagation type surface plasmon resonance (PSPR: Propagating) propagating on a metal surface. Surface Plasmon Resonance) and localized surface plasmon resonance (LSPR: Localized Surface Plasmon Resonance). Propagation type surface plasmon resonance is a state in which resonance occurs due to interaction between an electric field generated around plasma-oscillating free electrons and incident light, and the plasma oscillation and electromagnetic waves traveling along the interface are coupled. Electron compression waves (surface plasmon polaritons, SPP: Surface Plasmon Polaritons) propagate along the metal surface. On the other hand, the localized surface plasmon resonance is a state in which the metal nanostructure such as the metal nanoparticles is polarized/induced by the plasma vibration and electric dipoles are generated.

The surface plasmon resonance is used for a sensor such as an affinity sensor that detects the presence or absence of adsorption of a target substance and the strength of the interaction, and is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2011-141265 (Patent Document 1). There is described a sensor chip including a base material having a portion and a diffraction grating that is formed on the flat portion and has a surface formed of a metal and that includes a specific protrusion on which a target substance is arranged. However, in the sensor chip as described in Patent Document 1, the device becomes expensive because it is necessary to detect the change in the surface plasmon resonance angle due to the change in the concentration of the target substance existing on the metal surface with the optical system. There is a problem that there is a tendency to increase the size and that it is difficult to integrate and to increase the throughput for processing a large number of samples at the same time.

Further, Japanese Patent Application Laid-Open No. 2000-356587 (Patent Document 2) includes a substrate and metal fine particles fixed on the surface of the substrate as a single film separated from each other without being aggregated. A localized plasmon resonance sensor having a sensor unit is described. However, in the localized plasmon resonance sensor described in Patent Document 2, the change in the refractive index of the medium in the vicinity of the surface of the metal fine particles due to the adsorption or deposition of the target substance on the metal fine particles is measured by measuring the absorbance of light transmitted between the metal fine particles. Since it is detected by measuring, it is necessary to strictly control the size and arrangement of the metal fine particles, and it is difficult to sufficiently enhance the intensity of the detection signal because it is the absorbance, which is a problem. Was there.

Surface plasmon resonance is also used to improve photoelectric conversion efficiency in a photoelectric conversion element. For example, JP 2012-38541 A (Patent Document 3) discloses a transparent substrate, a transparent electrode layer, Plasmon resonance photoelectric conversion provided with an anode electrode in which a metal fine particle layer, a semiconductor thin film made of an n-type semiconductor, and an adsorption layer of a dye are sequentially laminated, and a cathode electrode arranged on the anode electrode via an electrolyte containing a redox species. The elements are described.

Further, the applicant of the present application has found that a sensor chip in which a transparent electrode, an n-type transparent semiconductor film, and a plasmon resonance film electrode are arranged in this order, a plasmon polariton enhanced sensor chip in which a prism is arranged, the transparent electrode, and An international application was filed on August 9, 2018 (PCT/JP2018/29979) for an electric measurement type surface plasmon resonance sensor provided with an electric measuring device for directly measuring a current value or a voltage value from the plasmon resonance membrane electrode. According to such an electric measurement type surface plasmon resonance sensor, downsizing and high throughput can be easily achieved, and an electric measurement type surface plasmon resonance sensor chip having sufficient sensor accuracy and an electric measurement type surface plasmon resonance sensor chip used therefor can be provided. It becomes possible to provide.

JP, 2011-141265, A JP, 2000-356587, A JP 2012-38541 A

However, when the photoelectric conversion element as described in Patent Document 3 is applied to a sensor, the present inventors need to control metal fine particles, and it is difficult to improve the sensor sensitivity. In addition, it has been found that there is a problem in that the sample itself, which is the measurement target, is redox-reduced due to the oxidation/reduction reaction of the electrolyte, which affects the accuracy of the sensor.

Furthermore, as a result of further studies by the present inventors, in the electric measurement type surface plasmon resonance sensor chip including the plasmon polariton enhanced sensor chip and the electric measurement device, a higher level of sensitivity may be required. I found a thing.

The present invention has been made in view of the above problems of the prior art, is easy to miniaturize and high throughput, and an electric measurement type surface plasmon resonance sensor having sufficient sensor sensitivity and an electric measurement used therefor. (EN) Provided are a surface plasmon resonance sensor chip and a surface plasmon polariton change detection method using the same.

As a result of intensive studies to achieve the above object, the present inventors have combined a prism, a transparent electrode, an n-type transparent semiconductor film, and a plasmon resonance film electrode in a chip, and further combined a reflection resonance film in this order. The arriving light is converted into surface plasmon polaritons propagating through the plasmon resonance film electrode by arriving at the plasmon resonance film electrode with incident light incident from the prism side at an incident angle within a specific range. It was found that this can be directly detected as an electric signal from the transparent electrode and the plasmon resonance film electrode. Further, the magnitude of the detected electric signal changes with high accuracy in accordance with the refractive index of the sample in the vicinity of the plasmon resonance film electrode, and by combining the reflection resonance film, the sensor sensitivity is further improved. Has been achieved. Furthermore, since the refractive index of the sample corresponds to the concentration and state of the sample, the chip having the above configuration is used as a sensor chip capable of measuring the concentration change and state change of the sample by detecting the surface plasmon polariton change. It has been found that this is possible, and the present invention has been completed.

That is, the electrical measurement type surface plasmon resonance sensor of the present invention,
A sensor chip in which a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are arranged in this order, and a prism are the prism, the transparent electrode, the n-type transparent semiconductor film, and the plasmon. A resonance membrane electrode, and a plasmon polariton enhanced sensor chip arranged in the order of the reflection resonance membrane;
An electrical measuring device for directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
It is characterized by including.

Further, the electric measurement type surface plasmon resonance sensor of the present invention is
Plasmon resonance membrane electrode capable of converting incident light into surface plasmon polaritons,
The plasmon resonance film electrode is disposed on the incident light side, transmits the incident light, and the transmitted incident light is emitted from the plasmon resonance film electrode by interacting with the plasmon resonance film electrode. N-type transparent semiconductor film capable of receiving hot electrons,
A reflection resonance film, which is disposed on the opposite side of the plasmon resonance film electrode from the n-type transparent semiconductor film and is capable of internally resonating an electric field change due to surface plasmon resonance generated by the plasmon resonance film electrode;
as well as,
A transparent electrode capable of taking out hot electrons transferred from the n-type transparent semiconductor film as an electric signal,
A sensor chip including
A prism capable of controlling the angle of the incident light so that the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film;
And a plasmon polariton enhanced sensor chip including:
An electrical measuring device capable of directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
It is characterized by including.

As a preferred mode of the above electric measurement type surface plasmon resonance sensor, in the sensor chip, the thickness of the reflection resonance film is expressed by the following formula (1):
│Δθ│≦2°・・・(1)
[In the formula (1), Δθ is a current value measured by making light incident on the sensor chip within a range in which the incident angle (θ) with respect to the surface of the sensor chip in contact with the prism is 0 to 90°. At this time, within the range of ±25° of the incident angle (θ _cp ) when the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film, the current with respect to the energy of the incident light is Angle _obtained by subtracting the incident angle (θ _CAmin ) at which the output current ratio is the minimum value (CA _min ) from the incident angle (θ _CAmax ) at which the output current ratio (CA) that is the ratio of the values is at the maximum value (CA _max ). Indicates the amount of change. ]
It is preferable that the thickness satisfies the condition shown by.

Further, as a preferable mode of the electric measurement type surface plasmon resonance sensor, in the sensor chip, a combination of the n-type transparent semiconductor film and the plasmon resonance film electrode is a combination that forms a Schottky barrier. Is preferred.

Further, as a preferable mode of the electric measurement type surface plasmon resonance sensor, in the sensor chip, the thickness of the plasmon resonance membrane electrode is preferably 200 nm or less (however, not including 0), and In the sensor chip, it is also preferable that the reflection resonance film is a film made of at least one selected from the group consisting of metal oxides, semiconductors, and organic substances.

Further, as a preferable mode of the electric measurement type surface plasmon resonance sensor, in the sensor chip, the n-type transparent semiconductor film is TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , Fe ₂ O ₃ , TaON, WO. ₃ and In ₂ O ₃ is preferably a film made of at least one n-type semiconductor selected from the group consisting of.

Furthermore, as a preferred form of the electric measurement type surface plasmon resonance sensor, it is preferable that the sensor chip further comprises a molecular bonding film on the side opposite to the plasmon resonance film of the reflection resonance film, and It is also preferable that the sensor chip further includes an oxide film between the plasmon resonance film electrode and the reflection resonance film.

The electric measurement type surface plasmon resonance sensor chip of the present invention is a sensor chip used in the above-mentioned electric measurement type surface plasmon resonance sensor, and includes a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film. It is characterized in that they are arranged in this order.

In the surface plasmon polariton change detection method of the present invention, a sensor chip in which a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are arranged in this order, a prism, the prism, the transparent A plasmon polariton enhanced sensor chip in which an electrode, the n-type transparent semiconductor film, the plasmon resonance film electrode, and the reflection resonance film are arranged in this order;
An electrical measuring device for directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
A method for detecting a change in surface plasmon polaritons using an electric measurement type surface plasmon resonance sensor having
Irradiating light from the prism side, and totally reflecting the light passing through the prism, the transparent electrode, and the n-type transparent semiconductor film between the plasmon resonance film electrode and the n-type transparent semiconductor film. And interact with the plasmon resonance membrane electrode to generate surface plasmon polaritons,
Hot electrons generated by the surface plasmon polaritons and transferred to the n-type transparent semiconductor film are taken out from the transparent electrode as an electric signal,
Detecting a change in surface plasmon polaritons by measuring a change in current value or voltage value between the transparent electrode and the plasmon resonance film electrode by the electrical measuring device,
It is a method characterized by that.

