JP2016085160A - Spr sensor cell and spr sensor - Google Patents

Abstract

To provide an SPR sensor having very excellent detection sensitivity and capable of being manufactured at low cost.
An SPR sensor cell comprising an underclad layer, a core layer provided so that at least a part thereof is adjacent to the underclad layer, and a metal layer covering the core layer, wherein the metal layer However, the SPR sensor cell contains 95% by weight or more of Ag, the extinction coefficient of the metal layer is greater than 4, and the refractive index of the metal layer is less than 0.4.
[Selection] Figure 1

Description

  The present invention relates to an SPR sensor cell and an SPR sensor.

  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.

  However, in recent years, there has been an increasing demand for detection of minute changes and / or trace components with a small amount of specimen, and further improvement in detection sensitivity is also required in analysis using the SPR sensor as described above. On the other hand, since a highly accurate sensor is very expensive, a cheaper SPR sensor is required.

JP 2000-19100 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 that has a very excellent detection sensitivity and can be manufactured at low cost. .

  According to previous studies by the present inventors, it has been found that by reducing the refractive index of the core layer, the amount of wavelength shift of the SPR peak accompanying the change in the state of the analysis sample can be increased, thereby improving the sensitivity. (For example, JP2012-215541A). However, when the SPR peak is largely shifted to the long wavelength side, the SPR peak may occur in the near infrared light region. In this case, a near-infrared light source and a light receiving element are required, but these devices are expensive. In addition, the near-infrared spectroscope has a problem of poor sensitivity performance.

According to the present invention, an SPR sensor cell is provided. The SPR sensor cell of the present invention comprises 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 metal layer comprising: Ag is contained at 95% by weight or more, the extinction coefficient of the metal layer is larger than 4, and the refractive index of the metal layer is less than 0.4.
In one embodiment, the refractive index of the core layer is 1.34 to 1.43.
In one embodiment, the SPR sensor cell generates an SPR peak in the wavelength region of 600 nm to 725 nm.
In one embodiment, the metal layer contains at least one metal selected from the group consisting of Al, Pd, Cu and Ge.
According to another aspect of the present invention, an SPR sensor is provided. This SPR sensor includes the SPR sensor cell described above.

  According to the SPR sensor cell of the present invention, by using a metal layer having a specific refractive index and extinction coefficient, even if the wavelength shift amount is increased using a core layer having a low refractive index, the near red Measurement without using external light is possible. As a result, a device for near-infrared light is not required, and a low-cost and highly sensitive SPR sensor can be obtained. Furthermore, the metal layer excellent in stability can be obtained by forming the metal layer containing 95% by weight or more of Ag.

It is a schematic perspective view explaining the SPR sensor cell by preferable embodiment of this invention. It is an Ia-Ia line schematic sectional drawing of the SPR sensor cell shown in FIG. FIG. 3 is a schematic cross-sectional view of an SPR sensor cell according to another preferred embodiment of the present invention. 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. FIG. 2 is a schematic sectional view taken along line Ia-Ia of the SPR sensor cell shown in FIG. In the following description of the SPR sensor cell, when referring to a direction, the upper side of the drawing is the upper side, and the lower side of the drawing is the lower side.

  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 is embedded in the under cladding layer 11 so that the upper surface of the under cladding layer 11 is exposed. It has a core layer 12, an under cladding layer 11, and a metal layer 13 that covers the core layer 12. The under clad layer 11 and the core layer 12 constitute an optical waveguide, and function together with the metal layer 13 as the detection unit 10 that detects the state of the sample and / or its change. In the illustrated form, the SPR sensor cell 100 includes a sample placement unit 20 provided so as to be adjacent to the detection unit 10. The sample placement portion 20 is defined by the over clad layer 14. The over clad layer 14 may be omitted as long as the sample placement portion 20 can be appropriately provided. 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 (thickness from the upper surface of the core 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. Embedded in the upper end. The direction in which the core layer 12 extends is the direction in which light propagates in the optical waveguide.

