JP2004354130A - Sensor head, sensor head manufacturing method, and sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor head, having high sensitivity to a change in permittivity, dispensing with a spectroscope or components such as a diffraction grating for acquiring wavelength spectrum, and having a reduced number of components, and to provide a sensor head manufacturing method and a sensor device. <P>SOLUTION: This sensor head is structured as a permittivity sensor head used in detecting a change in permittivity from a change in a resonance absorption spectrum of localized plasmons caused by irradiated illumination light. The sensor head comprises a substrate 101 and metallic thin wires 102 regularly arranged in a fixed direction on the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sensor head, a method of manufacturing the sensor head, and a sensor device, and more particularly, to a dielectric sensor, a chemical sensor including a biosensor used for medical care, health diagnosis, and food inspection.
[0002]
[Prior art]
In recent years, the demand for medical diagnosis, food inspection, and the like has been increasing, and the development of small, high-speed sensing, and low-cost biosensors has been demanded. For this reason, biosensors using an electrochemical method using electrodes and FETs have been manufactured by applying semiconductor processing technology.
Further, there is a demand for a sensor that is more integrated, lower in cost, and can be used in any measurement environment, and a sensor using surface plasmon resonance as a transducer is expected to be promising.
For example, a minute change in the dielectric constant near the metal surface is detected using surface plasmon resonance generated on a metal thin film provided on the surface of the total reflection prism. In addition, a chemical sensor that detects the presence or absence of a specific substance by combining with materials that cause selective binding such as antigen adsorption and DNA in an antigen-antibody reaction by detecting a minute dielectric constant near the surface It is.
[0003]
Furthermore, recently, for the purpose of highly sensitive sensing, a localized plasmon resonance sensor using metal fine particles as shown in Patent Document 1 has been proposed. In this method, a substrate on which metal fine particles are fixed is irradiated with light, and the absorbance of the light transmitted through the metal fine particles is measured by a spectrometer to detect a change in the medium near the metal fine particles.
[0004]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-356587
[Problems to be solved by the invention]
However, the technique disclosed in Patent Document 1 requires a spectroscope in order to measure the absorbance of light transmitted through the metal fine particles, which increases the number of components and the like.
Therefore, the present invention has a high sensitivity to a change in dielectric constant, does not require components such as a spectroscope or a diffraction grating for acquiring a wavelength spectrum, and has a small number of components, a sensor head, and a method of manufacturing a sensor head. A sensor device is provided.
[0006]
[Means for Solving the Problems]
The present invention provides a sensor head, a method of manufacturing the sensor head, and a sensor device configured as described below.
That is, the present invention uses a sensor head configured as a dielectric constant sensor head, which is used when detecting a change in dielectric constant from a change in resonance absorption spectrum of localized plasmon due to irradiated illumination light, comprising: a substrate; And metal thin wires regularly arranged in a certain direction.
Further, the present invention provides a chemical sensor for detecting a reaction caused by a contact between a sensor material and a test object based on a change in a resonance absorption spectrum of localized plasmons due to illumination light applied to a sensor head as a change in dielectric constant. A sensor head configured as a head is provided with a substrate and fine metal wires regularly arranged in a certain direction on the substrate, and the surface of the fine metal wire is modified with the sensor material. It is characterized by the following. At this time, the sensor material can be composed of a chemical sensor material, a biosensor material, or the like.
Further, in the sensor head of the present invention, the length of the thin metal wire in a direction parallel to the substrate orthogonal to the arrangement direction of the thin metal wires on the substrate may be larger than the wavelength of the irradiation light. it can.
Further, the thin metal wire in the sensor head of the present invention may have a cross-sectional size smaller than the wavelength of the irradiation light.
In the present invention, the cross-sectional size can be arranged so as to change regularly, or the distance between adjacent thin metal wires can be arranged so as to change regularly, or the cross-sectional size can be changed. They can be arranged so that the size and the distance between adjacent metal wires vary regularly.
