JP2001074647A - Sensor plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sensor plate that can easily retain a specimen material and has improved sensitivity. SOLUTION: The sensor plate is provided with a plate-shaped optical waveguide 3 where light entering from a specific side end face is transmitted while repeating total reflection, a specimen material retention part 7 for retaining the liquid-like specimen material at a specific position on the upper surface of the optical waveguide 3, and a hydrophobic film 5 for covering the upper surface of the optical waveguide 3 excluding the specimen material retention part 7, where the specimen material retention part 7 is set to specific length along the propagation direction of light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor plate.
The present invention relates to a sensor plate for quantifying a sample by analyzing the light.

[0002]

2. Description of the Related Art Conventionally, in the field of biochemical analysis, immunoassay has been widely used as a method for detecting an extremely small amount of protein in a specimen. In this immunization method, a predetermined antigen concentration in a specimen is quantified by a specific immune reaction between an antigen (a protein to be detected) and an antibody (an antibody produced using the antigen). This immunization method can measure even a specimen in which a plurality of types of antigens are mixed without isolating the antigen to be detected. This is different from the chemical measurement method or the physical measurement method.

[0003] Among the immunization methods, there are various methods as described below.

[0004] radio immunoassay: RIA (radioimmunoassay) [enzyme immunoassay: EIA (enzyme immunoassay)] fluoroimmunassay: FIA (fluorescence immunoassay)

[0005] The RIA method has recently been rarely used because it requires the use of isotopes. Also, EI
The method A is widely used at present because the immune reaction can be easily measured. Furthermore, the FIA method is positioned as a highly sensitive and highly accurate measurement method. Among the EIA methods, a method using a solid phase for antibody measurement is particularly described in ELISA (Enzyme link).
This method is referred to as an “ed immunosorbent assay”, and the ELISA includes the following two methods.

A. Indirect method: a method using an antigen as a solid phase b. Antibody capture method: a method using an anti-IgM antibody as a solid phase

[0007] The above-mentioned ELISA method is used for quantification of an antibody against a specific pathogen, quantification of an antibody against an allergen, and screening of a monoclonal antibody. The measurement kit used for the ELISA method includes:
Generally, a microplate in which 96 concave portions are formed is used, and an immunoreaction measurement is performed on this microplate. Therefore, a large number of samples can be measured at the same time, and in recent years, many automated immune reaction measuring devices have been on the market.

[0008] Many reagent manufacturers provide various reagents as assay kits for the ELISA method. For example, there is tPA, an enzyme that acts indirectly in the direction of dissolving fibrin involved in blood coagulation and thrombus in blood. PAI-1 is an enzyme that suppresses tPA and acts in the direction of blood coagulation and thrombus formation.

Incidentally, a so-called SPR sensor is known as a sensor used in an immune reaction measuring device.
This SPR sensor is a sensor using the surface plasmon resonance phenomenon, and is measured based on the following principle. That is, 50
A thin metal film (such as gold or silver) having a thickness of about nm is deposited on the bottom surface of the prism having a high refractive index. Then, predetermined light is incident from the prism side toward the metal thin film at an angle equal to or greater than the critical angle. Since the metal thin film is translucent at about 50 nm, the light incident from the prism side passes through the metal thin film, reaches the surface of the metal thin film on the side opposite to the prism, and reaches the surface of the metal thin film on the side opposite to the prism. Generate an evanescent field.

By adjusting the incident angle of the light, the wave number of the evanescent field and the wave number of the surface plasmon resonance can be matched, and the surface plasmon resonance can be excited on the surface of the metal thin film. In this case, the wave number of the surface plasmon resonance depends on the dielectric constant of the metal thin film and the refractive index of the specimen fixed to the surface opposite to the prism when viewed from the metal thin film. Therefore, the refractive index and the dielectric constant of the specimen can be checked. As described above, since the optical system and the sample are located on opposite sides of the metal thin film as a boundary, it is easy to construct a sensor.

By applying the above principle, an SPR sensor for an immune reaction measuring device using an optical fiber has been developed (B.
Manufactured by IACORE-trade name: BIACORE Probe). In the SPR sensor using this optical fiber, first, the clad on the outer peripheral surface of the distal end portion of the optical fiber is removed, and the end surface of the distal end of the optical fiber is cut or polished. Coated. In addition, a metal thin film (such as gold or silver) is coated on the outer peripheral surface of the tip of the optical fiber. Further, the metal thin film on the outer peripheral surface of the distal end of the optical fiber is covered with a dielectric film, and the antibody used for the immunological reaction measurement is fixed on the dielectric film. A predetermined light source is provided on the other end side of the optical fiber so that light can be introduced into the optical fiber.