The reason why the above object is achieved by the configuration of the present invention is not always clear, but the present inventors speculate as follows. That is, the electric measurement type surface plasmon resonance sensor chip of the present invention (hereinafter, simply referred to as “sensor chip” in some cases) and the electric measurement type surface plasmon resonance sensor using the prism and the prism in combination (hereinafter, sometimes, simply (Hereinafter referred to as “sensor”), when the plasmon resonance film electrode is irradiated with light from the prism side and the light passing through the prism is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film, Energy bleeding (evanescent wave) occurs on the back side of the reflected surface. Therefore, when the incident angle of light with respect to the interface is a critical angle (hereinafter, referred to as “total reflection angle”) or more, the evanescent wave generated at the place of total reflection interacts with the plasmon resonance film in contact with the back side. Then, the above surface plasmon polaritons are excited. At this time, since the incident angle of the incident light can be controlled by the prism so as to be the above-mentioned angle of total reflection, the generated surface plasmon polaritons are sufficiently enhanced.

Then, the surface plasmon polaritons sufficiently polarize the plasmon resonance film electrode to release hot electrons and form hot holes. The released hot electrons form the Schottky barrier with the plasmon resonance film electrode. It is possible to smoothly move to the opposite transparent electrode via the n-type transparent semiconductor film. Therefore, in the sensor chip of the present invention and the sensor using the same and the prism, the present inventors can sufficiently detect the surface plasmon polariton from the plasmon resonance film electrode and the transparent electrode as an electric signal. Guess.

Further, in the sensor chip of the present invention and the sensor using the sensor chip and the prism, a reflection resonance film is further provided so that the electric field change inside the reflection resonance film is caused by the surface plasmon resonance generated by the plasmon resonance film electrode. The induced electric field change is propagated and reflected at the interface of the reflection resonance film on the side opposite to the plasmon resonance film electrode, so that resonance of the electric field change occurs inside the reflection resonance film. The present inventors infer that this causes the generated surface plasmon resonance to be amplified and the electric signal (current) extracted from the transparent electrode to become more sensitive.

Further, in the sensor chip of the present invention and the sensor using the prism in combination with the sensor chip, the change in the refractive index in the vicinity of the plasmon resonance film electrode causes the above-mentioned total reflection, that is, the incident that causes the surface plasmon polaritons. The range of the angle (incident angle of light incident from the prism side) and the strength of the generated surface plasmon polaritons are changed. Furthermore, since the electric field generated in the plasmon resonance film electrode by the incidence of light is enhanced by the surface plasmon polaritons, the amount of current that changes according to the change in the electric field changes depending on the strength of the surface plasmon polaritons. Therefore, the present inventors presume that the change in the refractive index of the sample near the plasmon resonance film electrode can be measured with sufficient accuracy. Therefore, according to the sensor chip of the present invention and the sensor using this and the prism, by detecting the change of the surface plasmon polariton, it is possible to monitor the concentration change and the state change of the sample with high accuracy, and The present inventors presume that since the detection signal is an electric signal, the intensity thereof can be electrically increased easily and can be easily measured as a current.

According to the present invention, it is possible to provide an electric measurement type surface plasmon resonance sensor which is easy to be miniaturized and has high throughput and has sufficient sensor sensitivity, and an electric measurement type surface plasmon resonance sensor chip used therefor. Become.

1 is a schematic vertical sectional view showing a preferred embodiment 1 of a plasmon polariton enhanced sensor chip. 1 is a schematic vertical sectional view showing a preferred first embodiment of an electric measurement type surface plasmon resonance sensor. 6 is a graph showing a relationship between an incident angle and an output current ratio when light is incident on a sensor chip and a current value is measured. It is a schematic diagram which shows the incident angle ((theta) degree) of the light which injects from the prism side. It is a schematic longitudinal cross-sectional view showing a second preferred embodiment of the plasmon polariton enhanced sensor chip. It is a schematic longitudinal cross-sectional view showing a preferred embodiment 3 of the plasmon polariton enhanced sensor chip. It is a schematic longitudinal cross-sectional view showing a preferred embodiment 4 of the plasmon polariton enhanced sensor chip. It is a schematic longitudinal cross-sectional view showing a preferred embodiment 5 of the plasmon polariton enhanced sensor chip. It is a schematic longitudinal cross-sectional view showing a preferred embodiment 6 of the plasmon polariton enhanced sensor chip. It is a schematic diagram which shows the electric current value measuring method of Test Example 1 and Test Example 2. 5 is a graph showing the results of measuring each sample solution using the chip with prism obtained in Comparative Example 1. 3 is a graph showing the results of measuring each sample solution using the chip with prism obtained in Example 1. 5 is a graph showing the results of measuring each sample solution using the chip with prism obtained in Example 2. 5 is a graph showing the results of measuring each sample solution using the chip with prism obtained in Example 3. 7 is a graph showing the relationship between the refractive index of each sample solution and the normalized current value when each sample solution was measured using the chips with prisms obtained in Comparative Example 1 and Examples 1 and 2. 9 is a graph showing the relationship between the incident angle of light, the current value, and the output current ratio in the chip with prism and chip 1 obtained in Comparative Example 1. 6 is a graph showing the relationship between the thickness of the reflection resonance film, the absolute value of the angle change amount, and the sensitivity in the chip 2. 9 is a graph showing the relationship between the thickness of the reflection resonance film, the absolute value of the angle change amount, and the sensitivity in the chip 3. 6 is a graph showing the relationship between the thickness of the reflection resonance film, the absolute value of the angle change amount, and the sensitivity in the chip 4.

Hereinafter, the present invention will be described in detail with reference to its preferred embodiments. The electric measurement type surface plasmon resonance sensor of the present invention is
A sensor chip in which a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are arranged in this order, and a prism are the prism, the transparent electrode, the n-type transparent semiconductor film, and the plasmon. A resonance membrane electrode, and a plasmon polariton enhanced sensor chip arranged in the order of the reflection resonance membrane;
An electrical measuring device for directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
It is equipped with.

Further, the electrical measurement type surface plasmon resonance sensor of the present invention,
Plasmon resonance film electrode capable of converting incident light into surface plasmon polaritons,
The plasmon resonance film electrode is disposed on the incident light side, transmits the incident light, and the transmitted incident light is emitted from the plasmon resonance film electrode by interacting with the plasmon resonance film electrode. N-type transparent semiconductor film capable of receiving hot electrons,
A reflection resonance film, which is arranged on the opposite side of the plasmon resonance film electrode from the n-type transparent semiconductor film and is capable of internally resonating an electric field change due to surface plasmon resonance generated by the plasmon resonance film electrode;
as well as,
A transparent electrode capable of taking out hot electrons transferred from the n-type transparent semiconductor film as an electric signal,
A sensor chip including
A prism capable of controlling the angle of the incident light so that the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film;
And a plasmon polariton enhanced sensor chip including:
An electrical measuring device capable of directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
It is also equipped with.

Further, the electric measurement type surface plasmon resonance sensor chip of the present invention is a sensor chip used in the electric measurement type surface plasmon resonance sensor of the present invention, and includes a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and The reflection resonance film is arranged in this order.

Hereinafter, with reference to the drawings, an electric measurement type surface plasmon resonance sensor (hereinafter, "sensor"), a plasmon polariton enhanced sensor chip (hereinafter, "enhanced sensor chip"), and an electrical measurement type surface plasmon resonance sensor chip (hereinafter, " A more specific description will be given by taking a preferred form of the "sensor chip") as an example, but the present invention is not limited thereto. In the following description and drawings, the same or corresponding elements will be denoted by the same reference symbols, without redundant description.

FIG. 1A shows a first preferred form of the enhanced sensor chip (preferred embodiment 1; enhanced sensor chip 110). As shown in FIG. 1A, in the preferred embodiment 1, the enhancement sensor chip 110 includes a transparent electrode (hereinafter, “transparent electrode 2”), an n-type transparent semiconductor film (, on a prism (hereinafter, “prism 1”). Hereinafter, a sensor chip (photoelectric conversion unit) including a "n-type transparent semiconductor film 3"), a plasmon resonance film electrode (hereinafter, "plasmon resonance film electrode 4"), and a reflection resonance film (hereinafter, "reflection resonance film 5") In the preferred embodiment 1, the sensor chip 11) is laminated so that the prism 1, the transparent electrode 2, the n-type transparent semiconductor film 3, the plasmon resonance film electrode 4, and the reflection resonance film 5 are laminated in this order.

Further, FIG. 1B shows a first preferable form of the sensor (preferred embodiment 1; sensor 510). As shown in FIG. 1B, in the preferred embodiment 1, a sensor 510 includes an enhanced sensor chip 110 including a prism 1 and a sensor chip 11, a transparent electrode 2 and a plasmon resonance film electrode 4 of the sensor chip 11 and an external circuit (external). An electrical measuring device (electrical measuring device 21) electrically connected through the circuits 31 and 31').

(prism)
The prism 1 has a function of totally reflecting incident light between the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4. That is, in the embodiment of the present disclosure, the prism 1 controls the angle of incident light so that the total reflection condition between the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4 is satisfied. The incident light whose angle is controlled by the prism 1 is totally reflected between the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4, that is, at the interface between the plasmon resonance film electrode 4 and the n-type transparent semiconductor film 3. To do. When the following adhesive layer is further provided, the incident light whose angle is controlled by the prism 1 is an interface between the plasmon resonance film electrode 4 and the adhesive layer or an interface between the adhesive layer and the n-type transparent semiconductor film 3. Is totally reflected at. Further, when the following adhesive layer is composed of two or more layers, the incident light whose angle is controlled by the prism 1 is the interface between the plasmon resonance film electrode 4 and the adhesive layer, or the adhesive layer and the n-type transparent semiconductor film 3. Total reflection occurs at the interface with or, or the interface between two adjacent layers.

