JP2005147891A - Surface plasmon resonance sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact surface plasmon resonance sensor for which the S/N ratio is improved. <P>SOLUTION: The surface plasmon resonance sensor 2 comprises a transparent chip substrate 13, having parallel surfaces constituting a sensor body; a surface plasmon resonance detecting surface 16, constituted of a sensitive film and a metal film provided for one surface of the chip substrate 13; a diffraction grating 15 provided for the other surface of the chip substrate for making incident light incident onto the surface plasmon resonance detecting surface 16 at a prescribed angle; a light-receiving means 22, mounted to the other surface of the chip substrate for outputting the intensity of reflected light reflected at the surface plasmon resonance detecting surface 16; and stray light preventing means 31-33 for absorbing, interfering with, or reflecting the noise light for preventing light other than light of the order used for generating the phenomenon of surface plasmon resonance from being incident onto the light-receiving means 22 as noise among lights diffracted by the diffraction grating 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface plasmon resonance sensor for performing qualitative and quantitative measurement of a target as a detection target substance, and more particularly to a compact structure using a diffraction grating, which further prevents stray light and prevents S / S. The present invention relates to a surface plasmon resonance sensor with an improved N ratio.

  In the surface plasmon resonance sensor, for example, in order to measure the interaction of biomolecules at the molecular level, one of the biomolecules that cause the interaction is fixed on the sensor chip surface, and the sample liquid containing the molecules that act on this is flown through the microchannel. And so on through the sensor chip surface. A minute change in refractive index near the sensor chip surface due to the binding / dissociation between two molecules is detected as a surface plasmon resonance signal, and the change with time of this signal is displayed as a graph called a sensorgram. Then, by monitoring the interaction of molecules on the surface of the sensor chip in real time, it is possible to detect a target (such as a trace substance) that is specifically recognized for the sensor chip.

  There are several methods for measuring devices using such surface plasmon resonance because of differences in the arrangement of optical systems. These are described in “Real-time analysis experiment method of biological material interaction (Kazuhiro Nagata, Hiroshi Handa, edited by Springer Fairlark Tokyo Co., Ltd.)”. On the other hand, as a patent document relating to a surface plasmon resonance measuring apparatus, for example, Japanese Patent Application Laid-Open No. 9-292333 discloses a surface plasmon resonance sensor capable of performing analysis on a large number of sample solutions at once and obtaining high analysis accuracy. Proposed. Here, FIGS. 6 and 7 are diagrams showing the planar shape and the side surface shape of the surface plasmon resonance sensor described in the publication.

In the surface plasmon resonance sensor 200, five light beams 240 are condensed from the incident side cylindrical lens 221 through the incident side cylindrical lens 222 that is converted into parallel light in a plan view and further condensed by the incident side cylindrical lens 223. The interface between the prism 230 and the five metal films 210 is simultaneously irradiated.
On the other hand, the light beam 240 totally reflected at the interface 231 between the metal film 210 and the prism 230 is detected by the light detection means 250 via the emission-side cylindrical lens 224 that is collimated and the emission-side cylindrical lens 225 that is condensed. .

  The light detection signal Sm output for each light receiving element array of the light detection means 250 indicates the intensity I of the totally reflected light beam 240 for each incident angle θ. In addition, since light incident at a specific incident angle θSP excites surface plasmons at the interface between the metal film 210 and the sample liquid 260, the reflected light intensity I sharply decreases for this light. Therefore, the incident angle θSP can be obtained by using the light detection signal S output for each light receiving element of the light detection means 250, and the quantitative property and affinity of the specific substance in the sample liquid 260 are analyzed from the temporal change of the θSP. can do.

Since the light beams 240 are irradiated toward the five metal films 210, the light detection signals S1, S2, S3, S4, and S5 are output for each light receiving element array of the light detection means 250, and each metal film is output. Analysis of five sample liquids 260 in contact with 210 can be simultaneously performed, and a plurality of sample liquids 260 can be collectively performed at a short time interval.
Japanese Patent Laid-Open No. 9-292333 (page 2-3, FIG. 1) Experiments on real-time analysis of biological material interactions (Kazuhiro Nagata, Hiroshi Handa, edited by Springer Fairlark Tokyo)

  However, the conventional surface plasmon resonance sensor 200 described in Patent Document 1 includes the semiconductor laser array 220, the prism 230, the cylindrical lenses 221 to 225, and the light detection unit 250 on the left and right sides of the drawing, which is the traveling direction of the light beam 240. They are arranged in one direction. For this reason, the components of the surface plasmon resonance sensor 200 are widely arranged across the metal film 210 that is the measurement position, and the surface plasmon resonance sensor 200 is enlarged.

