JP2014185894A - SPR sensor cell and SPR sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SPR sensor cell and an SPR sensor having quite excellent detection sensitivity.SOLUTION: An SPR sensor cell serving as an SPR sensor includes: an underclad layer; a core layer formed to be adjacent to the underclad layer at least in part; and a metal layer coating the core layer. The core layer includes a first core layer and a second core layer with a refractive index lower than the first core layer. The first core layer is arranged between the second core layer and the metal layer.

Description

  The present invention relates to an SPR sensor cell and an SPR sensor. More specifically, the present invention relates to an SPR sensor cell and an SPR sensor provided with an optical waveguide.

  Conventionally, in fields such as chemical analysis and biochemical analysis, an SPR (Surface Plasmon Resonance) sensor including an optical fiber has been used. In an SPR sensor including an optical fiber, a metal thin film is formed on the outer peripheral surface of the tip portion of the optical fiber, an analysis sample is fixed, and light is introduced into the optical fiber. Among the introduced light, light of a specific wavelength generates surface plasmon resonance in the metal thin film, and the light intensity is attenuated. In such an SPR sensor, the wavelength for generating surface plasmon resonance usually varies depending on the refractive index of the analysis sample fixed to the optical fiber. Therefore, if the wavelength at which the light intensity is attenuated after the occurrence of surface plasmon resonance is measured, the wavelength at which the surface plasmon resonance is generated can be identified, and if it is detected that the attenuation wavelength has changed, the surface plasmon resonance is detected. Since it can be confirmed that the wavelength to be generated has changed, the change in the refractive index of the analysis sample can be confirmed. As a result, such an SPR sensor can be used for various chemical analysis and biochemical analysis such as measurement of sample concentration and detection of immune reaction.

  In the SPR sensor including such an optical fiber, since the tip end portion of the optical fiber has a fine cylindrical shape, there is a problem that it is difficult to form a metal thin film and fix the analysis sample. In order to solve such a problem, for example, a core through which light passes and a clad covering the core are provided, and a through-hole that reaches the surface of the core is formed at a predetermined position of the clad, and this through-hole is supported. There has been proposed an SPR sensor cell in which a metal thin film is formed on the surface of the core at the position (for example, Patent Document 1). According to such an SPR sensor cell, it is easy to form a metal thin film for generating surface plasmon resonance on the core surface and to fix the analysis sample to the surface. Further, in such an SPR sensor cell, it has been proposed to improve the detection accuracy of the SPR sensor cell by continuously changing the refractive index of the region on the under cladding layer side in the core layer (Patent Document 2).

  However, in recent years, in chemical analysis and biochemical analysis, there is an increasing demand for detection of minute changes and / or trace components, and further improvement in detection sensitivity of the SPR sensor cell is required.

JP 2000-19100 A JP 2012-107902 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an SPR sensor cell and an SPR sensor having extremely excellent detection sensitivity.

According to the present invention, an SPR sensor cell is provided. The SPR sensor cell of the present invention is an SPR sensor having an under cladding layer, a core layer provided so that at least a part thereof is adjacent to the under cladding layer, and a metal layer covering the core layer, The core layer includes a first core layer and a second core layer having a lower refractive index than the first core layer, and the first core layer includes the second core layer and the metal layer. It is arranged between.
In a preferred embodiment, the difference (ΔN = N ₁ −N ₂ ) between the refractive index (N ₁ ) of the first core layer and the refractive index (N ₂ ) of the second core layer is 0.001 < The relationship ΔN <0.045 is satisfied.
In a preferred embodiment, the thickness (T ₁ ) of the first core layer is 2 μm to 15 μm.
In a preferred embodiment, a ratio (T ₁ / T ₂ ) of the thickness (T ₁ ) of the first core layer to the thickness (T ₂ ) of the _second core layer is 0.7 or less.
In a preferred embodiment, the refractive index (N ₁ ) of the first core layer satisfies a relationship of 1.34 ≦ N ₁ ≦ 1.43.
According to another aspect of the present invention, an SPR sensor is provided. The SPR sensor of the present invention includes the SPR sensor cell.

