JP2013033000A - Optical device, detection apparatus and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device, a detection apparatus and a detection method capable of securely detecting a detection object, even a comparatively large object such as a virus or a bacterium.SOLUTION: An optical device 10 comprises a first substrate 11 and a second substrate 12 facing the first substrate. The first substrate 11 includes first convex portions 11B on a conductor surface, projecting from a first surface 11A facing the second substrate and aligned in first direction X parallel to a plane of the first substrate at an interval P1. The second substrate 12 includes second convex portions 12B on a conductor surface, projecting from a second surface 12A facing the first substrate and aligned at a maximum interval P2 in the first direction. If light incident on specimens 1, 2 interposed between the first and second substrates is λ, λ>P1>P2 is satisfied.

Description

  The present invention relates to an optical device, a detection apparatus, a detection method, and the like used for, for example, Raman spectroscopic detection.

  An ordinary Raman spectroscope has a feature that a fingerprint spectrum of a substance to be detected can be obtained, but has a problem that a Raman signal is weak and detection sensitivity is low, and its use is limited. However, as will be described later, by irradiating a metal nanostructure smaller than half the wavelength of light with light, a localized enhanced surface plasmon resonance (LSPR) is formed in which a strong enhanced electric field is formed in the vicinity of the metal nanostructure. The phenomenon is known. Furthermore, a phenomenon called surface enhanced Raman scattering (SERS), in which Raman scattered light is enhanced by an enhanced electric field, is also known. It becomes possible to specify from the fingerprint spectrum. By utilizing this principle, it becomes possible to detect and identify a very small amount of target molecule with high sensitivity.

  Patent Document 1 describes a method in which a liquid sample containing microorganisms is dropped onto a SERS active substrate on which metal nanoparticles are arranged, and then a fixing solution (consisting of agarose gel and glycerol) for fixing the microorganisms is dropped. Yes.

In Patent Document 2, SiO ₂ and TiO ₂ are formed on a dielectric lattice (period: 360 nm) made of an epoxy resin, and then a fine SiO ₂ column is formed, and a silver nanostructure is formed on the upper end portion thereof. A sensor structure is disclosed. In this structure, an enhanced electric field is generated by guided-mode resonance in a dielectric lattice, and a stronger enhanced electric field is created by exciting localized surface plasmon resonance of the silver nanostructure on the surface.

  In Patent Document 3, at least two SERS substrates on which metal particles are non-uniformly adhered on a transparent substrate are arranged in parallel, and Raman scattered light is generated from each SERS active substrate to enhance detection sensitivity. (Paragraph 0028 and FIG. 9).

JP 2010-223671 A US Published Patent Application 2010/0085566 WO2007 / 049477

  According to Patent Document 1, it is desirable that microorganisms be fixed in close proximity to the enhanced electric field formed by the metal nanoparticles that enhance the SERS signal. However, whether or not the state will be realized simply by dropping the fixing solution. It will be up to you.

  In the sensor structure of Patent Document 2, a strong enhanced electric field is formed only in the vicinity of the silver nanostructure. Therefore, for a relatively large detection target such as a virus or a bacterium, there is a region where the enhanced electric field extends. There is a problem that the detection becomes relatively small and appropriate detection cannot be performed. This problem is also present in the structure of Patent Document 3.

  An object of some aspects of the present invention is to provide an optical device, a detection apparatus, and a detection method that can reliably detect a relatively large detection target such as a virus or a bacterium.

(1) One aspect of the present invention is
A first substrate;
A second substrate facing the first substrate;
Have
The first substrate has a first convex portion of a conductor surface protruding from a first surface facing the second substrate, and the first convex portion has a period P1 in a first direction along the first surface. Arranged in
The second substrate has a second convex portion of a conductor surface protruding from a second surface facing the first substrate, and the second convex portion is arranged with a maximum period P2 in the first direction,
The present invention relates to an optical device that satisfies λ>P1> P2, where λ is the wavelength of light incident on a sample sandwiched between the first and second substrates.