  On the other hand, the present applicant has proposed a surface plasmon resonance sensor that deflects light using a diffraction grating in Japanese Patent Application No. 2003-160234, which has been filed earlier, in order to solve such an increase in size. However, when a diffraction grating is used for deflecting light, only the diffracted light of the order that is useful for generating the surface plasmon resonance phenomenon needs to reach the light receiving part, but other diffracted light is reflected as stray light. Repeatedly, a new problem that a part of the light enters the light receiving portion and the S / N ratio of the sensor is lowered occurs. In particular, when light is tilted and made incident on the diffraction grating due to the deterioration of transmittance, the 0th-order light having high intensity becomes stray light and enters the light receiving unit, which greatly reduces the S / N ratio of the sensor. It became a problem.

  Therefore, an object of the present invention is to provide a compact surface plasmon resonance sensor having an improved S / N ratio in order to solve such a problem.

  The surface plasmon resonance sensor of the present invention is a surface plasmon resonance composed of a transparent chip substrate having parallel surfaces constituting a sensor body, and a sensitive film and a metal film provided on one surface of the chip substrate. A detection surface, a diffraction grating provided on the other surface of the chip substrate so that incident light is incident on the surface plasmon resonance detection surface at a predetermined angle, and the intensity of reflected light reflected from the surface plasmon resonance detection surface are output. Therefore, light other than the order used to generate the surface plasmon resonance phenomenon among the light diffracted by the light receiving means attached to the other surface of the chip substrate and the diffraction grating as noise to the light receiving means. In order to prevent the light from entering, it has stray light preventing means for absorbing, interfering or reflecting the light that becomes the noise.

In the surface plasmon resonance sensor of the present invention, the diffracted light used to generate the surface plasmon resonance phenomenon is primary light, and the stray light preventing means transmits light through which zero-order light in the chip substrate passes. It is a light absorption material arranged on the road.
In the surface plasmon resonance sensor according to the present invention, the stray light preventing means may be disposed at two positions on the one surface side of the chip substrate with the surface plasmon resonance detection surface sandwiched between the other surface side of the chip substrate. Is characterized in that concave portions are formed at positions facing the surface plasmon resonance detection surface and filled with a light absorbing material.

Further, in the surface plasmon resonance sensor of the present invention, the stray light preventing means reflects on a portion other than a place where the surface plasmon resonance detection surface, the diffraction grating, and the light receiving means are arranged with respect to a parallel surface of the chip substrate. It is characterized in that a prevention film is provided.
In the surface plasmon resonance sensor of the present invention, the diffracted light used to generate the surface plasmon resonance phenomenon is first-order light, and the stray light preventing means is configured to receive the zero-order light from the chip substrate. It is a reflection surface that reflects the zero-order light provided on one surface of the chip substrate toward the incident direction of the zero-order light.

  Therefore, in the surface plasmon resonance sensor of the present invention, the diffracted light that has passed through the diffraction grating is incident on the surface plasmon resonance detection surface at a predetermined angle, and the reflected light reaches the light receiving means, whereby the target in the sample liquid is The qualitative and quantitative determination of trace substances can be measured from the change in reflected light intensity when interacting with the surface plasmon resonance detection surface. At that time, the first-order diffracted light is used to generate the surface plasmon resonance phenomenon, and the other orders of diffracted light become stray light and repeatedly reflected in the chip substrate, so that the light-receiving means overlaps with the first-order diffracted light. , It becomes noise and lowers the S / N ratio. Therefore, it is necessary to prevent the diffracted light other than the primary light, in particular, the 0th-order light having a high intensity from being repeatedly reflected and entering the light receiving means so as to overlap the primary light. In this respect, in the surface plasmon sensor of the present invention, the light that is repeatedly reflected as stray light in the chip substrate is absorbed by the light absorbing material, transmitted by the antireflection film such as an interference filter, or the incident direction of the light on the reflecting surface. The intensity is very small so that it does not reach the light receiving means or does not pose a problem as noise even if it reaches.