  The core layer 12 is disposed such that the upper surface thereof is flush with the upper surface of the under cladding layer 11. By arranging the upper surface of the core layer so as to be flush with the upper surface of the under cladding layer, the metal layer can be efficiently arranged only on the upper side of the core layer. Furthermore, the core layer is disposed 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 refractive index (N _CO ) of the core layer 12 is preferably 1.43 or less, more preferably less than 1.40, and further preferably 1.38 or less. By setting the refractive index of the core layer to 1.43 or less, the detection sensitivity can be significantly improved. The lower limit of the refractive index of the core layer is preferably 1.34. If the refractive index of the 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 can be used. it can.

The refractive index (N _CO ) of the core layer 12 is higher than the refractive index (N _CL ) of the under cladding layer 11. The difference (N _CO -N _CL ) between the refractive index of the core layer and the refractive index of the under cladding layer is preferably 0.010 or more, more preferably 0.020 or more, and further preferably 0.025 or more. . If the difference between the refractive index of the core layer and the refractive index of the under cladding layer is within such a range, the optical waveguide of the detection unit can be set to a so-called multimode. Therefore, the amount of light transmitted through the optical waveguide can be increased, and as a result, the S / N ratio can be improved. Further, the difference between the refractive index of the core layer and the refractive index of the under cladding layer is preferably 0.15 or less, more preferably 0.10 or less, and still more preferably 0.050 or less. If the difference between the refractive index of the 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 of the core layer 12 is, for example, 5 μm to 200 μm, 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 length (waveguide length) of the core layer 12 is, for example, 2 mm to 50 mm, and preferably 10 mm to 20 mm.

  As a material for forming the core layer 12, any appropriate material can be used as long as the effects of the present invention can be obtained. 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 other than fluororesins). Can be mentioned. 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 can be formed of a material similar to the material forming the core layer and having a refractive index adjusted to be lower than that of the core layer.

  As shown in FIGS. 1 and 2, the metal layer 13 is formed so as to uniformly cover at least a part of the upper surfaces of the under cladding layer 11 and the core layer 12. If necessary, an easy adhesion layer (not shown) may be provided between the under cladding layer and the core layer and the metal layer. By forming the easy adhesion layer, the under clad layer, the core layer, and the metal layer can be firmly fixed.

The metal layer 13 has an extinction coefficient greater than 4 and a refractive index less than 0.4. According to the metal layer having such an extinction coefficient and refractive index, when used in combination with a low refractive index core layer (for example, N _CO ≦ 1.43), visible light region, preferably 600 nm to 725 nm. SPR peak can be generated in the wavelength region of. In the present specification, the extinction coefficient means an extinction coefficient at a wavelength of 650 nm. Moreover, a refractive index means the refractive index in wavelength 650nm.

  The extinction coefficient of the metal layer 13 is larger than 4, preferably 4.1 or more, more preferably 4.15 or more.

  The refractive index of the metal layer 13 is less than 0.4, preferably 0.3 or less, more preferably 0.2 or less. Further, the lower limit of the refractive index of the metal layer may be 0.12.

  The metal layer 13 contains 95% by weight or more of silver (Ag). The content of Ag is preferably 96% by weight or more, more preferably 97% by weight or more. The metal layer may be an alloy containing Ag in the above content.

  Components other than Ag contained in the metal layer 13 (hereinafter may be referred to as “subcomponents”) are not limited as long as the above extinction coefficient and refractive index are satisfied. Specific examples of the subcomponent include aluminum (Al), palladium (Pd), copper (Cu), germanium (Ge), and the like. An accessory component may be used independently and may be used in combination of 2 or more type. By using a combination of Ag and a predetermined amount of subcomponents, a metal layer having a desired extinction coefficient and refractive index and excellent in stability can be suitably obtained.

  The content of the subcomponent in the metal layer 13 can be appropriately set with the upper limit of 5% by weight depending on the desired extinction coefficient and refractive index. The Al content can be, for example, 0.1 wt% to 1 wt%. The content of Pd can be, for example, 0.1% by weight to 1% by weight. The Cu content can be, for example, 0.1 wt% to 3 wt%. The Ge content can be, for example, 4% to 5% by weight.