Further, in the present invention, the thin metal wire may be made of gold or an alloy containing gold.
Further, in the method for manufacturing a sensor head for manufacturing any one of the above sensor heads of the present invention, a step of forming a metal thin film on a substrate, and a step of patterning a resist material on the metal thin film formed on the substrate. And a step of etching the metal thin film formed on the substrate using the resist pattern obtained in the above step as an etching mask, whereby the sensor head can be manufactured. Further, when manufacturing the chemical sensor head, after the step of etching the metal thin film, the etched metal thin film is subjected to a surface treatment, and a sensor material is bonded to the surface of the metal thin film, thereby manufacturing the chemical sensor head. can do. In the step of patterning the resist material in the method for manufacturing a sensor head, any one or more of contact lithography, near-field exposure, and nanoimprinting can be used.
Further, in the sensor device of the present invention, using any one of the above sensor heads, a light source for irradiating the sensor head with light, and a light detecting means for detecting a spatial distribution of light transmitted or reflected by the sensor head Thus, a sensor device can be configured. At this time, a bandpass filter can be provided between the light source and the sensor head, and the light source can be constituted by a laser or a semiconductor laser. Further, it is possible to configure a polarizing element that controls the polarization such that the magnetic field direction of the light emitted from these light sources is in the longitudinal direction of the thin metal wire of the sensor head.
Further, in the sensor device of the present invention, the substrate of the sensor head is transparent in a wavelength range of the light emitted from the light source, and the light detecting unit irradiates and transmits the thin metal wire array from the light source. It can be configured to detect light.
Further, in the sensor device of the present invention, the arrangement of the thin metal wires of the sensor head has a periodic array structure in which a thin metal wire array having a specific arrangement is used as a repeating unit. It is provided in
The light detecting means may be constituted as a light detecting means for independently detecting the spatial distribution of the transmitted or reflected light from the plurality of sets of the periodic array structure.
In the sensor device of the present invention, the sensor head can be integrated with a microchemical analysis system manufactured by using a semiconductor process, a DNA chip, a protein chip, or the like.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to the following examples.
[0008]
【Example】
[Example 1]
FIG. 1 shows the configuration of the chemical sensor device according to the first embodiment of the present invention.
In FIG. 1, 101 is a transparent substrate, 102 is a thin metal wire array formed on the substrate, 103 is a tungsten lamp as a light source, and 104 is a collimating lens for collimating light from the light source.
The collimating lens 104 converts the light from the light source into parallel light and irradiates the substrate 101 on which the thin metal wires are arranged. Reference numeral 105 denotes a polarizer for controlling the polarization of the irradiation light. Reference numeral 107 denotes a narrow-band bandpass filter, which transmits only light having a specific wavelength among light from the light source.
When the electric field vector of the incident light is orthogonal to the longitudinal direction of the fine line, the coupling efficiency with the localized plasmon polariton of the fine line increases. Reference numeral 106 denotes an area sensor which can receive a reflected light from the substrate 101 and acquire a spatial profile image of the reflected light.
[0009]
Here, the length of the thin metal wire 102 in a direction parallel to the substrate orthogonal to the arrangement direction of the thin metal wires on the substrate is longer than the irradiation light wavelength, and the cross-sectional size is smaller than the irradiation light wavelength. .
Further, the distance between the fine wires is larger than the reach (電 100 nm) of the electric field of the localized plasmon polariton excited on the surface of one fine wire, and the distance is constant in this embodiment.
In such a metal wire, scattering and absorption increase at a specific wavelength due to localized plasmon resonance. The wavelength at which such resonance occurs depends on the material of the metal, the size of the thin metal wire such as the distance between the thin wires and / or the cross-sectional size, and the dielectric constant of the surrounding medium. Regarding the dielectric constant of the last surrounding medium, a change in the dielectric constant within a range of plasmon spread (広 が り 100 nm) is detected as a shift of the resonance peak.