  According to the present invention, the core layer is composed of two layers having different refractive indexes, and the layer having the higher refractive index is disposed on the metal layer side, whereby light incident on the core layer is unevenly distributed on the metal layer side. be able to. As a result, the SPR is preferably excited and the SPR signal (as a result, the S / N ratio) increases, so that an SPR sensor cell and an SPR sensor excellent in detection sensitivity can be provided.

It is a schematic perspective view explaining the SPR sensor cell by preferable embodiment of this invention. (A) is a schematic plan view of the SPR sensor cell shown in FIG. 1, (b) is AA sectional drawing of (a). It is a schematic sectional drawing explaining an example of the manufacturing method of the SPR sensor cell of this invention. It is a schematic sectional drawing explaining the SPR sensor by preferable embodiment of this invention.

A. SPR Sensor Cell FIG. 1 is a schematic perspective view illustrating an SPR sensor cell according to a preferred embodiment of the present invention. 2A is a schematic view of the SPR sensor cell shown in FIG. 1 as viewed from above, and FIG. 2B is a cross-sectional view taken along line AA in FIG.

  As shown in FIGS. 1 and 2, the SPR sensor cell 100 is formed in a bottomed frame shape having a substantially rectangular shape in plan view, and includes an under cladding layer 11 formed on the substrate 10, a core layer 12, and a metal layer. 13. The core layer 12 is composed of a first core layer 12a and a second core layer 12b having a lower refractive index than the first core layer. The under cladding layer 11 and the core layer 12 constitute an optical waveguide, and function as a detection unit that detects the state of the sample and / or its change together with the metal layer 13 covering the core layer 12. The SPR sensor cell 100 includes a sample placement unit 20 that is placed so that a sample (for example, solution or powder) to be analyzed is in contact with a detection unit (substantially a metal layer). In the illustrated form, the sample placement portion 20 is defined by the overcladding layer 14, but the overcladding layer 14 may be omitted as long as the sample placement portion 20 can be appropriately provided. The substrate 10 may also be omitted depending on the purpose. In the sample placement unit 20, a sample to be analyzed (for example, a solution or a powder) is placed in contact with the detection unit (substantially a metal layer).

  The under cladding layer 11 is formed in a substantially rectangular flat plate shape having a predetermined thickness in plan view. The thickness of the under cladding layer is, for example, 5 μm to 400 μm.

  The core layer 12 is formed in a substantially prismatic shape extending in a direction orthogonal to both the width direction of the undercladding layer 11 (left and right direction in FIG. 2) and the thickness direction. Arranged on the top surface. The core layer is formed so that both end surfaces in the extending direction thereof are flush with both end surfaces in the corresponding direction of the under cladding layer. The direction in which the core layer extends is the direction in which light propagates in the optical waveguide.

  The core layer 12 includes a first core layer 12a and a second core layer 12b. The first core layer 12a is disposed on the upper surface of the second core layer 12b (in other words, between the second core layer 12b and the metal layer 13).

The refractive index (N ₁ ) of the first core layer 12a is, for example, 1.650 or less, preferably 1.43 or less, more preferably less than 1.40, and even more preferably 1.38 or less. is there. By setting the refractive index of the first core layer to 1.43 or less, the detection sensitivity can be significantly improved. The lower limit of the refractive index of the first core layer is, for example, the refractive index (N _CL ) +0.002 of the under cladding layer 11. For example, the first core layer has a refractive index of 1.34 or more. If the refractive index of the first core layer is 1.34 or more, SPR can be excited even with an aqueous sample (water refractive index: 1.33), and a general-purpose material is used. can do. In the present specification, the refractive index means a refractive index at a wavelength of 830 nm.

