Preparation method of SERS (Surface Enhanced Raman Scattering) substrate for multi-component residue detection

Abstract

The invention belongs to the technical field of preparation of SERS (Surface Enhanced Raman Scattering) substrates, and particularly relates to a preparation method of an SERS substrate for multi-component residue detection, which comprises the following steps: selecting a patterned sapphire substrate with a micro-nano structure surface; designing a plurality of arrangement modes, and establishing a laminated body physical model in which longitudinal layers of the multi-element SERS effect material are deposited and distributed layer by layer; according to a physical vapor deposition method and a chemical vapor deposition method, obtaining a laminated body substrate with a multi-layer deposition structure; using a mechanical cutting method to obtain a flat surface with transverse distribution of the multi-element material; a mechanical scribing method is used for scribing the ordered array structure, and the processing step of the SERS substrate with the multi-element materials distributed in the transverse direction and the longitudinal direction is completed; and soaking the processed SERS substrate in the solution, drying, and evaluating the SERS activity through a Raman spectrum to complete the preparation. By constructing transverse and longitudinal distribution of multi-component materials on the surface of the SERS substrate, the detection sensitivity of multi-component residues can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of SERS substrate preparation, and particularly relates to a method for preparing an SERS substrate for multi-component residue detection. Background Art

[0002] As an emerging spectral detection technology, surface-enhanced Raman scattering (SERS) technology uses the "fingerprint characteristics" of molecules to identify target substances, and has significant advantages in terms of detection cycle, technical difficulty, and detection cost. Therefore, SERS technology has become one of the methods with great application potential and research value in trace detection fields such as environmental detection, food safety, and biomedicine. However, with the requirements of detection technology and inspection scope for SERS technology, especially for the detection of multi-component substances in complex mixtures, such as the detection of harmful substances in foods such as milk and tea, the detection sensitivity of the current SERS substrates is unstable. Therefore, there is an urgent need to develop an SERS substrate suitable for multiple detection substances.

[0003] Since different substances to be detected have different detection sensitivities to different SERS effect materials, if it is possible to explore and construct a multi-component SERS effect material to be distributed in a certain way and applied to the same SERS substrate, and realize the combination and redistribution of the SERS effect material on the substrate, the ability of SERS to detect multi-component substances will be raised to a new level.

[0004] Currently, common SERS substrate materials are generally of a single type or in the form of a fixed two types of materials. Therefore, when detecting multi-component substances to be detected, the detection ability is very limited. In order to prepare an SERS substrate with higher sensitivity, it is possible to consider breaking through the conventional thinking, combining multi-component SERS effect materials in a certain pattern by deposition, and combining methods such as machining to obtain an SERS substrate with a multi-material distribution in the horizontal and vertical directions, so that it can be competent for the highly sensitive detection of multi-component residues. Summary of the Invention

[0005] According to the above deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing an SERS substrate for multi-component residue detection, which can increase the detection sensitivity of multi-component residues by constructing a horizontal and vertical distribution of multi-materials on the surface of the SERS substrate.

[0006] To achieve the above object, the present invention provides a method for preparing an SERS substrate for multi-component residue detection, including the following steps: S1. Select a patterned sapphire substrate with a micro-nano structured surface as the substrate mold for longitudinally depositing multi-component SERS effect materials; S2. Design various permutations by combining three factors: material type, deposition thickness, and deposition order, and establish a physical model of a laminate for the vertical layer-by-layer deposition distribution of a multi-component SERS effect material, where the material types are gold, silver, transition metal oxides, and two-dimensional materials; S3. According to physical vapor deposition and chemical vapor deposition methods, and based on the physical model of the laminate, select any one permutation and perform layer-by-layer deposition of the multi-component SERS effect material on a patterned sapphire substrate with a micro-nano structured surface to obtain a laminate substrate with a multi-layer deposition structure; S4. Use mechanical cutting method, set the cutting thickness, and horizontally cut the surface material of the laminate substrate to obtain a flat surface with a lateral distribution of multi-component materials; S5. Use mechanical scribing method to scribe an ordered array structure on the surface with a lateral distribution of multi-component materials, and form grooves or structures with a vertical distribution of multi-component materials in the scribing depth direction to complete the processing step of the SERS substrate with a horizontal and vertical distribution of multi-component materials; S6. Immerse the processed SERS substrate in a test molecule solution containing two or more components, then naturally dry it in a dust-free environment, and evaluate the SERS activity by Raman spectroscopy after drying to complete the preparation of the SERS substrate.