[0010]
In addition, the following size effects occur in thin lines having different sizes as described above. By irradiating light of a specific wavelength and when any specific thin line (fine line 1) is at the resonance peak in the localized plasmon, a slightly larger size fine line (fine line 2) has a slight distance from the resonance peak. The light irradiation is shifted, and the resonance absorption is weaker than that of the thin line 1.
When the dielectric constant of the medium increases under irradiation of light of the same wavelength, the first thin line deviates from the resonance peak, so that the resonance absorption is weakened, while the second thin line approaches the resonance peak and the resonance absorption becomes strong. To go. This behavior can be regarded as a change in the spatial distribution of absorption, that is, a change in the spatial distribution of reflected light.
[0011]
In the metal thin-wire array 102, the size of the thin wire is slightly different spatially, so that a change in absorption of the illumination light can be detected by the area sensor 106 as a change in the spatial distribution of the reflected light. Further, signal processing such as model function fitting and interpolation is performed on the aerial image acquired by the area sensor to detect a slight change in the spatial distribution and to improve the S / N of the signal.
In the embodiment shown here, the narrowing of the spectrum of the light source by the band-pass filter 107 is not essential. A change in the absorption spectrum due to a change in the dielectric constant involves not only a shift in the absorption peak but also a change in the absorption intensity. Therefore, even with a method of detecting the spatial distribution of reflection with respect to broad irradiation light, if appropriate signal processing is performed, the spatial distribution of fluctuation in absorption corresponding to a change in dielectric constant can be obtained.
[0012]
Such a dielectric constant sensor functions as a chemical sensor by modifying the surface of the thin metal wire with a material having specific binding characteristics. That is, the sensor head whose surface is modified is brought into contact with an object to be inspected such as a liquid to be inspected or a gas to be inspected, and the sensor material reacts with the object to be inspected. The amount of specific binding is quantitatively obtained as a change in the dielectric constant detected by the dielectric constant sensor.
Specific examples of the sensor material that causes such a reaction include the following (1) to (4).
(1) A thin metal wire is modified with an antibody substance which specifically binds to an antigen substance contained in a test object to prepare a sensor material.
(2) A complex of an analogous substance to be measured and an enzyme contained in a test object is used as a sensor material, and the antigen, which is the substance to be measured, comes into contact with the complex, so that the complex is dissociated, and the enzyme and the object to be measured are used. An antigen-antibody complex with the substance is formed.
(3) DNA
(4) The material of the thin metal wire (102 in FIG. 1) in the ion-selective electrode sensor head is selected from metals in general. In particular, gold, silver, and copper have a large surface plasmon generated, and the present invention is not limited thereto. It is suitable for. Above all, gold is chemically stable and can be chemically modified by various known means, and is most suitable for constructing a chemical sensor.
Any sensor material may be used as long as the sensor material reacts with the test object to cause a change in the film thickness, a change in the refractive index, a change in the absorption spectrum, and a change in the fluorescence spectrum. Materials used for chemical sensors including biosensors such as sensors, enzyme immunosensors, and bioaffinity sensors can be used.
[0013]
[Example 2]
A method for manufacturing the sensor head according to the second embodiment of the present invention will be described with reference to FIG. 2, first, a quartz substrate 201 is prepared (FIG. 2A).
Next, a 50 nm-thick metal thin film 202 is formed on the quartz substrate 201 by sputtering (FIG. 2B).
Next, an electron beam resist 203 was formed on the metal thin film 202 by spin coating, and was exposed by an electron beam drawing apparatus. After the development, a resist pattern having a distance between the patterns of 100 nm and a width of the pattern of 20 nm to 500 nm is obtained (FIG. 2D). Next, using the resist pattern as an etching mask, the metal thin film 202 is etched (FIG. 2E), the resist is removed, and a thin metal wire array is formed (FIG. 5F).