  The metal layer 13 may be a single layer or may have a laminated structure of two or more layers. When it has a laminated structure, the metal layer may be composed of a layer containing 95% by weight or more of Ag (Ag-containing layer) and another metal layer, and is composed of two or more different Ag-containing layers. Also good. 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 has a rectangular frame in plan view so that the outer periphery of the over clad layer 11 and the core layer 12 is substantially the same as the outer periphery of the under clad layer 11 in plan view. It is formed into a shape. A portion surrounded by the upper surfaces of the under-cladding layer 11 and the core layer 12 and the over-cladding layer 14 is defined as a sample placement portion 20. By arranging the sample in the section, the metal layer of the detection unit 10 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 is preferably 5 μm to 2000 μm, 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, as illustrated in FIG. 3, a protective layer 15 may be provided between the under cladding layer 11 and the core layer 12 and the metal layer 13. In this case, the protective layer 15 can be formed as a thin film having the same shape as that of the under cladding layer in plan view so as to cover all the upper surfaces of the under cladding layer 11 and the core layer 12. 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.

  Further, for example, in the relationship between the core layer and the under cladding layer, at least a part of the core layer may be provided so as to be adjacent to the under cladding layer. For example, in the above embodiment, the configuration in which the core layer is embedded in the under cladding layer has been described. However, the core layer may be provided so as to penetrate the under cladding layer. Moreover, it is good also as a structure which forms a core layer on an under clad layer and surrounds the predetermined part of the said core layer with an over clad 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. 4A to 4I are schematic cross-sectional views for explaining an example of the method for producing the SPR sensor cell of the present invention.

  First, as shown in FIG. 4A, the material 12 'for forming the core layer is disposed on the surface of the mold 30 having the recess corresponding to the shape of the core layer. Next, as shown in FIG. 4B, the transfer film 40 is bonded to the surface of the mold 30 while being pressed by the pressing means 50 in a predetermined direction, and the recess is filled with the core layer forming material 12 ′. Excess core layer forming material 12 'is removed. Thereafter, as shown in FIG. 4C, the core layer forming material 12 ′ filled in the recesses is irradiated with ultraviolet rays, and the material is cured to form the core layer 12. Further, as shown in FIG. 4D, the transfer film 40 is peeled from the mold 30 and the core layer 12 is transferred onto the transfer film 40.

  Next, as shown in FIG. 4E, an undercladding layer forming material 11 ′ is applied so as to cover the core layer 12. Alternatively, unlike the illustrated example, the under-cladding layer forming material 11 ′ is previously coated on another support (for example, a corona-treated PET film), and the under-cladding layer forming material 11 ′ is used as the core layer 12. The support and the transfer film 40 may be bonded to cover the substrate. Thereafter, as shown in FIG. 4 (f), the under cladding layer forming material 11 ′ is irradiated with ultraviolet rays, and the material is cured to form the under cladding layer 11. Thereafter, as shown in FIG. 4G, the transfer film 40 is peeled and removed, and the top and bottom are reversed.

  The irradiation condition of the ultraviolet rays can be appropriately set according to the type of 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, an easy-adhesion layer (not shown) is formed on the under cladding layer 11 and the core layer 12 as necessary. The easy adhesion layer is formed, for example, by sputtering chromium or titanium.

  Next, as shown in FIG. 4 (h), the metal layer 13 is formed so as to cover the core layer 12 on the core layer and the undercladding layer (on the protective layer when the protective layer is formed). Form. Specifically, the metal layer 13 is formed, for example, by vacuum deposition, ion plating, or sputtering of a material for forming the metal layer through a mask having a predetermined pattern.

