JP2013233762A - Method of manufacturing minute spiny structure and sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a minute spiny structure that can be used for detection of a hypersensitive molecular, and to provide a sensor using a minute spiny structure.SOLUTION: A minute spiny structure in which an interval between a tip and a tip of spine is controlled constant is manufactured by a method having a polymer arrangement step of arranging polymer particles at a recess of a substrate having a minute uneven structure; a deposition step of depositing metal on a surface of a substrate on which polymer particles are arranged; and a polymer removal step of removing the polymer particles. A big Raman amplification effect is obtained by the minute spiny structure.

Description

  The present invention relates to a method for producing a fine spinous structure and a sensor.

  Conventionally, the periodic fine concavo-convex structure is used for various optical elements. Lithography that exposes the surface of a material coated with a photosensitive substance to form a pattern is widely used in the production of semiconductor and liquid crystal panel substrates, but it requires a large-scale device and is expensive. There is. As a simpler method, a method of forming a fine concavo-convex structure based on a buckling phenomenon is known. For example, there is a method in which a hard surface layer is formed on a uniaxially stretched substrate, and then the stretched state of the substrate is released to form a striped periodic uneven structure (see Patent Document 1). In this method, in addition to the relationship between the elastic modulus of the substrate and the surface layer material, the period and aspect ratio of the concavo-convex structure can be controlled by the ratio of the length in the stretching direction during stretching and the length in the stretching direction during non-stretching. it can. Alternatively, stripes, zigzag patterns, wrinkle patterns, etc. can also be formed by stretching the substrate in the three-dimensional direction, forming a hard thin film on the surface, and then releasing the stretched state of the substrate (non-patent document). Reference 1).

  By the way, in recent years, the use of such a fine concavo-convex structure for ultrasensitive molecular detection has been studied. When a certain type of metal microstructure is irradiated with light, it causes a collective oscillation of electrons due to light called a surface plasmon resonance effect at a specific point on the surface, and this plasmon effect amplifies the Raman scattering signal of nearby surface molecules. It is known. Furthermore, it is also known that this Raman amplification effect is particularly great due to the gaps between the metal nanoparticle aggregates. This phenomenon is used in surface enhanced Raman spectroscopy (SERS).

  As an example of using the fine concavo-convex structure for SERS, for example, it has been proposed to use a silver-deposited surface on a fine concavo-convex structure having a wrinkle pattern produced by using stretching in a three-dimensional direction (Non-Patent Document 2). See).

JP 2009-96081 A

Endo et al., The 91st Annual Meeting of the Chemical Society of Japan (2011) Preliminary Proceedings III 3D7-41 Endo et al., 19th Autumn Meeting of the Japan Society for Plastic Processing (2011) Preliminary Lecture Collection D-222

  In the case of the above surface, the Raman enhancement effect was obtained due to the presence of narrow gaps (recesses) in the wrinkle pattern, but the width was random, so the sensitivity varied depending on the measurement point. was there. Moreover, it was difficult to produce a wrinkle pattern having a recess having a desired width.

  Therefore, if a fine structure is used in which the part that brings about the Raman enhancement effect has a specific regularity, it is expected to suppress the variation in sensitivity depending on the measurement point and stably obtain a large Raman amplification effect. There was no such way.

  An object of the present invention is to provide a method for producing a fine spinous structure that can be used for ultrasensitive molecular detection such as SERS by controlling the tip-to-tip spacing to be constant. It is another object of the present invention to provide a sensor using a fine spiny structure formed by the manufacturing method.

  The inventors of the present invention have made extensive studies to solve the above problems, and have completed the present invention as described below.

  (1) A polymer arranging step for arranging polymer particles in the concave portions of a substrate having a fine concavo-convex structure, a vapor deposition step for depositing metal on the surface of the substrate on which the polymer particles are arranged, and a polymer removing for removing the polymer particles And a process for producing a fine spinous structure comprising the steps of:

  (2) The manufacturing method according to (1), wherein the concave portions of the fine concavo-convex structure are formed in a stripe shape or a zigzag shape.

  (3) A step of stretching the base material, a step of forming a surface layer having a larger elastic modulus than the base material on the base material while maintaining the stretched state of the base material, and a stretched state of the base material (1) or (2) manufacturing method which further has the process of obtaining the board | substrate which has the said fine concavo-convex structure by cancelling | releasing.

  (4) A sensor using the fine spinous structure produced in any one of (1) to (3).

  ADVANTAGE OF THE INVENTION According to this invention, the fine spinous structure which can be utilized for ultrasensitive molecular detections, such as SERS, can be produced by controlling the space | interval of the tip of a spine uniformly, and is excellent using this structure. Sensor can be made.