The refractive index (N ₂ ) of the second core layer 12 b is higher than the refractive index (N _CL ) of the under cladding layer 11 and lower than the refractive index (N ₁ ) of the first core layer. According to the second core layer having such a refractive index, a part of the light incident on the second core layer can be transferred to the first core layer. As a result, light uniformly incident on the entire core layer (the first core layer and the second core layer) is unevenly distributed in the first core layer near the metal layer, so that the amount of light contributing to SPR excitation can be reduced. Can be increased. The refractive index (N ₂ ) of the second core layer is preferably set so as to satisfy the relationship with the refractive index of the first core layer and / or the refractive index of the underclad layer described later.

The difference (ΔN = N ₁ −N ₂ ) between the refractive index of the first core layer 12a and the refractive index of the second core layer 12b preferably satisfies the relationship 0.001 <ΔN <0.045, and more Preferably, the relationship of 0.005 ≦ ΔN ≦ 0.040 is satisfied, and more preferably the relationship of 0.005 ≦ ΔN ≦ 0.030 is satisfied. If the difference between the refractive index of the first core layer and the refractive index of the second core layer is within such a range, light incident on the entire core layer is efficiently unevenly distributed in the first core layer. Can do.

The difference (N ₂ −N _CL ) between the refractive index of the second core layer 12b and the refractive index of the under cladding layer 11 is preferably 0.001 or more. With such a refractive index difference, incident light can be confined in the core layer 12 and can function as the core of the optical waveguide. Furthermore, the refractive index difference is more preferably 0.010 or more, and further preferably 0.020 or more. With such a refractive index difference, the optical waveguide can be a so-called multimode, and the amount of light transmitted through the optical waveguide can be increased. As a result, the S / N ratio can be improved. it can. Further, the difference between the refractive index of the second core layer and the refractive index of the under cladding layer is preferably 0.15 or less, more preferably 0.10 or less, and further preferably 0.050 or less. If the difference between the refractive index of the second core layer and the refractive index of the under cladding layer is within such a range, light having a reflection angle that causes SPR excitation can exist in the core layer.

The thickness (T ₁ ) of the first core layer 12a can be, for example, 2 μm to 20 μm, preferably 2 μm to 15 μm, more preferably 2 μm to 10 μm. If the thickness of the first core layer exceeds 15 μm, the effect of uneven light distribution may be insufficient. If it is less than 2 μm, there may be a single mode. On the other hand, the thickness (T ₂ ) of the second core layer 12b is, for example, 3 μm to 198 μm, and is preferably set to satisfy the relationship with the thickness of the first core layer described later. The thickness of the core layer 12 (total thickness of the first core layer and the second core layer) is, for example, 5 μm to 200 μm, and preferably 20 μm to 200 μm. Moreover, the width | variety of a core layer is 5 micrometers-200 micrometers, for example, Preferably they are 20 micrometers-200 micrometers. With such a thickness and / or width, the optical waveguide can be a so-called multimode.

The ratio (T ₁ / T ₂ ) of the thickness (T ₁ ) of the first core layer 12a to the thickness (T ₂ ) of the _second core layer 12b is preferably 0.7 or less, more preferably 0.6 or less. More preferably, it is 0.5 or less, and particularly preferably 0.45 or less. Thus, by making the first core layer thinner than the second core layer, the degree of light uneven distribution can be increased, so that SPR excitation can be preferably generated. The lower limit of T ₁ / T ₂ is not particularly limited, but may be set to 0.02, for example, from the viewpoint of downsizing the SPR sensor cell.

  As a material for forming the first core layer 12a and the second core layer 12b, any appropriate material can be used as long as the above refractive index can be obtained. For example, specific examples include fluororesins, epoxy resins, polyimide resins, polyamide resins, silicone resins, acrylic resins, and modified products thereof (for example, fluorene-modified products, deuterium-modified products, and fluorine-modified products in cases other than fluorine resins) ). These may be used alone or in combination of two or more. These can be used as a photosensitive material, preferably by blending a photosensitive agent. The under-cladding layer 11 is made of a material similar to the material forming the first core layer and / or the second core layer, and adjusted to have a refractive index lower than that of the second core layer. Can be formed.