A method for measuring an immune reaction of the SPR sensor having the above-described configuration will be described. First, as for light introduced into the optical fiber, light of a specific wavelength excites surface plasmon resonance at the tip of the optical fiber. The wavelength of the light that excites the surface plasmon resonance changes depending on the refractive indices of the dielectric film and the antibody. The intensity of light having a wavelength that causes surface plasmon resonance is attenuated. Therefore, the immune response can be measured by comparing the wavelength of the light that attenuates the most before the immune reaction with the wavelength of the light that attenuates the most after the immune reaction. In addition, SPR sensors using prisms have been developed in addition to those using optical fibers.

Further, as a sensor plate used for a different type of SPR sensor, there is disclosed a sensor plate in which a transparent substrate and a metal thin film are formed on the transparent substrate (Japanese Patent Application Laid-Open No. HEI 1-1990).
No. 1-64213). The sensor plate (referred to as a sample plate in the above-mentioned publication) has a metal thin film formed on the entire surface of a transparent substrate, a binding reaction film formed on the surface of the metal thin film, and a hydrophobic film surrounding the binding reaction film. Is formed. When an immunoreaction measurement is actually performed using this sensor plate, the sample is brought into contact with the binding reaction film, the binding reaction film is irradiated once with light from the transparent substrate side, and the wavelength distribution of reflected light, etc. Is measured to determine the amount of the sample.

[0014]

However, each of the above-mentioned prior arts has the following disadvantages. That is, when an SPR sensor is configured by an optical fiber, it is necessary to form a metal thin film (for example, Au is vapor-deposited) on the outer peripheral surface of the tip of the core of the optical fiber. However, since the optical fiber itself is fine, there has been an inconvenience that a metal thin film cannot be appropriately formed.

[0015] When an immunological reaction is actually measured, it is necessary to immobilize the antibody on the surface of the metal thin film. As described above, the tip of the core of the optical fiber is fine and cylindrical. As a result, it is difficult to immobilize the antibody.

Further, in the sensor plate disclosed in Japanese Patent Application Laid-Open No. H11-64213, since the quantification is performed by one-time reflection of the light on the binding reaction film, there is an inconvenience that the sensitivity in the immunoreaction measurement cannot be increased. I was Also, even if the sensor plate is formed such that light is repeatedly reflected in the transparent substrate, the surface plasmon resonance is also generated in the metal thin film other than the region corresponding to the coupling reaction film because the metal thin film is formed over the entire surface. Arose,
Measurement accuracy is reduced.

Further, as a structure of a conventional sensor plate, there has been a structure in which a plate-shaped core is sandwiched between two clad members. In this case, in addition to polishing the surface of the core, polishing of the clad or cladding may be performed. A bonding step with the core is required, and the manufacturing cost cannot be reduced.

[0018]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the prior art and to provide a sensor plate which can easily hold a sample and has good sensitivity.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a plate-shaped optical waveguide through which light incident from a predetermined side end face is repeatedly reflected and transmitted, and an upper surface of the optical waveguide. A specimen holding unit that holds a liquid sample at a predetermined position, and a hydrophobic film that covers the upper surface of the optical waveguide except for the sample holding unit, and has a predetermined length along the light propagation direction. , Is adopted.

With the above configuration, when measuring a liquid sample, the sample is filled in the sample holding unit. At this time, since the sample holding unit is surrounded by the hydrophobic film, the sample stays without flowing out of the sample holding unit.
In this state, when light is irradiated from the side end surface of the optical waveguide, the light propagates while repeating total reflection. When light is reflected by the sample holding unit, the characteristics of the reflected light change according to the characteristics of the sample. By analyzing the change in the characteristic of the reflected light, the change in the optical waveguide due to the sample can be known.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] [Overall Overview] A first embodiment will be described with reference to FIG. The sensor plate 1 includes a plate-shaped optical waveguide 3 through which light passes, and a hydrophobic film 5 covering the upper surface of the optical waveguide 3.
Is the main component. The specimen holding part 7 is formed on a part of the upper surface of the optical waveguide 3.