As the prism 1, a triangular prism in the shape of a triangular prism (a right-angle prism (a right-angled isosceles triangle having an angle of 45°, a right-angled triangle having angles of 60° and 30°), an equilateral triangular prism, etc.); a trapezoidal prism shape Trapezoidal prism; a cylindrical prism in which one side surface of a cylinder is flat (the length (side) between the plane (rectangle) and the top and bottom of the cylinder is shorter than the diameter of the circle of the top and bottom) A spherical prism in which one side surface of the sphere is in the shape of a plane (the diameter of the plane (circle) may be smaller than the diameter of the sphere); and a pentagonal prism in the shape of a pentagon. To be Among these, as the prism 1, from the viewpoint that the incident light entering the prism tends to reach the plasmon resonance film electrode 4 more efficiently, in addition to the triangular prism as shown in FIG. A prism or a spherical prism, preferably a right-angled prism; a semi-cylindrical prism whose short side length is equal to the diameter of the circles of the top and bottom surfaces; or a hemisphere where the diameter of the plane circle is equal to the diameter of the sphere More preferably, it is a prism.

As a sensor, one prism 1 may be arranged for one sensor chip (photoelectric conversion unit), or two or more prisms 1 may be arranged in an array, or two or more prisms may be arranged. One prism 1 may be arranged for a plurality of photoelectric conversion units.

The size of the prism 1 is not particularly limited, and is the longest side when the surface in contact with the sensor chip is a polygon, or otherwise the diameter of the circumscribed circle of the surface in contact with the sensor chip. Is preferably 10 nm to 10 cm, more preferably 50 nm to 5 cm, and even more preferably 100 nm to 3 cm. It should be noted that nanometer- to micrometer-sized prisms can be molded using patterning techniques such as laser ablation, electron beam lithography, nanoimprint lithography, and optical interference lithography. It can be obtained by performing optical polishing after cutting. If the size of the prism 1 is less than the lower limit, the manufacturing difficulty increases and the performance as a prism decreases, so that the performance as a sensor tends to decrease. On the other hand, if the size exceeds the upper limit, the prism 1 becomes a sensor. It tends to be difficult to downsize.

When the prism 1 is a triangular prism, as shown in FIG. 1A, the transparent electrode 2, the n-type transparent semiconductor film 3, the plasmon resonance film electrode 4, and the reflection resonance film 5 are arranged on the side surface of the triangular prism. It is preferable that the light is incident on the surface other than the side surface. When the prism 1 is a trapezoidal prism, the transparent electrode 2, the n-type transparent semiconductor film 3, and the plasmon resonance film are formed on the surface of the trapezoidal pillar that forms the lower base of the trapezoid (lower bottom surface). It is preferable that the electrode 4 and the reflection resonance film 5 are arranged, and that light is incident from the surface forming the hypotenuse of the trapezoid.

As for the triangular prism and the trapezoidal prism, the angle formed by the surface of each prism on which the incident light enters and the surface in contact with the sensor chip (the sensor chip 11 in the preferred embodiment 1) is 5 to 85°. Is more preferable, 15 to 75° is more preferable, and 25 to 65° is still more preferable.

Further, when the prism 1 is a cylindrical prism or a spherical prism, the transparent electrode 2, the n-type transparent semiconductor film 3, the plasmon resonance film electrode 4, and the reflection resonance film 5 are arranged on the planes of the prisms. Preferably, the light is incident on the curved surface.

As the cylindrical prism, when the diameter of the cylinder is 1, when the plane is the bottom surface, the intersection of the arc from the center of the bottom surface at the intersection of a straight line extending in the vertical direction from the center of the bottom surface and the arc. The ratio of the distance (hereinafter referred to as “prism height”) to the diameter of the cylinder (prism height/cylinder diameter) is preferably less than 1 (not including 0), and is 0.2 or more. It is more preferably less than 0.8, and further preferably 0.4 or more and less than 0.6.

As the spherical prism, when the diameter of the sphere is 1, when the plane is the bottom surface, the ratio of the height from the center of the bottom surface (hereinafter, referred to as “prism height”) to the diameter of the sphere. The (prism height/sphere diameter) is preferably less than 1 (not including 0), more preferably 0.2 or more and less than 0.8, and 0.4 or more and less than 0.6. Is more preferable.

In the triangular prism, the cylindrical prism, and the spherical prism, when the angle or the prism height is less than the lower limit or exceeds the upper limit, light can be incident at an incident light angle that can excite surface plasmon polaritons. There is a tendency that it becomes difficult and that the sensitivity and accuracy of the sensor decrease due to the light being reflected multiple times inside the prism.

When the prism 1 is a pentaprism, the transparent electrode 2, the n-type transparent semiconductor film 3, the plasmon resonance film electrode 4, and the reflection resonance film 5 are provided on one of the side surfaces of the pentagonal prism. It is preferable that the light beams are arranged and light is incident from any one of the remaining four faces.

The material of the prism 1 is not particularly limited and includes, for example, glass, polymer (polymethylmethacrylate, polystyrene, polyethylene, epoxy, polyester, etc.), sulfur, ruby, sapphire, diamond, zinc selenide (ZnSe), Zinc sulfide (ZnS), germanium (Ge), silicon (Si), cesium iodide (CsI), potassium bromide (KBr), thallium bromoiodide, calcium carbonate (CaCO ₃ ), barium fluoride (BaF ₂ ), Examples thereof include magnesium fluoride (MgF ₂ ) and lithium fluoride (LiF). The material of the prism 1 may be liquid, water, oil, glycerol, diiodomethane, α-bromonaphthalene, toluene, isooctane, cyclohexane, 2,4-dichlorotoluene, ethylbenzene, dibenzyl ether, aniline, Examples thereof include styrene, an organic compound solution (sucrose solution, etc.), and an inorganic compound solution (potassium chloride solution, sulfur-containing solution), and one of these may be used alone or two or more thereof may be used in combination. ..

A light source for incident light may be disposed inside the prism 1 regardless of the shape and material of the prism 1.

(Transparent electrode)
The transparent electrode 2 has a function of taking out hot electrons (electrons), which are emitted along with the surface plasmon polaritons generated in the plasmon resonance film electrode 4 and have moved in the n-type transparent semiconductor film 3 as an electric signal, It functions as a counter electrode of the resonance membrane electrode 4, and the plasmon resonance membrane electrode 4, the electrical measuring device (the electrical measuring device 21 in the preferred embodiment 1) and, if necessary, an external circuit (lead wire, ammeter, etc.); In the first embodiment, they are electrically connected via the external circuits 31 and 31'). Moreover, the transparent electrode 2 needs to be able to transmit light. In the present invention, the phrase “a film, an electrode, a layer, a substrate, and the like can transmit light” means that at least one of wavelengths of 400 to 1500 nm with respect to one surface of the film, the electrode, the layer, the substrate, or the like. It means that the light transmittance when light of a wavelength is vertically incident is 40% or more, and the light transmittance is preferably 50% or more, more preferably 60% or more.

The material of the transparent electrode 2 can be appropriately selected and used from materials conventionally used as transparent electrodes in the semiconductor field, and examples thereof include copper (Cu), gold (Au), silver (Ag), and platinum. (Pt), zinc (Zn), chromium (Cr), aluminum (Al), titanium (Ti), titanium nitride (TiN), ITO (Indium tin oxide), FTO (Fluorine-doped tin oxide), and other elements ( Examples thereof include transparent conductive materials such as metal oxides such as ZnO doped with aluminum and gallium), and thin films and net-like shapes made of a laminate of these materials. Further, examples of the material of the transparent electrode 2 include an n-type semiconductor forming the following n-type transparent semiconductor film. In the sensor chip, the transparent electrode 2 and the n-type transparent semiconductor film 3 are made of the same material. It may be a layer. In this case, the n-type transparent semiconductor film 3 also serves as the transparent electrode 2.

The thickness of the transparent electrode 2 (excluding the case where the n-type transparent semiconductor film 3 also serves as the transparent electrode 2) is usually 1 to 1000 nm.

In the present invention, the thickness and boundaries of films, electrodes, layers, substrates, etc. are measured and confirmed by observation with a scanning electron microscope (SEM) or transmission electron microscope (TEM), Rutherford backscattering analysis (RBS). can do.

(N-type transparent semiconductor film)
The n-type transparent semiconductor film 3 has a function of receiving hot electrons emitted when the plasmon resonance film electrode 4 is sufficiently polarized by the surface plasmon resonance film polariton excited by the plasmon resonance film electrode 4. The film is a semiconductor film. The n-type transparent semiconductor film 3 needs to be able to transmit light.

Examples of the n-type semiconductor include an inorganic oxide semiconductor, and one of these may be a single material or a composite material of two or more materials. Examples of the inorganic oxide semiconductor include titanium dioxide (TiO ₂ ), zinc oxide (ZnO), tin dioxide (SnO ₂ ), gallium nitride (GaN), gallium oxide (GaO), strontium titanate oxide (SrTiO ₃ ), and oxide. Examples thereof include iron (Fe ₂ O ₃ ), tantalum oxynitride (TaON), tungsten oxide (WO ₃ ), indium oxide (In ₂ O ₃ ), and their composite oxides. Among them, the n-type semiconductor is composed of TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , Fe ₂ O ₃ , TaON, WO ₃ and In ₂ O ₃ from the viewpoint of high transparency and high conductivity. It is preferably at least one semiconductor selected from the group, and is at least one semiconductor selected from the group consisting of TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , Fe ₂ O ₃ and In ₂ O _3. Is more preferable.