After performing a surface treatment on the thin metal wire array, the sensor material 204 is bonded (FIG. 5G).
[0014]
Here, the method of producing a micro-aperture pattern using an electron beam lithography apparatus has been described. In addition, various scanning methods utilizing the principles of a focused ion beam processing apparatus, a scanning tunnel microscope, an atomic force microscope, and a near-field optical microscope are described. It may be manufactured using a probe processing device, an X-ray exposure device, an EUV exposure device, or an electron beam stepper.
In addition, a simple and low-cost sensor head can be realized by using an exposure apparatus using near-field light described in JP-A-11-14505 or using a known nanoimprint method.
[0015]
[Example 3]
Third Embodiment FIG. 3 shows a configuration of a permittivity sensor device for obtaining a spatial distribution of absorption from transmitted light of a sensor body according to a third embodiment of the present invention.
In the dielectric constant sensor device of the present embodiment, first, monochromatic light from a semiconductor laser 301 is incident on a sensor head 303 via a lens 302. The transmitted light transmitted through the sensor head 303 is detected by the area sensor 304, and spatial distribution information of the transmitted light intensity is obtained. When the size of the sensor head manufactured finely and the size of the area sensor are different from each other, a sensor device utilizing the spatial resolution of the area sensor can be configured by using an optical system that performs scaling in this manner.
[0016]
[Example 4]
FIG. 4 shows a configuration of a dielectric constant sensor head according to Embodiment 4 of the present invention.
In FIG. 4, reference numeral 401 denotes a metal substrate, 402 denotes a dielectric thin film formed on the metal substrate, and 403 denotes a thin metal wire array formed on the dielectric thin film. Here, the arrayed thin metal wires 403 have a length in a direction parallel to the substrate orthogonal to the arrangement direction of the thin metal wires on the substrate, which is longer than the irradiation light wavelength, and the cross-sectional size of the thin wires is smaller than the irradiation light wavelength. Is also getting smaller. Also, unlike the first embodiment, the thin wires have the same cross-sectional size. On the other hand, the interval between the fine lines is slightly different from 5 nm to 200 nm.
[0017]
A metal thin film 401 having a thickness of 500 nm is formed over a quartz substrate by a sputtering method. A 50 nm thick SiO ₂ 402 and a 50 nm thick metal thin film were formed thereon.
An electron beam resist was formed by spin coating and exposed by a near-field exposure device. After the development, a resist pattern having a distance between the patterns of 100 nm and a width of the pattern of 20 nm to 500 nm was obtained. The metal thin film was etched using the resist pattern as an etching mask. The resist was removed to form a thin metal wire array 403. After performing surface treatment on the metal thin wire array 403, the sensor material is bonded.
[0018]
The localized plasmon resonance of a metal wire has a resonance spectrum that depends on the distance between the wires when the distance between the wires is 100 nm or less. In addition, since this resonance spectrum also depends on the dielectric constant of the surrounding medium, it is possible to detect a change in the dielectric constant by using a thin metal wire array having a configuration like 403 according to the same detection principle as in the first embodiment. And a chemical sensor using the same.
[0019]
[Example 5]
FIG. 5 shows a configuration of a dielectric constant sensor according to Embodiment 5 of the present invention.
In FIG. 5, reference numeral 501 denotes a transparent substrate, and reference numeral 502 denotes a thin metal wire array formed on the substrate. Here, the arrayed thin metal wires 502 have a length in the direction parallel to the substrate orthogonal to the arrangement direction of the thin metal wires on the substrate, which is longer than the irradiation light wavelength, and the cross-sectional size of the thin wires is smaller than the irradiation light wavelength. Is also getting smaller. Also, unlike the first and fourth embodiments, the cross-sectional size of the thin line and the interval between the thin lines are slightly different from each other. The localized plasmon resonance of a metal wire has a resonance spectrum depending on the shape of the wire and the distance between the wires.