[Optical Waveguide] The optical waveguide 3 is made of a transparent material, for example, glass or transparent plastic. The optical waveguide 3 of the present embodiment has a single plate shape, and light is incident from one side end surface 3a. The surface of the one end surface 3a and the other end surface 3b opposed to the end surface 3a are smoothly polished so that light can easily pass therethrough.

The upper and lower surfaces of the optical waveguide 3 are also polished smoothly. This is so that the light incident on the optical waveguide 3 is totally reflected on the upper and lower surfaces of the optical waveguide 3 and is appropriately propagated from one end face 3a to the other end face 3b. That is, light enters and is totally reflected on, for example, the upper surface of the optical waveguide 3, and the reflected light is totally reflected on the lower surface of the optical waveguide 3. By repeating this, light is propagated.
Here, the material is selected so that the refractive index of the optical waveguide 3 is larger than that of a hydrophobic film 5 and air, which will be described later.

[Hydrophobic film] The upper surface of the optical waveguide 3 is covered with a hydrophobic film 5. The material of the hydrophobic film 5 is a fluororesin or the like. Here, in FIG. 1, the hydrophobic film 5 has a predetermined thickness, but is actually thinner than the optical waveguide 3. In FIG. 1, for convenience of description, the thickness of the hydrophobic film 5 is exaggerated.

Various materials can be considered as the material of the hydrophobic film 5. For example, PTFE (PolyTetra Fluoro Ethyle
ne), FEP (Fluorinated Ethylene Propylene Copolym)
er), PFA (Tetra Fluoro Ethylene-PerFluoro Alkylv
inyl ether Copolymer) or ETFE (Ethylene Tet)
ra Fluoro Ethylene) can be used. Various methods are conceivable for forming the hydrophobic film 5. For example, a spin coating method, a dip coating method, a roll coating method, a vacuum evaporation method, or the like can be used.

The thickness of the hydrophobic film 5 is not particularly limited, but is appropriately selected according to the viscosity and surface tension of the sample (sample) to be quantified. For example, when a sample having a large viscosity or a sample having a large surface tension is used, a hydrophobic film having a small thickness may be used. On the other hand, when using a specimen having a small viscosity or surface tension, it is desirable to form a thick hydrophobic film.

[Sample Holder] A sample holder 7 on which the hydrophobic film 5 is not formed is formed substantially at the center of the hydrophobic film 5. The sample holder 7 has a rectangular planar shape, and is formed from one end face 3a on the light incident side to the other end face 3b opposed thereto. still,
The shape of the sample holding unit 7 is an example, and may be an elliptical shape or another shape. FIG. 1B is a side sectional view of the sensor plate 1. As shown in this figure, one end face 3
The light incident from a propagates through the upper and lower surfaces of the optical waveguide 3 while repeating total reflection, is transmitted while being reflected by the above-described specimen holding unit 7, and is emitted from the other end surface 3b. At this time, the sample holding unit 7 is formed to be long along the light propagation direction. Specifically, the light is reflected multiple times by the sample holding unit 7 based on the thickness of the optical waveguide and the critical angle of total reflection. It is long enough to Therefore, light attenuation (resonance of the plasmon wave and the evanescent wave) is repeated, and the measurement sensitivity is improved.

FIG. 1C is a cross-sectional view showing a state in which the sample holding portion 7 of the sensor plate 1 is filled with the sample 9 to be quantified. Since the sample holding unit 7 is surrounded by the hydrophobic film 5, even if the sample 9 is filled, the sample holding unit 7 does not easily overflow from the sample holding unit 7.

[Measurement of Sample] Next, the actual measurement of the sample 9 will be described with reference to FIG. FIG. 2A is a cross-sectional view showing a state where the lower part of the optical waveguide 3 is left open to the air. In order for light incident in such a state to be propagated by total reflection, the following conditions must be satisfied. That is, if the refractive index of the optical waveguide 3 is n1, the refractive index of the hydrophobic film 5 is n2, and the refractive index of air is n3, n
It is necessary to satisfy 1> n2 and n1> n3. Further, when the sensor plate 1 is used by being mounted on the fixed base 10, if the refractive index of the fixed base 10 is n4, n1> n2
In addition, the condition of n1> n4 must be satisfied. In addition, when the optical waveguide 3 is mounted on the fixed base 10 via the matching oil, the refractive index of the matching oil needs to be smaller than the refractive index n1 of the optical waveguide 3.