The thickness of the n-type transparent semiconductor film 3 (including the case where the n-type transparent semiconductor film 3 also serves as the transparent electrode 2) is preferably 1 to 1000 nm, more preferably 5 to 500 nm, and more preferably 10 to More preferably, it is 300 nm. If the thickness is less than the lower limit, the n-type transparent semiconductor cannot exist as a film and tends to fail to function sufficiently as a semiconductor. On the other hand, when the amount exceeds the upper limit, the light transmittance tends to decrease, or the resistance tends to increase, which makes it difficult for current to flow.

(Plasmon resonance membrane electrode)
The plasmon resonance film electrode 4 has a function of converting incident light (incident light) into surface plasmon polaritons, and is a film made of a plasmonic material capable of generating surface plasmon polaritons by interaction with light. .. Further, it has a function of extracting the surface plasmon polariton as an electric signal, functions as a counter electrode of the transparent electrode 2, the transparent electrode 2, the electrical measuring device (the electrical measuring device 21 in the preferred embodiment 1), and If necessary, they are electrically connected via an external circuit (conductor, ammeter, etc.; in the preferred embodiment 1, the external circuits 31 and 31').

Examples of the plasmonic material include metals, metal nitrides, and metal oxides, and one of these may be a single material or a composite material of two or more materials. Above all, as the preferable plasmonic material, the metal is gold (Au), silver (Ag), aluminum (Al), copper (Cu), platinum (Pt), palladium (Pd), zinc (Zn). , And sodium (Na). The metal nitride is titanium nitride (TiN), and the metal oxide is ITO (Indium tin oxide), FTO (Fluorine-doped tin oxide), and other elements. Examples thereof include ZnO doped with (aluminum, gallium, etc.). Among them, the plasmonic material is preferably at least one selected from the group consisting of Au, Ag, Al, Cu, Pt, Pd, and TiN, and is composed of Au, Ag, Al, Cu, and Pt. More preferably, it is at least one selected from the group.

The thickness of the plasmon resonance film electrode 4 is preferably 200 nm or less (not including 0), more preferably 1 to 150 nm, further preferably 5 to 100 nm, and more preferably 10 to 60 nm. It is even more preferred to be present. When the thickness is less than the lower limit, the plasmon resonance film electrode tends to be unable to exist as a film, and when the thickness exceeds the upper limit, an evanescent wave reaching a surface opposite to a surface on which light is incident. Becomes weak, and sufficient surface plasmon polaritons cannot be excited. In addition, the thickness of the plasmon resonance film electrode 4 tends to allow a wider range of refractive indices (preferably 1.33 to 1.40) to be measured as the refractive index of the sample to be measured. Is particularly preferably 10 to 34 nm, and particularly preferably 35 to 60 nm from the viewpoint of increasing the rate of change of the current value with respect to the change of the refractive index.

(Reflection resonance film)
The reflection resonance film 5 has a function of internally resonating the electric field change due to the surface plasmon resonance generated by the plasmon resonance film electrode 4, and more specifically, by the surface plasmon resonance generated by the plasmon resonance film electrode 4. , An electric field change is caused inside, and the electric field change is propagated and reflected at the interface on the side opposite to the plasmon resonance film electrode 4, thereby causing resonance of the electric field change inside the reflection resonance film, Has a function of amplifying the generated surface plasmon resonance.

Examples of the material of the reflection resonance film 5 include metal oxides (for example, titanium dioxide (TiO ₂ ), iron oxide (II) (FeO), iron oxide (III) (Fe ₂ O ₃ ), and silicon dioxide (SiO ₂ ). ) Etc.), semiconductors other than the above metal oxides (for example, silicon (Si), germanium (Ge), and doped materials thereof), organic substances (for example, polyethylene (PE), dimethylpolysiloxane (PDMS), polymethacryl). Examples thereof include synthetic resins such as methyl acidate (PMMA, acrylic resin); polymer polymers such as cellulose and ethylene glycol, and one of these may be a single material or a composite material of two or more materials. .. Above all, from the viewpoint that the higher the refractive index of the reflection resonance film 5 is, the thinner the thickness tends to be, the material of the reflection resonance film 5 is a metal oxide such as TiO ₂ or SiO ₂ , and Si. It is preferably at least one selected from the group consisting of semiconductors such as, and more preferably at least one selected from the group consisting of metal oxides such as TiO ₂ and semiconductors such as Si.

The thickness of the reflection resonance film 5 is expressed by the following formula (1) from the viewpoint of achieving particularly sufficient improvement in sensor sensitivity:
│Δθ│≦2°・・・(1)
It is preferable that the thickness satisfies the condition shown by.

In the formula (1), Δθ is a value obtained when light is incident on the sensor chip within a range in which the incident angle (θ) with respect to the surface of the sensor chip in contact with the prism is 0 to 90°. In the range of ±25° of the incident angle (θ _cp ) when the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film, the current value with respect to the energy of the incident light is Change in angle _obtained by subtracting the incident angle (θ _CAmin ) at which the output current ratio becomes the minimum value (CA _min ) from the incident angle (θ _CAmax ) at which the output current ratio (CA), which is the ratio, becomes the maximum value (CA _max ). Indicates the amount.

For example, when light is incident on the sensor chip and the current value is measured within a range in which the incident angle (θ) with respect to the surface of the sensor chip in contact with the prism is 0 to 90°, FIG. As shown in FIG. 4, the change of the current value within the range of ±25° of the incident angle (θ _cp ) when the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film (Fig. In 2, the output current ratio (CA) is observed as a peak. At this time, the sharper the peak is, that is, the steeper the peak is, the higher the sensor sensitivity is, and the peak can be made sharper by providing the reflection resonance film.

As shown in FIG. 2, Δθ in the formula (1) is ±25 of an incident angle (θ _cp ) when the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film. Within the range of °, the output current ratio is the minimum value (CA) from the incident angle (θ _CAmax ) where the output current ratio (CA), which is the ratio of the current value to the energy of the incident light, is the maximum value (CA _max ). _min ), the incident angle (θ _CAmin ) can be reduced to obtain the angle change amount, and |Δθ| is an absolute value thereof. The value of |Δθ| is preferably 2° or less, more preferably 1.5° or less, and further preferably 1° or less, as in the above formula (1).

In the present invention, the sensor sensitivity, the output current ratio (CA) is the maximum value _{(CA max)} become incident angle (theta _CAmax) the output current ratio is the minimum value from the _{(CA min)} become incident angle (theta _Camin) Absolute value (|Δθ|[°]) of the above-mentioned amount of change in angle (Δθ), and a value (ΔI) obtained by subtracting the minimum value (CA _min ) from the maximum value (CA _max ) of the output current ratio. The absolute value (|ΔI|[%]) of each can be obtained and expressed as the ratio (|ΔI|/|Δθ|[%]). The larger the value of the sensor sensitivity (|ΔI|/|Δθ|[%]), the better the sensor sensitivity.

It should be noted that the light emitted from the prism 1 side goes straight (incident light 400) when, for example, as shown in FIG. As shown in (b), when the light is incident at an angle other than vertical, it is refracted by the prism 1 (incident light 400). Therefore, in the present invention, as shown in (a) and (b) of FIG. 3, the incident angle (θ°) of the light incident from the prism side is set to the photoelectric conversion unit (FIG. 3 is defined as the incident angle with respect to the surface of the sensor chip 16) which is in contact with the prism 1. The same applies when the light source of the incident light is inside the prism.

(Oxide film)
FIG. 4 shows a second preferred form of the enhanced sensor chip (preferred embodiment 2). The sensor chip constituting the enhanced sensor chip may further include another layer as long as the effect of the present invention is not impaired. For example, the reflection resonance film 5 may be a semiconductor or organic substance other than the metal oxide. In the case where the reflection resonance film 5 is formed of the sensor chip (photoelectric conversion unit) 12 shown in FIG. 4, the reflection resonance film 5 is directly laminated on the plasmon resonance film electrode 4 between the plasmon resonance film electrode 4 and the reflection resonance film 5. The oxide film 6 may be further provided mainly for the purpose of preventing a decrease in current value caused by the above (enhanced sensor chip 120).

Examples of the material of the oxide film 6 include titanium dioxide (TiO ₂ ), silicon dioxide (SiO ₂ ), chromium oxide (Cr ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), nickel oxide (NiO). ), and one of these may be used alone or two or more kinds of composite materials may be used. Among them, from the viewpoint of stability as an oxide film, the material of the oxide film 6 is preferably at least one selected from the group consisting of TiO ₂ , SiO ₂ , and Cr ₂ O ₃ , and TiO ₂ and More preferably, it is at least one selected from the group consisting of SiO ₂ . Further, the oxide film 6 may be a single layer containing at least one of these or a multi-layer in which two or more such single layers are laminated.

When the oxide film 6 is further provided, the thickness thereof is preferably 300 nm or less, and 200 nm or less from the viewpoint that the intensity of the surface plasmon resonance generated by the plasmon resonance film electrode 4 tends to decrease as the thickness increases. It is more preferably not more than 100 nm, further preferably not more than 100 nm, still more preferably not more than 50 nm.

(Transparent substrate)
FIG. 5 shows a third preferred form of the enhanced sensor chip (preferred embodiment 3). As the sensor chip constituting the enhanced sensor chip, for example, as in the sensor chip (photoelectric conversion unit) 13 shown in FIG. 5, the sensor chip 13 is mainly supported between the prism 1 and the transparent electrode 2. For the purpose, it may further comprise a transparent substrate 7 (enhanced sensor chip 130).

The material of the transparent substrate 7 is not particularly limited as long as it can transmit light, and examples thereof include high molecular weight organic compounds such as glass and plastics and films, and the transparent substrate 7 includes at least one of them. It may be a single layer containing a seed or a multi-layer in which two or more such single layers are laminated. When the transparent substrate 7 is further provided, the thickness thereof is usually 0.01 to 2 mm.

