Palladium nanoneedle surface-enhanced raman scattering substrate and preparation method thereof
By preparing SERS substrates with palladium nanoneedle structures in situ on various substrates, the problems of complex preparation, high cost, poor reproducibility and poor substrate compatibility in the existing technology have been solved, realizing high sensitivity and high reproducibility detection and expanding the application scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HANGZHOU INST FOR ADVANCED STUDY UCAS
- Filing Date
- 2026-02-26
- Publication Date
- 2026-06-30
AI Technical Summary
Existing SERS substrate fabrication processes are complex, costly, have poor reproducibility, are prone to damage and contamination during the transfer process, have poor substrate compatibility, and are limited in the types of substrates applicable to target devices.
A laser-induced method was used to prepare SERS substrates with palladium nanoparticle structures in situ on various substrates. This method included substrate cleaning, preparation of chalcogenide palladium thin film layers, and laser irradiation to form nanoparticle structures, avoiding complex photolithography and substrate transfer processes.
It achieves a simple preparation process, low cost, high detection sensitivity, good reproducibility, wide applicability, avoids transfer damage and contamination, and expands application scenarios.
Smart Images
Figure CN121740835B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical analysis and detection technology, specifically to a palladium nanoparticle tip surface-enhanced Raman scattering substrate and its preparation method. Background Technology
[0002] Surface-enhanced Raman scattering (SERS) technology generates a strong local electromagnetic field near metal nanostructures, which can significantly amplify the Raman signal of the analyte molecules. It is an important detection method in trace analysis, environmental monitoring, biomedical detection and other fields.
[0003] Most existing SERS substrates utilize precious metal nanoparticles such as gold and silver, and nanostructures are fabricated on silicon wafers, glass sheets, or metal substrates using processes such as chemical reduction, sputtering deposition, electrochemical deposition, nanoimprinting, and photolithography / electron beam etching. While these substrates can achieve high Raman enhancement, they generally suffer from the following drawbacks:
[0004] First, existing preparation processes are complex, often requiring multiple steps such as photolithography, etching, and transfer. This is not only cumbersome and time-consuming, but also highly dependent on cleanroom environments and specialized equipment. This results in high equipment costs, hindering rapid adoption in ordinary laboratories or industrial settings.
[0005] Second, existing SERS substrate fabrication technologies have shortcomings in terms of reproducibility and stability. The size, spacing, and arrangement of nanostructures are highly sensitive to the enhancement effect of SERS substrates. Traditional fabrication processes are easily affected by process disturbances, resulting in large fluctuations in the enhancement factor between different batches of substrates, and even at different locations within the same chip, making it difficult to guarantee the reproducibility of detection results.
[0006] Third, existing nanostructures must first be fabricated on a rigid substrate before being transferred to the target device substrate (such as microfluidic chips, flexible substrates, etc.) for practical applications. During the transfer process, the nanostructures are susceptible to damage and peeling caused by mechanical forces, and may also introduce contamination, thereby introducing additional signal noise and testing uncertainties.
[0007] Fourth, the applicable target device substrate types of existing SERS substrates are limited. Due to limitations in manufacturing processes and material systems, existing SERS substrates are often only compatible with a few target device substrate types, and have poor compatibility with complex devices (such as microfluidic chips, fiber end faces, flexible substrates, etc.).
[0008] Palladium and its compounds possess unique advantages in catalysis, sensing, and other fields. Therefore, some literature has attempted to utilize palladium-based materials as Raman enhancement platforms. However, current research mainly focuses on particulate or thin-film palladium-based structures, and a simple, controllable, and in-situ fabrication scheme for palladium nanoparticle-tip structure SERS substrates capable of being generated on target device substrates has not yet been developed.
[0009] Therefore, there is a need for a new approach to SERS substrates that is simple to fabricate, can be generated in situ on a variety of substrates, and has high sensitivity and high reproducibility. Summary of the Invention
[0010] To address the aforementioned issues, this invention provides a palladium nanoparticle tip surface-enhanced Raman scattering (SERS) substrate and its preparation method. This substrate offers advantages such as simple fabrication process, in-situ generation on various target device substrates, high detection sensitivity, and good reproducibility. It effectively solves the problems of complex fabrication, high cost, poor reproducibility, easy damage and contamination during transfer, and poor substrate compatibility of existing SERS substrates, meeting the demand for high-performance SERS substrates in multiple fields such as trace analysis, environmental monitoring, and biomedical detection.
