JP2003215027A - Curved-surface reflected-light sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflected-light sensor capable of solving conventional problems and being inexpensively manufactured with having no mechanical movable parts. <P>SOLUTION: The curved-surface reflected-light sensor is provided with a sensor chip having a reflecting surface, a light source, and an optical detector and detects the difference of the intensity of reflected light which depends on the angle of incidence of light from the light source to the reflecting surface. The reflecting surface of the sensor chip is constituted of a curved surface. The optical detector is constituted in such a way as to measure the reflected light at different locations and measure the intensity of reflection at an angle of incidence, which is different according to a location for measuring reflected light. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor that uses a light reflection phenomenon. More specifically, the present invention relates to a sensor that detects a difference in reflected light intensity depending on the incident angle of light.

[0002]

2. Description of the Related Art An optical measurement technique that uses evanescent light that totally reflects light and seeps out on its reflection surface has been widely studied and applied. A method of measuring the optical properties of a liquid with a total reflection optical system using a prism is called an ATR method, which has been widely researched and widely used. In addition, a method for measuring the optical thickness or the refractive index on the side opposite to the incident light with high sensitivity by using an optical system that causes a surface plasmon resonance by light using a surface having a thin film of gold, silver, etc. as a reflecting surface is available. It is called SPR sensor and is sold. In these measurement methods using reflection of light, it is important to measure or determine the incident angle of light at the time of measurement, because the state of the measurement target is measured from the difference in reflection intensity depending on the incident angle of light. That is, the relationship between the incident angle and the reflectance must be determined from the positions of the light source, the photodetector, and the angle of the reflecting surface. FIG. 7 shows a typical optical arrangement of a sensor using light reflection. In the figure, reference numeral 20 indicates a prism, reference numeral 21 indicates a gold thin film forming a reflecting surface, and reference numeral 22 indicates a sample. Thus, when the reflecting surface 21 is a flat surface, the light emitted from the light source is reflected by the reflecting surface 2
The optical path is adjusted so that it is reflected at 1 and enters the photodetector. In such a sensor, when adjusting or measuring the incident angle, the incident angle is mechanically changed, or the reflected light is measured at different positions by using a light beam condensed on the reflecting surface, or A method is used in which light emitted from a light source that can be regarded as a point light source measures reflected light from different points in a reflection plane at different points. There is also a method of condensing incident light in a minute area so that the reflecting surface can be regarded as a flat surface. In the SPR sensor, monochromatic light is incident from the opposite surface of the sample at a certain angle, and the angle at which the evanescent wave and the surface plasmon generated on the metal surface resonate are measured.
FIG. 8 shows a typical optical system for SPR measurement. Reference numeral 20 in the figure
22 to 22 respectively show a prism, a gold thin film and a sample, as in FIG. In this SPR sensor, the light emitted from the light source is condensed into wedge-shaped light and is incident on the prism. A sensor chip is arranged on the bottom of the prism through a material for matching the refractive index, and the sensor chip is irradiated with light under the condition of total reflection. The evanescent wave and surface plasmon wave generated on the gold thin film side resonate at a certain incident angle, and when the intensity of the reflected light is measured by a photodetector such as CCD, the resonance occurs at the angle at which the resonance occurs as shown in FIG. A low valley is observed. The angle at which resonance occurs depends on the optical properties (refractive index) of the surface. For example, when molecules bind to the surface in an antigen-antibody reaction, the refractive index of the surface changes, and the angle at which the valley appears changes slightly. To do. By measuring this change with time, the interaction of the molecules on the surface can be measured. Alternatively, the refractive index of the measured object can be measured from the wavelength at which the SPR phenomenon occurs by changing the wavelength of the irradiation light. The SPR sensor is being applied to an immunosensor using an antigen-antibody reaction, detection of DNA, detection of interaction between a receptor and protein, and the like.