  Therefore, according to the present invention, since the surface plasmon resonance detection surface is provided on one surface of the transparent chip substrate and the diffraction grating and the light receiving means are provided on the other surface, without using a movable device, Further, it is not necessary to complicate the optical lens system, and a compact surface plasmon resonance sensor can be provided. Then, in order to prevent the diffracted light other than the order used for generating the surface plasmon resonance phenomenon from being diffracted by the diffraction grating, the light that becomes the noise is prevented from entering the light receiving means as noise. It has become possible to provide a surface plasmon resonance sensor having an improved S / N ratio because it has means for preventing stray light that absorbs, interferes with or reflects.

Next, an embodiment of a surface plasmon resonance sensor according to the present invention will be described below with reference to the drawings.
First, the structure and principle of the surface plasmon resonance sensor will be briefly described. FIG. 1 is a simplified view of a part of a surface plasmon resonance sensor. In the surface plasmon resonance sensor 100, a gold film 112 is formed to a thickness of about 45 nm on one surface of a transparent chip substrate 111 made of glass or the like. This is because some kind of metal such as gold or silver is necessary for surface plasmon resonance. Generally, gold is used for reasons such as chemical inactivity and good generation efficiency of surface plasmon resonance signals. Note that a binding substance (ligand, molecular recognition element) that specifically binds by interacting with a specific detection species is applied on the metal layer.

  The surface plasmon resonance sensor 100 can measure the intensity of the reflected light 115 reflected by the boundary surface between the chip substrate 111 and the gold film 112 when the incident light 114 is given at an angle θ as shown in the figure. Therefore, in the measuring apparatus using the surface plasmon resonance sensor 100, incident light 114 is incident from a light source such as a laser diode as shown in FIG. 1, and the totally reflected reflected light 115 is reflected by a photodiode array (not shown) or the like. Light is received by the light receiving means, and the intensity of the reflected light 115 is detected.

  When light is irradiated so as to be totally reflected at the interface between the chip substrate 111 and the gold film 112, an evanescent wave is excited. At a specific incident angle, the oscillation period of the evanescent wave is equal to the period of the surface plasmon wave generated on the surface of the gold film 112, and the surface plasmon is excited by the resonance phenomenon. As a result, since the energy of incident light is used for surface plasmon resonance, the intensity of the reflected light 115 is significantly reduced. Here, FIG. 2 is a surface plasmon resonance curve showing the incident angle dependence of the reflected light intensity detected by the surface plasmon resonance sensor, but when the incident angle dependence of the reflected light intensity is measured as shown in FIG. A “light valley” in which the intensity of the reflected light 115 is attenuated at a specific angle is observed. This optical phenomenon is surface plasmon resonance. Surface plasmon resonance depends on the wavelength and angle of incident light.When excited, the optical energy of a light component having a specific incident angle or specific wavelength shifts to a surface plasmon wave, and the corresponding incident angle or wavelength is changed. The reflected light is reduced.

  Surface plasmon resonance also depends on the refractive index of the sample liquid on the surface of the metal layer. If the refractive index of the sample liquid changes, the resonance angle changes when the wavelength is constant, and when the incident angle is constant. Changes the resonance wavelength. Therefore, the refractive index of the sample liquid on the surface of the metal layer can be analyzed by examining the resonance angle or the resonance wavelength based on the intensity of the reflected light. When the refractive index on the surface of the gold film 112 changes and the resonance angle shifts from A to B as shown in FIG. 2, if the temporal change in the shift amount is detected, the qualitative information about the sample liquid and the like Quantitative information can be obtained. Therefore, in the surface plasmon resonance sensor of the present embodiment, for example, the incident angle is fixed to θ1 in FIG. 2, and the qualitative and quantitative measurement of the target in the sample liquid is measured from the change ΔI in the reflected light intensity shifted.