[0011] The embodiments of the present invention adopt the following technical solutions:
[0012] In a first aspect, the present invention provides a palladium nanoparticle tip surface-enhanced Raman scattering substrate, comprising: a substrate layer and a continuous chalcogenide palladium thin film layer located on the substrate layer;
[0013] Among them, some regions of the chalcogenide palladium thin film layer have nanoneedle-tip structures induced by in-situ laser.
[0014] Preferably, the substrate layer is selected from one of the following: silicon wafer, quartz glass, sapphire, flexible polymer substrate, microfluidic chip substrate, metal foil, optical fiber end face, or microlens array.
[0015] Preferably, the material of the chalcogenide palladium thin film layer is selected from any of the following:
[0016] Palladium sulfide, palladium selenide, or palladium telluride in stoichiometric proportions;
[0017] Non-stoichiometric palladium sulfide, palladium selenide, or palladium telluride;
[0018] Binary chalcogenide palladium alloy or ternary chalcogenide palladium alloy;
[0019] Palladium sulfide-based co-doped systems, palladium selenide-based co-doped systems, or palladium telluride-based co-doped systems.
[0020] Preferably, the thickness of the chalcogenide palladium thin film layer is 5~100 nm.
[0021] Preferably, the nanotip structure is a nanotip array formed after laser irradiation;
[0022] The height of the nanoneedle tip is 40~400nm, the surface of the nanoneedle tip has a rough structure, and there is a nanoscale gap between adjacent nanoneedles that generates surface-enhanced Raman scattering effect.
[0023] Secondly, the present invention also provides a method for preparing a palladium nanoparticle tip surface-enhanced Raman scattering substrate, comprising:
[0024] Select the target device substrate as the substrate layer, and clean and dry the substrate layer.
[0025] A continuous chalcogenide palladium thin film layer was prepared on the substrate layer;
[0026] A portion of a chalcogenide palladium thin film was irradiated with a laser of specific parameters to induce the formation of a nanoneedle structure, resulting in a palladium nanoneedle surface-enhanced Raman scattering substrate.
[0027] Preferably, the cleaning process involves ultrasonic cleaning using an organic solvent and deionized water in sequence.
[0028] Preferably, the palladium chalcogenide thin film layer is prepared by one of the following methods: chemical vapor deposition, mechanical stripping and transfer, sputtering deposition, pulsed laser deposition, evaporation deposition, or solution deposition followed by annealing.
[0029] Preferably, the wavelength of the laser is 488nm, 532nm, 633nm or 785nm; the power of the laser is 1~20mW; and the single-point exposure time of the laser is 0.1~10s.
[0030] Preferably, by changing the laser scanning path, single-point exposure time, and step spacing, the nanoneedle tip structure can be formed into a linear array, a dot array, or a patterned array.
[0031] This invention provides a palladium nanotip surface-enhanced Raman scattering (SERS) substrate and its fabrication method. The substrate fabrication process is simple and involves few steps, and can be completed under both conventional Raman and CVD systems. By controlling the laser wavelength, power, and exposure time, nanotip structures are directly formed on the surface of a continuous palladium chalcogenide thin film, achieving a high SERS enhancement effect. The continuous palladium chalcogenide thin film can be grown in situ on the substrate layer, avoiding damage and contamination during the transfer process and improving the reproducibility and stability of the detection results. It exhibits good compatibility and application prospects with various substrates (including microfluidic chips, silicon wafers, glass, flexible substrates, etc.). Attached Figure Description
[0032] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:
[0033] Figure 1 A schematic diagram of a palladium nanoparticle tip surface-enhanced Raman scattering substrate according to an embodiment of the present invention is shown;
[0034] Figure 2A 3D schematic diagram of the nanotip structure according to Embodiment 1 of the present invention is shown under an atomic force microscope.