[0003]

As described above, the sensor utilizing the reflection of light measures the state of the object to be measured from the difference in the reflection intensity which differs depending on the incident angle of the light, so that it is necessary to measure or determine the incident angle. However, since the reflection surface of a conventional sensor is a flat surface, in order to measure or determine the incident angle, a device that performs an angle scan of the incident light, a mechanism that allows light to be incident at multiple angles, or a width is used. A device for injecting light at a certain angle was necessary. For this reason, an expensive and complicated structure such as a special optical system and a mechanical movable device is required. In addition, even if the optical system is devised, it is difficult to make the measuring portion small in the measurement of the fluid if the reflecting surface is a flat surface, which is unsuitable for trace measurement. Further, it is generally difficult to stably form a uniform metal thin film on the inner surface of a tubular object having a curved surface, which is inconvenient to directly manufacture a tubular flow path as a sensor. An object of the present invention is to solve the above-mentioned conventional problems and to provide a reflected light sensor that has no mechanically movable parts and can be manufactured at low cost.

[0004]

In order to achieve the above object, a curved surface reflected light sensor according to the present invention comprises a sensor chip having a reflecting surface, a light source, and a photodetector, and a reflection from the light source. In a photosensor for detecting a difference in reflected light intensity depending on an incident angle of light on a surface with a photodetector, the reflecting surface of the sensor chip is formed by a curved surface, and the reflected light at different positions is measured by the photodetector. It is possible to measure the reflection intensity at different incident angles depending on the position where the reflected light is measured.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a curved reflected light sensor according to the present invention will be described below with reference to an embodiment shown in the accompanying drawings.

FIG. 1 is a schematic diagram showing the principle of a curved surface reflected light sensor according to the present invention. In the figure, reference numeral 1 indicates a sensor chip, and the sensor chip 1 includes a plate-shaped transparent body 1a. The transparent body 1a is formed with a through hole 1b forming a sample flow path, and a metal thin film 1c forming a reflecting surface is formed on the inner surface of the through hole 1b. Further, in the figure, reference numeral 2 indicates a light source, reference numeral 3 indicates a photodetector, and reference numeral 3a indicates a polarization filter provided in the photodetector. According to the curved surface reflected light sensor configured as described above, since the metal thin film 1c forming the reflective surface is formed on the inner surface of the through hole 1b and has a curved surface, the light X is emitted from the light source 2 at a constant incident angle. Metal thin film 1c
The light detection device 3 can detect a plurality of reflected lights Y having different incident angles only by making the light incident on the light.

Next, one specific embodiment of the SPR photosensor according to the present invention will be described with reference to FIGS. Figure 2
3 is a schematic top view of the SPR sensor according to the present invention, and FIG. 3 is a right side view of FIG. In the figure, reference numeral 5 indicates a sensor chip, reference numeral 6 indicates a light source, and reference numeral 7 indicates a CCD camera constituting a photodetector. The sensor chip 5 includes a transparent plate glass 5a. A through hole 5b that forms a sample flow path is formed in the plate-shaped glass 5a, and a gold thin film (not shown: see FIG. 1) is formed on the inner surface of the through hole 5b. In this embodiment, the side surface of the glass plate of the material BK7 having a thickness of 1 mm is polished and used as the plate glass 5a. The through hole 5b formed in the plate glass 5a was processed by Daiwa Techno Systems Co., Ltd. The inner diameter is 1 mm, and the gold thin film on the inner surface of the through hole 5b is formed with a thickness of 50 nm by a sputtering method using a sputtering device manufactured by Japan Seed Research Institute. Since the plate-shaped glass 5a is thin, the gold thin film can be uniformly attached to the inner surface of the through hole formed in the glass by the sputtering method, and at the same time, the homogeneous gold thin film can be attached to many glass substrates. . Silver can be used instead of this gold. Further, chromatography tubes 5d for flowing a sample solution are liquid-tightly adhered to both sides of the plate glass 5a, that is, both ends of the through hole 5b. The semiconductor laser light (wavelength: 6 mm) from the light source has a beam diameter of 0.5 mm so that the lower half in the radial direction of the through hole 5b of the sensor chip 5 configured as described above is irradiated with light from the side surface.
90 nm). Then, the polarization filter 7a was attached to the CCD sensor of the CCD camera 7 (CS8330 manufactured by Tokyo Denshi Kogyo Co., Ltd.), and the polarization filter was placed in contact with the surface of the plate-shaped glass 5a from which the reflected light emerges. The polarization filter 7a was adjusted so that the P-polarized reflected light could be observed. Under the conditions described above, the inside of the through hole 5b was made air, and the distribution of the intensity of the reflected light was measured. As a result, as shown in FIG. 4, a portion where the reflection was weak was observed in the intensity distribution of the reflected light measured by the CCD 7. It was Next, the tube 5d attached to the through hole 5b forming the flow path was connected to a pump (not shown) to flow water. In this case, compared to the case of air, CC corresponding to the light reflected at a position closer to the emission side is used.
The portion with weak reflection intensity moved to the position on D. Furthermore, when a 1 M KCl solution was flown as a sample into the through hole 5b, the position where the reflection intensity was weak on the CCD 7 moved only when KCl was passing through the glass. From this result, it can be confirmed that the refractive index of the sample in the through hole 5b forming the channel can be measured by the SPR method.