  As shown in FIG. 2, the metal layer 13 is formed so as to uniformly cover the upper surface of the core layer 12 (substantially, the first core layer 12a). Unlike the illustrated example, the upper surface and both side surfaces of the core layer may be covered with a metal layer. Further, not only the core layer but also the exposed portion (the portion where the core layer is not disposed) on the upper surface of the under cladding layer may be covered with a metal layer. Preferably, an easily bonding layer (not shown) may be provided between the core layer 12 (substantially, the first core layer 12a) and the metal layer 13. By forming the easy adhesion layer, the core layer and the metal layer can be firmly fixed.

  Examples of the material for forming the metal layer 13 include gold, silver, platinum, copper, aluminum, and alloys thereof. The metal layer may be a single layer or may have a laminated structure of two or more layers. The thickness of the metal layer (when having a laminated structure, the total thickness of all layers) is preferably 20 nm to 70 nm, and more preferably 30 nm to 60 nm.

  As a material for forming the easy-adhesion layer, chrome or titanium is typically given. The thickness of the easy adhesion layer is preferably 1 nm to 5 nm.

  As shown in FIG. 1, the over clad layer 14 is formed in a rectangular frame shape in plan view so that the outer periphery of the over clad layer 11 is substantially the same as the outer periphery of the under clad layer 11 in plan view. The core layer 12 penetrates the lower end of the substantially central portion in the width direction. A portion surrounded by the upper surface of the under-cladding layer and the core layer and the over-cladding layer is partitioned as the sample placement portion 20. By arranging the sample in the section, the detection unit (substantially the metal layer 13) and the sample come into contact with each other, and detection is possible. Furthermore, by forming such a partition, the sample can be easily placed on the surface of the metal layer, so that workability can be improved.

  Examples of the material for forming the over clad layer 14 include a material for forming the core layer and the under clad layer, and silicone rubber. The thickness of the over clad layer (thickness from the upper surface of the core layer 12) is preferably 5 μm to 2000 μm, and more preferably 25 μm to 200 μm. The refractive index of the overcladding layer is preferably lower than the refractive index of the core layer. In one embodiment, the refractive index of the overclad layer is equivalent to the refractive index of the underclad layer.

  Although SPR sensor cells according to preferred embodiments of the present invention have been described, the present invention is not limited thereto. For example, you may provide a protective layer in the exposed part (part where a core layer is not arrange | positioned) of an under clad layer upper surface, or the exposed part (part which is not coat | covered with a metal layer) of a core layer side surface. By providing the protective layer, for example, when the sample is in a liquid state, the core layer and / or the clad layer can be prevented from swelling due to the sample. Examples of the material for forming the protective layer include silicon dioxide and aluminum oxide. These materials can preferably be adjusted to have a refractive index lower than that of the core layer. The thickness of the protective layer is preferably 1 nm to 100 nm, more preferably 5 nm to 20 nm.

  Furthermore, regarding the relationship between the core layer and the under cladding layer, it is sufficient that at least a part of the core layer is provided adjacent to the under cladding layer. For example, in the above-described embodiment, the configuration in which the core layer is formed on the under cladding layer has been described. However, the core layer has an under surface so that only the upper surface (more specifically, the upper surface of the first core layer) is exposed. It may be embedded in the cladding layer or may be provided so as to penetrate the under cladding layer.

  Furthermore, the number of core layers in the SPR sensor may be changed according to the purpose. Specifically, a plurality of core layers may be formed at a predetermined interval in the width direction of the under cladding layer. With such a configuration, since a plurality of samples can be analyzed simultaneously, the analysis efficiency can be improved. As the shape of the core layer, any appropriate shape (for example, a semi-cylindrical shape or a convex column shape) can be adopted depending on the purpose.

  Furthermore, a lid may be provided on the top of the SPR sensor cell 100 (sample placement unit 20). With such a configuration, the sample can be prevented from coming into contact with the outside air. Further, when the sample is a solution, a change in concentration due to evaporation of the solvent can be prevented. When the lid is provided, an inlet for injecting the liquid sample into the sample placement portion and a discharge port for discharging from the sample placement portion may be provided. With such a configuration, the sample can be flowed and continuously supplied to the sample placement unit, so that the characteristics of the sample can be continuously measured.

