Flexible piezoelectric SERS substrate and bronze cultural relic in-situ detection system thereof

Abstract

The invention relates to the technical field of cultural relic protection, and discloses a flexible piezoelectric SERS (Surface Enhanced Raman Scattering) substrate and a bronze cultural relic in-situ detection system thereof. The composite material comprises the following components: 70-90 parts of polyvinylidene fluoride, 10-30 parts of barium titanate nanoparticles, 7-9 parts of a gold film, 55-85 parts of silver nanoparticles, 1-2 parts of graphene oxide, 1-5 parts of a heat stabilizer, 20-50 parts of a plasticizer, 5-20 parts of magnetic nanoparticles, 1-10 parts of quantum dots and 0.5-2 parts of a surfactant. Through the synergistic effect of all the components, the polyvinylidene fluoride and the barium titanate nanoparticles respectively play roles of providing flexible support and enhancing piezoelectric effect, the advantages of in-situ, lossless and high-sensitivity detection on the surface of the bronze cultural relic, accurate acquisition of material component information, convenience in operation, reliable and accurate detection result and the like are jointly realized, and the detection application range is widened. The problem that in bronze cultural relic detection, in-situ and lossless obtaining of cultural relic surface material composition information is difficult is solved.

Description

Technical Field

[0001] This invention relates to the field of cultural relic protection technology, specifically to a flexible piezoelectric SERS substrate and its in-situ detection system for bronze artifacts. Background Technology

[0002] In the field of cultural relic protection and research, bronze artifacts carry profound historical and cultural value, and accurately obtaining information about their surface material composition is crucial. However, the testing of bronze artifacts has long faced numerous challenges. Traditional testing methods often require sampling of the artifacts. For example, chemical analysis methods require scraping or drilling samples from the surface of the artifact. This process inevitably damages the artifact, altering its original appearance and violating the basic principles of cultural relic protection. This damage is unacceptable, especially for precious and non-renewable bronze artifacts.

[0003] While some non-destructive testing technologies can detect elemental composition without damaging cultural relics, they have limitations in detecting complex organic residues and distinguishing different compounds of the same element. The information they provide is not comprehensive or accurate enough to provide in-depth analysis of the detailed composition of the material on the surface of cultural relics.

[0004] Although in-situ detection is theoretically possible, in practical applications, the surface of bronze artifacts is usually irregular and has complex conditions such as rust and textures, making it difficult for the detection probe to fit closely to the surface of the artifact. This affects the acquisition and accuracy of the detection signal, resulting in insufficient and incomplete information on the surface material composition. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a flexible piezoelectric SERS substrate and its in-situ detection system for bronze artifacts, solving the problem of obtaining information on the material composition of the artifact surface in an in-situ and non-destructive manner during the detection of bronze artifacts.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a flexible piezoelectric SERS substrate, comprising the following components by weight: 70-90 parts of polyvinylidene fluoride, 10-30 parts of barium titanate nanoparticles, 7-9 parts of gold film, 55-85 parts of silver nanoparticles, 1-2 parts of graphene oxide, 1-5 parts of heat stabilizer, 20-50 parts of plasticizer, 5-20 parts of magnetic nanoparticles, 1-10 parts of quantum dots, and 0.5-2 parts of surfactant.

[0007] By adopting the above technical solutions, each component plays a unique role. For example, polyvinylidene fluoride provides flexible support and basic piezoelectric properties, barium titanate nanoparticles enhance the piezoelectric effect, and gold films help silver nanoparticles grow and conduct electricity, as well as enhance Raman signals. Through synergistic effects, the substrate has the advantages of in-situ, non-destructive, and highly sensitive detection, which can accurately obtain information on the material composition of bronze artifacts, ensure reliable and accurate detection results, and provide strong support for the protection and research of bronze artifacts.

[0008] A method for fabricating a flexible piezoelectric SERS substrate, comprising the following steps:

[0009] S1. Dissolve polyvinylidene fluoride in an organic solvent to form a polyvinylidene fluoride solution;

[0010] S2. Add barium titanate nanoparticles, heat stabilizer, plasticizer, magnetic nanoparticles, quantum dots and surfactant to polyvinylidene fluoride solution, stir evenly to form a mixed solution;

[0011] S3. Coat the mixed solution onto the substrate and dry to form a polyvinylidene fluoride composite film;

[0012] S4. Gold films are prepared on the surface of polyvinylidene fluoride composite films by physical vapor deposition or chemical plating.

[0013] S5. Silver nanoparticles were prepared on the surface of a gold thin film by chemical reduction or electrochemical deposition.

[0014] S6. Graphene oxide is applied to the surface of silver nanoparticles by drop coating, spin coating or spray coating.

[0015] Preferably, step S1 specifically includes: accurately weighing 70-90 parts of polyvinylidene fluoride powder, adding it to a three-necked flask containing 500-800 parts of N,N-dimethylformamide organic solvent, placing the three-necked flask on a magnetic stirrer at room temperature, and continuously stirring at a speed of 300-500 rpm for 3-5 hours until the polyvinylidene fluoride powder is completely dissolved, forming a uniform, transparent polyvinylidene fluoride solution without obvious particles or precipitates.