  Then, the surface plasmon resonance sensor of this embodiment is demonstrated. FIG. 3 is a cross-sectional view showing the surface plasmon resonance sensor of the first embodiment. The surface plasmon resonance sensor 1 includes a sensor substrate 11 made of a silicon substrate, an antireflection film 12, a transparent chip substrate 13 such as glass, and an antireflection film 14 stacked in layers. The antireflection film 12 is provided with an equally spaced diffraction grating 15 as an optical path deflecting means, and the other antireflection film 14 is provided with a plasmon resonance detection surface 16. The sensor substrate 11 has a circular, polygonal, or scratched opening 17 that guides light to the chip substrate 13, and only stray light from a certain angle is extracted from the irradiated light. It is also possible to attach an aperture 18 that cuts at the entrance.

The incident light 7 to the surface plasmon resonance sensor 1 is, for example, laser light from a red laser provided as a light source, and the incident light (hereinafter referred to as “laser light”) 7 is guided through the opening 17. A diffraction grating 15 is provided on one surface of the chip substrate 13 as optical path deflecting means. That is, the diffraction grating 15 deflects the laser light 7 and causes the light to enter the plasmon resonance detection surface 16 at a predetermined angle.
By the way, since the incident angle differs depending on the target to be measured, it is necessary to design so that suitable incident light and reflected light can be obtained. In particular, in the present embodiment, as shown in FIG. 2, the resonance angle (incident angle) for taking the change ΔI in reflected light intensity is fixed, but the incident angle θ1 is set so that the change ΔI becomes large.

  On the other hand, in the present embodiment, the surface plasmon resonance sensor 1 is a light useful for generating the surface plasmon resonance phenomenon among the diffracted lights (0th order light, first order light, second order light, etc.) generated by the diffraction grating 15. The primary light S1 is used (generally, the primary light S1 is also used). Therefore, the primary light S1 must be incident on the plasmon resonance detection surface 16 at an incident angle θ1. Therefore, in order to make the primary light S1 incident at an incident angle θ1, in the present embodiment, the laser light 7 is incident on the diffraction grating 15 at an angle θ2.

  A chip substrate 13 having parallel surfaces up and down is provided with a diffraction grating 15 on one surface thereof, and a plasmon resonance detection surface 16 in which a gold film 20 and a sensitive film 21 are overlaid on the opposite surface. Yes. Further, the chip substrate 13 is provided with a photodiode 22 as a light receiving means on the same surface as the diffraction grating 15. The upper and lower surfaces of the chip substrate 13 are provided with diffraction gratings 15, plasmon resonance detection surfaces 16, and antireflection films 12 and 14 on portions other than the photodiodes 22. This is because the diffraction grating 15 used as the optical path deflecting means prevents diffracted light other than the primary light S1 used for surface plasmon resonance from being repeatedly reflected in the chip substrate 13 and becoming stray light.

  That is, in the surface plasmon resonance sensor 1, as described above, the primary light is generated as light that causes the surface plasmon resonance phenomenon among the diffracted light (0th order light, 1st light, 2nd light,...) Generated by the diffraction grating 15. S1 is used. The other orders of diffracted light become stray light and reflect inside the chip substrate 13, but if it enters the photodiode 22 with the primary light, it becomes noise and the S / N of the sensor. The ratio will be reduced. In particular, the 0th-order light S0 that is not diffracted has a higher intensity than the first-order light S1, and this is a major cause of reducing the S / N ratio of the sensor. Therefore, in this embodiment, the antireflection films 12 and 14 are provided on the upper and lower surfaces of the chip substrate 13 in order to cope with such a problem.

Next, the operation of the surface plasmon resonance sensor 1 having the above configuration will be described below.
In the surface plasmon resonance sensor 1, the laser beam 7 incident on the opening 17 at a predetermined angle θ 2 is selected by the polarizing plate (not shown) and only the P-polarized light is irradiated to the diffraction grating 15. The laser beam 7 diffracted by the diffraction grating 15 travels through the chip substrate 13 and is incident on the plasmon resonance detection surface 16 at an angle θ1.

  When the reflected light that has generated surface plasmon resonance on the plasmon resonance detection surface 16 is received by the photodiode 22, an output voltage proportional to the intensity of the reflected light is generated there. Then, the measurement signal output from the photodiode 22 is transmitted to an arithmetic processing unit (not shown), and qualitative and quantitative information based on the measurement signal is analyzed based on the change ΔI in reflected light intensity.