  In one aspect of the present invention, a propagating surface plasmon (PSP) is excited on the first surface of the first substrate. Propagating surface plasmons propagate along the first surface, and localized surface plasmons (LSP) are excited around the second convex portions of the second surface of the second substrate. This localized surface plasmon excites an enhanced electric field around the second convex portion, which is a hot site having a relatively high density. Therefore, even a relatively small sample molecule that enters between the second protrusions, or a relatively large sample molecule that does not enter between the second protrusions but can enter between the first protrusions, Surface enhanced Raman scattering (SERS) occurs due to the interaction between the enhanced electric field and sample molecules. Thus, strong surface-enhanced Raman scattering can be caused by the enhanced electric field.

  (2) In one aspect of the present invention, the distance between the first convex portion and the second convex portion is 100 nm or less, and the first and second substrates can be opposed to each other. In this way, since the sample can be positioned within the range of the electric field leakage distance, strong surface-enhanced Raman scattering can be generated by the enhanced electric field.

  (3) In one aspect of the present invention, the first period may be 400 to 600 nm, and the second period may be 20 to 100 nm. If it carries out like this, infrared light larger than 600 nm can be used as a wavelength of incident light, and also the density of the 2nd convex part as a hot site where an enhanced electric field is excited can be secured high.

  (4) In one aspect of the present invention, the second substrate is movable relative to the first substrate between a position facing the first substrate and a position not facing the first substrate. Can be supported. Thus, the first and second substrates can be opposed to each other after the sample is held on one of the first and second substrates while the first and second substrates are not opposed to each other.

  (5) In one embodiment of the present invention, when the molecular size of the sample is D, P2 <D <P1 can be satisfied. In this way, even a sample larger than the period P2 can be positioned between the first protrusions of the maximum period P1, and can be detected using the enhanced electric field around the high density second protrusions. it can.

(6) Another aspect of the present invention is:
The optical device described above;
A light source;
A light detection unit;
Have
The sample is held between the first and second substrates of the optical device;
The optical device emits light from the sample by being irradiated with light from the light source,
The light detection unit relates to a detection device that detects light from a specific substance contained in the sample.

  According to another aspect of the present invention, as described above, the optical device can generate strong surface-enhanced Raman scattering by the enhanced electric field, so that the Raman scattered light emitted from the specific substance in the sample can be detected with high detection sensitivity. It can be detected at the part.

(7) Still another aspect of the present invention is
Holding the sample on the first facing surface of the first substrate having a first convex portion that is arranged at a period P1 in the first direction and protrudes from the first surface;
A second substrate having a second protrusion that is arranged in the first direction with a maximum period P2 (P2 <P1) and protrudes from a second surface facing the first substrate is defined as the first surface and the second surface. Arranging the surfaces so that they face each other;
Irradiating a sample sandwiched between the first and second substrates with a wavelength λ (λ> P1), and emitting light reflecting the sample;
Detecting light from a specific substance contained in the sample from light from the sample;
It is related with the detection method which has.

  According to another aspect of the present invention, since the sample sandwiched between the first and second substrates can generate strong surface-enhanced Raman scattering by the enhanced electric field, the Raman scattered light reflecting the specific substance in the sample is generated. Detection is possible with high detection sensitivity. Moreover, the setting of the sample on the first substrate can be performed without interference with the second substrate.

FIG. 1A to FIG. 1C are views showing an optical device according to the first embodiment of the present invention. 2A is a diagram showing generation of Rayleigh scattered light and Raman scattered light, FIG. 2B is a diagram showing a Raman spectrum of acetaldehyde, and FIG. 2C and FIG. It is a figure which shows the reinforcement | strengthening electric field which arises in the vicinity of 2 convex parts. It is a figure which shows the reinforcement | strengthening electric field which acts on the sample which penetrates between 2nd convex parts. It is a characteristic view showing the relationship between the thickness of the dielectric (the distance between the first convex part and the second convex part) interposed between the first and second substrates and the strength of the local electric field. It is a figure which shows the specific example of a detection apparatus. It is a control system block diagram of a detection apparatus. FIG. 7A and FIG. 7B are diagrams for explaining extraction of spectrum intensity. FIG. 8A to FIG. 8E are diagrams showing a method for manufacturing a substrate constituting an optical device. It is a figure which shows the apparatus which implements the optical interference exposure shown to FIG. 8 (A). 10 (A) and 10 (B) are diagrams showing an exposure pattern of convex portions created by the optical interference exposure apparatus shown in FIG. FIG. 11A to FIG. 11D are diagrams showing a manufacturing method different from those in FIG. 8A to FIG. It is a figure which shows the modification of an optical device. FIG. 13A to FIG. 13D are diagrams illustrating modifications of the optical device in which the second substrate can be moved relative to the first substrate.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Optical device 1.1. Structure of Optical Device FIGS. 1A to 1C show an optical device 10 according to this embodiment. As illustrated in FIG. 1A, the optical device 10 includes a first substrate 11 and a second substrate 12. The first substrate 11 has first protrusions 11B that protrude from the first surface 11A and are arranged in the first direction X with a period P1. The surface 11C of the 1st board | substrate 11 and the 1st convex part 11B is a metal (conductor). In this embodiment, the board | substrate 11 and the 1st convex part 11B are formed with the dielectric material.

