Measuring substrate and method for manufacturing measuring substrate

Abstract

A measuring substrate 1 comprises: an insulating member 10; and metal particles 20 arranged on the insulating member 10. The metal particles 20 arranged on the insulating member 10 are arranged in a single layer in at least a part of the region. The metal particles 20 each have a core-shell structure which includes a core part 21 and a shell part 22 covering the core part 21 and composed of a metal.

Description

Measurement substrate and method for manufacturing the same

[0001] The present invention relates to a measurement substrate and a method for manufacturing the measurement substrate.

[0002] In recent years, various sensors utilizing surface adsorption, such as medical sensors utilizing antigen-antibody reactions, have been developed. These sensors require a transducer material that converts the amount of surface adsorption into another signal with high sensitivity. As an example of such a sensor material, spectroscopic analysis utilizing surface plasmon resonance (SPR), which occurs when metals such as gold, silver, and platinum are irradiated with light, has attracted attention. The principle of this technology is as follows.

[0003] Generally, light does not couple with electron waves (plasmons), but on metal surfaces, a mode of electron waves that couples with light occurs due to boundary conditions specific to the surface. This is called surface plasmons. Methods for exciting surface plasmons include forming a diffraction grating on the metal surface to couple light with plasmons, and using evanescent waves. An example of a sensor that utilizes surface plasmon resonance is a sensor consisting of a total internal reflection prism and a metal film formed on the surface of the prism that contacts a target substance. With this configuration, the refractive index of the surface changes depending on the minute amount of antigen adsorption in an antigen-antibody reaction, which in turn changes the wavelength of the surface plasmon resonance. Therefore, the minute amount of antigen adsorption can be sensed from the change in resonance wavelength.

[0004] Patent Document 1 discloses a method for manufacturing a substrate for SPR measurement, comprising: an insulating member preparation step of preparing an insulating member having a positive or negative charge on its surface; a colloidal crystal dispersion preparation step of preparing a charged colloidal crystal dispersion in which colloidal crystals made of metal colloidal particles having a charge of the opposite sign to the surface charge of the insulating member are dispersed in a dispersion medium; and a surface formation step of bringing the charged colloidal crystal dispersion into contact with the insulating member to form a monolayer structure of metal colloidal crystals on the insulating member.

[0005] In the manufacturing method described in Patent Document 1, a charged colloidal crystal dispersion is brought into contact with an insulating member, and one layer of charged colloidal crystals is adsorbed onto the insulating member by electrostatic attraction. In this way, a substrate for SPR measurement can be manufactured in which two-dimensional charged metal colloidal crystals are arranged at a predetermined lattice spacing on the insulating member.

[0006] Therefore, the manufacturing method described in Patent Document 1 does not require complex pattern formation techniques such as lithography to control the arrangement of metal particles, making manufacturing easy, and it is also said to be possible to manufacture a substrate for SPR measurement that can be used to construct a localized surface plasmon sensor with high detection sensitivity, because two-dimensional charged metal colloidal crystals are arranged on an insulating member at a predetermined lattice spacing.

[0007] Japanese Patent Application Laid-Open No. 2020-34543

[0008] When a biosensor effectively utilizes the near-infrared wavelength region (around 650 to 1000 nm), which is known as the "biological window" and through which light easily penetrates living organisms, it is necessary to shift the peak wavelength of surface plasmon resonance to the longer wavelength side, for example, by using metal particles with large particle diameters.

[0009] However, in the manufacturing method described in Patent Document 1, the particle diameter of the gold particles used as the metal particles is typically 150 to 200 nm, and if the particle diameter is larger than this, the weight increases, making it difficult to prepare a dispersion of colloidal crystals, and therefore difficult to form a two-dimensional colloidal crystal layer on an insulating member.

[0010] The above problem is not limited to the SPR measurement substrate, but is a problem common to measurement substrates having the same configuration as the SPR measurement substrate.

[0011] The present invention has been made to solve the above problems, and aims to provide a measurement substrate that allows metal particles to be arranged in a single layer on an insulating member even if the particle diameter of the metal particles is large. Another aim of the present invention is to provide a method for manufacturing a measurement substrate that allows a single layer structure of metal colloidal crystals made of metal particles to be formed on an insulating member even if the particle diameter of the metal particles is large.