  In the present embodiment, the incident angle θ1 to the plasmon resonance detection surface 16 is set by the incident angle θ2 of the laser beam 7 and the diffraction grating 15, and as shown in FIG. 2, information on the reflected light intensity at the angle θ1 is obtained. can get. Therefore, the refractive index changes depending on the presence or absence of the target in the sensitive film 21 and the resonance angle is shifted by Δθ, so that the reflected light intensity at the resonance angle θ1 also changes by ΔI. Therefore, this difference can be detected by the measurement signal, and as a result, the qualitative and quantitative values of the target can be obtained as information.

  On the other hand, the 0th-order light S0 is incident on the chip substrate 13 through the diffraction grating 15, but does not directly hit the plasmon resonance detection surface 16 but hits the antireflection film 14 provided adjacently. The antireflection film 14 made of an interference filter does not transmit all the 0th-order light S0 but partially reflects it. The light further passes through the opposite antireflection film 12, and the intensity of the 0th-order light S0 decreases while repeating such transmission. This is not limited to the 0th-order light, and the diffracted light generated by the diffraction grating 15 is weakened by repeating the transmission through the antireflection films 12 and 14, and as a result, stray light in the chip substrate 13 is suppressed. The

Therefore, the surface plasmon resonance sensor 1 of the present embodiment uses the diffraction grating 15 to reflect the primary light S1 that generates the surface plasmon resonance phenomenon from the plasmon resonance detection surface 16 formed on the same chip substrate 13, and thus the photodiode. Since it was made to inject into 22, the whole sensor was able to be made compact.
Furthermore, in this embodiment, by using the diffraction grating 15, the diffracted light can be repeatedly reflected in the chip substrate 13 and become stray light, but is transmitted by the antireflection films 12 and 14 provided on the upper and lower surfaces of the chip substrate 13. As a result, the amount of the zero-order light S0 that causes noise reaching the photodiode 22 can be suppressed, and the S / N ratio can be improved.

  As described above, in the surface plasmon resonance sensor 1 of the first embodiment, the anti-reflection films 12 and 14 can reduce the S / N ratio caused by using the diffraction grating 15 while reducing the size. It has been solved. Next, a surface plasmon resonance sensor that more effectively reduces the 0th-order light S0 and improves the S / N ratio will be described below with reference to the drawings. FIG. 4 is a cross-sectional view showing the surface plasmon sensor of the second embodiment. In addition, the same code | symbol is attached | subjected about the component similar to the thing of 1st Embodiment, and detailed description is abbreviate | omitted.

  The surface plasmon resonance sensor 2 includes a sensor substrate 11 made of a silicon substrate or the like and a transparent chip substrate 13 made of glass or the like, and a diffraction grating 15 and a photodiode 22 are provided between them. A plasmon resonance detection surface 16 is provided on the opposite surface of the chip substrate 13. An opening 17 is formed in the sensor substrate 11, and an aperture 18 for cutting stray light is attached thereto. And in the surface plasmon resonance sensor 2 of this embodiment, the light absorption blocks 31-33 are provided in the chip board | substrate 13 in order to prevent the fall of S / N ratio.

  In the light absorption blocks 31 to 33, cubic concave portions 35 to 37 are formed at predetermined positions of the chip substrate 13, and the concave portions 35 to 37 are filled with a light absorbing material. As the light absorbing material constituting the light absorbing blocks 31 to 33, an appropriate material is selected depending on the light 7 to be irradiated. For example, when a red laser is used as the light source, the light absorbing material corresponds to the wavelength of the red laser light. Is selected. Specific examples of the red laser include SDA8303 (phthalocyanine-metal complex dye) manufactured by Tosco Corporation. Accordingly, the light absorption blocks 31 to 33 are formed by filling the recesses 35 to 37 of the chip substrate 13. The light absorbing material should be black or a material that absorbs the laser light used (green if using a red laser), black silicone adhesive, etc. in consideration of ease of use and availability. But it ’s okay.

