JP6673663B2 - Localized surface plasmon resonance sensor - Google Patents

Description

  The present invention relates to a detection technique, and to a localized surface plasmon resonance sensor.

  The surface plasmon resonance sensor is used in various fields because it can detect a very small amount of sample (for example, see Patent Documents 1 to 5). However, in the sensor disclosed in Patent Document 1, it is necessary to set the incident angle of light so as to satisfy the condition of total reflection, and a precise optical system is required. Also, a prism for detecting a change in angle is required. Therefore, there is a problem that the device becomes complicated. The sensors disclosed in Patent Documents 2, 3, and 4 have a problem that signal strength is weak and detection accuracy is low. Further, although the sensors disclosed in Patent Documents 2, 3, and 4 have a simplified optical system as compared with the sensor disclosed in Patent Document 1, it is still difficult to reduce the size or the size of the sensor is reduced. The configuration must be complicated. The sensor disclosed in Patent Literature 5 has a problem that miniaturization is limited because the light source and the light receiver must be arranged in a straight line.

  Further, in each of the sensors disclosed in Patent Documents 2, 3, 4, and 5, since the sample is interposed in the optical path, the sensor is affected by the chromaticity and thickness of the sample, and the signal intensity decreases and the S / There is a problem that the N ratio tends to deteriorate. On the other hand, the sensor disclosed in Patent Document 1 has a high S / N ratio because no sample is interposed in the optical path, but requires the above-described precise optical system.

Japanese Patent No. 5607593 Japanese Patent No. 3452837 Japanese Patent No. 5167486 Japanese Patent No. 4231701 Japanese Patent No. 5460113

  Therefore, an object of the present invention is to provide a localized surface plasmon resonance sensor that does not require a complicated optical system, can be miniaturized, and has high detection accuracy.

  According to the aspect of the present invention, (a) a light-transmitting substrate, and (b) a plurality of openings provided on a surface of the light-transmitting substrate and generating localized surface plasmon resonance are provided at regular intervals. Localized surface plasmon, comprising: a metal thin film, (c) an inspection light source that irradiates the back surface of the light transmitting substrate with inspection light, and (d) a photodetector that detects reflected light of the inspection light from the metal thin film. A resonance sensor is provided.

  The above-described localized surface plasmon resonance sensor may detect a sample on a metal thin film. Alternatively, the above-described localized surface plasmon resonance sensor may further include a gas adsorption layer disposed on the metal thin film. The gas adsorption layer may be a porous adsorbent.

  The above localized surface plasmon resonance sensor may further include a heater connected to the metal thin film, or may further include a heater connected to the gas adsorption layer. Further, the above-described localized surface plasmon resonance sensor may further include a heating power supply for applying a voltage to the metal thin film and causing the metal thin film to generate heat. Furthermore, the above-mentioned localized surface plasmon resonance sensor may further include a heating light source for irradiating the metal thin film with heating light including a plasmon resonance wavelength in the metal thin film.

  In the above localized surface plasmon resonance sensor, the optical axes of the inspection light source and the light receiver may be substantially perpendicular to the back surface of the light transmitting substrate. The optical axis of the inspection light source and the optical axis of the light receiver may be substantially parallel.

  The above-described localized surface plasmon resonance sensor may further include a first optical fiber connected to the inspection light source and a second optical fiber connected to the light receiver.