[0012] The measurement substrate of the present invention includes an insulating member and metal particles arranged on the insulating member. The metal particles arranged on the insulating member are arranged in a single layer in at least a portion of the insulating member. The metal particles have a core-shell structure including a core portion and a shell portion made of metal that covers the core portion.

[0013] The method for manufacturing a measurement substrate of the present invention comprises an insulating member preparation step of preparing an insulating member having a positive or negative charge on its surface; a colloidal crystal dispersion preparation step of preparing a charged colloidal crystal dispersion in which metal colloidal crystals composed of metal particles with a core-shell structure having a charge of the opposite sign to the surface charge of the insulating member are dispersed in a dispersion medium; and a surface formation step of contacting the charged colloidal crystal dispersion with the insulating member to form a monolayer structure of the metal colloidal crystals on the insulating member.

[0014] According to the present invention, it is possible to provide a measurement substrate that allows metal particles to be arranged in a single layer on an insulating member even if the particle diameter of the metal particles is large.Furthermore, according to the present invention, it is possible to provide a method for manufacturing a measurement substrate that allows a single layer structure of metal colloidal crystals made of metal particles to be formed on an insulating member even if the particle diameter of the metal particles is large.

[0015] FIG. 1 is a perspective view schematically showing an example of a measurement substrate of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a measurement substrate of the present invention. FIG. 3 is a plan view schematically showing another example of a measurement substrate of the present invention. FIG. 4 is a perspective view schematically showing yet another example of a measurement substrate of the present invention. FIG. 5 is a process diagram schematically showing an example of a method for manufacturing a measurement substrate of the present invention. FIG. 6 is a perspective view schematically showing an example of an insulating member prepared in the insulating member preparation step S11. FIG. 7 is a schematic view showing an example of a colloidal crystal dispersion prepared in the colloidal crystal dispersion preparation step S12. FIGS. 8A and 8B are perspective views schematically showing an example of a surface formation step S13. FIG. 9 is a perspective view schematically showing an example of a measurement substrate obtained by the method for manufacturing a measurement substrate of the present invention.

[0016] The measurement substrate and the method for manufacturing the measurement substrate of the present invention will be described below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope that does not change the gist of the present invention. A combination of two or more of the individual desirable configurations of the present invention described in the following embodiments also constitutes the present invention.

[0017] The measurement substrate of the present invention is used as a substrate for optical measurements such as a substrate for surface plasmon resonance (SPR) measurements.

[0018] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, and other scales may differ from those of the actual product. In the drawings, the same or equivalent parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and duplicate explanations will be omitted.

[0019] Fig. 1 is a perspective view schematically showing an example of a measurement substrate of the present invention, and Fig. 2 is a cross-sectional view schematically showing an example of a measurement substrate of the present invention.

[0020] The measuring substrate 1 shown in FIGS. 1 and 2 includes an insulating member 10 and metal particles 20 .

[0021] 1 and 2, the insulating member 10 is a conductive substrate 11 having an insulating film 12 formed on its surface. In this case, a MIM (Metal-Insulator-Metal) structure can be formed on the measuring substrate 1.

[0022] The conductive substrate 11 is, for example, an insulating substrate 13 having a metal film 14 provided on its surface. Alternatively, the conductive substrate 11 may be a metal substrate or the like.

[0023] The insulating substrate 13 may be, for example, a glass substrate or a ceramic substrate.

[0024] The metal film 14 can be formed by a method such as vapor deposition, sputtering, or chemical plating.

[0025] When the measurement substrate 1 is a substrate for SPR measurement, the type of the metal film 14 is preferably a noble metal such as gold or silver that can exhibit strong plasmon resonance.

[0026] The thickness of the metal film 14 is, for example, 1 nm or more and 100 nm or less. If the thickness of the metal film 14 is 100 nm or less, when the measurement substrate 1 is an SPR measurement substrate, the strength of the electric field due to excitation of localized surface plasmons becomes stronger, thereby increasing the sensitivity in MIM-type SPR measurement. Furthermore, if the thickness of the metal film 14 is 1 nm or more, pinholes are less likely to occur in the metal film 14.

[0027] The insulating film 12 preferably has a positive or negative charge. That is, the surface of the insulating member 10 preferably has a positive or negative charge.