In this embodiment, by providing the light absorption block 31 in the chip substrate 13 in this way, the surface plasmon resonance sensor 2 formed compactly is not enlarged, and the light absorption blocks 31 to 33 and the upper and lower surfaces of the chip substrate 13 are also provided. And the stray light is efficiently absorbed by increasing the number of times of reflection.
Further, in the present embodiment, the light absorption blocks 31 to 33 provided in the chip substrate 13 are provided at three positions by shifting the positions as illustrated. This uses the primary light S1 as light for causing the surface plasmon resonance phenomenon, but only this primary light S1 reflects from the diffraction grating 15 to the plasmon resonance detection surface 16 and reaches the photodiode 22. While the optical path of the primary light S1 is formed, the diffracted light of other orders is arranged so as to block the optical path.

  In the present embodiment, the three light absorption blocks 31 to 33 are provided in the chip substrate 13, but it is not always necessary to provide all of them, and even a part of them functions effectively. That is, since the zero-order light having a high intensity causes noise, it is necessary to prevent the light from reflecting inside the chip substrate 13 and becoming stray light. Therefore, if there is a light absorption block 31 that directly acts on the 0th-order light S0, the 0th-order light S0 is repeatedly reflected on this, so that noise can be suppressed and a reduction in the S / N ratio can be prevented. Therefore, at least the light absorption block 31 may be provided on the chip substrate 13.

Then, the effect | action is demonstrated about the surface plasmon resonance sensor 2 of this embodiment which consists of such a structure.
The laser beam 7 applied to the surface plasmon resonance sensor 2 is diffracted by the diffraction grating 15 provided on one surface of the chip substrate 13. Of the diffracted light, in particular, the primary light S1 passes through the light absorption blocks 31 to 33 provided in the chip substrate 13 and enters the plasmon resonance detection surface 16 at a predetermined angle. Then, the reflected light reflected from the plasmon resonance detection surface 16 enters the light receiving side photodiode 22 which is in the same plane as the incident side diffraction grating 15.

The reflected light that has generated surface plasmon resonance at the plasmon resonance detection surface 16 is thereafter received by the photodiode 22, where an output voltage proportional to the intensity of the reflected light is generated. Then, the measurement signal output from the photodiode 22 is transmitted to an arithmetic processing unit (not shown), and qualitative and quantitative information based on the measurement signal is analyzed based on the change ΔI in reflected light intensity.
As shown in FIG. 2, the incident angle of θ1 is set by the incident light angle and the diffraction grating 15, and information on the reflected light intensity at that angle is obtained. Therefore, the refractive index changes depending on the presence or absence of the target in the sensitive film 21 and the resonance angle is shifted by Δθ, so that the reflected light intensity at the resonance angle θ1 also changes by ΔI. Therefore, this difference can be detected by the measurement signal, and as a result, the qualitative and quantitative values of the target can be obtained as information.

  On the other hand, while such measurement is performed, the 0th-order light S0 diffracted by the diffraction grating 15 proceeds to the light absorption block 31 and is mostly absorbed, and further partially reflected is absorbed by the light absorption blocks 31 to 33 repeatedly. Is done. That is, the 0th-order light S0 having a high intensity should be noted as noise, and this must be absorbed by the light absorption block 31. However, not all is absorbed at once, and some are reflected. A part of the reflected zero-order light S0 further passes through the chip substrate 13, and a part of the reflected light is reflected and absorbed by the light absorption block 31 again. Such absorption is repeated by the light absorption blocks 31 to 33. When the light absorption blocks 31 to 33 are reached, the intensity becomes very small and the noise is suppressed to a very low level.

Further, the diffracted light other than the primary light S1 is also absorbed and weakened by the light absorption blocks 31 to 33. As a result, stray light in the chip substrate 13 is similarly suppressed. Then, when the light reaches the photodiode 22, the intensity becomes very small, and the noise is suppressed to a very low level.
In particular, in the present embodiment, the light absorption blocks 31 to 33 are large in thickness, so that the light absorption efficiency is good, and the distance between the light absorption blocks 31 to 33 and the surface of the chip substrate 13 is narrow. The number of times increases and the absorption effect is high.