FIG. 1 is a schematic top view of a localized surface plasmon resonance sensor according to a first embodiment of the present invention. FIG. 2 is a schematic side view of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 2 is a schematic side view of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. 5 is an example of a reflection spectrum measured by the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 4 is a schematic perspective view of a localized surface plasmon resonance sensor according to the related art. FIG. 4 is a schematic side view of a localized surface plasmon resonance sensor according to the related art. FIG. 1 is a schematic perspective view of a localized surface plasmon resonance sensor according to a first embodiment of the present invention. FIG. 2 is a schematic side view of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 9 is a schematic side view of a localized surface plasmon resonance sensor according to a second embodiment of the present invention. FIG. 11 is a schematic side view of a localized surface plasmon resonance sensor according to a third embodiment of the present invention. FIG. 11 is a schematic side view of a localized surface plasmon resonance sensor according to a third embodiment of the present invention. FIG. 14 is a schematic top view of a localized surface plasmon resonance sensor according to a fourth embodiment of the present invention. FIG. 14 is a schematic side view of a localized surface plasmon resonance sensor according to a fourth embodiment of the present invention. FIG. 14 is a schematic side view of a localized surface plasmon resonance sensor according to a fifth embodiment of the present invention. FIG. 15 is a schematic top view of a localized surface plasmon resonance sensor according to a sixth embodiment of the present invention. It is a typical side view of the localized surface plasmon resonance sensor concerning a 7th embodiment of the present invention. It is a typical side view of the localized surface plasmon resonance sensor concerning a 7th embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a manufacturing process of the localized surface plasmon resonance sensor according to the first embodiment of the present invention. 6 is a scanning electron micrograph of a localized surface plasmon resonance sensor according to Example 2 of the present invention. 5 is an atomic force micrograph of a localized surface plasmon resonance sensor according to Example 2 of the present invention. 9 is a reflection spectrum obtained by the localized surface plasmon resonance sensor according to Example 2 of the present invention. 9 is a transmission spectrum obtained by a localized surface plasmon resonance sensor according to Example 2 of the present invention. 9 is a reflection spectrum obtained by a localized surface plasmon resonance sensor according to Example 3 of the present invention. 9 is a transmission spectrum obtained by a localized surface plasmon resonance sensor according to Example 3 of the present invention. 9 is an absorption spectrum obtained by a localized surface plasmon resonance sensor according to Example 3 of the present invention. 9 is a graph showing the results of Example 4 of the present invention.

  Hereinafter, embodiments of the present invention will be described. However, the description and drawings forming part of the present disclosure should not be understood as limiting the present invention. From the present disclosure, various alternative technologies and operation technologies should be apparent to those skilled in the art, and it should be understood that the present invention includes various embodiments and the like that are not described herein.

(First Embodiment)
As shown in FIGS. 1 and 2, a localized surface plasmon resonance sensor according to the first embodiment includes a light-transmitting substrate 1 and a localized surface plasmon provided on the surface of the light-transmitting substrate 1. A plurality of openings 12A, 12B, 12C,... That cause resonance are provided at regular intervals, an inspection light source 3 that irradiates inspection light 13 to the back surface of the light-transmitting substrate 1, and a metal thin film 2 And a light receiver 4 for detecting the reflected light 14 of the inspection light from the light source.

  The light transmitting substrate 1 is transparent to the inspection light emitted from the inspection light source 3. As a material of the light transmissive substrate 1, for example, glass such as quartz glass and resin such as acrylamide can be used.

  The metal thin film 2 is made of a material that is substantially opaque to the inspection light emitted from the inspection light source 3 and reflects the inspection light emitted from the inspection light source 3. As a material of the metal thin film 2, for example, aluminum (Al), gold (Au), silver (Ag), copper (Cu), a light non-transmissive substance of a composite of these metals, and the like can be used. The thickness of the metal thin film 2 is several tens to several hundreds of nm, but is not limited thereto. The thickness of the metal thin film 2 is appropriately set so that a desired reflectance is obtained.

  Each of the plurality of openings 12A, 12B, 12C,... Provided in the metal thin film 2 has, for example, a square shape, and each side has a length of several hundred nm, for example, 300 nm. The plurality of openings 12A, 12B, 12C,... Are provided, for example, at the same interval as the length of one side. However, the shape, size, and interval of each of the plurality of openings 12A, 12B, 12C,... Are not particularly limited as long as localized surface plasmon resonance can be generated. For example, each of the plurality of openings 12A, 12B, 12C,... May be circular, triangular, hexagonal, polygonal, annular, and C-shaped.

  Preferably, the size of each of the plurality of openings 12A, 12B, 12C,... Is smaller than the wavelength of the inspection light. Also, preferably, the width of each of the plurality of openings 12A, 12B, 12C,... Is equal to or less than the distance between the plurality of openings 12A, 12B, 12C,. It is 1/3 or more and 1 or less, or 2/3 or less of the interval of. For example, the total area of the plurality of openings 12A, 12B, 12C,... Is smaller than the area of a portion of the metal thin film 2 where the plurality of openings 12A, 12B, 12C,.