It is a figure which shows an example of the preparation methods of the fine spiny structure of this invention. It is a figure which shows the SEM observation image of the state which spin-coated polystyrene particle | grains to the fine concavo-convex structure, and was arranged in stripe form. It is a figure which shows the SEM observation image of the produced fine spiny structure. It is a figure which shows the Raman scattering analysis result measured by making the produced fine spinous structure absorb 4-mercaptopyridine.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. .

  The method for producing a fine spiny structure of the present invention includes a polymer arranging step of arranging polymer particles in a concave portion of a substrate having a fine concavo-convex structure, and a vapor deposition step of depositing metal on the surface of the substrate on which the polymer particles are arranged. And a polymer removing step of removing the polymer particles. According to the method of the present invention, even if there is variation in the width of the concave portion of the fine concavo-convex structure, the distance between the tips of the spines of the fine spinous structure is controlled to be constant according to the size of the polymer particles arranged in the concave portion. can do. The part between the tips of the spines of the fine spine structure is likely to be a part that provides a Raman amplification effect, and the sensitivity can be adjusted by controlling the size of the distance between the tips of the spines. The Raman amplification effect can also be adjusted by changing the combination of the metal species to be deposited, metal deposition conditions, and the like. Hereafter, each process of the manufacturing method of the fine spiny structure of this invention is demonstrated in detail using FIG.

[Polymer alignment process]
This is a step of arranging polymer particles 40, which form a spine-like structure, in the recesses of the substrate 10 (FIG. 1 (a)) having a fine relief structure (FIG. 1 (b)). By arranging the polymer particles 40 in a line along the recesses of the fine concavo-convex structure in a row, it is possible to produce a structure in which the spinous structures face each other.

  The fine concavo-convex structure used here is not particularly limited as long as it has a structure that allows the polymer particles 40 to be arranged in an orderly manner with a certain period, but preferably has concave portions formed in a stripe shape or a zigzag shape. . More preferably, the concave portions are formed in a stripe shape.

  The fine concavo-convex structure in which the concave portion forms a stripe shape or a zigzag shape can be obtained by a known method. For example, it can be obtained by stretching the stretchable substrate 20, forming the surface layer 30 while maintaining the stretched state, and then releasing the stretched state of the substrate. Hereinafter, this method will be described in detail.

  Examples of the stretchable base material 20 include polysiloxane polymers such as polydimethylsiloxane (PDMS) and diphenylsiloxane, silicone resin, silicone rubber, natural rubber, synthetic rubber, polyethylene terephthalate (PET), and polymethyl methacrylate ( PMMA), polyolefins such as polycarbonate, polyethylene and polypropylene, fluorinated polymers such as polyurethane, polystyrene, polytetrafluoroethylene and polyvinylidene fluoride, polyvinyl chloride, polymethylhydrogensiloxane, copolymers and blends thereof. The elastic modulus of the material used for the substrate 20 is preferably 0.5 to 10 MPa.

  The film thickness of the substrate 20 is preferably 0.3 to 20 mm. If it is thinner than 0.3 mm, it is easily broken during stretching, and if it is thicker than 20 mm, it is difficult to form a fine relief structure when the stretched state is released.

  As for the stretching method of the base material 20, for example, as in Patent Document 1, stress may be applied in a uniaxial direction parallel to the surface of the base material 20. The stretching ratio of the base material 20 (length in the stretching direction during stretching / length in the stretching direction during non-stretching) is preferably 1.1 to 10, more preferably 1.1 to 1.8, still more preferably. 1.2-1.7. Alternatively, as in Non-Patent Document 1, the film may be stretched by applying stress in a direction substantially perpendicular to the substrate surface.

  Next, the surface layer 30 is formed on the base material 20 while maintaining the stretched state. The material of the surface layer 30 is not particularly limited as long as it is a material that has a larger elastic modulus than the material used for the base material 20 and can form a fine concavo-convex structure along with the cancellation of stretching. Ceramic, carbon, silicone resin, Examples thereof include thermosetting resins such as melamine resin and epoxy resin, polyamide, polyamideimide, polyimide, polyethylene terephthalate, polycarbonate, and acrylic resin. The elastic modulus of the material used for the surface layer 30 is preferably 0.5 to 100 GPa.

  The thickness of the surface layer 30 is preferably 1 to 50,000 nm. A single layer or a plurality of layers may be stacked.