[0028] The insulating film 12 having a positive charge may be, for example, at least one insulating film selected from a silica film modified with a silane coupling agent having an aminopropyl group and a film formed by adsorption of polyethyleneimine and poly(2-vinylpyridine).

[0029] The negatively charged insulating film 12 may be formed by adsorption of a negatively charged polymer, for example. To impart a negative charge to the insulating film, methods such as adsorption of an anionic polymer electrolyte such as polyacrylic acid or polystyrene sulfonic acid, or introduction of a negative charge such as a silanol group can be used.

[0030] The thickness of the insulating film 12 is not particularly limited, and may be smaller than the thickness of the metal film 14 , may be the same as the thickness of the metal film 14 , or may be larger than the thickness of the metal film 14 .

[0031] The metal particles 20 are arranged in a single layer on the insulating member 10. In other words, the metal particles 20 are arranged two-dimensionally on the insulating member 10. It is preferable that the metal particles 20 are arranged in a single layer in the entire region of the insulating member 10, but it is sufficient that the metal particles 20 are arranged in a single layer in at least a part of the region.

[0032] For example, when observing the measurement substrate 1 using a microscope such as an optical microscope or an electron microscope, if the metal particles 20 are observed only when the height of the sample stage is set to a certain height, it can be confirmed that the metal particles 20 are arranged in a single layer on the insulating member 10.

[0033] As shown in FIG. 2, the metal particle 20 has a core-shell structure including a core 21 and a shell 22 made of metal that covers the core 21 .

[0034] When the metal particles 20 have a core-shell structure, the specific gravity can be different between the core portion 21 and the shell portion 22. Therefore, by making the specific gravity of the core portion 21 smaller than the specific gravity of the shell portion 22, it is possible to suppress an increase in weight even if the particle diameter of the metal particles 20 is increased, compared to when the metal particles 20 are solid particles made of metal. Therefore, it is possible to arrange metal particles 20 with large particle diameters in a single layer on the insulating member 10 using the method described below.

[0035] The shell portion 22 only needs to cover at least a portion of the surface of the core portion 21. Therefore, the shell portion 22 may cover only a portion of the surface of the core portion 21, or may cover the entire surface of the core portion 21. Metal particles 20 in which the shell portion 22 covers only a portion of the surface of the core portion 21 and metal particles 20 in which the shell portion 22 covers the entire surface of the core portion 21 may be mixed.

[0036] As described above, the specific gravity of the core portion 21 is preferably smaller than the specific gravity of the shell portion 22. By adjusting the specific gravities of the core portion 21 and the shell portion 22, the particle diameter of the metal particles 20 can be increased, which makes it possible to utilize not only the near-infrared wavelength range (around 650 to 1000 nm), which is called the "biological window" and through which light easily penetrates living organisms, but also higher wavelength ranges, and this is expected to improve the detection sensitivity as a biosensor.

[0037] Furthermore, when the core 21 of the metal particle 20 is made of an electrical insulator, the peak wavelength of the surface plasmon resonance can be shifted to the longer wavelength side even if the particle diameter is the same, compared to when the metal particle 20 is a solid particle made of metal. This is presumably because the presence of an electrical insulator inside the metal particle 20 increases the amplitude of the plasmon.

[0038] The core portion 21 is made of, for example, silicon oxide, titanium oxide, or polystyrene. ２ silicon oxide or TiO２ Titanium oxide such as titanium dioxide is preferred. The core 21 may be made of an inorganic material or an organic material. The core 21 may be made of an electrical insulator.

[0039] The shell portion 22 is made of, for example, gold or silver. From the viewpoint of suppressing oxidation and sulfurization of the metal particles 20, gold is preferred.

[0040] Among them, the core portion 21 is made of SiO ２ Preferably, the shell portion 22 is made of gold.

[0041] The shell portion 22 preferably has a charge of the opposite sign to the surface charge of the insulating member 10. In other words, the surface of the metal particle 20 preferably has a charge of the opposite sign to the surface charge of the insulating member 10.