Therefore, the surface plasmon resonance sensor 2 of the present embodiment uses the diffraction grating 15 as in the first embodiment, and the plasmon resonance in which the primary light S1 that generates the surface plasmon resonance phenomenon is formed on the same chip substrate 13. Since the light is reflected by the detection surface 16 and incident on the photodiode 22, the entire sensor can be made compact.
In this embodiment, the S / N ratio is improved by preventing stray light. However, since the light absorption blocks 31 to 33 are provided in the chip substrate 13, as described above, the light depends on the thickness. The absorption efficiency was high, and the distance from the surface of the chip substrate 13 was narrow, so that the number of repetitions of absorption increased and the absorption effect increased. Therefore, it is possible to suppress the amount of zero-order light S0 that causes noise to reach the photodiode 22, and to improve the S / N ratio. Furthermore, since the light absorption blocks 31, 32 are arranged so as to block the optical path of the diffracted light other than the primary light S1 generated in the diffraction grating 15, stray light can be effectively prevented also in this respect, This contributes to the improvement of the S / N ratio.

As mentioned above, although one Embodiment of the surface plasmon resonance sensor was described, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.
In the above-described embodiment, the light-preventing block formed in the chip substrate by filling the anti-reflection film or the light absorbing material using the interference filter as the stray light preventing means is proposed. That is, they are intended to prevent stray light by transmitting and absorbing light, but in addition to this, for example, as shown in FIG. The reflective surface 40 may be formed on the chip substrate 13 so as to be reflected toward the incident direction of S0.

It is the figure which simplified and showed the detection part of the surface plasmon resonance sensor. It is the surface plasmon resonance curve which showed the incident angle dependence of the reflected light intensity detected by a surface plasmon resonance sensor. It is sectional drawing which showed 1st Embodiment of the surface plasmon resonance sensor. It is sectional drawing which showed 2nd Embodiment of the surface plasmon resonance sensor. It is the figure which showed the stray light prevention means by reflection of a surface plasmon resonance sensor. It is the top view which showed the conventional surface plasmon resonance sensor. It is the side view which showed the conventional surface plasmon resonance sensor.

Explanation of symbols

1, 2 Surface plasmon resonance sensor 11 Sensor substrate 12, 14 Antireflection film 13 Chip substrate 15 Diffraction grating 16 Plasmon resonance detection surface 18 Aperture 19 Incident light 20 Gold film 21 Sensitive film 22 Photodiodes 31, 32, 33 Light absorption block S0 0th order light S1 1st order light

Claims (5)

A transparent chip substrate having parallel surfaces constituting the sensor body, and
A surface plasmon resonance detection surface composed of a sensitive film and a metal film provided on one surface of the chip substrate;
A diffraction grating provided on the other surface of the chip substrate so that incident light is incident on the surface plasmon resonance detection surface at a predetermined angle;
Light receiving means attached to the other surface of the chip substrate to output the intensity of the reflected light reflected from the surface plasmon resonance detection surface;
Of the light diffracted by the diffraction grating, in order to prevent light other than the order used for generating the surface plasmon resonance phenomenon from entering the light receiving means as noise, the light that becomes the noise is absorbed, A surface plasmon resonance sensor comprising: stray light preventing means for interference or reflection. In the surface plasmon resonance sensor according to claim 1,
The diffracted light used to generate the surface plasmon resonance phenomenon is primary light, and the stray light preventing means is a light absorbing material disposed on an optical path through which zero-order light in the chip substrate passes. A surface plasmon resonance sensor. In the surface plasmon resonance sensor according to claim 2,
The stray light preventing means includes two positions sandwiching the surface plasmon resonance detection surface on one surface side of the chip substrate, and a position facing the surface plasmon resonance detection surface on the other surface side of the chip substrate. The surface plasmon resonance sensor is characterized in that a recess is formed in each of which is filled with a light absorbing material. In the surface plasmon resonance sensor according to claim 1,
The stray light preventing means includes an antireflection film provided on a portion of the chip substrate other than the surface where the surface plasmon resonance detecting surface, the diffraction grating, and the light receiving means are disposed with respect to the parallel surface of the chip substrate. A featured surface plasmon resonance sensor. In the surface plasmon resonance sensor according to claim 1,
The diffracted light used to generate the surface plasmon resonance phenomenon is first-order light, and the stray light preventing means is provided on one surface of the chip substrate where the zero-order light of the chip substrate reaches. A surface plasmon resonance sensor characterized in that the surface plasmon resonance sensor is a reflecting surface that reflects zero-order light toward an incident direction of the zero-order light.

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