Further, when the transparent substrate 7 is further provided, an intermediate layer (not shown) may be further provided between the prism 1 and the transparent substrate 7 mainly for the purpose of closely adhering the transparent substrate 7. The material of the intermediate layer is not particularly limited as long as it can transmit light, and examples thereof include glycerol, water, polymer (polymethylmethacrylate, polystyrene, polyethylene, epoxy, polyester, etc.), oil, diiodomethane, α-bromonaphthalene, toluene, isooctane, cyclohexane, 2,4-dichlorotoluene, organic compound solution (sucrose solution, etc.), inorganic compound solution (potassium chloride solution, sulfur-containing solution), ethylbenzene, dibenzyl ether, aniline, styrene Among these, one kind may be used alone or two or more kinds may be used in combination.

(Adhesive layer)
FIG. 6 shows a fourth preferred form of the enhanced sensor chip (preferred embodiment 4). As the sensor chip constituting the enhanced sensor chip, particularly when the plasmon resonance film electrode 4 is made of the above metal, the n-type transparent semiconductor film 3 and the plasmon can be used like the sensor chip (photoelectric conversion part) 14 shown in FIG. An adhesive layer 8 may be further provided mainly for the purpose of more firmly fixing the plasmon resonance film electrode 4 to the resonance film electrode 4 (enhanced sensor chip 140).

Examples of the material of the adhesive layer 8 include titanium (Ti), chromium (Cr), nickel (Ni), and titanium nitride (TiN), and the adhesive layer includes a single layer containing at least one of them. It may be a layer or a multi-layer in which two or more such single layers are laminated. Further, the adhesive layer 8 may not cover the entire boundary surface between the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4. However, since the evanescent wave reaching the surface opposite to the surface on which the light is incident becomes weak and the surface plasmon polaritons of sufficient strength cannot be excited, the n-type transparent semiconductor film is used in the sensor chip. 3 and the plasmon resonance film electrode 4 are preferably arranged close to each other, and the distance between the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4 is preferably 25 nm or less, preferably 1 to 10 nm. More preferably. Therefore, when the adhesive layer 8 is further provided, the thickness thereof is preferably 25 nm or less, more preferably 1 to 10 nm.

(Molecular bonding film)
FIG. 7 shows a fifth preferred form of the enhanced sensor chip (preferred embodiment 5). In the enhanced sensor chip, like the sensor chip (photoelectric conversion unit) 15 shown in FIG. 7, the reflection resonance film 5 on the side opposite to the plasmon resonance film 4 is mainly intended to facilitate binding of biomolecules and the like. A molecular bond film 9 made of a material different from the material of the reflection resonance film 5 may be further provided on the surface (enhanced sensor chip 150).

Examples of the material of the molecular bonding film 9 include gold (Au), silver (Ag), copper (Cu), platinum (Pt), titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and silicon dioxide (SiO ₂ ). ), zinc oxide (ZnO), and aluminum oxide (Al ₂ O ₃ ), and one of these may be a single material or a composite material of two or more materials. Among them, the material of the molecular bonding film 9 is selected from the group consisting of Au, Ag, Cu and Pt from the viewpoint of more efficiently reflecting the electric field change generated by the plasmon resonance film electrode 4 in the reflection resonance film 5. At least one selected from the group consisting of Au and Pt is more preferred from the viewpoint of higher stability when exposed to the atmosphere or a solution. Further, the molecular bonding film 9 may be a single layer containing at least one of these or a multi-layer in which two or more such single layers are laminated.

When the molecular bonding film 9 is further provided, the thickness thereof is preferably 1 to 100 nm from the viewpoint that the intensity of the surface plasmon resonance generated by the plasmon resonance film electrode 4 tends to decrease as the thickness increases. It is more preferably 1 to 50 nm, further preferably 1 to 25 nm.

(Sample layer)
FIG. 8 shows a sixth preferred form of the enhanced sensor chip (preferred embodiment 6). In the enhanced sensor chip, as shown in FIG. 8, on the surface of the reflection resonance film 5 opposite to the plasmon resonance film 4, or on the molecular bonding film described above, mainly for holding a sample to be measured. 9 (not shown in FIG. 8) may further comprise a sample layer 10 (enhanced sensor chip 160). As the sample layer 10, even if the sample layer is arranged so as to be supplied at an arbitrary flow rate, it is divided into cells so as to be contained in a constant volume. It may be.

In the sensor chip constituting the enhanced sensor chip, the combination of the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4 (adhesive layer 8 if the adhesive layer 8 is further provided) forms a Schottky barrier. Is preferred. The sensor chip forming the Schottky barrier means that the transparent electrode 2 of the sensor chip is connected to the working electrode of the voltage applying means such as a semiconductor analyzer, and the plasmon resonance film electrode 4 is connected to the counter electrode and the reference electrode of the voltage applying means. Then, it can be confirmed by measuring the current value when a voltage is applied to the working electrode in the range of -1.5 to +1.5V. As the current value, the maximum value of the absolute values of the current value between 0V and +1.5V is 1/5 or less of the maximum value of the absolute value of the current value between -1.5V and less than 0V. Is more preferable, it is more preferably 1/10 or less, further preferably 1/20 or less. If this ratio exceeds the upper limit value, the rectification characteristics are weakened, and noise during measurement increases, which tends to reduce the sensitivity and accuracy of the sensor.

When the work function of the n-type transparent semiconductor film 3 is φS and the work function of the plasmon resonance film electrode 4 (or the adhesive layer 8) is φM, the combination for forming such a Schottky barrier has the following formula: φS< This is a combination that satisfies the condition represented by φM.

The value of the work function of each material is known, and as the work function (φS) of the n-type transparent semiconductor film 3, for example, (I) Akihito Imanishi et al. Phys. Chem. C, 2007, 111(5), p. 2128-2132; (II) Min Wei et al., Energy Procedure, 2012, Volume 16, Part A, p. 76-80; (III) David Ginley et al., "Handbook of Transparent Conductors,"2011; (IV)L. F. Zagonel et al. Phys. : Condens. Matter, 2009, 21, 31; (V)E. R. Batasta et al. Phys. Chem. B, 2002, 106(33), p. 8136-8141; (VI) Gy. Vida et al., 2003, Microsc. Microanal. , 9(4), p. 337-342; (VII)W. J. Chu et al. Phys. Chem. B, 2003, 107(8), p. 1798-1803, titanium dioxide (TiO ₂ ): 4.0 to 4.2 (I), zinc oxide (ZnO): 4.71 to 5.08 (II), tin dioxide (SnO ₂ ): 5 respectively. .1(III), strontium titanate (SrTiO ₃ ):4.2(IV), diiron trioxide (Fe ₂ O ₃ ):5.6(V), tungsten oxide (WO ₃ ):5.7( VI), tantalum oxynitride (TaON): 4.4 (VII), and indium oxide (In ₂ O ₃ ): 4.3 to 5.4 (III).

As the work function (φM) of the plasmon resonance membrane electrode 4 (or the adhesive layer 8), for example, in (VIII) The Chemical Society of Japan, “Chemical Handbook, Basic Edition, Revised 4th Edition”, II-489, respectively. (Au): 5.1 to 5.47, silver (Ag): 4.26 to 4.74, aluminum (Al): 4.06 to 4.41, copper (Cu): 4.48 to 4.94 , Platinum (Pt): 5.64 to 5.93, Palladium (Pd): 5.55, and (IX) Takashi Matsukawa et al., Jpn. J. Appl. Phys. , 2014, 53, 04EC11, it is described that titanium nitride (TiN): 4.4 to 4.6.

Therefore, as a combination of the n-type transparent semiconductor film 3 forming the Schottky barrier and the plasmon resonance film electrode 4 (or the adhesive layer 8), a combination satisfying the above conditions is selected from these work functions (φS, φM). Can be selected and adopted appropriately. Among these, as the combination of the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4 (or the adhesive layer 8), any one of TiO ₂ and Au, Ag, Al, Cu, Pt, Pd, or TiN is used. , ZnO and any one of Au, Pt, and Pd, SnO ₂ and one of Au, Pt, and Pd, SrTiO ₃ and Au, Ag, Al, Cu, Any one of Pt, Pd, and TiN, a combination of Fe ₂ O ₃ and Pt, a combination of WO ₃ and Pd, TaON and Au, Ag, Cu, Pt, Pd, and TiN. A combination with one of these, a combination of In ₂ O ₃ with any one of Pt and Pd is preferable, a combination of TiO ₂ with one of Au, Ag, Cu, Pt and Pd, a combination with ZnO. A combination with Pt, a combination with SnO ₂ and Pt, a combination with SrTiO ₃ and any one of Au, Ag, Cu, Pt and Pd, and a combination of TaON and Au, Cu, Pt and Pd. More preferred is a combination with In, and a combination of In ₂ O ₃ and Pt.

The enhanced sensor chip and the sensor chip of the present invention are not limited to Embodiments 1 to 6 (enhanced sensor chips 110 to 160, sensor chips 11 to 15) of the enhanced sensor chip described above. For example, the transparent substrate 7 and Any combination of these, such as including any sample layer 10 (not shown). Further, as the enhanced sensor chip of the present invention, one may be used alone, or a plurality may be arranged and arranged in a row or a plane.

(Electrical measuring device (electrical measuring means))
The sensor of the present disclosure includes the prism 1 and the enhanced sensor chip (eg, the enhanced sensor chip 110 in the preferred embodiment 1) including the sensor chip (eg, the sensor chip 11 in the preferred embodiment 1), and the sensor chip. Electrical measuring device (for example, electrical measuring device 21 in the preferred embodiment 1) that directly measures a current value or a voltage value from the transparent electrode 2 and the plasmon resonance film electrode 4 of FIG. The transparent electrode 2, the plasmon resonance film electrode 4, and the electrical measuring device are connected via an external circuit (for example, the external circuits 31 and 31' in the preferred embodiment 1).