  The second substrate 12 has second convex portions 12B protruding from the second surface 12A and arranged in the first direction X with the maximum period P2 (P2 <P1). In this embodiment, the 2nd board | substrate 12 is a dielectric material, and the 2nd convex part 12B is a metal.

  FIG. 1B shows a state where the sample 2 is held on the first substrate 11. The sample 2 contains a detection substance, and is a liquid sample in this embodiment. The liquid sample 2 is dropped on the first substrate 11 with a dropper or the like.

  FIG. 1C shows the optical device 10 in a state at the time of detection. The first substrate 11 and the second substrate 12 are disposed to face each other with the sample 2 sandwiched between the first surface 11A and the second surface 12A. In particular, in FIG. 1C, the molecular size of the sample 2 is relatively large and cannot enter between the second protrusions 12B having the maximum period P2, but it enters between the first protrusions 11B having the period P1. Yes. When the molecular size of the sample is D, P2 <D <P1 is satisfied.

  In the present embodiment, since the surface 11C of the first substrate 11 is metal and does not transmit light, incident light is incident from the second substrate 12 side as shown in FIG.

1.2. Light Detection Principle An explanatory diagram of the detection principle of Raman scattered light is shown as an example of a light detection principle reflecting a fluid sample, with reference to FIGS. 2 (A) to 2 (D). As shown in FIG. 2A, incident light (frequency ν) is irradiated onto a detection target sample (sample molecule) 2 adsorbed on the optical device 10. In general, most of the incident light is scattered as Rayleigh scattered light, and the frequency ν or wavelength of the Rayleigh scattered light does not change with respect to the incident light. A part of the incident light is scattered as Raman scattered light, and the frequency (ν−ν ′ and ν + ν ′) or wavelength of the Raman scattered light reflects the frequency ν ′ (molecular vibration) of the sample molecule 2. That is, the Raman scattered light is light reflecting the sample molecule 2 to be inspected. A part of the incident light causes the sample molecule 1 to vibrate and loses energy, but the vibration energy of the sample molecule 2 may be added to the vibration energy or light energy of the Raman scattered light. Such a frequency shift (ν ′) is called a Raman shift.

  FIG. 2B shows an example of acetaldehyde as a fingerprint spectrum unique to the target molecule. With this fingerprint spectrum, the detected substance can be identified as acetaldehyde. However, the Raman scattered light is very weak and it is difficult to detect a substance that exists only in a trace amount.

  FIG. 2D shows a state in which the sample molecule 1 having a small size is inserted between the second convex portions 12B instead of the sample molecule 2 having a large size shown in FIG. As shown in FIG. 2D, the enhanced electric field 13 is formed in the gap between the adjacent second convex portions 12B in the region where the incident light is incident. In particular, as shown in FIG. 2C, when the incident light is irradiated onto the second convex portion 12B that is smaller than the wavelength λ of the incident light, the electric field of the incident light exists on the surface of the second convex portion 12B. Acts on free electrons to cause resonance. Thereby, the electric dipole due to free electrons is excited in the second convex portion 12B, and an enhanced electric field 13 stronger than the electric field of the incident light is formed. This is also called Localized Surface Plasmon Resonance (LSPR). This phenomenon is a phenomenon peculiar to the electric conductor of the 2nd convex part 12B which has a convex part of 1-1000 nm smaller than the wavelength of incident light.