[0007] As a preferred embodiment of the present invention, in S1, the patterned sapphire substrate has a functionalized curved surface formed by an ordered array of micro-nano structures, and the micro-nano structures are spherical, pyramid-shaped, or conical.

[0008] As a preferred embodiment of the present invention, in S2, the transition metal oxides include titanium dioxide, copper oxide, and zinc oxide, and the two-dimensional materials include graphene and molybdenum disulfide.

[0009] As a preferred embodiment of the present invention, in S2, the arrangement method is specifically that for each material, its deposition thickness is set, and the deposition order of each material is set, where each material can be deposited in multiple layers.

[0010] As a preferred embodiment of the present invention, in S3, gold, silver, and transition metal oxides are deposited using physical vapor deposition, that is, a vacuum multi-target magnetron sputtering coating machine is used for deposition, and two-dimensional materials are deposited using chemical vapor deposition method, and finally a multi-layer material stack with a curved structure in the longitudinal section is formed, that is, a SERS substrate with a multi-layer deposition structure surface layer.

[0011] As a preferred embodiment of the present invention, in S4, ultra-precision turning is used to horizontally cut the surface material of the multi-layer deposition structure.

[0012] As a preferred embodiment of the present invention, in S5, two sets of mutually perpendicular parallel lines are scribed on the surface with a lateral distribution of multi-component materials using atomic force scribing to form a surface micro-texture.

[0013] As a preferred embodiment of the present invention, in S6, a binary mixed solution of rhodamine 6G with a concentration of 10 -7 M and malachite green with a concentration of 10 -6 M is prepared. The SERS substrate with lateral and longitudinal distributions of multi-component materials is immersed in the binary mixed solution for 20 minutes. When evaluating the SERS activity by Raman spectroscopy, a 633 nm laser is used for excitation, with a power of 5 mW and an exposure time of 20 s, and the characteristic peak values of the Raman signals of R6G molecules and MG molecules are observed.

[0014] The beneficial effects of the present invention are as follows: The present invention fully considers the sensitivities of different SERS-effect materials to different detection molecules, and at the same time considers the mutual interference of multi-component substances to be detected. Based on deposition technology and machining technology, the preparation of a multi-component material SERS substrate is realized, providing technical support for the sensitive detection of multi-component substances to be detected.

[0015] The present invention proposes a method for preparing an SERS substrate for multi-component residue detection, and details the preparation process of an SERS substrate with lateral and longitudinal distributions of multi-component materials by depositing layer by layer on the deposited surface of a substrate with a functional curved surface and using mechanical cutting methods and scribing methods, which can improve the adaptability and sensitivity of the SERS substrate, and thus realize the effective detection of multi-component substances to be detected. Description of the Drawings

[0016] Figure 1 is the process schematic diagram of the present invention; Figure 2 is the PSS structure diagram used in the embodiment of the present invention, Figure 2 in which (a) is the surface structure of a 2-inch PSS; Figure 2 in which (b) is the surface structure of a 4-inch PSS; Figure 3 is the cross-sectional schematic diagram of the laminated substrate with a multi-layer deposition structure after cutting in the embodiment of the present invention, Figure 3 in which (a) is the cross-sectional schematic diagram of the surface of a 2-inch structured PSS after cutting; Figure 3 in which (b) is the cross-sectional schematic diagram of the surface of a 4-inch structured PSS after cutting; Figure 4 is the atomic force scribing path schematic diagram in the embodiment of the present invention; Figure 5 is the surface-enhanced Raman test curve diagram of the binary solution in the embodiment of the present invention. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are further described below in conjunction with the accompanying drawings: like Figure 1 As shown, a SERS substrate preparation method for multi-component residue detection includes the following steps: S1. Select a patterned sapphire substrate with a micro-nanostructure surface as a substrate mold for vertically depositing multi-SERS effect materials; S2. Design multiple arrangement methods based on the combination of three factors: material type, deposition thickness, and deposition order, and establish a physical model of a stack of multi-layer SERS effect materials with layer-by-layer deposition distribution, where the material types are gold, silver, transition metal oxides, and two-dimensional materials (i.e., multi-layer SERS effect materials); S3, according to the physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods, according to the physical model of the laminate, select an arrangement method based on the material type, deposition thickness, and deposition order, and perform layer-by-layer deposition of multi-layer SERS effect materials on the patterned sapphire substrate with a micro-nano structure surface to obtain a laminate substrate with a multi-layer deposition structure; S4, using a mechanical cutting method, setting a cutting thickness, horizontally cutting the surface material of the laminate substrate to obtain a flat surface with a lateral distribution of multiple materials; S5, using a mechanical scratching method to scratch an ordered array structure on the surface with the multi-materials distributed horizontally, forming grooves or structures with the multi-materials distributed vertically in the scratching depth direction, and completing the SERS substrate processing steps with the multi-materials distributed horizontally and vertically; S6. Immerse the processed SERS substrate in a solution of molecules to be tested containing two or more components, and then dry it naturally in a dust-free environment. After drying, evaluate the SERS activity by Raman spectroscopy to complete the preparation of the SERS substrate.