The material of the external circuit is not particularly limited, and any known material for the conductive wire can be appropriately used, and examples thereof include metals such as platinum, gold, palladium, iron, copper, and aluminum. The electrical measuring device is not particularly limited as long as it can measure a voltage value or a current value, and examples thereof include a semiconductor device analyzer, a current measuring device, and a voltage measuring device.

(Surface plasmon polariton change detection method)
The surface plasmon polariton change detection method of the present invention is a method of detecting a change in surface plasmon polariton using the above electrical measurement type surface plasmon resonance sensor (sensor),
Irradiating light from the prism side, and totally reflecting the light passing through the prism, the transparent electrode, and the n-type transparent semiconductor film between the plasmon resonance film electrode and the n-type transparent semiconductor film. And interact with the plasmon resonance membrane electrode to generate surface plasmon polaritons,
Hot electrons generated by the surface plasmon polaritons and transferred to the n-type transparent semiconductor film are taken out from the transparent electrode as an electric signal,
Detecting a change in surface plasmon polaritons by measuring a change in current value or voltage value between the transparent electrode and the plasmon resonance film electrode by the electrical measuring device,
Is the way.

In the sensor of the present disclosure, light (incident light) that has been irradiated with light from the prism 1 side and has passed through the prism 1, the transparent electrode 2 and the n-type transparent semiconductor film 3 is incident on the plasmon resonance film electrodes 4 and n. By performing total reflection with the transparent semiconductor film 3, the surface plasmon polariton is generated by interacting with the plasmon resonance film electrode 4. More specifically, the light that has passed through the n-type transparent semiconductor film 3 adheres to the plasmon resonance film electrode 4 at the interface between the n-type transparent semiconductor film 3 and the plasmon resonance film electrode 4, or when the adhesion layer 8 is provided. The interface with the layer 8, the interface between the adhesive layer 8 and the n-type transparent semiconductor film 3, or the interface between the plasmon resonance film electrode 4 and the adhesive layer 8 when the adhesive layer 8 is composed of two or more layers, or the adhesive. Total reflection is performed at the interface between the layer 8 and the n-type transparent semiconductor film 3 or at the interface between two adjacent layers in the adhesive layer 8, and the evanescent wave generated by the total reflection interacts with the plasmon resonance film electrode 4 and the surface thereof. Plasmon polaritons occur.

The generated surface plasmon polaritons sufficiently polarize the plasmon resonance film electrode 4 to generate hot electrons, which move to the n-type transparent semiconductor film 3 and are extracted from the transparent electrode 2 as an electric signal. At this time, the transparent electrode 2 is electrically connected to the plasmon resonance membrane electrode 4 through the external circuit, and a change in current between the transparent electrode 2 and the plasmon resonance membrane electrode 4 is measured by the electrical measuring device to obtain a surface. Changes in plasmon polaritons can be detected. The hot electrons thus observed as an electric signal are considered to be the hot electrons generated in the vicinity of the interface inside the plasmon resonance film electrode 4, and thus the hot electrons observable as an electric signal are plasmon resonance. It is presumed that the hot electrons are generated in a region where the thickness of the plasmon resonance film electrode 4 is about 20% away from the n-type transparent semiconductor film 3 inside the film electrode 4.

When the wavelength of the light incident from the prism 1 side becomes longer, the range of the incident angle of the incident light that causes the surface plasmon polaritons becomes narrower, while the strength of the generated surface plasmon polaritons is increased. Therefore, the light to be incident on the prism 1 (irradiated light) is not particularly limited according to the purpose, but may be light in the visible light wavelength region or near-infrared light wavelength region, which is 400 to 1500 nm. The wavelength is preferable, the wavelength of 500 to 1000 nm is more preferable, and the wavelength of 600 to 900 nm is further preferable.

Also, when the intensity of light incident from the prism 1 side increases, the amount of current generated by the surface plasmon polaritons increases. Therefore, the intensity of the light incident on the prism 1 is not particularly limited according to the purpose, but is preferably 0.01 to 500 mW, more preferably 0.1 to 50 mW, and 0.1 More preferably, it is ˜5 mW. If the intensity of the light is less than the lower limit, the amount of current generated by the surface plasmon polaritons tends to be too small to obtain sufficient sensor accuracy, while if it exceeds the upper limit, the plasmon resonance membrane electrode 4 In the above, there is a tendency that heat is generated and the measurement sensitivity is lowered.

In the sensor of the present disclosure, by disposing the sample to be measured in the vicinity of the plasmon resonance film electrode (preferably within 300 nm from the surface of the plasmon resonance film electrode, for example, in the sample layer 10), the refractive index of the sample Since the change in the surface plasmon polaritons due to the change (change in concentration, change in state) can be detected as an electric signal, the change in state of the sample can be monitored by measuring the electric signal. Further, the concentration or state of the sample can be determined by comparing with the electric signal measured in the sample having a known concentration or state in advance.

Also, by changing the incident angle of the light incident from the prism side according to the sample to be measured, the sensor accuracy can be further improved.

For example, with respect to the sample containing the target substance and the medium, which is held on the surface of the reflection resonance film 5 opposite to the plasmon resonance film 4 or on the molecular bonding film 9, preferably in the sample layer 10, Changes in surface plasmon polaritons due to changes in concentration and changes in state can be detected as electrical signals. In this case, the target substance is not particularly limited, and includes small molecule compounds such as antibodies, nucleic acids (DNA, RNA, etc.), proteins, bacteria, drugs, etc.; ions; small molecule compounds in a gaseous state, volatile substances, etc. Can be mentioned. The medium includes a solution and a gas, the solution is water; a buffer solution, an electrolyte solution such as a strong electrolyte solution, and the gas is an inert gas such as nitrogen gas or helium gas. To be

(Method for manufacturing electric measurement type surface plasmon resonance sensor and plasmon polariton enhanced sensor chip)
The method of manufacturing the sensor of the present disclosure and the enhanced sensor chip including the prism 1 and the sensor chip is not particularly limited, but preferably, the transparent electrode 2, the n-type transparent semiconductor film 3, and the plasmon resonance film electrode are preferably provided on the prism 1. 4 and the reflection resonance film 5 are preferably sequentially formed in this order and laminated. The method for forming the transparent electrode 2, the n-type transparent semiconductor film 3, the plasmon resonance film electrode 4, and the reflection resonance film 5 is not particularly limited, but examples thereof include a sputtering method and an ion method. Examples thereof include a plating method, an electron beam evaporation method, a vacuum evaporation method, a chemical vapor deposition method, a spin coating method, an atomic layer deposition method (ALD), and a plating method. In the case of using the sputtering method, when the n-type transparent semiconductor film 3 made of a metal oxide is formed, the film may be formed while being oxidized by using a metal as a target (reactive sputtering). Further, when the oxide film 6 is provided, the oxide film may be formed by the above method, and the oxide film 6 is formed by forming a film made of a metal forming the oxide film 6 and then exposing the film to the atmosphere or oxygen. May be formed.

Further, in the method of manufacturing the sensor, the method of electrically connecting the transparent electrode 2 and the plasmon resonance film electrode 4 of the sensor chip to the electrical measuring device through an external circuit is not particularly limited, and a conventionally known method may be appropriately used. Can be adopted and connected.

Examples will be described below more specifically, but the present invention is not limited to the following examples.

(Comparative Example 1)
First, an ITO substrate (glass substrate: S-TIH11, glass substrate thickness: 1.1 mm, area: 19×19 mm) in which a transparent electrode made of an ITO film (indium tin oxide) was formed on one surface of the glass substrate , ITO film: highly durable transparent conductive film 5Ω, manufactured by Geomatec Co., Ltd.) was prepared. Then, using a sputtering apparatus 1 (QAM-4-ST, manufactured by ULVAC Kyushu Co., Ltd.) and TiO ₂ (Titanium Dioxide, 99.9%, manufactured by Furuuchi Chemical Co., Ltd.) as a target, TiO ₂ was formed on the ITO film. _A 200 nm thick film (n-type transparent semiconductor film (TiO ₂ film)) was formed. Then, using the sputtering apparatus 1 and using Au (99.99%, manufactured by Kojundo Chemical Laboratory Co., Ltd.) as a target, a film (Plasmon resonance film) made of Au and having a thickness of 30 nm was formed on the TiO ₂ film. A chip (photoelectric conversion part (sensor chip)) in which an electrode (Au film) is formed and a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), and a plasmon resonance film electrode (Au film) are laminated in this order. ) Got.

Then, diiodomethane (first-class, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was applied to the surface of the obtained chip opposite to the ITO film on the glass substrate, and a right-angle prism (S-TIH11, manufactured by Tokiwa Optical Co., Ltd., A chip (with a prism) in which a prism, a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), and a plasmon resonance film electrode (Au film) are laminated in this order by closely adhering the slopes with a refractive index of 1.77) Chips).

(Example 1)
A chip in which a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), and a plasmon resonance film electrode (Au film) were laminated in this order was obtained in the same manner as in Comparative Example 1. Then, using the sputtering apparatus 1, _TiO 2 as a target (Titanium Dioxide, 99.9%, Furuuchi Chemical Co., Ltd.) using, in the plasmon resonance layer on the electrode, a thickness of 5nm consisting TiO ₂ as a protective film A film (oxide film) was formed. Then, using a sputtering apparatus 2 (SH-250, manufactured by ULVAC, Inc.) and Si (99.999%, manufactured by Kojundo Chemical Laboratory Co., Ltd.) as a target, a thickness of Si formed on the protective film. A film having a thickness of 70 nm (reflection resonance film (Si film)) is formed, and a glass substrate, ITO film, n-type transparent semiconductor film (TiO ₂ film), plasmon resonance film electrode (Au film), oxide film, reflection resonance film ( A chip (photoelectric conversion part (sensor chip)) in which the Si film) was laminated in this order was obtained. A prism, a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), a plasmon resonance film electrode (Au film), an oxide film, and a reflection film were formed in the same manner as in Comparative Example 1 except that this was used as a chip. A chip (chip with prism) in which a resonance film (Si film) was laminated in this order was obtained.