  On the other hand, FIG. 3 is an enlarged view of FIG. Large sample molecules 2 cannot enter between the second protrusions 12B, but can enter between the first protrusions 11B. In the present embodiment, localized surface plasmons and propagation surface plasmons can be used in combination. When light is incident on the grating surface having the first protrusions 11B of the first substrate 11, surface plasmons are generated due to the irregularities of the grating. If the polarization direction of the incident light is orthogonal to the groove direction of the grating, the vibration of the electromagnetic wave is excited with the vibration of free electrons in the metal grating. Since the vibration of the electromagnetic wave affects the vibration of free electrons, surface plasmon polariton, which is a system in which both vibrations are combined, is formed.

  The surface plasmon polariton propagates along the surface 11C of the first substrate 11. Specifically, the surface plasmon polariton propagates along the interface between air and the metal lattice, and excites a strong enhanced electric field 14 localized in the vicinity of the metal lattice (first convex portion 11B). The coupling of the surface plasmon polariton is sensitive to the wavelength λ of light and satisfies the period P1 <λ, and particularly preferably has a period P1 slightly smaller than the wavelength λ, the coupling efficiency is high.

  When sample molecules 2 having a relatively large size exist between the first convex portions 11B, surface-enhanced Raman scattering occurs therefrom. In this way, the enhanced electric field 14 is excited from the incident light in the air propagation mode via the surface plasmon polariton, and surface enhanced Raman scattering is expressed by the interaction between the localized enhanced electric fields 13 and 14 and the target. That is, when a large sample molecule 2 exists between the first convex portions 11B, the Raman scattered light by the sample molecule 2 is enhanced by both the enhanced electric field 13 and the enhanced electric field 14, and the signal intensity of the Raman scattered light becomes strong. . In such surface-enhanced Raman scattering, the detection sensitivity can be increased even if the amount of sample molecules 2 is very small.

  In the present embodiment, assuming that an infrared wavelength λ (for example, 633 nm) larger than 600 nm is used as incident light, the period P1 can be set to 400 to 600 nm. Moreover, since the period P2 is smaller than the period P1 and increases the density of hot sites, it can be set to 20 to 100 nm. Further, the period P2 may not be regular, and the second protrusions 12B may be randomly arranged as the maximum period P2. Furthermore, although the said embodiment formed the convex parts 11B and 12B with the one-dimensional period about the 1st direction X, it forms the convex parts 11B and 12B similarly arranged with the periods P1 and P2 also in the 2nd direction Y. May be. In this way, the polarization dependence of incident light is eliminated, and circularly polarized light can be used.

1.3. FIG. 4 shows the relationship between the first convex portion 11B and the second convex portion 12B. A dielectric (SiO ₂ layer) is interposed between the first convex portion 11B and the second convex portion 12B. It is the characteristic view which measured thickness. Here, the thickness of the dielectric corresponds to the distance between the first convex portion 11B and the second convex portion 12B.

As shown in FIG. 4, the electric field enhancement greatly depends on the thickness of the dielectric. FIG. 4 shows the relationship between the intensity of the signal peak with a Raman shift wavenumber of 730 cm ⁻¹ and the thickness of the dielectric in the spectrum of the detection target substance. From this, it can be seen that the electric field enhancement becomes maximum when the thickness of the dielectric is around 40 nm. The thickness of the dielectric film, that is, the distance between the first convex portion 11B and the second convex portion 12B is set to 100 nm or less, preferably 20 to 60 nm. Can be secured. In addition, the result of FIG. 4 measured the 1st board | substrate 11 as a metal film without the 1st convex part 11B. This is because, when the flat first protrusion 11B is formed, if the thickness of the dielectric is changed, the unevenness ratio of the first protrusion 11B also changes, so it is difficult to know only the effect of the thickness of the dielectric.

1.4. Sample The sample 2 containing the substance to be detected is a substance having a size of about 100 nm or less, such as an organic molecule or a virus that can be sandwiched between the first and second substrates 11 and 12, and is in a state suitable for gas. A liquid contained in a solvent is suitable.

  In the security field, detection purposes include detection of narcotics and explosives, detection of flammable dangers, etc. performed at airports, ports, and transportation facilities. In the medical and health field, those that detect various viruses that cause infectious diseases such as influenza, those that detect hydrogen sulfide, methyl mercaptan, and dimethyl sulfide in oral gas to determine periodontal disease, breath Those that test for asthma by detecting nitric oxide (NO) contained in the gas, those that conduct screening screening for cancer by detecting volatile organic compounds (VOC) contained in the breath gas, breath gas Those that monitor fat burning by detecting acetone contained in water, those that monitor cholesterol by detecting isoprene contained in exhaled breath, volatile organic compounds (VOC) contained in indoor air, benzene, toluene, Examples include xylene, ethylbenzene, styrene, and formaldehyde testing.