[0018] Patterned Sapphire Substrate (PSS) is a substrate with a specific pattern formed on a sapphire substrate by photolithography and etching techniques.

[0019] In this embodiment, 2-inch and 4-inch patterned sapphire substrates are used as molds, respectively. The 2-inch and 4-inch patterned sapphire substrates have different surface micro-nano structures, such as Figure 2 shown.

[0020] from Figure 2 It can be seen that the micro-nano structures on the surface of the 2-inch and 4-inch patterned sapphire substrates are arranged in an ordered array, and the overall surface has a complex functional curve surface.

[0021] The surface-structured substrate can also be prepared by precision machining as the base mold to replace the patterned sapphire substrate. The precision machining methods include plasma high-temperature machining, micro-EDM, electron beam, ion beam, etc.

[0022] In S1, the patterned sapphire substrate has a functionalized curve surface formed by an ordered array of micro-nano structures, and the micro-nano structures are spherical, pyramid-shaped or conical.

[0023] In S2, the transition metal oxides include titanium dioxide, copper oxide, zinc oxide, and the two-dimensional materials include graphene and molybdenum disulfide.

[0024] The arrangement method is specifically as follows: for each material, its deposition thickness is set, and the deposition order of each material is set. Among them, each material can be deposited in multiple layers. Generate the stacked materials of each layer in order in tabular form, as shown in Table 1.

[0025] Table 1 Arrangement methods of material types, deposition thicknesses, and deposition orders

[0026] It can be seen from Table 1 that by designing various arrangement methods combined with three factors of material type, deposition thickness, and deposition order, multiple preparation schemes for SERS substrates with horizontal and vertical distributions of multiple materials can be formed. The sequence selection in Table 1 is an example of one of the arrangement methods.

[0027] In S3, gold, silver, and transition metal oxides are deposited by physical vapor deposition, that is, a vacuum multi-target magnetron sputtering coating machine is used for deposition, and two-dimensional materials are deposited by chemical vapor deposition method, and finally a multi-layer material stack with a curved structure in the longitudinal section is formed, that is, an SERS substrate with a multi-layer deposition structure surface layer.

[0028] The vacuum multi-target magnetron sputtering coating machine is a high-performance equipment for both scientific research and production, equipped with more than 2 magnetron targets, and has the function of multi-target time-sharing / simultaneous sputtering.

[0029] In S4, the surface layer material of the multi-layer deposition structure is horizontally cut by ultra-precision turning. Ultra-precision turning is a machining method with extremely high machining accuracy, the form accuracy can reach the sub-micron level, and the surface roughness can reach the nano level. Its principle is to use a high-speed and high-precision turning tool to machine the workpiece.

[0030] By controlling the cutting thickness, a substrate with the same arrangement method (when the material type, deposition thickness, and deposition order remain completely unchanged) can be prepared, and substrates with different horizontal and vertical distributions can be obtained according to the different positions of the cutting plane.

[0031] Taking the arrangement order of ②④③⑤③①⑥ in Table 1 as an example, the vertical sectional view of the stacked substrate with a multi-layer deposition structure after cutting is as follows Figure 3 shown, where different colors represent different material types, and 1, 2, and 3 on the left represent the cutting surfaces corresponding to different cutting thicknesses. From Figure 3 it can be seen that for the distribution of SERS effect materials deposited on patterned sapphire substrates with different sizes and structures, it is different, and different lateral multi-material distributions of surface materials will be obtained by mechanical cutting at different cross-sections.

[0032] In S5, atomic force scribing (a type of mechanical micro-scribing) is used to scribe two groups of mutually perpendicular parallel lines with a depth of 2 μm on the surface with a lateral multi-material distribution to form a surface micro-texture. The schematic diagram of the atomic force scribing path is as follows Figure 4 shown. Atomic force scribing is a micro-nano processing technology based on an atomic force microscope. Its principle is to scan the material surface with a probe (tool) and apply a certain force to perform micro-nano scale scribing processing on the material surface. This technology can achieve precise micro-nano structure processing with high processing accuracy and can precisely control the scribing depth and shape.