[0035] Figure 3 A cross-sectional schematic diagram of the nanoneedle tip structure according to Embodiment 1 of the present invention is shown;
[0036] Figure 4 A 3D schematic diagram of the nanotip structure according to Embodiment 2 of the present invention is shown under an atomic force microscope;
[0037] Figure 5 A cross-sectional schematic diagram of a nanoneedle tip structure according to Embodiment 2 of the present invention is shown. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0039] One embodiment of the present invention provides a palladium nanoparticle tip surface-enhanced Raman scattering substrate. Figure 1 A schematic diagram of a palladium nanoparticle tip surface-enhanced Raman scattering substrate is shown. (Refer to...) Figure 1 As shown, the substrate includes: a base layer 1 and a continuous chalcogenide palladium thin film layer 2 located on the base layer 1; wherein, a portion of the chalcogenide palladium thin film layer 2 has a nanoneedle-tip structure 3 induced by in-situ laser.
[0040] The substrate 1 serves as the main support for the substrate, supporting a continuous chalcogenide palladium thin film 2 with nano-needle-shaped structures 3 in a portion of the area.
[0041] The material of the substrate 1 can be flexibly selected according to the actual application scenario. Specifically, the substrate 1 can be selected from one of the following: silicon wafer, quartz glass, sapphire, flexible polymer substrate, microfluidic chip substrate, metal foil, optical fiber end face, or microlens array.
[0042] The substrate 1 needs to be able to stably attach a continuous chalcogenide palladium thin film 2, and withstand the corresponding conditions (such as temperature or energy) during subsequent laser irradiation without undergoing significant physical or chemical changes.
[0043] The palladium chalcogenide thin film layer 2 serves as the carrier layer for the nanoneedle structure 3, and its material is selected from any of the following: stoichiometric palladium sulfide, palladium selenide, or palladium telluride; non-stoichiometric palladium sulfide, palladium selenide, or palladium telluride; binary palladium chalcogenide alloy or ternary palladium chalcogenide alloy; palladium sulfide-based co-doped system, palladium selenide-based co-doped system, or palladium telluride-based co-doped system.
[0044] Chalcogenide palladium materials have good photothermal response characteristics and can undergo morphology reconstruction under laser local heating, providing a good material basis for the formation of nanoneedle structure 3.
[0045] The thickness of the palladium chalcogenide thin film layer 2 is 5~100nm, preferably 5~20nm. This thickness range ensures good adhesion between the palladium chalcogenide thin film layer 2 and the substrate layer 1, while ensuring effective absorption of laser energy, which facilitates the subsequent laser-induced formation of a stable nanoneedle structure 3.
[0046] The nanotip structure 3 is an array or cluster of nanotips formed in a portion of the chalcogenide palladium thin film layer 2 after laser irradiation, and is the core region for realizing the surface-enhanced Raman scattering effect.
[0047] The nanoneedle structure 3 has high-density nano-tip, nano-gap and multi-scale rough structure.
[0048] Multi-scale roughness is manifested in the following two aspects:
[0049] On the one hand, the height of the nanoneedle tip is 40~400nm, and a nanoscale gap is formed between adjacent nanoneedles, which is a macroscopic roughness. The hot spots formed in the nanoscale gap between adjacent nanoneedles generate a strong electromagnetic enhancement effect, thereby realizing the surface-enhanced Raman scattering effect and significantly enhancing the Raman signal of the analyte molecule.
[0050] On the one hand, the surface of the nanoneedle tip has a rough structure, which is microscopic roughness. The surface of the nanoneedle tip is not absolutely smooth, and there are tiny protrusions or depressions, which make the tip and the gaps form dense hot spots, thereby achieving high sensitivity and high reproducibility.
[0051] Another embodiment of the present invention provides a method for preparing a palladium nanoparticle tip surface-enhanced Raman scattering substrate.
[0052] The preparation method includes: selecting the target device substrate as the substrate layer, cleaning and drying the substrate layer; preparing a continuous chalcogenide palladium thin film layer on the substrate layer; irradiating a portion of the chalcogenide palladium thin film layer with a laser of specific parameters to induce the formation of a nanoneedle structure, thereby obtaining a palladium nanoneedle surface-enhanced Raman scattering substrate.
[0053] First, prepare the basal layer.