  Examples of viruses to be detected include not only influenza viruses but also the following viruses. According to the classification system of the International Virus Classification Committee, the following classifications are applied, but all viruses are also covered.

Group 1 (Group I) double-stranded DNA
Group 2 (Group II) single-stranded DNA
Group 3 (Group III) double-stranded RNA
Group 4 (Group IV) Single-stranded RNA + strand (acts as mRNA)
Group 5 (Group V) Single-stranded RNA-Strand Group 6 (Group VI) Single-stranded RNA + Strand Reverse Transcription Group 7 (Group VII) Double-Stranded DNA Reverse Transcription Representative viruses include respirovirus, Rubra virus, orthomyxovirus, adenovirus, rhinovirus, papilloma virus, polyoma virus, parvovirus, alphavirus, flavivirus, hepacivirus, hepatovirus, ebola virus, arenavirus, retrovirus, and the like. In any case, these sizes are about several tens to 100 nm.

2. Specific Configuration of Detection Device FIG. 5 shows a specific configuration example of the detection device of the present embodiment. In the detection apparatus 100 shown in FIG. 5, the optical device 10 shown in FIG. 1C is detachably arranged. A cover 103 is rotatably supported at the end of the casing 101 of the detection apparatus 100 via a hinge 102. A pressing member such as a leaf spring 104 is disposed inside the cover 103. Therefore, when the cover 103 is opened and the optical device 10 shown in FIG. 1C is arranged, and the cover 103 is closed and locked, the optical device 10 is maintained in the state of FIG. . In FIG. 5, the optical device 10 shown in FIG. 1C is arranged upside down so that light is incident from the second substrate 12 side.

  The detection apparatus 100 includes an optical system 30, a light source 50, a light detection unit 60, a processing unit 70, and a power supply unit 80 in a housing 101.

  For example, the linearly polarized light source 50 having a single wavelength is, for example, a laser light source, and a vertical cavity surface emitting laser can be preferably used from the viewpoint of miniaturization, but is not limited thereto.

  The light from the light source 50 is collimated by the collimator lens 310 constituting the optical system 30. A polarization control element may be provided downstream of the collimator lens 310 and converted to linearly polarized light. However, if a surface emitting laser is used as the light source 50 as described above and light having linearly polarized light can be emitted, the polarization control element can be omitted.

  The light collimated by the collimator lens 310 is guided by the half mirror (dichroic mirror) 320 toward the optical device 10, collected by the objective lens 330, and incident on the optical device 10. In the optical device 10, metal nanoparticles 220 shown in FIGS. 6B and 6C are formed. Rayleigh scattered light and Raman scattered light by, for example, surface-enhanced Raman scattering are emitted from the optical device 10. Rayleigh scattered light and Raman scattered light from the optical device 10 pass through the objective lens 330, and are guided toward the light detection unit 60 by the half mirror 320.

  Rayleigh scattered light and Raman scattered light from the optical device 10 are collected by the condenser lens 340 and input to the light detection unit 60. First, the light detection unit 60 reaches the optical filter 610. Raman scattered light is extracted by an optical filter 610 (for example, a notch filter). This Raman scattered light is further received by the light receiving element 630 via the spectroscope 620. The spectroscope 620 is formed of, for example, an etalon using Fabry-Perot resonance, and the pass wavelength band can be made variable. The wavelength of light passing through the spectroscope 620 can be controlled (selected) by the control unit 70. The light receiving element 630 obtains a Raman spectrum peculiar to the sample molecule 1, and the sample molecule 1 can be specified by collating the obtained Raman spectrum with previously stored data.