An oxide film made of a dielectric material such as silicon dioxide (SiO ₂ ), chromium oxide (Cr ₂ O ₃ ), nickel oxide (NiO), or titanium oxide (TiO ₂ ) between the light transmitting substrate 1 and the metal thin film 2 May be arranged.

  The inspection light source 3 and the light receiver 4 are arranged to face the rear surface of the light transmitting substrate 1. The inspection light emitted from the inspection light source 3 is a wide wavelength band light such as white light, but is not limited thereto. The inspection light may be visible light or near-infrared light. An optical filter may be provided between the light transmitting substrate 1 and the light receiver 4. The wavelength of light transmitted by the optical filter is appropriately set according to the plasmon resonance wavelength. The inspection light source 3 and the light receiver 4 may be stored in a housing 5 that blocks the influence of external light.

  The optical axes of the inspection light source 3 and the light receiver 4 may be substantially perpendicular to the back surface of the light-transmitting substrate 1, and the optical axis of the inspection light source and the optical axis of the light receiver may be substantially parallel. In this case, the inspection light is non-parallel light, and it is preferable that the light beam spreads after being irradiated from the inspection light source 3. Further, the optical axis of the inspection light source 3 and the optical axis of the photodetector 4 are located on the back surface of the light-transmitting substrate 1 so that the optical axis of the inspection light source and the optical axis of the photodetector intersect above the light-transmitting substrate 1. May be inclined.

  As shown in FIG. 3, the spectrum of light reflected on the back surface of the metal thin film 2 changes according to the dielectric constant of the sample 100 existing near the surface of the metal thin film 2. Specifically, the wavelength peak of light absorbed by localized surface plasmon resonance shifts according to the dielectric constant of the sample 100 existing on the surface of the metal thin film 2. The sample 100 is not particularly limited, but is, for example, a biological substance such as a chemical substance or a biochemical substance. For example, when ethanol is dropped near the surface of the metal thin film 2, as shown in FIG. 4, a decrease in the reflectance is confirmed at a wavelength of 980 nm in the reflected light spectrum. Since the dielectric constant of the sample 100 depends on the concentration and density of the sample 100, the concentration and density of the sample 100 can be measured from a change in the reflection spectrum. In measuring the change in the reflection spectrum, the shift of the absorption wavelength peak may be measured, or the change in the reflectance at a specific wavelength may be measured. When measuring a change in reflectance at a specific wavelength, an optical filter that transmits or attenuates a specific wavelength may be provided between the light transmitting substrate 1 and the light receiver 4.

  In a conventional localized surface plasmon resonance sensor using metal fine particles or metal nanodisks arranged on a substrate, the inspection light transmitted through the substrate is irradiated by irradiating the substrate with the metal fine particles or metal nanodisks with the inspection light. Is inspecting the spectrum. However, if the sample on the substrate has a color or is cloudy, the inspection light is absorbed by the sample or scattered by the sample, reducing the transmitted light and reducing the spectral resolution. There is. Further, even if the sample to be inspected is transparent itself, the same problem occurs if impurities are mixed in the sample.

  On the other hand, the metal thin film 2 in which the plurality of openings 12A, 12B, 12C,... Provided in the localized surface plasmon resonance sensor according to the first embodiment are provided at regular intervals is smaller than metal fine particles or metal nanodisks. It is also possible to reflect a lot of light. Therefore, even if the inspection light is irradiated from the back side of the light transmitting substrate 1, the intensity of the reflected light is high, and the resolution of the reflected light spectrum is high. Therefore, the sample 100 can be detected with high accuracy. Further, since the sample 100 does not exist on the optical path of the inspection light, the sample 100 can be detected with high accuracy without being affected by the color or turbidity of the sample 100.

  In a conventional localized surface plasmon resonance sensor using metal fine particles arranged on a substrate, the wavelength of light absorbed by plasmon resonance is in the range of about 400 nm to 600 nm. However, the metal material itself used as the material of the metal fine particles has a property of absorbing light. For example, the absorption wavelength of silver is 320 nm, the absorption wavelength of gold is 500 nm, and the absorption wavelength of copper is 600 nm. Therefore, since the absorption wavelength of light by the material of the metal microparticles and the absorption wavelength of light by plasmon resonance overlap, the detection sensitivity may be reduced.