(Example 2)
In the same manner as in Example 1, a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), a plasmon resonance film electrode (Au film), an oxide film, and a reflection resonance film (Si film) were laminated in this order. Got a chip. Then, using the sputtering apparatus 1, Au (99.99%, manufactured by Kojundo Chemical Laboratory Co., Ltd.) as a target was used, and a 10 nm-thick film (molecular bonding film) made of Au was formed on the reflection resonance film. (Au film)), and a glass substrate, ITO film, n-type transparent semiconductor film (TiO ₂ film), plasmon resonance film electrode (Au film), oxide film, reflection resonance film (Si film), molecular bonding film ( A chip (photoelectric conversion portion (sensor chip)) in which Au films were laminated in this order was obtained. A prism, a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), a plasmon resonance film electrode (Au film), an oxide film, a reflection film were formed in the same manner as in Example 1 except that this was used as a chip. A chip (chip with prism) in which a resonance film (Si film) and a molecular bonding film (Au film) were laminated in this order was obtained.

(Example 3)
A chip in which a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), and a plasmon resonance film electrode (Au film) were laminated in this order was obtained in the same manner as in Comparative Example 1. Then, using the sputtering apparatus 1, using TiO ₂ (Titanium Dioxide, 99.9%, manufactured by Furuuchi Chemical Co., Ltd.) as a target, a 122 nm-thick film (reflection film) made of TiO ₂ was formed on the plasmon resonance film electrode. A resonance film (TiO ₂ film) is formed, and a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), a plasmon resonance film electrode (Au film), and a reflection resonance film (TiO ₂ film) are laminated in this order. I got the chips. Further, in the same manner as in Example 2, a film (molecular bonding film (Au film)) made of Au and having a thickness of 10 nm was formed on the reflection resonance film (TiO ₂ film), and the glass substrate, the ITO film, and the n film were formed. -Type transparent semiconductor film (TiO ₂ film), plasmon resonance film electrode (Au film), reflection resonance film (TiO ₂ film), molecular bonding film (Au film) laminated in this order (photoelectric conversion part (sensor chip)) ) Got. A prism, a glass substrate, an ITO film, an n-type transparent semiconductor film (TiO ₂ film), a plasmon resonance film electrode (Au film), a reflection resonance film (in the same manner as in Example 1 except that this was used as a chip. A chip (chip with prism) in which a TiO ₂ film) and a molecular bonding film (Au film) were laminated in this order was obtained.

<Test Example 1>
The surface of the plasmon resonance film electrode of the prism-equipped chip obtained in Comparative Example 1 (the surface opposite to the n-type transparent semiconductor film) and the surface of the reflection resonance film of the prism-equipped chip obtained in Example 1 (the surface opposite to the oxide film) Surface), the sample layer is disposed so as to be in contact with each other on the surface (the surface opposite to the reflection resonance film) of the molecular binding film of the chip with prism obtained in Examples 2 to 3, and the sample is placed in the sample layer. Ultrapure water was filled as a solution. The sample layer was arranged so that the sample solution was in direct contact with the surface of each chip.

Further, the ITO film of the prism-equipped chip obtained in Comparative Example 1 and Examples 1 to 3 and the working electrode of the current measuring device (Electrochemical Analyzer Model 802D, manufactured by ALS/CH Instruments Inc.) were used as plasmon resonance film electrodes. The counter electrode and the reference electrode of the current measuring device were electrically connected to each other via a conductive wire.

Then, a 670 nm laser light (light source: CPS670F, manufactured by Thorlabs) was converted into p-polarized laser light through a polarizer (CMM1-PBS251/M, manufactured by Thorlabs), and this intensity was measured with a power meter (Model 843-R, Newport). (Manufactured by Mitsui Chemicals Co., Ltd.) and adjusted to be 4.0 mW. Next, as shown in FIG. 9, p-polarized laser light (4.0 mW) was irradiated from the prism side of the photoelectric conversion part (sensor chip 17) of the chip. The incident angle (θ[°]) of the p-polarized laser light (incident light) with respect to the glass substrate surface was changed between 40° and 80°, and the current value between the ITO film and the plasmon resonance film electrode at each incident angle [ μA] was measured. Further, as the sample solution, 10%, 20%, 30%, 40%, 50%; 2%, 4%, 6%, 8%, 10% instead of the ultrapure water (glycerol 0%). Or 1%, 2%, 3%, 4%, 5%, 6% glycerol (Glycerol) solution was used respectively, in the same manner as above, for each sample solution, the ITO film-plasmon at each incident angle. The current value [μA] between the resonance membrane electrodes was measured.

Each sample solution was measured using the chips with prisms obtained in Comparative Example 1 and Examples 1 to 3 (incident angle (θ [°]) and current value [μA] between ITO film and plasmon resonance film electrode). 10 (Comparative Example 1), FIG. 11 (Example 1), FIG. 12 (Example 2), and FIG. 13 (Example 3), respectively.

Regarding the results obtained in Comparative Example 1 and Examples 1 and 2, the refractive index of each sample solution at 22.1° C. and the normalized current value between the ITO film and the plasmon resonance film electrode [a. u. 14] is shown in FIG. First, the normalized current was calculated from the graph showing the relationship between the incident angle and the current value between the ITO film and the plasmon resonance film electrode in Comparative Example 1 and Examples 1 and 2 obtained above. The current value (a) at each incident angle is obtained when the value is set to 1, and then from the same graph, the incident angle at which the current value becomes highest when the 0% glycerol solution is measured (Comparative Example 1: 68. 6°, Example 1: 53.7°, Example 2: 53.0°), the current value at the incident angle (b) at the time of measuring the glycerol solution of each concentration, assuming that the current value is 1. Was calculated, and the ratio (a/b) of these current values was calculated and used as the normalized current value. The refractive index of the glycerol solution at each concentration at 22.1°C is shown in Table 1 below.

As is clear from the results shown in FIGS. 10 to 14, in the chip including the prism (for example, Comparative Example 1 and Examples 1 to 3), the incident angle of the laser light incident on the prism falls within a specific range. In that case (for example, 45 to 65° in FIG. 11), it was confirmed that the current value changed. This is because when the laser light is passed through the prism, the incident light is totally reflected at the interface with the plasmon resonance film electrode of the n-type transparent semiconductor film at a specific incident angle or more to generate an evanescent wave. This is because the electric current generated by the electric field change at the plasmon resonance film electrode arranged in the vicinity of the n-type transparent semiconductor film is changed by the surface plasmon polaritons excited by the. It is presumed that it was changed by.

Also, as is clear from the results shown in FIGS. 10 to 14, the current value changed according to the refractive index of the solution. This is because the strength of the surface plasmon polaritons, which causes a change in the amount of current generated by a change in the electric field at the plasmon resonance film electrode arranged near the n-type transparent semiconductor film, changes depending on the refractive index of the solution. The inventors speculate. Therefore, it was confirmed that the change in the refractive index of the sample near the plasmon resonance film electrode can be measured with sufficient accuracy by using the chip including the prism.

Further, as is clear from the results shown in FIGS. 11 to 14, the provision of the reflection resonance film (for example, Examples 1 to 3) makes the change in the current value steep and significantly improves the sensitivity of the sensor. confirmed. Further, even if a molecular bonding film capable of immobilizing biomolecules or the like is further laminated (for example, Examples 2 to 3), or a TiO ₂ film is used as a reflection resonance film (for example, Example 3). It was confirmed that the current value became steep and the excellent sensor sensitivity was maintained.

<Test Example 2>
In order to confirm the suitable film thickness of the reflection resonance film, the software (“DEVICE”, Lumerical. /) was used, and the electromagnetic field simulation was performed under the following conditions by the "stackfield command" therein.

[Chip configuration]
The electromagnetic field simulation is performed by a chip 1 in which a glass substrate, an n-type transparent semiconductor film (TiO ₂ film) and a plasmon resonance film electrode (Au film) are laminated in this order; a glass substrate, an n-type transparent semiconductor film (TiO ₂ film), Chip 2 in which a plasmon resonance film electrode (Au film), a reflection resonance film (Si film), and a molecular bonding film (Au film) are laminated in this order; the reflection resonance film of chip 2 is replaced with a Si film, and a TiO ₂ film is used. Chip 3; each of the chips 4 was replaced with the Si film as the reflection resonance film of the chip 2 and changed to the SiO ₂ film. In the electromagnetic field simulation, the light source was assumed to be inside the glass substrate.

[Parameter]
The parameters required by the stackfield command are as follows.
n: Refractive index of each layer As the refractive index of each layer, the complex refractive index (n: refractive index, k: extinction coefficient) shown in Table 2 below was used from the refractive index of the material forming each layer.
d: Thickness of each layer The thickness of each layer is as shown in Table 2 below. When the reflection resonance film is a Si film or a TiO ₂ film, the thickness is 0 to 500 nm, and the reflection resonance film is SiO _2. The thickness in the case of a film was varied between 0 and 1200 nm.
f: frequency of incident light Wavelength 1=670 nm, and frequency f=c/l (c: speed of light (2.99×10 ⁸ m/s).
theta: incident angle of light (θ)
The range was 0 to 90°.
res: Resolution Since the resolution of the stackfield command is equal to the number of divisions of the simulation range, the size of each calculation cell may change when the thickness of each layer is changed. Therefore, resolution res=(1+total thickness of each layer)/calculated cell size (rounded off, calculated cell size=0.01 nm ³ ).