  FIG. 6 is a control system block diagram of the detection apparatus 100 of FIG. As illustrated in FIG. 6, the detection apparatus 100 may further include, for example, an interface 120, a display unit 130, an operation unit 140, and the like. Further, as shown in FIG. 6, the processing unit 70 can include, for example, a CPU (Central Processing Unit) 71, a RAM (Random Access Memory) 72, a ROM (Read Only Memory) 73, and the like as control units. Further, in the detection apparatus 100, the light source drive circuit 52, the spectroscope drive circuit 622, the light receiving circuit 632, the detection circuit 152, the power supply unit 80, and the like are connected to the processing unit 70. The processing unit 70 can send a command to each unit shown in FIG. Furthermore, when the presence / absence of the optical device 10 and the ID are detected via the detection circuit 151 by the detector 150 shown in FIGS. 5 and 6, the processing unit 70 can execute spectral analysis using a Raman spectrum. The processing unit 70 can specify the sample molecules 1 and 2 that are target objects. The processing unit 70 can transmit the detection result by Raman scattered light, the spectroscopic analysis result by Raman spectrum, and the like to an external device (not shown) connected via the interface 120 and the terminal 121.

  As the power supply unit 150, a primary battery, a secondary battery, or the like can be used. In the case of a primary battery, the CPU 70 determines that the voltage has become equal to or lower than a specified voltage stored in the ROM 73 and displays battery replacement on the display unit 130. In the case of a secondary battery, the CPU 70 displays a charge on the display unit 130 if the voltage is equal to or lower than a specified voltage. The operator can see the display, connect a charger to the terminal 81, and charge the battery until it reaches a specified voltage.

FIGS. 7A and 7B are schematic explanatory diagrams of peak extraction of a Raman spectrum. FIG. 7A shows a Raman spectrum detected when a certain substance is irradiated with an excitation laser, and a Raman shift is represented by a wave number. In the example of FIG. 7A, the first peak (883 cm ⁻¹ ) and the second peak (1453 cm ⁻¹ ) are considered characteristic. The detection target substance in the fluid sample is specified by collating the obtained Raman spectrum with previously stored data (Raman shift and light intensity of the first peak, Raman shift and light intensity of the second peak, etc.). be able to.

FIG. 7B shows the signal intensity (white circle) when the light receiving element 630 detects the spectrum around the second peak in the spectroscopic element 620. When the spectroscopic element 620 is about 10 cm ⁻¹ and the resolution is fine, the Raman shift (black circle) of the second peak can be easily specified accurately.

3. Manufacturing Method of Optical Device FIGS. 8A to 8E show an example of a manufacturing method of the optical device 10. Although an example in which the substrate 200 is a quartz substrate is shown, the above-described first structure can be similarly formed on a substrate 200 made of another material, and is not limited to quartz. As shown in FIG. 8A, a resist 200A is applied to a clean quartz substrate 200 with an apparatus such as a spin coater and dried.

  As shown in FIG. 8B, laser interference exposure is performed to form a desired pattern 200B on the resist 200A. In the present embodiment, since the size of the convex portion 210 is smaller than the wavelength of light to be irradiated (here, the region from visible light to near infrared light), an electron beam exposure method or an ultraviolet laser is used as an exposure apparatus. The optical interference exposure method used can be used. The electron beam exposure method has a high degree of freedom in exposure, but has a limit in mass productivity. Therefore, an optical interference exposure method using an ultraviolet laser with excellent mass productivity was adopted. For example, a continuous wave YVO4 laser (wavelength 266 nm, maximum output 200 mW) can be used as a light source for interference exposure. A positive resist was used, and the resist film thickness was 1 μm. As for the resist exposure pattern, one pattern is a lattice pattern, and the other pattern is also a lattice pattern. Various patterns can be formed depending on the angle at which the two intersect, and the pattern can be reduced to half the laser wavelength. Is possible. A latent image of both interference fringes is formed in the resist, and the resist is developed to form a desired pattern 200B shown in FIG.

  Thereafter, as shown in FIG. 8C, a portion not protected by the resist pattern 200B is etched to provide a recess in the substrate 200. Further, as shown in FIG. 8D, the resist pattern remaining on the substrate is removed. Thereby, the convex part 210 remains on the substrate 200.

  After the convex portion 210 having the first structure is formed, a metal film (conductor film) 201 is formed by a sputtering apparatus or a vapor deposition apparatus. Initially, a thin metal film 201 is formed as a whole, but a large amount of metal gradually adheres to the vicinity of the projections and depressions, resulting in the shape of the metal nanoparticles 220 shown in FIG. 8E. The gap G of the metal nanoparticles 220 can be controlled by the thickness of the metal film 201. Since the size of the gap G has a structure for holding the metal nanoparticles 220, it is an important parameter. Examples of the metal include gold (Au), silver (Ag), copper (Cu), Pd (palladium), Pt (platinum), Rh (rhodium), Ru (ruthenium), Ta (tantalum), and Ti (titanium). , W (tungsten), Mo (molybdenum), or alloys or composites thereof.