  On the other hand, in the localized surface plasmon resonance sensor according to the first embodiment, plasmon resonance can be generated with an opening pattern larger than metal fine particles or the like that can cause plasmon resonance. The wavelength of the absorbed light is 600 nm or more, 700 nm or more, 800 nm or more, 900 nm or more, or 1000 nm or more. Therefore, the absorption wavelength of light by the metal material itself and the absorption wavelength of light by plasmon resonance do not easily overlap, and high detection sensitivity can be obtained.

  Further, as shown in, for example, FIGS. 5 and 6, in the conventional light transmission type localized surface plasmon resonance sensor, a light transmission 503 in which an inspection light source 503, metal fine particles and metal nanodisks are arranged on a housing substrate 530. The transparent substrate 501 and the light receiver 504 need to be arranged vertically. Accompanying this, the circuit block 523 connected to the inspection light source 503, the optical filter 508 between the light-transmitting substrate 501 and the light receiver 504, and the circuit block 524 connected to the light receiver 504 also include the housing substrate 530. Need to be arranged vertically. Therefore, it is difficult to reduce the size and thickness of the conventional light transmission type localized surface plasmon resonance sensor.

  On the other hand, as shown in FIGS. 7 and 8, in the localized surface plasmon resonance sensor according to the first embodiment, for example, a thin light emitting diode (LED) is used for the inspection light source 3 and If a thin photodetector is used, the circuit board 23, the inspection light source 3 connected to the circuit block 23, the circuit block 24, the light receiver 4 connected to the circuit block 24, and the light receiver 4 It is possible to stack the disposed optical filter 8, the light transmitting substrate 1, and the metal thin film 2 in which a plurality of openings are provided at regular intervals. Therefore, the localized surface plasmon resonance sensor according to the first embodiment can be easily reduced in size and thickness.

(Second embodiment)
The localized surface plasmon resonance sensor according to the second embodiment includes a first optical fiber 43 connected to the inspection light source 3 and a second optical fiber 44 connected to the light receiver 4, as shown in FIG. , Is further provided. Other components of the localized surface plasmon resonance sensor according to the second embodiment are the same as those of the first embodiment.

  One end face of the first optical fiber 43 is connected to the inspection light source 3. The other end face of the first optical fiber 43 is arranged such that the inspection light 13 emitted from the inspection light source 3 is incident on the light transmitting substrate 1. One end face of the second optical fiber 44 is connected to the light receiver 4. The other end face of the second optical fiber 44 is arranged so that the reflected light 14 is incident.

  The first optical fiber 43 and the second optical fiber 44 may be arranged, for example, in parallel.

(Third embodiment)
The localized surface plasmon resonance sensor according to the third embodiment further includes a gas adsorption layer 6 disposed on the metal thin film 2, as shown in FIG. Other components of the localized surface plasmon resonance sensor according to the third embodiment are the same as those of the first embodiment.

  The gas adsorption layer 6 is, for example, a porous adsorbent. The average pore size of the porous adsorbent is, for example, 0.5 nm to 50 nm. The thickness of the gas adsorption layer 6 is, for example, 10 nm to 2 μm. However, as long as the gas 106 can be adsorbed near the surface of the metal thin film 2, the structure of the gas adsorption layer 6 is not limited to these. The gas adsorption layer 6 may or may not fill the plurality of openings 12A, 12B, 12C,... Of the metal thin film 2.

  The gas adsorption layer 6 is made of, for example, a mesoporous material, a macroporous material, a composite meso / macroporous material, a porous coordination polymer (PCP), and a metal organic structure (MOF). For example, mesoporous materials have an average pore size of 2-50 nm and have a regular structure such as lamella, hexagonal, and cubic.

  Further, as a material of the gas adsorption layer 6, for example, a polymer, a metal, a silica material, clay, cellulose, silica gel, carbon nanotube, ceramic, zeolite, and a combination thereof can be used.