In actual measurement, light for measurement is irradiated from one end face 3a of the sensor plate 1. As a light source for irradiating light, a halogen lamp, a light emitting diode (LED) or the like (not shown) is used. Then, the light incident on the optical waveguide 3 is also reflected at a portion where the optical waveguide 3 and the specimen 9 are in contact. At this time, when the characteristic of the reflected light changes as the characteristic of the specimen 9 (spectral change caused by the resonance of the plasmon wave and the evanescent wave), the characteristic of the specimen 9 can be known by analyzing the change. However, it is necessary to check the reflection characteristics in advance by using a reference sample (not shown) as a reference, and to compare the result with the actually measured result of the sample.

The case where light passes through the optical waveguide 3 has been described above. However, the present invention is not limited to this. For example, a reflection film (not shown) functioning as a reflection mirror may be formed on the other end surface of the optical waveguide 3. As described above, when the reflective film is formed, when the light is transmitted from one end surface 3a to the other end surface 3b, and when the light is transmitted from the other end surface 3b to the one end surface 3a, the reflection film is formed in the region of the sample holding unit 7. Since the light is totally reflected, the sensitivity is improved.

[Second Embodiment] Next, a second embodiment will be described with reference to FIG. The same components as those in the first embodiment will be described using the same reference numerals. The same applies to the third and subsequent embodiments. This embodiment shares basic components with the first embodiment. However, a feature of this embodiment is that a lower covering surface 5a is formed on the lower surface of the optical waveguide 3. The reason why the lower coating surface 5a is formed on the lower surface of the optical waveguide 3 is to prevent unnecessary light from being mixed from the lower surface of the optical waveguide 3 and lowering the measurement accuracy.

Although various materials can be considered as the material of the lower covering surface 5a, the same material as the above-mentioned hydrophobic film 5 may be used. That is, PTFE (Poly Tetra Fluoro Ethylen
e), FEP (Fluorinated Ethylene Propylene Copolyme)
r), PFA (Tetra Fluoro Ethylene-PerFluoro Alkylvi)
nyl ether Copolymer) or ETFE (Ethylene Tetr)
a Fluoro Ethylene) can be used. Also,
As a forming method, a spin coating method, a dip coating method, a roll coating method, a vacuum evaporation method, or the like can be used. Also, the thickness of the lower coating film 5a is not particularly limited as in the case of the hydrophobic film 5.

The refractive index required for the lower coating film 5a is required to be smaller than the refractive index n1 of the optical waveguide 3 as in the case of the hydrophobic film 5.

[Third Embodiment] Next, a third embodiment will be described with reference to FIG. This embodiment has the same basic components as the first embodiment. However, the present embodiment is different in that the metal thin film 6 is formed on the surface of the optical waveguide 3 in a region corresponding to the specimen holding unit 7. The metal thin film 6 is formed to use the sensor plate 31 as, for example, an SPR sensor for measuring an immune reaction. Actually, a dielectric film 8 is further formed on the metal thin film 6, and an antigen (or an antibody) or the like is further fixed on the dielectric film 8.

The material of the metal thin film 6 is generally Au or the like, but is not particularly limited to Au.
For forming the metal thin film 6, a vacuum deposition method, a sputtering method, or the like is used. In the present embodiment, the case where the metal thin film 6 is formed on the sample holding unit 7 after forming the hydrophobic film 5 on the optical waveguide 3 has been described, but the present invention is not limited to this. . That is, the metal thin film 6 may be formed in advance on the optical waveguide 3 at a position corresponding to the sample holding unit 7, and then the hydrophobic film 5 may be formed.

As described above, the metal thin film 6 is formed on the surface of the optical waveguide 3.
Is formed, a surface plasmon resonance phenomenon occurs. That is, when light enters from one end face 3 a of the optical waveguide 3, light of a specific wavelength causes surface plasmon resonance in the metal thin film 6. This attenuates the intensity of light of this wavelength. The attenuation of the light of the specific wavelength becomes remarkable when the light is reflected to the region of the metal thin film 6 a plurality of times.
On the other end face 3b side, the wavelength distribution of the emitted light is measured. Then, by examining the difference between the wavelength distribution of the incident light and the wavelength distribution of the emitted light, it is possible to identify the wavelength at which the light intensity has attenuated. This makes it possible to use the sensor plate 31 as an SPR sensor to measure an immune reaction or the like.