  Finally, as shown in FIG. 4I, the over cladding 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 disposing a mold having the predetermined frame shape on the core layer and the under clad 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. In the case of using a photosensitive material, the over clad layer 14 can be formed by applying varnish to the upper surfaces of the core layer and the under clad layer, and after drying and 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. 5 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. The light source side optical fiber 112 and the measuring instrument side optical fiber 115 are preferably connected by 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, the sample is placed on the sample placement portion 20 of the SPR sensor cell 100, and the sample and the metal layer 13 are brought into contact with each other. 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. 5). The light introduced into the SPR sensor cell 100 (core layer 12) is transmitted through the SPR sensor cell 100 (core layer 12) while repeating total reflection in the core layer 12, and part of the light is on the upper surface of the core layer 12. Is incident on the metal layer 13 and 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. 5). 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.

<Measurement of refractive index>
For the refractive index of the metal layer, a 100 nm thick metal thin film was formed on a slide glass, and the value at a wavelength of 650 nm was measured by spectroscopic ellipsometry.

<Measurement of extinction coefficient>
As the extinction coefficient of the metal layer, a metal thin film having a thickness of 100 nm was formed on a slide glass, and a value at a wavelength of 650 nm was measured by spectroscopic ellipsometry.

<Evaluation of stability>
The appearance of the metal layer when the film was formed by sputtering on the slide glass was visually confirmed and evaluated according to the following criteria.
○: Discoloration is not recognized ×: Discoloration is recognized

<Elemental analysis>
The metal layer is dissolved with an acid, and ultrapure water is added to perform elemental analysis of the formed metal layer by inductively coupled plasma mass spectrometry (ICP-MS) and ICP emission spectroscopy (ICP-AES). The content of the component was calculated.

<Example 1>
The core layer forming material was dropped on the surface of a mold (length 200 mm, width 200 mm) having a concave portion for forming a core layer having a width of 50 μm and a thickness (depth) of 50 μm on the surface. One end of the corona-treated surface of a PP film (thickness: 40 μm) having a corona-treated one surface was brought into contact with the surface of the mold, and the other end was warped. In this state, the roller was rotated toward the other end side while pressing the roller from the PP film side against the contact portion between the mold and the PP film, and the two were bonded together. Thereby, the core layer forming material was filled in the concave portion of the mold, and the excess core layer forming material was extruded. Next, the obtained laminate was irradiated with ultraviolet rays from the PP film side, and the core layer forming material was completely cured to form a core layer (refractive index: 1.384). The core layer forming material is composed of 60 parts by weight of fluorine-based UV curable resin (DIC, trade name “OP38Z”) and 40 parts by weight of fluorine-based UV curable resin (DIC, trade name “OP40Z”). Was prepared by stirring and dissolving. Next, the PP film was peeled from the mold, and a substantially prismatic core layer having a thickness of 50 μm and a width of 50 μm was transferred onto the film.

  An undercladding layer forming material was applied on the PP film so as to cover the core layer. The undercladding layer forming material used was a fluorine-based UV curable resin (manufactured by Solvay Specialty Polymer Japan, trade name “Fluorolink MD700”). At this time, the coating was performed so that the thickness from the core layer surface (upper surface) was 100 μm. Next, ultraviolet rays were applied to cure the undercladding layer forming material to form an undercladding layer (refractive index: 1.347). Thereafter, the PP film was peeled and removed, and the under cladding layer and the core layer were turned upside down. As described above, an optical waveguide film having a core layer embedded in the under cladding layer was produced.

  The optical waveguide film was diced into a length of 22.25 mm and a width of 20 mm. Next, a metal layer forming material was sputtered through a mask having an opening having a length of 6 mm and a width of 1 mm to sequentially form metal layers (thickness: 30 nm) so as to cover the core layer. Specifically, sputtering was performed by placing a Pd fragment chip on the Ag target so that the Pd content of the metal layer was 0.5% by weight. Finally, a frame-shaped overcladding layer was formed by using a fluorine-based UV curable resin (trade name “Fluorolink MD700” manufactured by Solvay Specialty Polymer Japan Co., Ltd.) in the same manner as the undercladding layer was formed. In this manner, an SPR sensor cell similar to the SPR sensor cell shown in FIGS. 1 and 2 was produced.

  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 (trade name, manufactured by Ocean Optics, Inc.) is passed through a GI type 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. “HL-2000-HP” (white light) is connected to the incident side of the SPR sensor cell (core layer), and the light from the brightest place on the emission side end face of the core layer and the emission side end face of the under cladding layer is GI type light. The sample was introduced into the spectroscope via a multimode fiber (φ50 μm / 125 μm).

  Using the SPR sensor thus obtained, a transmittance spectrum is obtained when light is transmitted through the SPR sensor cell (optical waveguide) without placing the sample in the sample placement portion, and corresponds to the minimum value of the transmittance. The peak wavelength was measured. The results are shown in Table 1.

<Example 2>
Example 1 except that an Al fragment chip was used instead of the Pd fragment chip, and that the amount of Al placed on the Ag target was adjusted so that the Al content of the metal layer was 0.25 wt%. Similarly, an SPR sensor cell and an SPR sensor were produced. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 3>
Example 1 except that a Cu chip was used instead of the Pd chip and that the amount of Cu placed on the Ag target was adjusted so that the Cu content of the metal layer was 3% by weight. Thus, an SPR sensor cell and an SPR sensor were produced. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 4>
Example 1 except that a Ge fragment chip was used instead of the Pd fragment chip and that the amount of Ge placed on the Ag target was adjusted so that the Ge content of the metal layer was 5% by weight. Thus, an SPR sensor cell and an SPR sensor were produced. 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 only gold (Au) was used as the metal layer forming material. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 2>
An SPR sensor cell and an SPR sensor were produced in the same manner as in Example 1 except that only Ag was used as the metal layer forming material. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 3>
Example 1 except that a nickel (Ni) chip was used in place of the Pd chip and that the amount of Ni placed on the Ag target was adjusted so that the Ni content of the metal layer was 6% by weight. In the same manner as described above, an SPR sensor cell and an SPR sensor were produced. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 4>
The same procedure as in Example 1 except that a Ni chip was used in place of the Pd chip and that the amount of Ni placed on the Ag target was adjusted so that the Ni content of the metal layer was 3 wt%. Thus, an SPR sensor cell and an SPR sensor were produced. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 5>
The same procedure as in Example 1 except that a Ge fragment chip was used instead of the Pd fragment chip, and that the amount of Ge placed on the Ag target was adjusted so that the Ge content of the metal layer was 3% by weight. Thus, an SPR sensor cell and an SPR sensor were produced. The obtained SPR sensor was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Evaluation>
As shown in Table 1, in spite of using the same low refractive index core layer, in the SPR sensor of the example, an SPR peak occurs in the wavelength region of 725 nm or less. In the SPR sensor, an SPR peak occurs in a wavelength region longer than 725 nm. In the SPR sensor of Comparative Example 2, although the SPR peak occurs in the wavelength region of 725 nm or less, the stability of the metal layer is inferior. As described above, according to the SPR sensor cell and the SPR sensor of the present invention, it can be seen that high-sensitivity measurement is possible without using a device for near infrared light.

  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 10 Detection part 11 Under clad layer 12 Core layer 13 Metal layer 14 Over clad layer 20 Sample arrangement | positioning part 100 SPR sensor cell 110 Light source 120 Optical measuring device 200 SPR sensor

Claims (5)

An SPR sensor cell comprising 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 metal layer contains 95% by weight or more of Ag,
The extinction coefficient of the metal layer is greater than 4,
The refractive index of the metal layer is less than 0.4;
SPR sensor cell.   The SPR sensor cell according to claim 1, wherein the refractive index of the core layer is 1.34 to 1.43.   The SPR sensor cell according to claim 1, wherein an SPR peak is generated in a wavelength region of 600 nm to 725 nm. The SPR sensor cell according to any one of claims 1 to 3, wherein the metal layer contains at least one metal selected from the group consisting of Al, Pd, Cu, and Ge. An SPR sensor comprising the SPR sensor cell according to claim 1.