JPH11271215A - Surface plasmon resonance angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a SPR(surface plasmon resonance angle) detector capable of detecting a resonance angle caused by at least different two-wavelength lights to specify material at a real time or detecting its film thickness and dielectric constant at a real time and doing efficient detecting work. SOLUTION: A metal thin film 35 of required film thickness and dielectric constant is formed on the surface of a glass substrate 33 by using at least different two-wavelength lights with a required angle difference, and the incident angles of the respective lights onto a sensor chip 5 having a prism 19 adhered to the glass substrate 33 on the opposite side of the metal thin film 35 are varied by a variable light radiation device 3. Components of a sample adsorbed to the metal thin film 35 are specified or the film thickness and dielectric constant of the sample are measured, based on a resonance angle wherein the reflectivity of the lights radiated to the sensor chip 5 is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface plasmon resonance angle detecting device (hereinafter, referred to as a device) for specifying a component on a sensor chip based on the reflectance of light applied to the sensor chip in which a metal thin film is deposited on a glass substrate. SPR detection device).

[0002]

As a method of detecting a substance, a laser beam or the like condensed in a spot shape is applied to a sensor chip in which a metal thin film having an appropriate thickness and a dielectric constant is deposited on a glass substrate. A surface plasmon resonance angle detection method of irradiating light to detect a resonance angle at which the reflectance from a glass substrate is minimized and specifying a substance adsorbed on a metal thin film is generally known.

When a surface plasmon resonance angle detection method using light of a single wavelength is to be used to detect, for example, a multi-component mixed substance, only the resonance angles corresponding to all the components can be detected. Each substance could not be identified by detecting each resonance angle in the substance. In such a case, it is possible to sequentially irradiate light of different wavelengths to detect the respective resonance angles and to specify each component in the mixed system material by the difference in the resonance angle. And the detection time was prolonged, and each component in the mixed substance could not be detected in real time.

The thickness and dielectric constant of a substance adsorbed on a metal thin film can be calculated by processing simultaneous equations based on absorbance (reflectance) of different wavelengths detected by a surface plasmon resonance angle detection method. However, in the conventional method, light of different wavelengths is incident at the same angle,
At the same time, changes in light of different wavelengths could not be detected in real time.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional drawbacks. An object of the present invention is to identify a substance in real time by detecting a resonance angle of at least two different wavelengths of light. Another object of the present invention is to provide an SPR detection device capable of detecting the thickness and dielectric constant of the SPR in real time.

Another object of the present invention is to provide an SPR detection device capable of performing a detection operation efficiently.

[0007]

Therefore, according to the present invention, a metal thin film having a required thickness and a dielectric constant is formed on the surface of a glass substrate, and a prism is adhered to the glass substrate on the opposite side of the metal thin film. Surface plasmon resonance angle detection device that specifies a sample component adsorbed on a metal thin film based on the resonance angle at which the reflectance of light applied to the sensor chip is minimized, or measures the film thickness and dielectric constant of the sample Wherein a variable light irradiation device is provided for irradiating at least two different wavelengths of light on the sensor chip with a required angle difference and varying the incident angle of each light on the sensor chip.

Thus, the resonance angle of each light can be detected in real time by the light of different wavelengths emitted while varying the incident angle by providing an angle difference in the sensor chip.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view schematically showing an SPR detecting device.

FIG. 2 is an explanatory view showing the principle structure of the variable light irradiation device.

The SPR detection device 1 includes a variable light irradiation device 3,
A control device (shown in FIG. 1) that includes a sensor chip 5 and a light receiving device 7 and displays a correlation between an incident angle and a reflectance on a display device such as a CRT based on a detection signal from the light receiving device 7. Is connected.

The main body 13 of the variable light irradiation device 3 is attached to an arm 21 which rotates around a center of a prism 19 described later, and a servomotor and a step motor which can be numerically controlled are provided at the rotation base end of the arm 21. And the like (not shown). By the driving of the electric motor 23, the electric motor 23 makes a circular motion at a required angle (30 to 80 ± 2.5 °) described later. A white laser light irradiation device 15 is connected to the main body 13 by an optical fiber 17.

In the main body 13, a first dichroic mirror 25 is provided on the optical path of white laser light from the optical fiber 17,
It is mounted at an angle of 45 ° to the optical path. The first
The dichroic mirror 25 transmits only the green laser light having a wavelength of 534 nm out of the incident white laser light, and reflects the laser light of other wavelength components in a direction orthogonal to the optical path.