[Fourth Embodiment] Next, a fourth embodiment will be described with reference to FIG. In the present embodiment, the third
This embodiment has the same basic components as those of the first embodiment. However, in the present embodiment, the metal thin film 46 is
In that it is formed over the entire upper surface. That is, when the sensor plate 41 is manufactured, the metal thin film 46 is formed on the entire upper surface of the optical waveguide 3 in advance. In the case where the metal thin film 46 is formed on the whole, a pretreatment such as masking is not required, so that the manufacturing process is simplified.

The hydrophobic film 5 is formed on the surface of the metal thin film 46.
To form As a result, the metal thin film 46 is exposed on the sample holding unit 7, and the SP is formed by forming the dielectric film 8 on the metal thin film 46 exposed on the sample holding unit 7.
A sensor plate 41 as an R sensor can be configured. When the metal thin film 46 is entirely formed as in this embodiment, a surface plasmon resonance phenomenon occurs in a portion not in contact with the sample 9 (near one end 3a and the other end 3b). Can be considered. If the surface plasmon resonance phenomenon occurs in this part, it may be impossible to correctly quantify the specimen. Therefore, in order to solve such a problem, it is desirable that the specimen holding unit 7 is formed as long as possible along the light propagation direction so that total reflection does not occur in a part not touching the specimen 9.

[Fifth Embodiment] Next, a fifth embodiment will be described with reference to FIG. In the present embodiment, the fourth
This embodiment has the same basic components as those of the first embodiment. However, the present embodiment is different in that the lower coating film 5a is formed on the entire lower surface of the optical waveguide 3. As described above, when the lower coating film 5a is formed on the lower surface of the optical waveguide 3, unnecessary light is not mixed from the lower surface of the optical waveguide 3, and the measurement accuracy can be maintained at a high level.

[Sixth Embodiment] Next, a sixth embodiment will be described with reference to FIG. In the present embodiment, the first
This embodiment has the same basic components as those of the first embodiment. However, the present embodiment is characterized in that a plurality of sample holding units 67 are formed. More specifically, in this embodiment, eight sample holding units 67 are formed in parallel along a direction perpendicular to the direction in which light propagates. Although the size of each sample holding unit 67 in FIG. 7 is the same as that of the first embodiment, the width may be increased as necessary. Increasing the width increases the area where light reflects,
This is because sensitivity may be improved. Further, the number of the sample holding units 67 is also an example.
The number may be less than or equal to nine, or nine or more.

The actual measurement of the sample 9 is performed as follows. For example, when the light source that irradiates light and the light receiving unit that receives light are one set, the light source and the light receiving unit are positioned corresponding to the sample holding unit at a specific location, and the sample holding unit 67 is filled. The measurement is performed on the sample 9 that is present. When the first measurement is completed, the light source and the light receiving unit are subsequently positioned at positions corresponding to the adjacent sample holding unit 67. Then, measurement is performed. By repeating this, the measurement is performed for all the sample holding units 67. This allows
It is possible to quickly measure many items and other samples.

The sensor plate 61 may be moved instead of moving the light source and the light receiving section. That is, the light source and the light receiving unit are fixed, and the sensor plate 61 is placed on a movable table (not shown). Then, in the same manner as described above, the sensor plate 61 is moved so as to correspond to each sample holding section 67. Thus, the sensor plate 6
When moving 1, the light source and the light receiving unit that require optical positioning accuracy are fixed.
An improvement in the positioning accuracy of the optical system can be expected.

In addition, the light source and the light receiving unit are connected to the sample holding unit 6.
The number of samples 9 can be measured for each sample holding unit 67 by providing the same number as the number 7 and turning on each light source one by one in order. As described above, when a plurality of light sources are provided, a small light source such as an LED is used to secure a degree of freedom in arrangement. It is also because it has advantages such as low power consumption. However, when the light from the light source is transmitted to the sensor plate 61 using an optical fiber or the like, the degree of freedom in positioning the light source is improved, so that a small light source need not be used.

[Seventh Embodiment] Next, a seventh embodiment will be described with reference to FIG. In the present embodiment, the sixth
This embodiment has the same basic components as those of the first embodiment. However, the present embodiment is different in that a lower coating film 65a is formed on the entire lower surface of the optical waveguide 63. As described above, when the lower coating film 65a is formed on the lower surface of the optical waveguide 63, unnecessary light does not enter from the lower surface of the optical waveguide 53, and the measurement accuracy can be maintained high.