  According to FIGS. 8A to 8E, the second convex portion 12B on the second substrate 12 can be suitably formed, but also when the first convex portion 11B is formed on the first substrate 11. Applicable.

  FIG. 9 shows a schematic configuration diagram of an optical interference exposure method using an ultraviolet laser. As the light source 160, an ultraviolet laser having a wavelength of 266 nm and an output of 200 mW capable of continuous oscillation (CW) was used. The laser light emitted from the laser light source 160 is turned back by the mirror 162 via the shutter 161 and branched to both sides by the half mirror 163. The mirrors 164A and 164B are turned around, and the beams are expanded through the objective lenses 165A and 165B and the pinholes 166A and 166B. The spread ultraviolet laser is irradiated to the masks 167A and 167B to form interference fringes, and the substrate 200 coated with a resist is irradiated. At this time, various patterns can be exposed by the exposure configuration of the interference fringes. This pattern can be monitored by the monitor 169A by imaging with the CCD camera 169.

  10 (A) and 10 (B) show typical examples of exposure patterns that can be created by the optical interference exposure method. FIG. 10A shows the second convex portion 12B of the one-dimensional array shown in FIG. FIG. 10B is an example in which the second protrusions 12B are two-dimensionally arranged in the X and Y directions.

11A to 11C show a manufacturing method different from the optical interference exposure method described in FIG. First, a thin conductive film 201 of metal shown in FIG. 11B is formed on a substrate 200 such as quartz or borosilicate glass having a clean surface shown in FIG. 11A by vapor deposition or sputtering. As the conductor film 201, Au (gold), Ag (silver), aluminum (Al), copper (Cu), or the like is selected. The conductor film 220 is desirably a uniform and flat film as much as possible. Next, the metal island 221 is formed with a vapor deposition machine. In order to form the metal island 221, the metal atoms that have reached the conductor film 220 on the substrate 200 diffuse and settle down, so that if the surface diffusion length is too large, the island is not connected and the islands are connected. It becomes a film. The surface diffusion length is affected by the temperature of the substrate 200 and the wettability of the substrate 200 and the deposited metal. The lower the temperature of the substrate 200, the smaller the surface diffusion length. Specifically, an example of an island structure in which an Ag pressure is approximately 10 ⁻³ (Pa), a deposition rate is approximately 0.02 nm / second, and the substrate 200 is not heated is illustrated in FIG. It shows as a photograph of a microscope. One island has a size of about 10 to 50 nm and is randomly formed. When these metal islands 221 are irradiated with laser light, the size of the island 221 is smaller than the wavelength of the light, so that the free electrons resonate with the electric field of the light and have a strong dipole moment, resulting in a strong enhanced electric field. Will be formed. The types of metal forming the metal island 221 are Au (gold), Ag (silver), Al (aluminum), Cu (copper), Pd (palladium), Pt (platinum), Rh (rhodium), Ru (ruthenium). , Ta (tantalum), Ti (titanium), W (tungsten), Mo (molybdenum), or a composite structure, which can be selected according to the target molecule.

4). Other Modifications Although the present embodiment has been described in detail as described above, those skilled in the art can easily understand that many modifications that do not substantially depart from the novel matters and effects of the present invention are possible. .

  FIG. 12 shows a modification of the optical device. On the first substrate 11, for example, by the manufacturing method shown in FIGS. 8A to 8E, a first convex portion 15 having a duty different from that of the first convex portion 11B in FIG. 1C is formed. . The second substrate 12 has a convex curved surface 16 that protrudes toward the first substrate 11 toward the center, and the second convex portion 12B is formed on the curved surface 16.

  When the first substrate 11 and the second substrate 12 are overlapped, if these substrates are warped, they are not overlapped in parallel, and the intervals are varied. In order to avoid this, for example, one of the second substrates 12 is processed into a convex curved surface 16 in advance, and the second convex portion 12B is formed thereon. As a result, the first substrate 11 and the second substrate 12 can be overlapped at a given interval substantially at the center. The convex processing dimension of the substrate may be determined according to the warp of the substrate, and it is only necessary that the central portion is convex to about 10 to 100 μm. However, since a fine structure is formed on the curved surface 16, the surface state of the curved surface 16 needs to be smoother than the fine structure. As an example of the processing method, the curved surface 16 can be formed by performing a lapping process to make the surface smooth after processing by lapping polishing using a concave tool and abrasive coating grains.