  Gas floating around the localized surface plasmon resonance sensor is adsorbed on the gas adsorption layer 6. When the gas is adsorbed by the gas adsorption layer 6, the apparent dielectric constant increases because the material density near the metal thin film 2 increases. As a result, the plasmon resonance wavelength changes, and the spectrum of light reflected on the back surface of the metal thin film 2 changes. Since the amount of adsorbed gas depends on the concentration of the gas, the concentration of the gas can be measured with high accuracy from the change in the reflection spectrum.

  Further, since the gas adsorption layer 6 protects the surface of the metal thin film 2, it is possible to improve the stability of the localized surface plasmon resonance sensor.

  As shown in FIG. 11, the localized surface plasmon resonance sensor according to the third embodiment includes a first optical fiber 43 connected to the inspection light source 3 and a second optical fiber connected to the light receiver 4. 44 may be further provided. The first optical fiber 43 and the second optical fiber 44 are the same as those in the second embodiment, and the description is omitted.

(Fourth embodiment)
The localized surface plasmon resonance sensor according to the fourth embodiment further includes a heater 7 connected to the metal thin film 2 as shown in FIGS. Other components of the localized surface plasmon resonance sensor according to the fourth embodiment are the same as those of the first embodiment. As the heater 7, a heating resistance element or the like can be used. Examples of the material of the heater 7 include metals such as chromium and nickel, oxide semiconductors such as tin oxide, semiconductors such as silicon, and carbon.

  As long as the heater 7 is in thermal contact with the metal thin film 2, the method of connecting the heater 7 to the metal thin film 2 is not particularly limited. The heater 7 may be attached to the metal thin film 2, may be incorporated in the metal thin film 2, or may be integrated with the metal thin film 2. Alternatively, the heater 7 and the metal thin film 2 may be connected by wire bonding. The metal thin film 2 heated by the heater 7 becomes a planar heating element.

  For example, when the detection target of the localized surface plasmon resonance sensor is a chemical substance or a biological substance, the metal thin film 2 is heated by the heater 7 to promote the chemical reaction or decomposition of the chemical substance or the biological substance on the metal thin film 2. It is possible to do. An example of the decomposition of a biological material includes dissociation of double-stranded DNA.

  In a conventional localized surface plasmon resonance sensor using metal fine particles or metal nanodisks, since the arranged metal fine particles and metal nanodisks are separated from each other, heat is conducted to all the placed metal fine particles and metal nanodisks. It is difficult to do that. On the other hand, in the localized surface plasmon resonance sensor according to the fourth embodiment, since the structure for generating localized surface plasmon resonance is provided in the metal thin film 2 which is a heat conductive film, the heat of the heater 7 is reduced. Can be transmitted to the entire metal thin film 2.

(Fifth embodiment)
The localized surface plasmon resonance sensor according to the fifth embodiment further includes a heater 7 connected to the gas adsorption layer 6, as shown in FIG. Other components of the localized surface plasmon resonance sensor according to the fifth embodiment are the same as those of the third embodiment. According to the localized surface plasmon resonance sensor according to the fifth embodiment, the gas molecules adsorbed on the gas adsorption layer 6 can be desorbed by heating the gas adsorption layer 6 with the heater 7.

(Sixth embodiment)
The localized surface plasmon resonance sensor according to the sixth embodiment further includes a heating power supply 17 for applying a voltage to the metal thin film 2 and causing the metal thin film 2 to generate heat, as shown in FIG. Other components of the localized surface plasmon resonance sensor according to the sixth embodiment are the same as those of the first embodiment. An electric current flows through the metal thin film 2 to which a voltage is applied by the heating power supply 17, and heat is generated. In this case, by forming the metal thin film 2 into a continuous folded structure, the electric resistance may be increased and Joule heat may be easily generated. The gas adsorption layer 6 shown in FIG. 10 may be arranged on the metal thin film 2 to which the heating power supply 17 is connected.