  Although the formation method of the surface layer 30 will not be specifically limited if the surface layer of said thickness can be formed, Oxygen plasma, vapor deposition, etc. are mentioned. For example, if a polysiloxane polymer such as PDMS is used for the base material 20, a new hard silica layer can be formed on the surface of the base material 20 by performing oxygen plasma treatment as it is. Alternatively, the surface layer 30 may be formed by vapor-depositing ceramic such as silica, titanium oxide, zinc oxide, and magnesium fluoride on the substrate 20.

  When the stretched state is released after the surface layer 30 is formed, a fine concavo-convex structure is formed. To release the stretched state, the stress applied to the base material may be eliminated and the base material may be returned to the initial state. Thereby, internal stress is released, surface buckling phenomenon occurs, and an uneven structure is formed. When stretching is performed in a uniaxial direction parallel to the base material surface, a striped or zigzag recess is easily formed on the whole after the stretched state is released, and can be used as the substrate 10. When stretching is performed in a direction substantially perpendicular to the substrate surface, a striped or zigzag recess is easily formed in a portion away from the central portion after the stretched state is released, and that portion is used as the substrate 10. That's fine.

  As an uneven | corrugated period, the width | variety of 50 nm-500 micrometers is preferable, and the width | variety of 0.5-3 micrometers is more preferable. As a height of a convex part, 20 nm-200 micrometers are preferable, and 0.2-1 micrometer is more preferable.

  In addition to the above, as a method for producing a fine concavo-convex structure in which the concave portions are formed in a stripe shape or zigzag shape, a relatively hard surface layer is formed on the base material of the polymer elastic body, and lateral stress is applied thereto. Examples thereof include a method of adding, a method of forming a resin surface layer on a heat-shrinkable base material, and then deforming by heating.

  The method of arranging the polymer particles 40 in the concave portions of the substrate 10 having the fine concavo-convex structure formed as described above may be performed by spin coating the polymer particle dispersion. It is preferable that the polymer particle dispersion is dropped on the substrate 10 having a fine concavo-convex structure and spin-coated at 1000 to 3000 rpm for 20 to 60 seconds.

  The polymer particles 40 are preferably particles having a diameter of 50 to 1000 nm so as to be arranged in a row in the concave portions of the fine concavo-convex structure. More preferably, particles having a diameter of 200 to 800 nm are used. When the polymer particle 40 having a small diameter is used, the distance between the tips of the spines having a fine spinous structure can be reduced.

  The material of the polymer particles 40 is not particularly limited as long as it can be easily removed in a later step and can form particles having the above-mentioned size, but polystyrene, polymethyl methacrylate, silica, and the like can be used. Among these, polystyrene particles are preferable, and can be used for spin coating as an aqueous dispersion. If it is a polystyrene particle, it can be dissolved and removed by immersing it in chlorine-based hydrocarbons such as chloroform and methylene chloride, aromatic hydrocarbons such as toluene and xylene, glycol ethers, glycol esters and citrus vegetable oils. .

[Vapor deposition process]
After the polymer particles 40 are arranged in the recesses of the substrate 10 having a fine uneven structure, a metal is vacuum-deposited on the surface on which the polymer particles are arranged (FIG. 1C). Examples of the metal to be deposited include gold, silver, aluminum, chromium, zinc, platinum, nickel, and the like. Gold, silver, and platinum are preferable, and gold and silver are particularly preferable. 10-150 nm is preferable and, as for the film thickness of the metal vapor deposition film 50, 20-100 nm is more preferable. A thicker film can produce an excellent sensor with a greater enhancement of the Raman effect.

[Polymer removal process]
When the polymer particles 40 are removed after the metal deposition, a void 60 is formed in the polymer particle 40, and in the vicinity of the void 60, a fine spine structure 70 in which the deposited metal portions are formed in a spine shape and face each other can be produced (FIG. d)). The method for removing the polymer particles 40 is not particularly limited as long as no removal residue is generated, but a method in which the polymer particles are dissolved by immersion in an organic solvent is preferable. The organic solvent to be used is not particularly specified as long as it dissolves the polymer particles 40 without dissolving the substrate 10. For example, when polystyrene is used for the polymer particles 40, the organic solvent may be immersed in chloroform. The immersion time is preferably 0.5 to 1 minute. The immersion in the organic solvent may be usually performed at room temperature.

[Use of fine spiny structure]
The fine spiny structure 70 obtained by the above method can be used for detecting a specimen with ultra-high sensitivity by SERS or the like, and a non-reflective substrate is produced in the same manner as a conventional periodic uneven structure. In addition, it can be applied to semiconductor circuit fabrication by arranging and transferring particles in a groove portion, or can be used for construction of a super-water-repellent substrate or protein sample interface by further surface modification.