[0042] 2, for example, when the surface of the insulating member 10 (insulating film 12 in the example shown in FIG. 2) has a positive charge and the surfaces of the metal particles 20 have a negative charge, the metal particles 20 are arranged at intervals on the insulating member 10 due to electrostatic repulsion acting between the metal particles 20. On the other hand, since the surface of the insulating member 10 has a positive charge, the negatively charged metal particles 20 are adsorbed to the surface of the insulating member 10 by electrostatic attraction.

[0043] 1, a two-dimensional colloidal crystal in which metal particles 20 are regularly arranged is preferably formed on an insulating member 10. In this case, the metal particles 20 are preferably arranged two-dimensionally and regularly on the insulating member 10 with spaces between them.

[0044] FIG. 3 is a plan view schematically showing another example of the measuring substrate of the present invention.

[0045] As shown in FIG. 3, a measurement substrate 1A may have regions (domains) in which metal particles 20 are regularly arranged two-dimensionally, and may be in a polycrystalline state where the metal particles 20 are aggregated in different directions.

[0046] Although not shown in Figures 1 or 3, when a two-dimensional colloidal crystal of metal particles 20 is formed on insulating member 10, there may be only a region where metal particles 20 are regularly arranged, or in addition to the region where metal particles 20 are regularly arranged, there may be a region where metal particles 20 are irregularly arranged.

[0047] The distance between the metal particles 20 is not particularly limited, but if the distance between the metal particles 20 is too small, for example, it becomes difficult for antibodies to enter, resulting in a decrease in detection sensitivity. On the other hand, if the distance between the metal particles 20 is too large, the number of metal particles 20 per unit area decreases, resulting in a decrease in performance. Therefore, it is necessary to appropriately set the distance between the metal particles 20. By appropriately setting the distance between the metal particles 20, for example, when the measurement substrate 1 is an SPR measurement substrate, surface plasmon resonance can be actively generated.

[0048] The distance between the metal particles 20 is measured as the average value of the interparticle distances for 100 to 200 metal particles 20 in a plan view such as that shown in FIG.

[0049] The average particle size of the metal particles 20 is preferably 100 nm or more and 500 nm or less.

[0050] As described above, because the metal particles 20 have a core-shell structure, even if the average particle diameter of the metal particles 20 is 100 nm or more, the metal particles 20 can be arranged in a single layer on the insulating member 10. The average particle diameter of the metal particles 20 may be 150 nm or more, or may be 200 nm or more.

[0051] On the other hand, when the average particle size of the metal particles 20 is 500 nm or less, the sedimentation rate in the liquid medium becomes slow, and thus three-dimensional crystals are more likely to be formed in the manufacturing method described below. The average particle size of the metal particles 20 may be 450 nm or less, or may be 400 nm or less.

[0052] The average particle size of the metal particles 20 is measured as the average value of particle sizes (diameters) of 100 to 200 metal particles 20 in a plan view such as that shown in FIG.

[0053] FIG. 4 is a perspective view schematically showing yet another example of the measuring substrate of the present invention.

[0054] The measuring substrate 2 shown in FIG. 4 includes an insulating member 10A and metal particles 20.

[0055] 4, the insulating member 10A is an insulating substrate, such as a glass substrate or a ceramic substrate.

[0056] The measuring substrate 2 shown in Fig. 4 has a common configuration with the measuring substrate 1 shown in Fig. 1, except that it includes an insulating member 10A instead of the insulating member 10. Like the insulating member 10, the surface of the insulating member 10A preferably has a positive or negative charge.

[0057] The measurement substrate of the present invention is preferably produced by the following method.

[0058] FIG. 5 is a process diagram schematically illustrating an example of a method for manufacturing a measurement substrate according to the present invention.

[0059] The method for manufacturing a measurement substrate of the present invention comprises an insulating member preparation step S11, a colloidal crystal dispersion preparation step S12, and a surface formation step S13.

[0060] FIG. 6 is a perspective view schematically illustrating an example of an insulating member prepared in the insulating member preparing step S11.

[0061] In the insulating member preparation step S11, an insulating member 10 having a surface with a positive or negative charge is prepared. In the example shown in Fig. 6, the surface of the insulating member 10 has a positive charge.

[0062] For example, when manufacturing the measurement substrate 1 shown in Fig. 1, an insulating member 10 is prepared, which is a conductive substrate 11 having an insulating film 12 formed on its surface. The conductive substrate 11 is, for example, an insulating substrate 13 having a metal film 14 formed on its surface. Alternatively, the conductive substrate 11 may be a metal substrate or the like.