After performing the simulation, the absorption amount of p-polarized light in the region of 20% thickness (10 nm) from the surface of the plasmon resonance film electrode (Au film) on the n-type transparent semiconductor film (TiO ₂ film) side was calculated. Also, regarding the reflected light, only the p-polarized component was acquired.

[Confirmation of simulation]
The ITO film of the prism-equipped chip obtained in Comparative Example 1 and the working electrode of a current measuring device (Electrochemical Analyzer Model 802D, manufactured by ALS/CH Instruments Inc.), the plasmon resonance film electrode and the counter electrode of the current measuring device, and a reference The poles and the poles are electrically connected to each other via a conductor wire. Then, a 670 nm laser light (light source: CPS670F, manufactured by Thorlabs) was converted into p-polarized laser light through a polarizer (CMM1-PBS251/M, manufactured by Thorlabs), and this intensity was measured with a power meter (Model 843-R, Newport). (Manufactured by Mitsui Chemicals Co., Ltd.) and adjusted to be 4.0 mW. Then, as shown in FIG. 9, p-polarized laser light (4.0 mW) was irradiated from the prism side of the photoelectric conversion part (sensor chip 17) of the chip. The incident angle (θ[°]) of the p-polarized laser light (incident light) with respect to the glass substrate surface was changed between 23° and 37°, and the current value between the ITO film and the plasmon resonance film electrode at each incident angle [ μA] was measured. The relationship between the incident angle (θ [°]) of the obtained light and the current value [μA] (left axis) is shown in FIG. 15 (solid line, measured value). On the other hand, for the chip 1, the incident angle (θ[°]) of light obtained by simulation and the output current ratio [%] (right axis), which is the ratio of the current value (output current energy) to the energy of the incident light. The relationship with and is also shown in FIG. 15 (dotted line, simulation).

As shown in FIG. 15, the relationship between the incident angle (θ) of light, the current value (A), and the output current ratio (CA) is similar between the measured value (solid line) and the simulated value (dotted line). It was confirmed that the simulation can be performed with high accuracy.

[Thickness of reflection resonance film]
For chips 2 to 4, the relationship between the incident angle of light (θ[°]) and the output current ratio [%] obtained by simulation is plotted, and the output current ratio (CA) becomes the maximum value (CA _max ). from the incident angle (theta _CAmax) the output current ratio is the minimum value from the _{(CA min)} become incident angle (theta _Camin) angle variation by subtracting the (Δθ [°]) and the output current maximum percentage _{(CA max)} The values (ΔI[%]) obtained by subtracting the minimum value (CA _min ) were obtained, and the sensitivity (|ΔI|/|Δθ|[%]) was calculated as the ratio of their absolute values. Next, the thickness (thickness, [nm]) of the reflection resonance film and the absolute value (angle difference, |Δθ|[°], left axis) and the sensitivity (Sensitivity, |ΔI|/|Δθ|[% ], the right axis). The obtained results are shown in FIG. 16 (chip 2), FIG. 17 (chip 3), and FIG. 18 (chip 4), respectively.

As shown in FIGS. 16 to 18, the thickness and the sensitivity of the reflection resonance film are the absolute value (|Δθ|) of the angle change amount (Δθ) in the thickness of the reflection resonance film when the sensitivity reaches the maximum value. Was confirmed to be the minimum. Moreover, it was confirmed that excellent sensitivity was achieved when the thickness of the reflection resonance film was such that |Δθ| was 2° or less.

As described above, according to the electrical measurement type surface plasmon resonance sensor of the present disclosure and the sensor chip used for the same, it is possible to provide the electrical measurement type surface plasmon resonance sensor having excellent sensor sensitivity and the sensor chip used for the same. Become. Further, since the sensor and the sensor chip of the present disclosure can detect surface plasmon polaritons as an electric signal, it is easy to reduce the size and increase the throughput.

Furthermore, in the sensor and the sensor chip of the present disclosure, it is possible to further stack a molecular binding film capable of binding biomolecules and the like, and since it does not affect the sample, more accurate measurement is possible. .. Therefore, the sensor and sensor chip of the present disclosure are very useful in future development of medical treatment, food, and environmental technology.

DESCRIPTION OF SYMBOLS 1... Prism, 2... Transparent electrode, 3... N-type transparent semiconductor film, 4... Plasmon resonance film electrode, 5... Reflection resonance film, 6... Oxide film, 7... Transparent substrate, 8... Adhesive layer, 9... Molecular bonding film 10... Sample layer, 11-17... Sensor chip (photoelectric conversion part), 21... Electrical measuring device, 31, 31'... External circuit, 110-160... Enhanced sensor chip, 200... Light source, 300... Polarizer, 400... Incident light, 510... Sensor.

Claims (12)

1. A sensor chip in which a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are arranged in this order, and a prism are the prism, the transparent electrode, the n-type transparent semiconductor film, and the plasmon. A resonance membrane electrode, and a plasmon polariton enhanced sensor chip arranged in the order of the reflection resonance membrane;
   An electrical measuring device for directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
   An electric measurement type surface plasmon resonance sensor having:
2. In the sensor chip, the thickness of the reflection resonance film is expressed by the following formula (1):
   │Δθ│≦2°・・・(1)
   [In the formula (1), Δθ is a current value measured by making light incident on the sensor chip within a range in which the incident angle (θ) with respect to the surface of the sensor chip in contact with the prism is 0 to 90°. At this time, within the range of ±25° of the incident angle (θ _cp ) when the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film, the current with respect to the energy of the incident light is Angle _obtained by subtracting the incident angle (θ _CAmin ) at which the output current ratio is the minimum value (CA _min ) from the incident angle (θ _CAmax ) at which the output current ratio (CA) that is the ratio of the values is at the maximum value (CA _max ). Indicates the amount of change. ]
   The electrical measurement type surface plasmon resonance sensor according to claim 1, which has a thickness satisfying the condition (1).
3. The electrical measurement type surface plasmon resonance sensor according to claim 1 or 2, wherein in the sensor chip, the combination of the n-type transparent semiconductor film and the plasmon resonance film electrode is a combination that forms a Schottky barrier.
4. The electrical measurement type surface plasmon resonance sensor according to any one of claims 1 to 3, wherein in the sensor chip, the thickness of the plasmon resonance film electrode is 200 nm or less (not including 0).
5. 5. The sensor chip according to claim 1, wherein the reflection resonance film is a film made of at least one selected from the group consisting of metal oxides, semiconductors, and organic substances. Electrical measurement type surface plasmon resonance sensor.
6. In the sensor chip, the n-type transparent semiconductor film is at least one selected from the group consisting of TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , Fe ₂ O ₃ , TaON, WO ₃ and In ₂ O ₃ . The electrical measurement type surface plasmon resonance sensor according to any one of claims 1 to 5, which is a film made of an n-type semiconductor.
7. The electrical measurement type surface plasmon resonance sensor according to any one of claims 1 to 6, wherein the sensor chip further comprises a molecular bonding film on a side of the reflection resonance film opposite to the plasmon resonance film.
8. The electrical measurement type surface plasmon resonance sensor according to any one of claims 1 to 7, wherein the sensor chip further includes an oxide film between the plasmon resonance film electrode and the reflection resonance film.
9. A sensor chip used in the electrical measurement type surface plasmon resonance sensor according to any one of claims 1 to 8, wherein a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are provided. An electric measurement type surface plasmon resonance sensor chip arranged in this order.
10. Plasmon resonance film electrode capable of converting incident light into surface plasmon polaritons,
    The plasmon resonance film electrode is disposed on the incident light side, transmits the incident light, and the transmitted incident light is emitted from the plasmon resonance film electrode by interacting with the plasmon resonance film electrode. N-type transparent semiconductor film capable of receiving hot electrons,
    A reflection resonance film, which is arranged on the opposite side of the plasmon resonance film electrode from the n-type transparent semiconductor film and is capable of internally resonating an electric field change due to surface plasmon resonance generated by the plasmon resonance film electrode;
    as well as,
    A transparent electrode capable of taking out hot electrons transferred from the n-type transparent semiconductor film as an electric signal,
    A sensor chip including
    A prism capable of controlling the angle of the incident light so that the incident light is totally reflected between the plasmon resonance film electrode and the n-type transparent semiconductor film;
    And a plasmon polariton enhanced sensor chip including:
    An electrical measuring device capable of directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
    An electric measurement type surface plasmon resonance sensor comprising:
11. It is a sensor chip used for the electric measurement type surface plasmon resonance sensor of Claim 10, Comprising: A transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are arranged in this order. Measurement type surface plasmon resonance sensor chip.
12. A sensor chip in which a transparent electrode, an n-type transparent semiconductor film, a plasmon resonance film electrode, and a reflection resonance film are arranged in this order, and a prism are the prism, the transparent electrode, the n-type transparent semiconductor film, and the plasmon. A resonance membrane electrode, and a plasmon polariton enhanced sensor chip arranged in the order of the reflection resonance membrane;
    An electrical measuring device for directly measuring a current value or a voltage value from the transparent electrode and the plasmon resonance film electrode,
    A method for detecting a change in surface plasmon polaritons using an electric measurement type surface plasmon resonance sensor having
    Irradiating light from the prism side, and totally reflecting the light passing through the prism, the transparent electrode, and the n-type transparent semiconductor film between the plasmon resonance film electrode and the n-type transparent semiconductor film. And interact with the plasmon resonance membrane electrode to generate surface plasmon polaritons,
    Hot electrons generated by the surface plasmon polaritons and transferred to the n-type transparent semiconductor film are taken out from the transparent electrode as an electric signal,
    Detecting a change in surface plasmon polaritons by measuring a change in current value or voltage value between the transparent electrode and the plasmon resonance film electrode by the electrical measuring device,
    Surface plasmon polariton change detection method.

Images