[0054] The substrate for the target device is selected as the base layer based on the target application scenario. For example, a microfluidic chip substrate is selected for microfluidic chip integration applications, while a flexible polymer substrate is selected for flexible device applications.
[0055] The selected substrate layer is cleaned to remove surface oil, impurities, and other contaminants, ensuring a clean surface. After cleaning, it is dried for later use, providing a favorable adhesion environment for the subsequent fabrication of the palladium chalcogenide thin film.
[0056] The specific cleaning process can be as follows: the substrate is placed in an organic solvent for ultrasonic cleaning, such as ethanol or acetone; then the substrate is transferred to deionized water for ultrasonic cleaning to remove residual organic solvent and impurities.
[0057] Next, a chalcogenide palladium thin film layer was prepared.
[0058] A continuous palladium chalcogenide thin film is prepared on the cleaned and dried substrate. The palladium chalcogenide thin film can be prepared using any of the following methods:
[0059] In-situ growth using chemical vapor deposition (CVD). Using palladium-containing precursors and sulfur / selenium / tellurium sources as reactants, and controlling conditions such as temperature, pressure, atmosphere, and time, the reaction is carried out in a CVD apparatus to grow palladium sulfide / palladium selenide / palladium telluride thin films in situ on the substrate surface. The film thickness is controlled at 5–100 nm, preferably 5–20 nm, forming a continuous chalcogenide palladium film layer.
[0060] Mechanical peeling and transfer. Bulk or large-area palladium chalcogenide sheets are prepared in advance, and a thin layer material with a thickness of 5~100nm, preferably 5~20nm, is obtained by mechanical peeling (e.g., tape peeling). The thin layer material is then transferred to the surface of the substrate to form a continuous palladium chalcogenide thin film layer.
[0061] Sputtering deposition method. Using palladium sulfide / palladium selenide / palladium telluride, or an alloy of the above-mentioned palladium sulfide / palladium selenide / palladium telluride as the sputtering target, sputtering is performed in a sputtering chamber under controlled conditions such as temperature, gas pressure, power, atmosphere and time, to deposit a chalcogenide palladium thin film layer with a thickness of 5~100nm, preferably 5~20nm, on the surface of the substrate.
[0062] Pulsed laser deposition (PLD) uses a bulk palladium chalcogenide material as the target. By controlling conditions such as gas pressure, pulse wavelength, energy density, pulse frequency, and time, laser irradiation is performed in a deposition chamber to cause the plasma formed by the evaporation of palladium chalcogenide material on the target surface to be deposited on the surface of the substrate, forming a palladium chalcogenide thin film layer with a thickness of 5~100nm, preferably 5~20nm.
[0063] Evaporation deposition method. Using palladium chalcogenide bulk or powder material as the evaporation source, and controlling conditions such as gas pressure, electron beam energy, and time, palladium chalcogenide material is deposited onto the surface of the substrate by electron beam heating to form a palladium chalcogenide thin film layer with a thickness of 5~100nm, preferably 5~20nm.
[0064] Solution deposition followed by annealing. A solution containing palladium salt and sulfur / selenium / tellurium source is mixed in a certain proportion to prepare a chalcogenide palladium precursor solution. The precursor solution is coated onto the surface of the substrate layer. After coating, it is placed in an oven to dry. After drying, it is placed in an annealing furnace to anneal the precursor to react and form a chalcogenide palladium thin film layer with a thickness of 5~100nm, preferably 5~20nm.
[0065] Finally, laser-induced formation of nanoneedle-like structures is performed.
[0066] The substrate layer forming the continuous palladium chalcogenide thin film is placed in a micro Raman system or laser processing system, and its position is adjusted so that the laser can be accurately focused on the target area of the palladium chalcogenide thin film.
[0067] Choose a laser of a suitable wavelength as the processing light source. The wavelength of the laser can be selected according to the light absorption characteristics of the chalcogenide palladium material. Specifically, it can be 488nm, 532nm, 633nm or 785nm, as long as the nanoneedle structure can be induced under the appropriate laser parameters.
[0068] Laser parameters are set as follows: power is 1~20mW, preferably 5~20mW; single-point exposure time is 0.1~10s, preferably 0.5~3s. The power and single-point exposure time can be adjusted according to the thickness of the palladium chalcogenide thin film and the light absorption characteristics of the palladium chalcogenide material. Rapid, in-situ, controllable generation of nanoneedles is achieved under specific power and single-point exposure time, without the need for additional etching or template processes.
[0069] The laser focal spot size and numerical aperture are determined by the microscope objective, as long as the laser is focused on the surface of the chalcogenide palladium thin film.
[0070] Under the set laser parameters, the target area of the palladium chalcogenide thin film was irradiated. During the irradiation, the palladium chalcogenide thin film absorbed the laser energy and generated a local heating effect, causing the local temperature to rise rapidly. This led to morphological reconstruction of the palladium chalcogenide material, ultimately forming a SERS active region with a nano-needle-like structure in the target area.
[0071] Because the laser parameters can be precisely controlled, the size, density, and gap of the nanoneedle tip can be effectively regulated, ensuring that the hot spot area is evenly distributed and the enhancement effect is stable.
[0072] If multiple SERS active regions need to be prepared, this can be achieved by moving the sample platform or scanning the laser focus.
[0073] Furthermore, by altering the laser scanning path, single-point exposure time, and step spacing, the nanotip structure can be configured into linear arrays, dot arrays, or patterned arrays. The shape and density of the nanotip structure can be flexibly adjusted to meet different detection requirements by changing the laser scanning path, single-point exposure time, and step spacing. For example, it can form linear arrays, dot arrays, or patterned arrays of custom shapes such as circles, squares, and triangles.
[0074] Compared with the prior art, the present invention has the following significant advantages.
[0075] The preparation process is simple and low-cost: The preparation method of this invention only includes three core steps: substrate preparation, palladium chalcogenide thin film preparation, and laser-induced formation of nanoneedle-shaped structures. It does not require complex photolithography, etching, template and other processes, and the equipment requirements are low. It can be completed with only ordinary CVD system, micro Raman system, laser processing system and so on. It greatly reduces the dependence on clean room environment and special high-end equipment, simplifies the preparation process, shortens the preparation cycle and reduces the preparation cost, and makes it easy to be quickly promoted and scaled up in ordinary laboratories and industrial applications.
[0076] Achieving in-situ preparation and avoiding transfer damage and contamination: The chalcogen palladium thin film layer of the present invention can be directly prepared on the substrate by in-situ growth, and then laser-induced formation of nanoneedle structures is performed on the same substrate. The entire process does not require transferring the chalcogen palladium thin film layer from one substrate to another, realizing in-situ integrated preparation of SERS substrate. This effectively avoids the structural damage, peeling and contamination problems caused by the transfer process in traditional preparation methods, reduces signal noise and test uncertainty, and significantly improves the accuracy and reliability of detection results.
[0077] With broad substrate adaptability and diverse application scenarios, the preparation method of this invention does not impose strict limitations on the substrate layer, and can be adapted to various substrates of different materials and forms, such as silicon wafers, quartz glass, sapphire, flexible polymer substrates, microfluidic chip substrates, metal foils, optical fiber end faces, and microlens arrays. This allows the SERS substrate of this invention to be effectively integrated with various functional devices such as microfluidic chips, flexible devices, optical fiber sensors, and microlens systems, expanding the application scenarios of SERS substrates and enabling them to be widely used in trace analysis, environmental monitoring, biomedical detection, and many other fields.
[0078] High detection sensitivity and good reproducibility: The SERS substrate of this invention forms a nanotip structure through laser induction, creating numerous nanoscale gaps between adjacent tips. This generates an extremely strong local electromagnetic field, significantly amplifying the Raman signal of the analyte molecule and achieving high-sensitivity detection. Simultaneously, laser parameters (wavelength, power, exposure time, etc.) can be precisely controlled, ensuring good controllability of the size, density, and gaps of the nanotips. The enhancement factor fluctuates minimally between different batches of substrates and between different regions of the same substrate, ensuring high reproducibility and stability of the detection results.
[0079] Highly scalable and easy to integrate: This invention can flexibly prepare multiple SERS active regions on the same substrate by moving the sample platform or scanning the laser focus, and the nano-needle structure can be controlled by adjusting the laser parameters. It can be combined with micro-nano fabrication technology and chip integration technology.
[0080] The present invention will be further described in detail below with reference to specific embodiments.
[0081] Example 1:
[0082] Substrate preparation: Select a monocrystalline silicon wafer as the substrate. Place the wafer in acetone and ultrasonically clean for 20 minutes (ultrasonic power 200W) to remove surface oil; then ultrasonically clean in deionized water for 15 minutes (ultrasonic power 150W). After cleaning, place the wafer in an 80℃ oven to dry for 40 minutes, then set aside.
[0083] Preparation of chalcogenide palladium thin film: A chalcogenide palladium thin film was prepared by in-situ growth using chemical vapor deposition (CVD). A silicon wafer was placed in a CVD reaction chamber, using a palladium precursor (palladium acetylacetonate) and a sulfur source (sulfur powder) as reactants. Argon gas was introduced into the reaction chamber as a protective atmosphere. After purging the air from the reaction chamber, the temperature was raised to 250°C and maintained for 60 minutes, resulting in the in-situ growth of a 10 nm thick palladium sulfide thin film on the silicon wafer surface.
[0084] Laser-induced formation of nanoneedle structures: A silicon wafer-palladium chalcogenide thin film sample was placed in a micro Raman spectroscopy system, and a 532 nm laser was selected as the processing light source. The power was set to 15 mW, the single-point exposure time to 2 s, the laser spot size to 1 μm, and the numerical aperture to 1.0. The laser was focused on the surface of the palladium chalcogenide thin film. Single-point irradiation was performed on the target area of the sample surface. After irradiation, palladium nanoneedle SERS substrates were obtained.
[0085] Figure 2 A 3D schematic diagram of the nanotip structure of Example 1 under an atomic force microscope (AFM) is shown. (Refer to...) Figure 2 As shown, the vertical axis represents the height, ranging from 0 to 340 nm. Figure 2The three-dimensional morphology of the nanoneedle tip structure is shown, and the nanoneedles are distributed in a high density. Figure 3 A schematic cross-sectional view of the nanoneedle structure of Example 1 is shown. (Refer to...) Figure 3 As shown, the horizontal axis represents position, ranging from 0 to 5 μm; the vertical axis represents height, ranging from -10 to 390 nm. Figure 3 The cross-sectional morphology of the nanoneedle structure in a certain area is shown, and it can be seen that the height distribution of the nanoneedles is relatively uniform and that nanoscale gaps are formed between adjacent tips.
[0086] Example 2:
[0087] Substrate preparation and chalcogenide palladium thin film preparation: Same as in Example 1.
[0088] Laser-induced formation of nanoneedle structures: A silicon wafer-palladium chalcogenide thin film sample was placed in a micro Raman spectroscopy system, and a 532 nm laser was selected as the processing light source. The power was set to 5 mW, the single-point exposure time to 0.5 s, the laser spot size to 1 μm, and the numerical aperture to 1.0. The laser was focused on the surface of the palladium chalcogenide thin film. Single-point irradiation was performed on the target area of the sample surface. After irradiation, palladium nanoneedle SERS substrates were obtained.
[0089] Figure 4 A 3D schematic diagram of the nanoneedle structure of Example 2 under an atomic force microscope is shown. (Refer to...) Figure 4 As shown, the vertical axis represents the height, ranging from 0 to 93.5 nm. Figure 4 Showing Figure 2 The three-dimensional morphology of the nanoneedle structure under different laser parameters shows that the laser parameters have a regulatory effect on the height and density of the nanoneedle. Figure 5 A schematic cross-sectional view of the nanoneedle structure of Example 2 is shown. (Refer to...) Figure 5 As shown, the horizontal axis represents position, ranging from 0 to 5 μm; the vertical axis represents height, ranging from 0 to 115 nm. Figure 5 Showing Figure 3 The cross-sectional morphology of the nanoneedle structure in some regions under different laser parameters shows the effect of laser parameters on the control of the nanoneedle structure.
[0090] Example 3:
[0091] Substrate preparation: Polydimethylsiloxane (PDMS) film was selected as the substrate. The PDMS film was ultrasonically cleaned in isopropanol for 20 minutes (ultrasonic power 200W); then ultrasonically cleaned in deionized water for 15 minutes (ultrasonic power 150W). After cleaning, it was dried and ready for use.
[0092] Preparation of chalcogenide palladium thin film: Chalcogenide palladium thin film was prepared by mechanical exfoliation and transfer. Bulk palladium selenide material was prepared by high-temperature solid-state reaction, and then adhered to the surface of the bulk palladium selenide with adhesive tape. The tape was then quickly peeled off to obtain a palladium selenide thin film with a thickness of 5 nm. This thin film was then transferred to the surface of a PDMS substrate to form a chalcogenide palladium thin film.
[0093] Laser-induced formation of nanoneedle structures: A PDMS-palladium selenide thin film sample was placed in a laser processing system, and a 633 nm laser was selected as the processing light source. The power was set to 8 mW, the single-point exposure time to 3 s, the laser spot size to 1 μm, and the numerical aperture to 1.0. The laser was focused on the surface of the palladium chalcogenide thin film. Single-point irradiation was performed on the target area of the sample surface. After irradiation, palladium nanoneedle SERS substrates were obtained.
[0094] Example 4:
[0095] Substrate preparation: A microfluidic chip was selected as the substrate. The microfluidic chip was ultrasonically cleaned in ethanol for 20 minutes (ultrasonic power 200W); then ultrasonically cleaned in deionized water for 15 minutes (ultrasonic power 100W). After cleaning, it was dried and ready for use.
[0096] Preparation of chalcogenide palladium thin films: Chalcogenide palladium thin films were prepared by sputtering deposition. Using palladium telluride alloy as the sputtering target, a microfluidic chip was fixed on the sample stage of the sputtering equipment. After evacuation, argon gas was introduced as the sputtering gas. The sputtering pressure was 0.5 Pa, the sputtering power was 80 W, and sputtering was performed at room temperature for 10 minutes to form a palladium telluride thin film with a thickness of 20 nm.
[0097] Laser-induced formation of nanoneedle structures: A microfluidic chip-palladium telluride thin film sample was placed in a micro Raman spectroscopy system, and a 785 nm laser was selected as the processing light source. The power was set to 20 mW, the single-point exposure time to 2 s, the laser spot size to 1 μm, and the numerical aperture to 1.0. The laser was focused on the surface of the palladium chalcogenide thin film. Single-point irradiation was performed on the target area of the sample surface. After irradiation, palladium nanoneedle SERS substrates were obtained.
[0098] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A palladium nanoparticle tip surface-enhanced Raman scattering substrate, characterized in that, include: A substrate layer and a continuous chalcogenide palladium thin film layer on the substrate layer; Among them, a continuous chalcogenide palladium thin film layer is grown in situ on the substrate, and some areas of the chalcogenide palladium thin film layer have nano-needle-tip structures induced by in situ laser. The nanoneedle structure is an array of nanoneedles formed after laser irradiation; The height of the nanoneedle tip is 40~400nm, the surface of the nanoneedle tip has a rough structure, and there is a nanoscale gap between adjacent nanoneedles that generates surface-enhanced Raman scattering effect.
2. The palladium nanoparticle tip surface-enhanced Raman scattering substrate according to claim 1, characterized in that, The substrate layer is selected from one of the following: silicon wafer, quartz glass, sapphire, flexible polymer substrate, microfluidic chip substrate, metal foil, optical fiber end face, or microlens array.
3. The palladium nanotip surface-enhanced Raman scattering substrate according to claim 1, characterized in that, The material of the chalcogenide palladium thin film layer is selected from any of the following: Palladium sulfide, palladium selenide, or palladium telluride in stoichiometric proportions; Non-stoichiometric palladium sulfide, palladium selenide, or palladium telluride; Binary chalcogenide palladium alloy or ternary chalcogenide palladium alloy; Palladium sulfide-based co-doped systems, palladium selenide-based co-doped systems, or palladium telluride-based co-doped systems.
4. The palladium nanotip surface-enhanced Raman scattering substrate according to claim 1, characterized in that, The thickness of the chalcogenide palladium thin film is 5~100 nm.