  13A to 13D show that the second substrate 12 is relative to the first substrate 11 at a position facing the first substrate 11 and a position not facing the first substrate 11. 1 shows an optical device 10 having a structure that is movably supported.

  FIG. 13A shows an initial state before the sample 2 is introduced. The first substrate 11 is placed in the central portion of the base 240, the sample absorbing portion 231 is disposed around the first substrate 11, and the cover 232 is fixed with a gap. The second substrate 12 is accommodated in a movable state between the base 230 and the cover 232. A lever 233 for moving the second substrate 12 is provided. An opening 234 for introducing the sample 2 is provided at the center of the cover 232. Although not shown, a protective sheet is provided in the opening 234 so that suspended matters do not enter inside, and the protective sheet can be removed before use. The base 230 is made of an optically transparent material, and is subjected to antireflection treatment or the like as necessary.

  FIG. 13B shows a state where the sample 2 is introduced. Only a suitable amount of the sample 2 containing the target substance to be detected in the liquid is dropped through the opening 234. At this time, since the second substrate 12 is in a position not facing the first substrate 11, the second substrate 12 does not interfere with the dropping path. The dropped sample 2 spreads on the first substrate 11. The sample 2 overflowing from the first substrate 11 is absorbed by the sample absorption unit 231.

  FIG. 13C shows a state where the sample 2 is held on the first substrate 11. The lever 233 is slid to move the second substrate 12, and the lever 233 is slid until it overlaps the first substrate 11. If the movable range of the lever 233 is determined, the first substrate 11 and the second substrate 12 overlap at a position where they face each other.

  FIG. 13D shows a state in which the sample 2 is introduced and the first substrate 11 and the second substrate 12 are overlaid. The sample 2 is sandwiched between the first substrate 11 and the second substrate 12.

  1, 2 sample (sample molecule), 10 optical device, 11 first substrate, 11A first surface, 11B, 15 first convex portion, 11C metal, 12 second substrate, 12A second surface, 12B second convex portion, 13, 14 Enhanced electric field, 16 curved surface, 30 optical system, 50 light source, 60 light detection unit, 100 detection device

Claims (7)

A first substrate;
A second substrate facing the first substrate;
Have
The first substrate has a first convex portion of a conductor surface protruding from a first surface facing the second substrate, and the first convex portion has a period P1 in a first direction along the first surface. Arranged in
The second substrate has a second convex portion of a conductor surface protruding from a second surface facing the first substrate, and the second convex portion is arranged with a maximum period P2 in the first direction,
An optical device, wherein λ>P1> P2 is satisfied, where λ is a wavelength of light incident on a sample sandwiched between the first and second substrates. In claim 1,
An optical device, wherein a distance between the first convex portion and the second convex portion is 100 nm or less, and the first and second substrates are opposed to each other. In claim 1 or 2,
The optical device is characterized in that the first period is 400 to 600 nm and the second period is 20 to 100 nm. In any one of Claims 1 thru | or 3,
The second substrate is supported so as to be movable relative to the first substrate at a position facing the first substrate and a position not facing the first substrate. Optical device. In any one of Claims 1 thru | or 4,
An optical device characterized by satisfying P2 <D <P1 where D is the molecular size of the sample. An optical device according to any one of claims 1 to 5,
A light source;
A light detection unit;
Have
The sample is held between the first and second substrates of the optical device;
The optical device emits light emitted from the sample by being irradiated with light from the light source,
The light detection unit detects light from a specific substance contained in the sample. Holding the sample on the first facing surface of the first substrate having a first convex portion of the conductor surface that is arranged in the first direction at a period P1 and protrudes from the first surface;
A second substrate arranged in the first direction with a maximum period P2 (P2 <P1) and having a second convex portion of a conductor surface protruding from a second surface facing the first substrate; Arranging the second surfaces to face each other;
Irradiating a sample sandwiched between the first and second substrates with a wavelength λ (λ> P1) and emitting light from the sample;
Detecting light from a specific substance contained in the sample from light from the sample;
A detection method characterized by comprising: