SERS (Surface Enhanced Raman Scattering) substrate based on millisecond pulse laser direct writing process

Abstract

The utility model provides an SERS (Surface Enhanced Raman Scattering) substrate based on a millisecond pulse laser direct writing process, which comprises ITO (Indium Tin Oxide) glass, a gold nano array is arranged on the ITO glass, the gold nano array consists of a plurality of gold nano islands, and the surfaces of the gold nano islands are provided with first rough structures. By applying the technical scheme, the accuracy of the SERS signal can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of plasmonic nanophotonics and optical sensing technology, especially a SERS base plate based on millisecond pulse laser direct writing process. BACKGROUND

[0002] Surface-enhanced Raman scattering (SERS) has been proven to be an ultrafast, multifunctional analytical technique with a detection limit reaching the single-molecule level, capable of delivering molecular fingerprint vibrational information. SERS has been widely applied in the fields of analytical chemistry, biology, and environmental science for trace detection of substances. Metal nanoparticles (such as gold, silver, and copper) on the surface of a SERS base plate can significantly enhance the local electromagnetic field through photoexcited surface plasmon resonance, referred to as the electromagnetic enhancement mechanism of SERS effect. SERS "hot spots" usually exist between adjacent noble metal nanostructures with a distance of less than 10 nm. Due to the limited penetration depth of Raman signals and the complex spatial distribution of "hot spots", it is difficult to obtain uniform and repeatable enhancement effects on the entire base plate. Compared with traditional two-dimensional SERS structures, three-dimensional SERS base plates can expand the interaction area between the base plate and the target analysis molecules, significantly improving the SERS performance of the base plate. Therefore, developing a simple and efficient technology to prepare large-area, uniform SERS "hot spot" structures, especially realizing three-dimensional SERS base plate structures, is the key to obtaining a high-sensitivity SERS platform. SUMMARY

[0003] Therefore, the utility model discloses a kind of SERS base plate based on millisecond pulse laser direct writing process, realize the accuracy of SERS signal is improved.

[0004] To achieve the above object, the utility model adopts the following technical scheme: a kind of SERS base plate based on millisecond pulse laser direct writing process, including ITO glass, the ITO glass is provided with gold nano array, the gold nano array is made of multiple gold nano islands, the gold nano island surface has first rough structure.

[0005] In a preferred embodiment, the first rough structure of the gold nano island is specifically a first gold particle aggregate distributed on the surface of the gold nano island.

[0006] In a preferred embodiment, the second rough structure is further provided between the gold nano islands.

[0007] In a preferred embodiment, the second rough structure is specifically a second gold particle aggregate distributed on the surface of the ITO glass.

[0008] In a preferred embodiment, the gold nano-island has a particle size of 200-500 nm.

[0009] In a preferred embodiment, the first gold particle aggregate attached to the gold nano-island has a particle size of 10-40 nm, and the gap between the first gold particle aggregates is less than 10 nm.

[0010] In a preferred embodiment, the second gold particle aggregate on the ITO glass surface has a particle size of 10-40 nm, and the gap between the second gold particle aggregates is greater than 20 nm.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] 1、Unlike the smooth gold nano-structure prepared by ordinary annealing process or continuous laser heat treatment, the gold nano-array obtained by the millisecond pulse laser direct writing process is attached with many small size gold nano-particles, and the rough gold nano-array can increase the contact area of the analyte and the SERS substrate.

[0013] 2、The gold nano-structure prepared by the millisecond laser pulse process makes the gold nano-particles gather on the large size gold nano-island, the "hot spot" distribution is extended longitudinally in a certain plane range, the interaction volume and surface area of light and matter are expanded, and the performance of the SERS substrate is improved.

[0014] 3、The SERS substrate obtained by using the discrete gold nano-island structure as a template has a height of 150-200 nm, and when testing the analyte with large size, such as virus, serum protein, etc., the structure is more beneficial to embed the target molecule into the "hot spot" structure of the substrate, and more complete and accurate SERS signal is obtained.

[0015] 4、The millisecond pulse laser direct writing technology can realize the preparation of the SERS substrate with high efficiency and large area. The "hot spot" density of the structure can be conveniently and accurately controlled by controlling the laser power, action time and scanning area, and the repeatability of the preparation of the SERS substrate is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The utility model discloses a kind of SERS substrate based on millisecond pulse laser direct writing process structure schematic view of preferred embodiment of the utility model;

[0017] Figure 2 It is the flowchart schematic view of preparing a kind of SERS substrate based on millisecond pulse laser direct writing process of preferred embodiment of the utility model;

[0018] Figure 3The image shows a scanning electron microscope (SEM) image of a SERS substrate based on a millisecond pulsed laser direct writing process, which is a preferred embodiment of the present invention. (a) is a SEM image with a 5 μm scale, and (b) is a SEM image with a 500 nm scale.

[0019] Figure 4 In the preferred embodiment of this utility model, the energy density is 151.3 W / m³. 2 The obtained SERS substrates were used to measure the Raman enhanced spectra of Rhodamine 6G molecules at excitation light of 633 nm and 785 nm, respectively.