A second dichroic mirror 27 is arranged on the optical path reflected from the first dichroic mirror 25. The second dichroic mirror 27 transmits blue laser light having a wavelength of 441 nm out of the incident laser light to the outside. The laser beam is emitted and the red laser beam having a wavelength of 636 nm is reflected in parallel with the green laser beam.

A lens 29 is provided on each optical path of the green laser light and the red laser light with a polarizer 31 provided.
Reference numeral 9 denotes a glass substrate 33 and a metal thin film 3 in the sensor chip 5 to be described later, respectively.
Convergence at the boundary of 5. The converged green laser light and red laser light are set so as to enter the prism 19 at an angle difference of about 5 °.

Sampling mirrors 28 and 30 are disposed on the optical paths of the green laser light and the red laser light between the polarizer 31 and the lens 29, and the sampling mirrors 28 and 30 transmit the transmitted green laser light and red laser light, respectively. A part of the light is reflected and the corresponding photodiode 28a
-Each light intensity is detected by 30a. Then, according to the detected light intensity, the first and second light receiving members 37.3 and 37.3 are used.
9 to obtain a detection signal of a constant level by variably controlling the signal amplification factor.

On the glass substrate 33 of the sensor chip 5, a metal thin film 35 is deposited. The metal thin film 35 has a two-layer structure of, for example, a gold thin film having a thickness of 5 ± 0.5 nm and a silver thin film having a thickness of 36 ± 3 nm. A semicircular prism 19 is closely attached to the glass substrate 33 on the opposite side of the metal thin film 35.

The light receiving device 7 is disposed on the opposite side of the variable light irradiation device 3 around the prism 19, and the light receiving device 7 is provided with a first light receiving member 37 for receiving green laser light and a first light receiving member 37 for receiving red laser light. And two light receiving members 39. Each of the first and second light receiving members 37 and 39 is formed of a photodiode array or a CCD array having a longitudinal width corresponding to the angle width described above. Further, each of the first and second light receiving members 3
Interference filters 41.4 on the front (incident side) of 7.39
The interference filter 41 selectively transmits green laser light and the interference filter 43 selectively transmits only red laser light to improve the S / N ratio due to disturbance light.

Next, the operation of detecting the resonance angle of a sample by the SPR detection device will be described.

FIG. 3 is an explanatory view showing a variable incident angle state of each light with respect to the sensor chip 5.

FIG. 4 is a diagram showing the correlation between the incident angle of each laser beam and the reflectance.

First, the incident angle of the prism 19 of the green laser light converged on the boundary surface of the metal thin film 35 of the glass substrate 33 is set to 3
0 ± 2.5 °, and therefore the electric motor 23 with the prism 19 of the red laser beam set at an incident angle of 35 ± 2.5 °.
Is driven to rotate the arm 21 with a width of about 50 °,
The angle of incidence of the green laser light with respect to the prism 19 is 30 ±
Variable scanning is performed in the range of 2.5 ° to 80 ± 2.5 ° and the incident angle of the red laser light is in the range of 35 ± 2.5 ° to 85 ± 2.5 °. And the glass substrate 3 according to each incident angle
The green laser light and the red laser light reflected from the boundary between the third and metal thin films 35 correspond to the first and second light receiving members 37.
The light is received at 39 and the reflectance according to each incident angle is detected.

At this time, when the metal thin film 35 is adsorbed, a part of the irradiated green laser light and red laser light is absorbed by each component in the sample, and the reflectance changes according to the incident angle. . Then, the resonance angle at which the reflectance is minimum, and therefore the absorption of the component of the sample is maximized, is detected, and the component in the sample is specified based on, for example, comparison with a previously detected resonance angle of pure water.

In the present embodiment, light having different wavelengths (green laser light and red laser light) is simultaneously irradiated to the sensor chip 5 with an angle difference, and the absorbance of each component in the sample adsorbed on the sensor chip 5 is calculated as follows: Therefore, each component in the sample can be detected in real time by detecting the reflectance and detecting the resonance angle at which the reflectance is minimized.

In the above description, white laser light was used as the light source to separate the laser light into green laser light and red laser light. As shown in FIG. 5, the present invention is applied to a frame 50 that moves in an arc along the outer periphery of a prism. For example, a structure is provided in which light sources 51a and 51b for red light and infrared light are provided, each light emitted from each of the light sources 51a and 51b is narrowed down into a spot shape, and the prism 19 is directly illuminated with a required angle difference therebetween. There may be.

In the above description, the green laser beam and the red laser beam collimated by the first and second dichroic mirrors are converged by a lens so as to have a required angle difference, as shown in FIG. The dichroic mirrors 61a and 61b are provided with angles as described above, and the lights transmitted or reflected by the respective dichroic mirrors 61a and 61b are directly incident on the sensor chip 5 so as to have a required angle difference. Is also good.