Next, a second embodiment of the curved reflected light sensor according to the present invention will be described. 5A to 5D are views showing manufacturing steps of a sensor chip for a curved reflected light sensor. In the figure, 10 is a glass plate (slide glass) of BK7. First, a groove 11 having a semicircular cross section is dug in the glass plate 10 with a dicing saw (model number DAD521) manufactured by Disco Corporation, and then the inside of the groove is polished. To give a mirror surface (FIGS. 5A and 5B). Next, a gold thin film 12 having a thickness of 50 nm is formed on the inner surface of the groove 11 by a sputtering method using a sputtering device manufactured by Japan Seed Research Institute (FIG. 5C). Then, a glass plate 13 is attached to the surface having the groove 11 by using a photo-curable adhesive (FIG. 5 (d)), and glass capillaries 14 are inserted into both ends of the groove 11 so that liquid does not leak. The sensor chip is completed by fixing with a photocurable adhesive (see FIG. 6). Laser light was incident on the sensor chip configured as described above in the direction of the arrow in FIG. 6, and the light emitted to the upper surface in FIG. 6 was measured by a CCD camera (not shown). As a result of the measurement, the SPR of the liquid flowing through the flow channel could be measured in the same manner as in Example 1.

[0009]

As described above, the curved surface reflected light sensor according to the present invention includes the sensor chip having the reflecting surface, the light source, and the light detecting device, and the incident angle of the light from the light source to the reflecting surface. In an optical sensor that detects a difference in reflected light intensity with a photodetection device, the reflection surface of the sensor chip is configured by a curved surface, and the photodetection device can measure the reflected light at different positions. Since it is configured so that the reflection intensity at different incident angles can be measured depending on the measurement position, the reflected light changes depending on the incident angle, which could not be measured without mechanical scanning or a complicated optical system. The strength can be measured with a simple optical system without a mechanical moving part. As a result, the measuring device can be made compact and robust, and it is possible to realize a sensor chip that can be mass-produced at low cost by measuring a small amount of sample and easily replacing it. Further, the sensor chip is configured such that a through hole is formed in a plate-shaped transparent body, a metal thin film that causes a surface plasmon resonance phenomenon is formed on an inner surface of the through hole, and a sample can be flown into the through hole. Or, on one surface of the plate-shaped transparent body, a groove having a semicircular cross section is formed, and a metal thin film that causes a surface plasmon resonance phenomenon is formed on the surface of this groove, and the upper surface of the groove is closed,
By configuring so that the sample can flow from the end of the groove into the groove, the passage through which the sample of the sensor chip flows becomes tubular, so that existing parts for connecting tubes for liquids can be used. In addition, it has the advantage of being able to easily prevent leakage with inexpensive parts, and when used for SPR measurement of the fluid inside the flow path, such as in HPLC detection devices, it can be easily added to existing liquid transfer tubes. A sensor chip can be connected, and a sensor having almost no liquid leakage problem can be obtained. Further, in manufacturing the sensor, if a film is formed by a sputtering method or the like, it is possible to easily mass-produce a metal thin film capable of SPR measurement. As described above, the effect of the present invention is extremely large especially as a sensor used in the fields of chemistry, medical care, and the environment.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the principle of a curved surface reflected light sensor according to the present invention.