[0020]
Further, since this resonance spectrum also depends on the dielectric constant of the surrounding medium, it is necessary to detect a change in the dielectric constant by using a thin metal wire array having a configuration like 502 according to the same detection principle as in the first and third embodiments. And a chemical sensor using the same can be configured.
Since both the shape and distance of the thin line can be applied as design parameters, it is possible to select an array shape such that the initial light intensity distribution is relatively flat. As a result, the dynamic range in detecting the spatial distribution can be increased.
[0021]
[Example 6]
FIG. 6 shows a configuration example in which the sensor head according to the sixth embodiment of the present invention is integrally formed with a microchemical analysis system (μ-TAS: also called a Micro Total Analysis System or a Lab-on-a-chip).
In the microchemical analysis system 901 shown in FIG. 6, the test liquid injected from the sample liquid injection section 902 reacts with the reaction liquid injected from the reaction liquid injection section 903 through the flow path 904, and then the detection section 905. To reach.
The detection unit 905 is provided with a thin metal wire array 906 for detection based on the principle of the present invention as shown in an enlarged view in the drawing. The test liquid reacts with the sensor material on the surface of the metal wire array. The detection unit 905 is irradiated with excitation light 907.
The light 908 transmitted from the light source 906 forms an image on the area sensor 911 via the lens 909 and is detected.
[0022]
[Example 7]
FIG. 7 shows a configuration example in which the sensor head according to the seventh embodiment of the present invention is formed integrally with a DNA chip or a protein chip.
Each detection cell 1002 of the DNA chip / protein chip 1001 shown in FIG. 7 is provided with a thin metal wire array 1003, and a sensor material is fixed on the surface. Here, the excitation light 1004 is irradiated, and the light transmitted from each detection cell is imaged on the surface of the CCD sensor 1007 via the lens 1006, so that the spatial distribution of each cell can be obtained in parallel.
As is clear from these, the sensor head of the present invention can be used in combination with various sensors, thereby increasing the signal intensity and enabling more accurate detection.
[0023]
【The invention's effect】
According to the present invention, a sensor head which has high sensitivity to a change in dielectric constant, does not require components such as a spectroscope or a diffraction grating for acquiring a wavelength spectrum, and has a small number of components, and a method of manufacturing the sensor head , A sensor device can be provided. Further, a highly sensitive chemical sensor and a chemical sensor having a large absorption spectrum and a large fluorescence spectrum intensity can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a sensor device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a method for manufacturing a sensor head according to a second embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of a dielectric constant sensor device according to a third embodiment of the present invention.
FIG. 4 is a diagram illustrating a configuration of a dielectric constant sensor head according to a fourth embodiment of the present invention.
FIG. 5 is a diagram illustrating a configuration of a dielectric constant sensor head according to a fifth embodiment of the present invention.
FIG. 6 is a diagram illustrating a configuration example in which a sensor head according to a sixth embodiment of the present invention is integrally formed with a microchemical analysis system (also referred to as a μ-TAS: Micro Total Analysis System or Lab-on-a-chip).
FIG. 7 is a diagram showing a configuration example in which a sensor head according to a seventh embodiment of the present invention is formed integrally with a DNA chip or a protein chip.