Further, as shown in FIG. 7, the respective light sources 51 and 53 for irradiating light of different wavelengths are arranged so as to irradiate the rotating polygon mirror 55 with a required angle difference, and the polygon mirror is illuminated. A variable light irradiating device is constituted by a first lens 57 that converts each light reflected with an angle difference from 55 into parallel rays and a second lens 61 that converges parallel rays at a required incident angle width with respect to the sensor chip 59. Alternatively, the sample may be specified by irradiating the sensor chip 59 with light of at least two types of wavelengths at an angle difference and detecting the resonance angle of each reflected light in real time.

In the above description, the green laser light and the red laser light separated from the white laser light are used. However, in the present invention, the red light and the red light depend on the sample to be detected and the type of the metal thin film to be deposited. Light of different wavelengths such as external light may be selected, and is not limited to the light source or the wavelength of light.

Further, in the above description, two types of light having different wavelengths are irradiated on the sensor chip with an angle difference to detect the components of the sample, and to detect the film pressure and the dielectric constant of the sample. It goes without saying that three or more types of light may be applied to the sensor chip as long as they have different wavelengths.

In the above description, a method for detecting a specific component in a multi-component substance has been described as an example. However, a method for determining the film thickness and dielectric constant of a substance adsorbed on a sensor chip is also applicable. .

[0032]

Thus, the present invention detects a resonance angle due to light of different wavelengths to specify a substance in real time,
Its film thickness and dielectric constant can be detected in real time. Further, according to the present invention, the detection operation can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing an SPR detection device.

FIG. 2 is an explanatory diagram showing a principle structure of a variable light irradiation device.

FIG. 3 is an explanatory view showing a variable incident angle state of each light with respect to a sensor chip 5;

FIG. 4 is a diagram showing a correlation between an incident angle of each laser beam and a reflectance.

FIG. 5 is an explanatory view showing a modified embodiment of the variable light irradiation device.

FIG. 6 is an explanatory view showing a modified embodiment of the variable light irradiation device.

FIG. 7 is an explanatory view showing a modified embodiment of the variable light irradiation device.

[Explanation of symbols]

1 SPR detection device, 3 variable light irradiation device, 5 sensor chip, 7 light receiving device, 19 prism, 33 glass substrate, 35 metal thin film

Claims (6)

[Claims] 1. A reflectance of light radiated to a sensor chip having a metal film having a required thickness and dielectric constant formed on a surface of a glass substrate and having a prism adhered to the glass substrate on the opposite side of the metal thin film. In a surface plasmon resonance angle detection device for identifying a sample component adsorbed on a metal thin film based on a resonance angle at which the minimum value is obtained, or measuring a film thickness or a dielectric constant of the sample, light of at least two different wavelengths is required. A surface plasmon resonance angle detection device provided with a variable light irradiation device that irradiates the sensor chip with an angle difference and changes the incident angle of each light to the sensor chip. 2. The variable light irradiation device according to claim 1, wherein the variable light irradiation device transmits or reflects light of a required wavelength from light emitted from a single light source to convert the light into a parallel light beam, and transmits the light selection member. Alternatively, a surface plasmon resonance angle detection device including a lens that causes reflected light of different wavelengths to enter a sensor chip at a required angle difference and converge. 3. The sensor according to claim 2, further comprising a micro-rotating device connected to the variable light irradiating device, and the variable light irradiating device reciprocatingly rotating at a required angle as the micro-rotating device is driven. A surface plasmon resonance angle detection device that changes the incident angle of light on a chip. 4. A light source according to claim 2, wherein the light source comprises a laser light irradiating device for irradiating white laser light, and the light selecting member transmits laser light of a specific wavelength out of the three primary color lights of white laser light and transmits the other light. And a second dichroic mirror that reflects laser light of different wavelengths and reflects laser light of a different wavelength among the laser lights reflected from the first dichroic mirror and transmits laser light of another wavelength and emits the same to the outside. Surface plasmon resonance angle detection device consisting of a dichroic mirror. 5. The device according to claim 4, wherein the light source, the first and second dichroic mirrors, and a main body on which the lens is mounted are connected to a micro-rotation device, and light is incident on the sensor chip as the micro-rotation device is driven. Surface plasmon resonance angle detector that changes the angle. 6. A light emitting device according to claim 4, wherein said first and second dichroic mirrors are connected to a minute driving device, and said first and second dichroic mirrors vibrate in accordance with the driving of said minute driving device to make light incident on the sensor chip. Surface plasmon resonance angle detector that changes the angle.