FIG. 2 is a schematic top view of an SPR sensor according to the present invention.

FIG. 3 is a right side view of FIG.

FIG. 4 is a graph showing the results of measuring the distribution of reflected light intensity with the inside of the through hole 5b being air.

5A to 5D are views showing manufacturing steps of a sensor chip for a curved-surface reflected light sensor.

FIG. 6 is a schematic top view of the sensor chip completed in the step shown in FIG.

FIG. 7 is a schematic diagram of a typical optical arrangement of a sensor that uses light reflection.

FIG. 8 is a schematic diagram of a typical SPR measurement optical system.

FIG. 9 is a graph showing the incident angle dependence of the reflectance observed by the SPR sensor.

[Explanation of symbols]

1 sensor chip 1a transparent body 1b through hole 1c Metal thin film 2 light sources 3 Photodetector X incident light Y reflected light 5 sensor chips 5a Plate glass 5b through hole 5d tube 6 light source 7 CCD camera 7a Polarizing filter 10 glass plates 11 grooves 12 gold thin film 13 glass plate 14 Ballas Capillary 20 prism 21 gold thin film 22 samples

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 000102739             NTT Advanced Technology             Corporation             2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo (72) Inventor Koji Suzuki             1-1-705 Kokura, Saiwai-ku, Kawasaki-shi, Kanagawa (72) Inventor Kazuyoshi Kurihara             4-1 Idasugiyama-cho, Nakahara-ku, Kawasaki-shi, Kanagawa             305 Claire Maison Oseto (72) Inventor Tsuru Iwasaki             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Tsutomu Horiuchi             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Osamu Niwa             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Tatsuya Tobita             2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo             Nutty Advance Technology Co., Ltd.             Inside the company (72) Inventor Hisao Tabei             2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo             Nutty Advance Technology Co., Ltd.             Inside the company F term (reference) 2G059 AA02 BB04 CC20 DD12 EE02                       EE05 GG01 GG04 HH02 HH06                       JJ19 KK04

Claims (4)

[Claims] 1. A sensor chip having a reflecting surface, and a light source,
A photosensor comprising a photodetector, wherein the photodetector detects the difference in reflected light intensity depending on the incident angle of light from the light source to the reflective surface, and the reflective surface of the sensor chip is formed by a curved surface, A curved reflected light sensor characterized in that it is possible to measure reflected light at different positions with a photodetector, and to measure reflected intensity at different incident angles depending on the position at which the reflected light is measured. 2. The sensor according to claim 1, wherein the curved reflected light sensor is a sensor that measures a refractive index using surface plasmon resonance. 3. The sensor chip has a through hole formed in a plate-shaped transparent body, and a metal thin film which causes a surface plasmon resonance phenomenon is formed on an inner surface of the through hole by a sputtering method, a vapor deposition method or an electroless plating method. The sensor according to claim 2, wherein the sensor is configured to allow the sample to flow through the through hole. 4. The sensor chip has a groove having a semicircular cross section formed on one surface of a plate-shaped transparent body, and a metal thin film which causes a surface plasmon resonance phenomenon is formed on the surface of the groove by a sputtering method, an evaporation method, or The sensor according to claim 2, wherein the sensor is formed by an electrolytic plating method, and the upper surface of the groove is closed so that the sample can flow from the end of the groove into the groove.