[0063] 4, an insulating member 10A, which is an insulating substrate, is prepared in the insulating member preparation step S11. The surface of the insulating member 10A has a positive or negative charge.

[0064] FIG. 7 is a schematic diagram showing an example of the colloidal crystal dispersion liquid prepared in the colloidal crystal dispersion liquid preparation step S12.

[0065] In the colloidal crystal dispersion preparation step S12, a charged colloidal crystal dispersion 30 is prepared in which metal colloidal crystals 25 made of metal particles 20 with a core-shell structure having an electric charge of the opposite sign to the surface charge of the insulating member 10 are dispersed in a dispersion medium. In the example shown in Fig. 7, the surfaces of the metal particles 20 have a negative charge.

[0066] Although not shown in FIG. 7, as explained in FIG. 1, the metal particle 20 has a core-shell structure including a core portion 21 and a shell portion 22 made of metal that covers the core portion 21.

[0067] For example, a compound (e.g., sodium 3-mercapto-1-propanesulfonate (MPS)) having a functional group (e.g., a mercapto group) that bonds with the metal constituting the shell portion 22 and a functional group that forms a negative charge (e.g., a sulfonic acid group or a carboxylic acid group) is added to a colloidal dispersion of metal particles 20. Then, by removing impurity ions by adding an ion exchange resin or the like, the electrostatic repulsion between the particles becomes sufficiently strong, forming a charged colloidal crystal structure in the dispersion, and a charged colloidal crystal dispersion 30 is prepared in which the metal particles 20 are arranged at predetermined intervals.

[0068] 8A and 8B are perspective views schematically illustrating an example of the surface forming step S13.

[0069] In the surface formation step S13, the insulating member 10 is brought into contact with the charged colloidal crystal dispersion 30 to form a single layer structure of metal colloidal crystals 25 on the insulating member 10.

[0070] Specifically, a negatively (or positively) charged colloidal crystal dispersion 30 is brought into contact with an insulating member 10 having a positive (or negative) charge, and only one layer of the colloidal crystal lattice is adsorbed onto the insulating member 10 by electrostatic attraction, and then the excess charged colloidal crystal dispersion 30 is washed away by washing with a solvent such as water.

[0071] FIG. 9 is a perspective view schematically showing an example of a measurement substrate obtained by the measurement substrate manufacturing method of the present invention.

[0072] By the above steps, for example, a measuring substrate 1 in which a two-dimensional colloidal crystal of metal particles 20 is formed on an insulating member 10 is obtained.

[0073] According to the method for manufacturing a measurement substrate of the present invention, a monolayer structure of metal colloidal crystals is formed, which makes it possible to control the arrangement of metal particles without using complex pattern formation techniques. As a result, the measurement substrate is easy to manufacture, and a sensor with high detection sensitivity can be constructed.

[0074] The present specification discloses the following:

[0075] <1> A measurement substrate comprising: an insulating member; and metal particles arranged on the insulating member, wherein the metal particles arranged on the insulating member are arranged in a single layer in at least a portion of the region, and the metal particles have a core-shell structure including a core portion and a shell portion made of metal and covering the core portion.

[0076] <2> The measuring substrate according to <1>, wherein the metal particles arranged on the insulating member are arranged in a single layer in all regions.

[0077] <3> The measurement substrate according to <1> or <2>, wherein the measurement substrate is an optical measurement substrate.

[0078] <4> The measurement substrate according to <3>, wherein the measurement substrate is a substrate for measuring surface plasmon resonance.

[0079] <5> The measuring substrate according to any one of <1> to <4>, wherein the metal particles have an average particle size of 100 nm or more and 500 nm or less.

[0080] <6> The measurement substrate according to any one of <1> to <5>, wherein the specific gravity of the core portion is smaller than the specific gravity of the shell portion.

[0081] <7> The measurement substrate according to <6>, wherein the core portion is made of silicon oxide, titanium oxide, or polystyrene.

[0082] <8> The measurement substrate according to <6> or <7>, wherein the shell portion is made of gold or silver.

[0083] <9> The measuring substrate according to any one of <1> to <8>, wherein the insulating member is an insulating substrate.