[0033] From Figure 4 it can be seen that the atomic force scribing tool scribes the surface texture with a certain depth along a certain path on the surface with a lateral multi-material distribution to form a SERS substrate with lateral and longitudinal multi-material distributions.

[0034] In S6, a binary mixed solution of rhodamine 6G (R6G) with a concentration of 10 -7 M and malachite green (MG) with a concentration of 10 -6 M is prepared, and the SERS substrate with lateral and longitudinal multi-material distributions is immersed in the binary mixed solution for 20 minutes; when evaluating the SERS activity by Raman spectroscopy, a 633 nm laser is used for excitation, the power is 5 mW, and the exposure time is 20 s to observe the characteristic peak positions of the Raman signals of R6G molecules and MG molecules.

[0035] The surface enhanced Raman test curve of the binary mixed solution is as follows Figure 5 shown. From Figure 5 it can be seen that the Raman shift peaks of R6G molecules are obvious at 613 cm -1 , 1360 cm -1 and 1510 cm -1 , and the Raman shift peaks of MG molecules are obvious at 1174 cm -1 , 1618 cm -1 . The Raman test of the binary solution on the SERS substrate designed and prepared in this example shows that different components can be effectively detected.

Claims

1. A method for preparing a SERS substrate for multi-component residue detection, characterized in that The following steps are involved: S1. Select a patterned sapphire substrate with a micro-nanostructure surface as a substrate mold for vertically depositing multi-SERS effect materials; S2. Design multiple arrangement methods based on the combination of three factors: material type, deposition thickness, and deposition order, and establish a stacked physical model of the vertical layer-by-layer deposition distribution of multi-layer SERS effect materials, where the material types are gold, silver, transition metal oxides, and two-dimensional materials; S3, according to the physical vapor deposition and chemical vapor deposition methods, according to the physical model of the laminate, select an arrangement mode, and deposit the multi-SERS effect material layer by layer on the patterned sapphire substrate with the micro-nano structure surface to obtain a laminate substrate with a multi-layer deposition structure; S4, using a mechanical cutting method, setting a cutting thickness, horizontally cutting the surface material of the laminate substrate to obtain a flat surface with a lateral distribution of multiple materials; S5, using a mechanical scratching method to scratch an ordered array structure on the surface with the multi-materials distributed horizontally, forming grooves or structures with the multi-materials distributed vertically in the scratching depth direction, and completing the SERS substrate processing steps with the multi-materials distributed horizontally and vertically; S6. Immerse the processed SERS substrate in a solution of molecules to be tested containing two or more components, and then dry it naturally in a dust-free environment. After drying, evaluate the SERS activity by Raman spectroscopy to complete the preparation of the SERS substrate.

2. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the above S1, the patterned sapphire substrate has a functionalized curved surface formed by an ordered array of micro-nano structures, and the micro-nano structures are spherical, pyramidal or conical.

3. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the S2, the transition metal oxides include titanium dioxide, copper oxide, and zinc oxide, and the two-dimensional materials include graphene and molybdenum disulfide.

4. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the above-mentioned S2, the arrangement method is specifically to set the deposition thickness of each material and set the deposition order of each material, wherein each material can be deposited in multiple layers.

5. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the S3 described above, gold, silver, and transition metal oxides are deposited using physical vapor deposition, that is, a vacuum multi-target magnetron sputtering coating machine is used for deposition, and two-dimensional materials are deposited using chemical vapor deposition, ultimately forming a multilayer material stack with a curved structure in the longitudinal cross-section, that is, a SERS substrate with a multilayer deposited structure surface.

6. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the above-mentioned S4, the surface material of the multi-layer deposition structure is horizontally cut using ultra-precision turning.

7. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the above-mentioned S5, two groups of mutually perpendicular parallel lines are scratched on the surface with the multi-material lateral distribution by using atomic force scratching to form a surface micro-texture structure.

8. The method for preparing a SERS substrate for multi-component residue detection according to claim 1, characterized in that: In the S6, the concentration is 10 -7 Rhodamine 6G and 10M -6 The SERS substrate with multi-material horizontal and vertical distribution was immersed in the two-component mixed solution of malachite green of M for 20 minutes. When the SERS activity was evaluated by Raman spectroscopy, 633nm laser excitation was used with a power of 5mW and an exposure time of 20s to observe the characteristic peaks of the Raman signals of R6G molecules and MG molecules.

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