  The above embodiments may be appropriately combined with each other.

B. Method for Manufacturing SPR Sensor Cell The SPR sensor cell of the present invention can be manufactured by any suitable method. Below, an example of the manufacturing method of the SPR sensor cell of this invention is demonstrated, referring FIG.

  First, as shown in FIG. 3A, a material 11 ′ for forming an under cladding layer is applied on the substrate 10. Next, as shown in FIG. 3B, the under cladding layer forming material 11 ′ is irradiated with ultraviolet rays, and the material is cured to form the under cladding layer 11. Next, the second core layer forming material 12b ′ is applied on the under cladding layer 11 and irradiated with ultraviolet rays to cure the material to form the second core layer 12b (FIG. 3C to FIG. 3C). (D)). Next, the first core layer forming material 12a ′ is applied onto the second core layer 12b and irradiated with ultraviolet rays to cure the material to form the first core layer 12a (FIG. 3E). ) To (f)). The irradiation conditions of the ultraviolet rays with respect to the forming material of each layer can be appropriately set according to the type of the material. If necessary, the material may be heated. Heating may be performed before ultraviolet irradiation, may be performed after ultraviolet irradiation, or may be performed in combination with ultraviolet irradiation.

  Next, the core layer 12 (the first core layer 12a and the second core layer 12b) is patterned into a predetermined shape by etching or the like (FIG. 3G). Thereafter, as shown in FIG. 3H, the metal layer 13 is formed so as to cover the upper surface of the core layer 12. Preferably, an easy adhesion layer (not shown) is formed on the upper surface of the core layer, and the core layer is covered with the metal layer 13 via the easy adhesion layer. The metal layer is formed by, for example, vacuum deposition, ion plating or sputtering of a material for forming the metal layer through a mask having a predetermined pattern. The easy adhesion layer is formed, for example, by sputtering chromium or titanium.

  Finally, as shown in FIG. 3I, the over clad layer 14 having the predetermined frame shape is formed. The over clad layer 14 can be formed by any appropriate method. For example, the over clad layer 14 is formed by placing a mold having the predetermined frame shape on the under clad layer and the core layer, filling the mold with a varnish of an over clad layer forming material, and drying, if necessary. It can be formed by curing and finally removing the mold. When a photosensitive material is used, the over clad layer 14 can be formed by applying varnish to the entire surface of the under clad layer and the core layer, and after drying, exposing and developing through a photomask having a predetermined pattern. .

  As described above, the SPR sensor cell shown in FIG. 1 can be manufactured.

C. SPR Sensor FIG. 4 is a schematic cross-sectional view illustrating an SPR sensor according to a preferred embodiment of the present invention. The SPR sensor 200 includes an SPR sensor cell 100, a light source 110, and an optical measuring instrument 120. The SPR sensor cell 100 is the SPR sensor of the present invention described in the above items A and B.

  Any appropriate light source can be adopted as the light source 110. Specific examples of the light source include a white light source and a monochromatic light source. The optical measuring instrument 120 is connected to any appropriate arithmetic processing device, and can store, display and process data.

  The light source 110 is connected to the light source side optical fiber 112 via the light source side optical connector 111. The light source side optical fiber 112 is connected to one end portion in the propagation direction of the SPR sensor cell 100 (core layer 12) through the light source side fiber block 113. A measuring instrument side optical fiber 115 is connected to the other end portion in the propagation direction of the SPR sensor cell 100 (core layer 12) via a measuring instrument side fiber block 114. The measuring instrument side optical fiber 115 is connected to the optical measuring instrument 120 via the measuring instrument side optical connector 116. It is preferable to connect with a multimode optical fiber capable of propagating light having a reflection angle capable of SPR excitation into the optical waveguide.