  In a conventional localized surface plasmon resonance sensor using metal fine particles or metal nanodisks, since the arranged metal fine particles and metal nanodisks are separated from each other, it is necessary to energize all the arranged metal fine particles and metal nanodisks. It is difficult. On the other hand, in the localized surface plasmon resonance sensor according to the sixth embodiment, since the structure that causes localized surface plasmon resonance is provided in the metal thin film 2, the entire metal thin film 2 is heated by the heating power supply 17. It is possible to apply and heat.

(Seventh embodiment)
As shown in FIG. 16, the localized surface plasmon resonance sensor according to the seventh embodiment further includes a heating light source 27 that irradiates the metal thin film 2 with heating light including a plasmon resonance wavelength in the metal thin film 2. Other components of the localized surface plasmon resonance sensor according to the seventh embodiment are the same as those of the first embodiment. When the heating light source 27 irradiates heating light that is a light including a plasmon resonance wavelength in the metal thin film 2 from the heating light source 27, the metal thin film 2 generates heat by photothermal conversion. As shown in FIG. 17, the gas adsorption layer 6 may be disposed on the metal thin film 2 irradiated with the heating light. In this case, the gas adsorption layer 6 is preferably transparent to heating light.

  In a conventional localized surface plasmon resonance sensor using metal fine particles or metal nanodisks, the plasmon resonance is weak, so that the photothermal conversion efficiency is low. On the other hand, in the localized surface plasmon resonance sensor according to the seventh embodiment, since the structure for generating localized surface plasmon resonance is provided in the metal thin film 2, it is possible to generate strong plasmon resonance. And the light-to-heat conversion efficiency is high.

(Example 1)
As shown in FIG. 18, a quartz substrate 201 was prepared as a light-transmitting substrate, and as shown in FIG. 19, a silicon (Si) thin film 202 having a thickness of 5 to 10 nm was formed on the quartz substrate 201 by sputtering. Thereafter, as shown in FIG. 20, a positive type electron beam resist (ZEP 520A-7, ZEON Corporation) is applied on the silicon thin film 202 to form a resist film 203, and as shown in FIG. A conductive resin (ESPACER, Showa Denko KK) was applied on the film 203 to form a conductive resin layer 204.

  Note that the silicon thin film 202 improves the adhesion of the resist film 203 and suppresses peeling of the resist film 203 and collapse of a pattern formed on the resist film 203. In addition, the conductive resin layer 204 can be omitted by increasing the thickness of the silicon thin film 202 to about 20 nm or by disposing a metal chrome film instead of the silicon thin film 202.

  Next, as shown in FIG. 22, the conductive resin layer 204 and the resist film 203 are irradiated with an electron beam using an electron beam drawing apparatus, and as shown in FIG. .. Are drawn so that 214A, 214B, 214C,... Thereafter, the conductive resin layer 204 is removed, and the resist film 203 is developed to remove a portion irradiated with the electron beam. As a result, as shown in FIG. The resist patterns 223A, 223B, 223C,... Were formed.

  Next, as shown in FIG. 25, aluminum was sputtered on the silicon thin film 202 and the plurality of cylindrical resist patterns 223A, 223B, 223C... To form a metal thin film 205 having a thickness of 20 to 100 nm. Thereafter, the plurality of cylindrical resist patterns 223A, 223B, 223C,... Were removed with an organic solvent. The organic solvent was vibrated by an ultrasonic cleaner. Along with this, the portion of the metal thin film 205 covering the plurality of cylindrical resist patterns 223A, 223B, 223C... Is also lifted off, and as shown in FIG. 215B, 215C... Were formed. Next, the resist residue was removed by oxygen plasma irradiation, and the silicon thin film 202 was oxidized and changed to an oxide film 206 as shown in FIG.

(Example 2)
In the same manner as in Example 1, a metal thin film having a thickness of 22 nm and having a plurality of square openings was formed on the light transmitting substrate. The length of the side of the opening was 300 nm, and the interval between adjacent sides of the plurality of openings was 300 nm. FIG. 28 shows a scanning electron microscope (SEM) photograph of the obtained metal thin film, and FIG. 29 shows an atomic force microscope (AFM) photograph thereof.

  When the obtained composite of the light-transmitting substrate and the metal thin film was irradiated with light, as shown in FIG. 30, high reflectance was confirmed and steep plasmon resonance characteristics were confirmed. In addition, as shown in FIG. 31, it was confirmed that the transmittance was approximately 20% or less in a wavelength band other than the plasmon resonance wavelength.