[Explanation of symbols]
101, 201, 401, 501: Substrates 102, 403, 502: Fine metal wire 103: Light source 301: Semiconductor laser 104, 302: Lens 105: Polarizer 106, 304: Area sensor 107: Bandpass filter 202: Metal thin film 203: Electron beam resist 303: sensor head 402: dielectric thin film

Claims (23)

A sensor head configured as a dielectric constant sensor head, which is used when detecting a change in dielectric constant from a change in resonance absorption spectrum of localized plasmons due to irradiated illumination light,
The sensor head according to claim 1, wherein the sensor head includes a substrate and fine metal wires regularly arranged in a predetermined direction on the substrate. The sensor head is configured as a chemical sensor head that is used to detect a reaction caused by contact between the sensor material and the test object based on a change in the resonance absorption spectrum of localized plasmons due to illumination light applied to the sensor head as a change in dielectric constant. A sensor head,
The sensor head according to claim 1, wherein the sensor head includes a substrate and fine metal wires regularly arranged in a predetermined direction on the substrate, and the surface of the fine metal wire is modified with the sensor material. The sensor head according to claim 2, wherein the sensor material is made of a chemical sensor material. The sensor head according to claim 2, wherein the chemical sensor material is formed of a biosensor material. The metal thin wire according to any one of claims 1 to 4, wherein a length in a direction parallel to the substrate orthogonal to an arrangement direction of the metal thin wires on the substrate is larger than a wavelength of the irradiation light. Item 2. The sensor head according to item 1. The sensor head according to claim 1, wherein the thin metal wire has a cross-sectional size smaller than a wavelength of the irradiation light. The sensor head according to claim 6, wherein the cross-sectional sizes are arranged so as to change regularly. The sensor head according to any one of claims 1 to 6, wherein the thin metal wires are arranged so that a distance between adjacent thin metal wires changes regularly. The sensor head according to any one of claims 1 to 6, wherein the thin metal wires are arranged so that the cross-sectional size and the distance between the thin metal wires are regularly changed. The sensor head according to claim 1, wherein the thin metal wire is gold or an alloy containing gold. A sensor head manufacturing method for manufacturing the sensor head according to any one of claims 1 to 10,
Forming a metal thin film on the substrate,
Patterning a resist material on the metal thin film formed on the substrate,
Etching the metal thin film formed on the substrate using the resist pattern obtained in the step as an etching mask;
A method for manufacturing a sensor head, comprising: A method for manufacturing a sensor head according to any one of claims 2 to 10, wherein after the step of etching a metal thin film in the method for manufacturing a sensor head according to claim 11,
A method for manufacturing a sensor head, comprising a step of subjecting an etched metal thin film to a surface treatment and bonding a sensor material to the surface of the metal thin film. 13. The method according to claim 11, wherein the step of patterning the resist material includes a step of forming a resist pattern using at least one of contact lithography, near-field exposure, and nanoimprinting. 3. The method for manufacturing a sensor head according to item 1. A sensor head according to any one of claims 1 to 10, a light source that irradiates the sensor head with light, and a light detection unit that detects a spatial distribution of light transmitted or reflected by the sensor head. A sensor device comprising: The sensor device according to claim 14, further comprising a bandpass filter between the light source and the sensor head. The sensor device according to claim 14, wherein the light source is a laser. The sensor device according to claim 14, wherein the light source is a semiconductor laser. 18. The device according to claim 14, further comprising a polarizing element that controls polarization such that a magnetic field direction of light emitted from the light source is a longitudinal direction of the thin metal wire of the sensor head. Sensor device. The substrate of the sensor head is transparent in a wavelength region of the light emitted from the light source, and the light detecting means has a configuration to detect light emitted from the light source to the metal thin wire array and transmitted therethrough. The sensor device according to any one of claims 14 to 18, wherein The arrangement of the metal thin wires of the sensor head has a periodic array structure in which a metal thin wire array composed of a specific arrangement is used as a repeating unit, and a plurality of these are provided on the substrate of the sensor head,
20. The light detecting device according to claim 14, wherein the light detecting device is configured to independently detect a spatial distribution of light transmitted or reflected from the plurality of sets of the periodic array structure. The sensor device according to claim 1. The sensor device according to any one of claims 14 to 20, wherein the sensor head is integrated into a microchemical analysis system manufactured using a semiconductor process. 21. The sensor device according to claim 14, wherein the sensor head is integrated with a DNA chip manufactured using a semiconductor process. 21. The sensor device according to claim 14, wherein the sensor head is integrated with a protein chip manufactured using a semiconductor process.

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