  The SPR sensor cell 100 is fixed by any appropriate sensor cell fixing device (not shown). The sensor cell fixing device is movable along a predetermined direction (for example, the width direction of the SPR sensor cell), and thereby, the SPR sensor cell can be arranged at a desired position.

  The light source side optical fiber 112 is fixed by a light source side optical fiber fixing device 131, and the measuring instrument side optical fiber 115 is fixed by a measuring instrument side optical fiber fixing device 132. The light source side optical fiber fixing device 131 and the measuring instrument side optical fiber fixing device 132 are respectively fixed on any appropriate six-axis moving stage (not shown), and the propagation direction and width direction of the optical fiber ( It is movable in a propagation direction and a direction orthogonal to the horizontal direction) and a thickness direction (a direction orthogonal to the propagation direction in the vertical direction) and a rotation direction around each of these directions.

  According to such an SPR sensor, the light source 110, the light source side optical fiber 112, the SPR sensor cell 100 (core layer 12), the measuring instrument side optical fiber 115, and the optical measuring instrument 120 can be arranged on one axis, Light can be introduced from the light source 110 to be transmitted.

  Hereinafter, an example of the usage pattern of such an SPR sensor will be described.

  First, a sample is arrange | positioned at the sample arrangement | positioning part 20 of the SPR sensor cell 100, and a sample and the metal layer 13 are made to contact. Next, predetermined light from the light source 110 is introduced into the SPR sensor cell 100 (core layer 12) via the light source side optical fiber 112 (see arrow L1 in FIG. 4). The light introduced into the SPR sensor cell 100 (core layer 12) repeats total reflection while a part of the light moves from the second core layer 12b to the first core layer 12a in the core layer 12, and the SPR sensor cell 100 ( While being transmitted through the core layer 12, some light is incident on the metal layer 13 on the upper surface of the core layer 12 (substantially, the upper surface of the first core layer 12 a) and is attenuated by surface plasmon resonance. . The light transmitted through the SPR sensor cell 100 (core layer 12) is introduced into the optical measuring instrument 120 through the measuring instrument side optical fiber 115 (see arrow L2 in FIG. 4). That is, in the SPR sensor 200, the light intensity of the light introduced into the optical measuring instrument 120 is attenuated at the wavelength that caused the surface plasmon resonance in the core layer 12. Since the wavelength for generating surface plasmon resonance depends on the refractive index of the sample in contact with the metal layer 13, the attenuation of the light intensity of the light introduced into the optical measuring instrument 120 is detected to detect the refractive index of the sample. Changes can be detected.

  For example, when a white light source is used as the light source 110, the optical measuring instrument 120 measures the wavelength at which the light intensity attenuates after transmission through the SPR sensor cell 100 (the wavelength that generates surface plasmon resonance), and the attenuation wavelength changes. If this is detected, a change in the refractive index of the sample can be confirmed. For example, when a monochromatic light source is used as the light source 110, the optical measuring instrument 120 measures the change (degree of attenuation) of the monochromatic light after passing through the SPR sensor cell 100, and the degree of attenuation changes. If it is detected, it can be confirmed that the wavelength for generating surface plasmon resonance has changed, and the change in the refractive index of the sample can be confirmed.

  As described above, such an SPR sensor cell can be used for various chemical analysis and biochemical analysis such as measurement of the concentration of a sample and detection of an immune reaction based on a change in the refractive index of the sample. More specifically, for example, when the sample is a solution, the refractive index of the sample (solution) depends on the concentration of the solution. Therefore, if the refractive index of the sample is detected, the concentration of the sample is measured. Can do. Furthermore, if it is detected that the refractive index of the sample has changed, it can be confirmed that the concentration of the sample has changed. For example, in detecting an immune reaction, an antibody is immobilized on the metal layer 13 of the SPR sensor cell 100 via a dielectric film, and a specimen is brought into contact with the antibody. Since the refractive index of the sample changes when the antibody and the specimen are immunoreacted, it is possible to determine that the antibody and the specimen have immunoreacted by detecting the change in the refractive index of the sample before and after contact between the antibody and the specimen. it can.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In Examples and Comparative Examples, the measurement wavelength of the refractive index is 830 nm unless otherwise specified.

<Measurement of refractive index>
The refractive index was measured at a wavelength of 830 nm using a prism coupler type refractive index measuring device by forming a 10 μm thick film on a silicon wafer.

<Example 1>
An SPR sensor cell was produced by the method shown in FIG. Specifically, a fluorine-based UV curable resin (manufactured by Solvay Specialty Polymer Japan Co., Ltd., trade name “Fomblin MD40”) is applied on the silicon wafer as an undercladding layer forming material, followed by UV curing to form a film-like material. An under cladding layer (refractive index: 1.320, thickness: 20 μm) was formed. Next, a fluorine-based UV curable resin (manufactured by Solvay Specialty Polymer Japan Co., Ltd., trade name “Fluorolink MD700”) is applied as a second core layer forming material on the upper surface of the under clad layer, and UV-cured to form a film-like material. A second core layer (refractive index: 1.348, thickness: 35 μm) was formed. Subsequently, a fluorine-based UV curable resin (manufactured by DIC, trade name “OP38Z”) is applied to the upper surface of the second core layer as a first core layer forming material, and UV-cured to form a film-shaped first layer. 1 core layer (refractive index: 1.372, thickness: 15 μm) was formed. Next, the film-like first core layer and second core layer were etched to form a core layer (first core layer and second core layer) patterned in a straight line having a width of 50 μm. Thereafter, the silicon wafer on which the under cladding layer and the core layer were formed was diced and cut to a predetermined size (20 mm × 22.25 mm). Next, gold was sputtered through a mask having an opening (1 mm width × 6 mm length) to form a metal layer (thickness: 30 nm) so as to cover the upper surfaces of the core layer and the under cladding layer. Finally, a frame-shaped overcladding layer having a recess corresponding to the shape of the core layer is obtained by filling the same material as the undercladding layer forming material into a predetermined frame-shaped mold and curing it, and then removing the mold. Formed. In this manner, an SPR sensor cell similar to the SPR sensor cell shown in FIGS. 1 and 2 was produced except that the upper surface of the undercladding layer was also covered with the metal layer.

  The SPR sensor cell obtained above, a halogen light source (Ocean Optics, trade name “HL-2000-HP”, white light), and a spectroscope (Ocean Optics, trade name “USB4000”) are on one axis. The SPR sensor as shown in FIG. Specifically, a halogen light source (manufactured by Ocean Optics, Inc., product) via a graded multimode fiber (φ50 μm / 125 μm) so that light from the light source is introduced into the incident side end face of the core layer of the SPR sensor cell. The name “HL-2000-HP” (white light) was connected to the incident side of the SPR sensor cell (core layer), and a spectrometer (trade name “USB4000” manufactured by Ocean Optics, Inc.) was connected to the output side. As a sample, 40 μL of pure water (refractive index: 1.33) was added to the sample placement portion of the SPR sensor cell, white light was incident on one end of the core layer, and light emitted from the other end was measured with a spectrometer. Then, a transmittance spectrum is obtained when the light intensity of each wavelength when the light is transmitted through the SPR sensor cell (optical waveguide) without setting the sample is 100%, and the absorption intensity at the minimum value of the transmittance is measured. did. Here, it shows that detection sensitivity is so high that this absorption intensity is large. The results are shown in Table 1.

<Example 2>
An SPR sensor cell and an SPR sensor were produced in the same manner as in Example 1 except that the thickness of the first core layer was 5 μm and the thickness of the second core layer was 45 μm. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 3>
As a first core layer forming material, 60 parts by weight of a fluorine-based UV curable resin (manufactured by DIC, trade name “OP38Z”) and 40 parts by weight of a fluorine-based UV curable resin (manufactured by DIC, trade name “OP40Z”) The first core layer (refractive index: 1.384) having a thickness of 5 μm was formed using a mixture of the above and fluorine-based UV curable resin (Solvay Specialty Polymer Japan) as a material for forming the second core layer. A SPR sensor cell and an SPR sensor were produced in the same manner as in Example 1 except that a second core layer (refractive index: 1.348) having a thickness of 45 μm was formed using a product name “Fluorolink MD700” manufactured by the company. did. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 4>
As a first core layer forming material, 60 parts by weight of a fluorine-based UV curable resin (manufactured by DIC, trade name “OP38Z”) and 40 parts by weight of a fluorine-based UV curable resin (manufactured by DIC, trade name “OP40Z”) The first core layer (refractive index: 1.384) having a thickness of 5 μm was formed using a mixture of the fluorinated UV curable resin (manufactured by DIC Corporation, as a material for forming the second core layer). An SPR sensor cell and an SPR sensor were produced in the same manner as in Example 1 except that a second core layer (refractive index: 1.372) having a thickness of 45 μm was formed using a trade name “OP38Z”. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 5>
An SPR sensor cell and an SPR sensor were produced in the same manner as in Example 1 except that the thickness of the first core layer was 20 μm and the thickness of the second core layer was 30 μm. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 6>
Forming the first core layer (refractive index: 1.399) with a thickness of 5 μm using a fluorine-based UV curable resin (manufactured by DIC, trade name “OP40Z”) as the first core layer forming material, As a material for forming the second core layer, a fluorine-based UV curable resin (trade name “Fluorolink MD700” manufactured by Solvay Specialty Polymer Japan Co., Ltd.) is used and a second core layer having a thickness of 45 μm (refractive index: 1. SPR sensor cell and SPR sensor were manufactured in the same manner as in Example 1 except that 348) was formed. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 1>
An SPR sensor cell and an SPR sensor were produced in the same manner as in Example 1 except that the second core layer was not formed and the thickness of the first core layer was 50 μm. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Evaluation>
As is clear from Table 1, it can be seen that the SPR sensor cell of the example has higher absorption intensity and excellent sensitivity than the SPR sensor cell of the comparative example. In particular, the SPR sensor cells of Examples 1 to 4 have a remarkably superior sensitivity with a significantly higher absorption intensity than the SPR sensor cells of the comparative examples. This is presumably because the refractive index difference between the first core layer and the second core layer, the thickness ratio, and the like are set appropriately.

  The SPR sensor cell and SPR sensor of the present invention can be suitably used for various chemical analysis and biochemical analysis such as measurement of sample concentration and detection of immune reaction.

DESCRIPTION OF SYMBOLS 11 Under clad layer 12 Core layer 12a 1st core layer 12b 2nd core layer 13 Metal layer 14 Over clad layer 20 Sample arrangement part 100 SPR sensor cell 110 Light source 120 Optical measuring device 200 SPR sensor

Claims (6)

An SPR sensor having an under cladding layer, a core layer provided so that at least a part thereof is adjacent to the under cladding layer, and a metal layer covering the core layer,
The core layer includes a first core layer and a second core layer having a lower refractive index than the first core layer;
The first core layer is disposed between the second core layer and the metal layer;
SPR sensor cell. The difference (ΔN = N ₁ −N ₂ ) between the refractive index (N ₁ ) of the first core layer and the refractive index (N ₂ ) of the second core layer is 0.001 <ΔN <0.045. The SPR sensor cell according to claim 1, wherein the relationship is satisfied. The first thickness of the core layer _{(T 1)} is a 2Myuemu～15myuemu, SPR sensor cell according to claim 1 or 2. The ratio (T ₁ / T ₂ ) of the thickness (T ₁ ) of the first core layer to the thickness (T ₂ ) of the _second core layer is 0.7 or less, any one of claims 1 to 3 An SPR sensor cell according to claim 1. 5. The SPR sensor cell according to claim 1, wherein a refractive index (N ₁ ) of the first core layer satisfies a relationship of 1.34 ≦ N ₁ ≦ 1.43. An SPR sensor comprising the SPR sensor cell according to claim 1.