(Example 3)
In the same manner as in Example 2, a 50 nm-thick metal thin film provided with a plurality of square openings was formed on the light transmitting substrate. The length of the side of the opening was 300 nm, and the interval between adjacent sides of the plurality of openings was 300 nm. When the obtained composite of the light-transmitting substrate and the metal thin film was irradiated with light, as shown in FIG. 32, high reflectance was confirmed and steep plasmon resonance characteristics were confirmed. Further, as shown in FIG. 33, it was confirmed that the transmittance was approximately 20% or less in a wavelength band other than the plasmon resonance wavelength. Further, as shown in FIG. 34, a steep plasmon resonance characteristic was also confirmed in the absorption spectrum.

(Example 4)
A localized surface plasmon resonance sensor provided with a parallel two-core optical fiber as shown in FIG. 9 was prepared. A plurality of rectangles having an opening width of 260 nm were provided at intervals of 540 nm in a 70 nm-thick metal thin film made of aluminum. A mixture of water and ethanol was used as a sample, and the change in reflectance when the mixing ratio of water and ethanol was changed was measured. The wavelength of the reflected light to be measured was 860 nm. As a result, as shown in FIG. 35, it was confirmed that the reflectance at the wavelength of 860 nm increased due to the change in the plasmon resonance wavelength as the ethanol concentration increased.

  The localized surface plasmon resonance sensor according to the embodiment of the present invention is used for an industrial gas sensor, a simple virus inspection device, an energy harvesting device, and a wireless transmission device for stably operating a volatile organic matter (VOC) processing device. The present invention can be used as a small and low power consumption environmental monitor, and a small and low power consumption health monitor mounted on a portable terminal for detecting bad breath and body odor. However, the method of using the localized surface plasmon resonance sensor according to the embodiment of the present invention is not limited to these.

REFERENCE SIGNS LIST 1 light transmitting substrate 2 metal thin film 3 inspection light source 4 light receiver 5 housing 6 gas adsorption layer 7 heater 8 optical filters 12A, 12B, 12C opening 17 heating power supplies 23, 24 circuit block 27 heating light source 30 housing substrate 100 sample 201 Quartz substrate 202 Thin film 202 Silicon thin film 203 Resist film 204 Conductive resin layer 205 Metal thin film 206 Oxide films 213A, 213B, 213C Modified portions 214A, 214B, 214C Circular patterns 215A, 215B, 215C Openings 223A, 223B, 223C Cylindrical resist Pattern 501 Light transmitting substrate 503 Inspection light source 504 Light receiver 508 Optical filter 523 Circuit block 524 Circuit block 530 Housing substrate

Claims (7)

A light-transmitting substrate;
A metal thin film provided on the surface of the light transmissive substrate, causing localized surface plasmon resonance, and having a plurality of openings provided at regular intervals,
An inspection light source for irradiating the back surface of the light-transmitting substrate with inspection light,
A light receiver that detects reflected light of the inspection light from the metal thin film,
Applying a voltage to the metal thin film, a heating power supply for causing the metal thin film to generate heat,
A localized surface plasmon resonance sensor comprising:   The localized surface plasmon resonance sensor according to claim 1, wherein the localized surface plasmon resonance sensor detects a sample on the metal thin film.   2. The localized surface plasmon resonance sensor according to claim 1, further comprising a gas adsorption layer disposed on the metal thin film.   The localized surface plasmon resonance sensor according to claim 3, wherein the gas adsorption layer is a porous adsorbent. To the back surface of the light transmitting substrate, wherein an inspection light source and the light receiver of the optical axis is substantially perpendicular, localized surface plasmon resonance sensor according to any one of claims 1 4. And the optical axis of the inspection light source, and the optical axis of the light receiver, but are substantially parallel, localized surface plasmon resonance sensor according to any one of claims 1 to 5. Further comprising, localized surface plasmon resonance sensor according to any one of claims 1 to 6 and the first optical fibers connected to the inspection light source, a second optical fiber connected to the light receiver, the.