[0020] Figure 5 Raman enhanced spectra of rhodamine 6G molecules on a SERS substrate obtained under millisecond pulsed laser irradiation at different energy densities according to a preferred embodiment of this invention; (a), (b), and (c) correspond to 71.6 W / m², respectively. 2 119.4 W / m 2 151.3 W / m 2 ;

[0021] Figure 6 This is a schematic diagram illustrating the enhanced Raman signals of the R6G molecule and the virus molecule in a preferred embodiment of this utility model. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] A SERS substrate based on millisecond pulsed laser direct writing process, reference Figures 1-6 The device includes an ITO glass 1, on which a gold nanoarray is disposed. The gold nanoarray is composed of multiple gold nanoislands 2, and the surface of the gold nanoislands 2 has a first rough structure.

[0026] The first rough structure of the gold nano-island 2 is specifically a first gold particle aggregate 21 distributed on the surface of the gold nano-island.

[0027] The second rough structure is further arranged between the gold nano-islands 2.

[0028] The second rough structure is specifically a second gold particle aggregate 3 distributed on the surface of the ITO glass 1.

[0029] The preparation of the millisecond pulse laser direct writing SERS substrate is introduced as follows:

[0030] The gold nanoparticles with a diameter of 5-10 nm are prepared by using the oxidation-reduction method, and a 100 mg / mL gold nanoparticle colloidal solution is prepared by selecting dimethylbenzene as a solvent. The solution is spin-coated on the ITO glass at a speed of 2000 rpm for 30 s, as shown in (a) of Figure 2 . Then, the discrete gold nano-island structure is obtained by using a muffle furnace for high-temperature annealing at 400 ℃ Figure 2 (b) of Figure 2 . The gold nanoparticle colloidal solution with a solubility of 70 mg / mL is spin-coated again at a speed of 1800 rpm for 30 s. Then, the millisecond pulse laser with an energy density of 151.3 W / m 2 is used to act on the sample, the spot diameter is 4 mm, and the action time is 10 min, as shown in (c) of Figure 2 . Finally, the gold nano-random structure with a rough surface is obtained, as shown in Figure 3 . The rhodamine 6G alcohol solution with a concentration of 10 -6 mol / L is drop-coated on the substrate, and the Raman signals are excited by using the excitation light sources with wavelengths of 633 nm and 785 nm, respectively, and the integration time is 1 s. The obtained enhanced Raman spectrum of rhodamine 6G is shown in Figure 4 . The obvious Raman enhancement signal can be observed, and the SERS performance and detection sensitivity of the substrate can reach the level of the current high-end preparation technology.

[0031] Influence of millisecond pulse laser with different energy densities on the Raman enhancement performance of SERS substrate

[0032] In the millisecond pulse laser direct writing step, the millisecond pulse laser with energy densities of 71.6, 119.4 and 151.3 W / m 2 is used to act on the sample, respectively, so that the gap and the structure surface roughness of the gold nano-island random array are changed, thereby affecting the SERS performance of the substrate. The rhodamine 6G alcohol solution with different concentrations is drop-coated on the above three kinds of substrates, and the Raman signals are excited by using the excitation light source with a wavelength of 785 nm, and the obtained enhanced Raman spectrum is shown in Figure 5 . The integration time is 1 s. The lowest solubility of the rhodamine 6G alcohol solution that can be tested by different substrates is different, as shown in Figure 5The energy densities are 71.6, 119.4, 151.3 W / m 2 respectively. The lowest solubility of Rhodamine 6G (R6G) is 10 -4 , 10 -5 , 10 - 6 mol / L respectively.

[0033] Comparison of SERS substrates prepared by direct writing of millisecond pulsed laser and traditional thermal treatment.

[0034] The distribution of "hot spots" of SERS substrates prepared by millisecond pulsed laser is extended longitudinally, realizing the three-dimensional distribution of "hot spots". Compared with traditional SERS substrates (here refers to annealed gold nanometer island structure), the surface area is significantly increased. The increase of the surface area of the substrate can effectively enhance the contact area between "hot spots" and R6G molecules, thereby amplifying the Raman signal. For larger size analytes, for example, viruses, viruses are usually tens to hundreds of nanometers, and are composed of complex components such as proteins, DNA, RNA, etc. Due to geometric constraints, most intact viruses cannot adapt to the "hot spots" of traditional SERS substrates (see Figure 6 (a)). However, using SERS substrates prepared by millisecond pulsed laser, larger viruses can be embedded in three-dimensional gold nanometer arrays (see Figure 6 (b)), thereby increasing the part of the virus surface into the substrate "hot spots", producing more comprehensive virus Raman peaks.

Claims

1. A SERS substrate based on a millisecond pulsed laser direct-write process, characterized in that, The ITO glass comprises a gold nano array formed by a plurality of gold nano islands, and the surface of the gold nano islands has a first rough structure. The first rough structure of the gold nano islands is a first gold particle aggregate distributed on the surface of the gold nano islands. The second rough structure is a second gold particle aggregate distributed on the surface of the ITO glass.

2. The SERS substrate based on a millisecond pulsed laser direct writing process according to claim 1, characterized in that, The second rough structure is a second gold particle aggregate distributed on the surface of the ITO glass.

3. The SERS substrate based on a millisecond pulsed laser direct writing process according to claim 1, characterized in that, The particle size of the gold nano islands is 200-500 nm.

4. The SERS substrate based on a millisecond pulsed laser direct writing process according to claim 3, characterized in that, The particle size of the first gold particle aggregate attached to the gold nano islands is 10-40 nm, and the gap between the first gold particle aggregates is less than 10 nm.

5. The SERS substrate based on a millisecond pulsed laser direct writing process according to claim 1, wherein, The particle size of the second gold particle aggregate on the surface of the ITO glass is 10-40 nm, and the gap between the second gold particle aggregates is greater than 20 nm.

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