Further, by forming a metal thin film (not shown) on the optical waveguide 63 in each sample holding section 67, the sensor plate 71 can be used as an SPR sensor. When an immunoreaction measurement is performed using the sensor plate 71 having a plurality of sample holding units 67, the same sample 9 may be filled in each of the sample holding units 67 and the immunoreaction measurement may be performed. A different sample may be filled every 67 and the immunological reaction may be measured. Further, different antigens (or antibodies) may be immobilized on each sample holding section 67, and multiple items of immune reaction measurement for the same sample may be performed.

[0047]

Since the present invention is constructed and functions as described above, according to this, it is possible to hold a specimen without processing a special recess or the like on the sensor plate. Further, since the sample holding portion has a predetermined length, the portion where the sample is in contact with the optical waveguide is reflected a plurality of times, and the accuracy of measurement can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing a sensor plate according to a first embodiment of the present invention, and FIG. 1 (A) is a perspective view, and FIG.
FIG. 1B is a side sectional view, and FIG. 1C is a side sectional view showing a state in which the sample is filled in FIG. 1B.

2A and 2B are cross-sectional views illustrating a case where measurement is performed with the sensor plate disclosed in FIG. 1; FIG. 2A illustrates a case where air is below the optical waveguide; FIG. Shows the case where is a fixed base.

FIG. 3 is a view showing a sensor plate according to a second embodiment of the present invention, and FIG. 3 (A) is a perspective view, and FIG.
FIG. 3B is a side sectional view, and FIG. 3C is a side sectional view showing a state in which the sample is filled in FIG. 3B.

FIG. 4 is a view showing a sensor plate according to a third embodiment of the present invention. FIG. 4 (A) is a perspective view, and FIG.
4B is a side sectional view, and FIG. 4C is a side sectional view showing a state in which the sample is filled in FIG. 4B.

FIG. 5 is a view showing a sensor plate according to a fourth embodiment of the present invention, and FIG. 5 (A) is a perspective view, and FIG.
FIG. 5B is a side sectional view, and FIG. 5C is a side sectional view showing a state in which the sample is filled in FIG. 5B.

FIG. 6 is a view showing a sensor plate according to a fifth embodiment of the present invention. FIG. 6 (A) is a perspective view, and FIG.
FIG. 6B is a side sectional view, and FIG. 6C is a side sectional view showing a state in which the sample is filled in FIG. 6B.

FIG. 7 is a view showing a sensor plate according to a sixth embodiment of the present invention, and FIG. 7 (A) is a perspective view, and FIG.
FIG. 7B shows a front sectional view when the sample is filled, and FIG.
(C) is a side sectional view when the sample is filled.

FIG. 8 is a view showing a sensor plate according to a seventh embodiment of the present invention, and FIG. 8 (A) is a perspective view, and FIG.
(B) shows a front sectional view when the sample is filled, and FIG.
(C) is a side sectional view when the sample is filled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor plate 3 Optical waveguide 5 Hydrophobic film 6 Metal thin film 7 Sample holding part 9 Sample

Claims (7)

[Claims] 1. A plate-shaped optical waveguide through which light incident from a predetermined side end surface is repeatedly reflected and transmitted, and a sample holding portion for holding a liquid sample at a predetermined position on an upper surface of the optical waveguide;
A sensor plate, comprising: a hydrophobic film that covers an upper surface of the optical waveguide except for the sample holding unit; and wherein the sample holding unit has a predetermined length along the light propagation direction. 2. The sensor plate according to claim 1, wherein the length of the sample holding unit is set to a length at which incident light is reflected at least twice in a region of the sample holding unit. 3. The sensor plate according to claim 1, further comprising a lower coating film that covers a lower surface of the optical waveguide. 4. The apparatus according to claim 1, wherein a predetermined metal thin film is provided in an area corresponding to said sample holding section.
The sensor plate as described. 5. A method according to claim 1, wherein a predetermined metal thin film is formed on the entire surface between the optical waveguide and the hydrophobic film.
Or the sensor plate according to 3. 6. The sensor plate according to claim 1, wherein at least two sample holding portions are formed. 7. The sensor plate according to claim 1, wherein said hydrophobic film is formed of a fluororesin.