[Response to sample diversification at SERS]
The fine spiny structure 70 obtained by the above method can be expanded to change the size of the gap 60 when a stretchable material is used for the base material 10. When the Raman amplification effect changes depending on the type of specimen, the size of the gap 60 can be changed and adjusted.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples.

[Test Example 1]
Both ends of a PDMS substrate having a thickness of 5 mm were fixed, and stretched to a stretching ratio of 1.15 in a direction parallel to the substrate. The oxygen plasma treatment time was 5 minutes in this state. When the stretched state was released, a striped uneven structure having an uneven period of 1.37 μm and a convex part height of 0.27 μm was obtained. A polystyrene particle-dispersed aqueous solution (polystyrene particle diameter of 500 nm, 4.7 wt%) was dropped into this, and it was applied by spin coating at 2000 rpm for 30 seconds. When observed by SEM, the polystyrene particles had an uneven structure as shown in FIG. A state of arrangement along the concave portions of the was observed. Silver was vacuum-deposited on this surface to a thickness of 70 nm. Thereafter, the substrate was immersed in chloroform for 30 seconds to remove the polystyrene particles. As shown in FIG. 3, the place where the polystyrene particles were arranged became voids, and a fine spiny structure was formed from the deposited silver.

[Test Example 2]
A fine spiny structure was produced in the same manner as in Test Example 1 except that the thickness of silver was changed to 50 nm in the vacuum deposition process.

[Test Example 3]
A fine spiny structure was produced in the same manner as in Test Example 1 except that the thickness of silver was changed to 30 nm in the vacuum deposition process.

[Test Example 4]
The substrate having a fine spine structure prepared in Test Example 1 was immersed in an aqueous 4-mercaptopyridine solution (1 mM) for 1.5 hours to form a self-assembled monolayer. The sample was immersed in distilled water for 30 minutes for washing, and a Raman spectrum was measured. When measured under conditions of an excitation wavelength of 532 nm, 1.5 W, an integration count of 1 and a measurement time of 30 seconds, a Raman spectrum as shown in FIG. 4A was obtained. FIG. 4B shows a state in which the striped uneven structure in Test Example 1 was formed, and then silver was directly vacuum-deposited to a thickness of 70 nm, and then immersed in an aqueous 4-mercaptopyridine solution as described above. And a Raman spectrum when a self-assembled monolayer is formed. FIG. 4C shows the results of Raman spectra measured after directly depositing 70 nm of silver on the PDMS substrate itself used in Test Example 1 and treating it with a 4-mercaptopyridine aqueous solution in the same manner. As can be seen from FIG. 4, the Raman spectrum using the fine spiny structure of (a) showed a large Raman enhancement effect as compared with the Raman spectrum of other structures. When the peak intensity at 1072 cm ⁻¹ was compared, it was (a) :( b) :( c) = 432: 8: 1.

[Test Example 5]
For the sample produced in Test Example 4, the Raman spectrum was measured in the same manner as in Test Example 4 except that the conditions for Raman spectrum measurement were excitation wavelength 785 nm. The peak intensity was quadrupled compared to the excitation wavelength of 532 nm.
The substrate having the fine spine structure prepared in Test Examples 2 and 3 was treated with a 4-mercaptopyridine aqueous solution in the same manner as in Test Example 4, and then the Raman spectrum was measured at an excitation wavelength of 785 nm. Comparing the peak intensity of 1093 cm ^−1, the peak intensity decreases as the vacuum deposited silver thickness becomes 70 nm, 50 nm, and 30 nm. The thicker the deposited metal film, the greater the intensity. It was.

10: Substrate having a fine uneven structure 20: Base material 30: Surface layer 40: Polymer particles 50: Metal deposition film 60: Void 70: Fine spiny structure

Claims (4)

A polymer alignment step of aligning polymer particles in the recesses of the substrate having a fine relief structure;
A deposition step of depositing a metal on the surface of the substrate on which the polymer particles are arranged;
And a polymer removing step of removing the polymer particles.   The manufacturing method according to claim 1, wherein the concave portion of the fine concavo-convex structure is formed in a stripe shape or a zigzag shape. Stretching the substrate;
Forming a surface layer having a larger elastic modulus on the base material while maintaining the stretched state of the base material;
The method according to claim 1, further comprising: obtaining a substrate having the fine concavo-convex structure by releasing the stretched state of the base material.   The sensor using the fine spinous structure produced in any one of Claim 1 to 3.