[0084] <10> The measuring substrate according to any one of <1> to <8>, wherein the insulating member is a conductive substrate having an insulating film formed on a surface thereof.

[0085] <11> The measurement substrate according to any one of <1> to <10>, wherein a two-dimensional colloidal crystal in which the metal particles are regularly arranged is formed on the insulating member.

[0086] <12> A method for manufacturing a measurement substrate, comprising: an insulating member preparation step of preparing an insulating member having a positive or negative charge on its surface; a colloidal crystal dispersion preparation step of preparing a charged colloidal crystal dispersion in which metal colloidal crystals composed of metal particles with a core-shell structure having an electric charge of the opposite sign to the surface charge of the insulating member are dispersed in a dispersion medium; and a surface formation step of contacting the charged colloidal crystal dispersion with the insulating member to form a monolayer structure of the metal colloidal crystal on the insulating member.

[0087] <13> The method for manufacturing a measurement substrate according to <12>, wherein the measurement substrate is an optical measurement substrate.

[0088] <14> The method for producing a measurement substrate according to <13>, wherein the measurement substrate is a substrate for surface plasmon resonance measurement.

[0089] <15> The method for manufacturing a measurement substrate according to any one of <12> to <14>, wherein the metal particles have an average particle size of 100 nm or more and 500 nm or less.

[0090] <16> The method for manufacturing a measurement substrate according to any one of <12> to <15>, wherein the specific gravity of the core portion is smaller than the specific gravity of the shell portion.

[0091] <17> The method for manufacturing a measurement substrate according to <16>, wherein the core portion is made of silicon oxide, titanium oxide, or polystyrene.

[0092] <18> The method for manufacturing a measurement substrate according to <16> or <17>, wherein the shell portion is made of gold or silver.

[0093] <19> The method for manufacturing a measuring substrate according to any one of <12> to <18>, wherein the insulating member is an insulating substrate.

[0094] <20> The method for manufacturing a measuring substrate according to any one of <12> to <18>, wherein the insulating member is a conductive substrate having an insulating film provided on its surface.

[0095] REFERENCE SIGNS LIST 1, 1A, 2 Measurement substrate 10, 10A Insulating member 11 Conductive substrate 12 Insulating film 13 Insulating substrate 14 Metal film 20 Metal particle 21 Core portion 22 Shell portion 25 Metal colloidal crystal 30 Charged colloidal crystal dispersion

Claims

1. An insulating member; metal particles arranged on the insulating member, the metal particles arranged on the insulating member are arranged as two-dimensional colloidal crystals in at least a portion of the region; The metal particles have a core-shell structure including a core portion and a shell portion made of metal that covers the entire surface of the core portion.

2. 2. The measurement substrate according to claim 1, wherein the metal particles arranged on the insulating member are arranged as a two-dimensional colloidal crystal in all regions.

3. The measurement substrate according to claim 1 or 2, wherein the measurement substrate is an optical measurement substrate.

4. The measurement substrate according to claim 3 , which is a substrate for measuring surface plasmon resonance.

5. 3. The measuring substrate according to claim 1, wherein the metal particles have an average particle size of 100 nm or more and 500 nm or less.

6. 3. The measuring substrate according to claim 1, wherein the specific gravity of the core portion is smaller than the specific gravity of the shell portion.

7. 7. The measuring substrate according to claim 6, wherein the core portion is made of silicon oxide, titanium oxide, or polystyrene.

8. The measurement substrate according to claim 6 , wherein the shell portion is made of gold or silver.

9. The measuring substrate according to claim 1 , wherein the insulating member is an insulating substrate.

10. 3. The measuring substrate according to claim 1, wherein the insulating member is a conductive substrate having an insulating film formed on a surface thereof.

11. an insulating member preparation step of preparing an insulating member having a surface with a positive or negative charge; a colloidal crystal dispersion preparation step for preparing a charged colloidal crystal dispersion in which metal colloidal crystals composed of metal particles with a core-shell structure having a charge of the opposite sign to the surface charge of the insulating member and including a core portion and a shell portion made of a metal that covers the entire surface of the core portion are dispersed in a dispersion medium; a surface formation step of contacting the charged colloidal crystal dispersion with the insulating member to form a two-dimensional colloidal crystal of the metal colloidal crystal on the insulating member.