[0016] Preferably, step S2 specifically includes: sequentially adding 10-30 parts of barium titanate nanoparticles with a particle size of 30-50 nm, 1-5 parts of hindered phenolic heat stabilizer, 20-50 parts of dioctyl phthalate plasticizer, 5-20 parts of magnetite magnetic nanoparticles with a particle size of 10-30 nm, 1-10 parts of cadmium sulfide quantum dots with a particle size of 2-6 nm, and 0.5-2 parts of polyethylene glycol octylphenyl ether surfactant to a polyvinylidene fluoride solution; treating the solution with an ultrasonic power of 60-100 W for 1-2 hours; and then stirring at a speed of 400-600 rpm for 2-3 hours to form a uniform and stable mixed solution.

[0017] Preferably, step S3 specifically includes: pouring the mixed solution into a polytetrafluoroethylene mold by solution casting, air-drying it in a room temperature fume hood for 24-48 hours, and then vacuum drying it at 50-70°C and 5-10Pa for 12-24 hours to form a polyvinylidene fluoride composite film with a thickness of 50-200μm.

[0018] Preferably, step S4 specifically includes: cutting the polyvinylidene fluoride composite film into a size of 5cm×8cm, rinsing it alternately with anhydrous ethanol and deionized water 3-5 times, fixing it on the sample stage of a magnetron sputtering instrument with a distance of 6-10cm between it and the gold target; evacuating to below 0.05-0.1Pa, introducing high-purity argon gas to a working pressure of 0.3-0.6Pa, and sputtering at a power of 100-180W for 6-10 minutes to deposit a gold film with a thickness of 7-9nm.

[0019] Preferably, step S5 specifically includes: preparing a 0.02-0.05 mol / L silver nitrate solution and an equal concentration of sodium citrate solution; adding 5-10 ml of the silver nitrate solution to a substrate container containing a gold film; adding an equal volume of sodium citrate solution; and reacting in an oil bath at 50-70°C with magnetic stirring at 300-500 rpm for 3-5 hours; after the reaction is completed, naturally cooling to room temperature; rinsing with deionized water 5-8 times; and then vacuum drying at 40-60°C and 5-8 Pa for 8-12 hours to form polyhedral silver nanoparticles with a particle size of 55-85 nm.

[0020] Preferably, step S6 specifically includes: adding 10-20 mg of graphene oxide, with a sheet thickness of 1-2 nm and a lateral dimension of 1-5 μm, to 10-20 ml of deionized water, and treating it under ultrasonic power of 40-60 W for 2-3 hours to form a homogeneous solution; using a pipette to take 0.1-0.3 ml of the graphene oxide solution and drop it onto the surface of a substrate containing silver nanoparticles, drying it under vacuum at 30-50 °C and 3-6 Pa for 6-10 hours, and then placing it in a vacuum tube furnace, introducing argon gas at a flow rate of 30-50 ml / min, and heating it to 180-220 °C at 3-5 °C / min and holding it for 1-2 hours to allow the graphene oxide to form a chemical bond with the silver nanoparticles.

[0021] An in-situ detection system for bronze artifacts on a flexible piezoelectric SERS substrate, comprising the following modules:

[0022] The flexible piezoelectric SERS substrate module is used in the in-situ detection system for bronze artifacts. By utilizing the surface-enhanced Raman scattering effect and the piezoelectric effect, it can identify the copper rust, corrosion products and organic residues on the surface of bronze artifacts without damaging their original appearance.

[0023] The signal acquisition module is used in the in-situ detection system for bronze artifacts to receive Raman scattered light signals generated by a flexible piezoelectric SERS substrate. With the help of fiber optic probes and Raman spectrometer components, the light signals are converted into processable electrical signals, providing raw data for subsequent signal analysis and processing, and enabling the understanding of the material composition information on the surface of bronze artifacts.

[0024] The signal processing module is used to process the electrical signal data corresponding to the Raman scattering light signal on the surface of the bronze artifact acquired by the signal acquisition module. Through noise reduction, characteristic peak identification, and component identification, valuable information is extracted, and the material composition and related conditions of the surface of the bronze artifact are analyzed.

[0025] The power module is used to provide stable power to the flexible piezoelectric SERS substrate in the in-situ detection system for bronze artifacts, so that its piezoelectric effect can be performed normally, ensuring that the entire detection process can proceed smoothly and that the surface composition of bronze artifacts can be effectively detected.

[0026] The positioning module is used in the in-situ detection system for bronze artifacts to determine the position of the flexible piezoelectric SERS substrate on the surface of the bronze artifact by magnetic or optical positioning methods.

[0027] The data storage module is used in the in-situ detection system for bronze artifacts to store the raw Raman signal data acquired by the signal acquisition module and the result data after analysis and processing by the signal processing module.

[0028] This invention provides a flexible piezoelectric SERS substrate and its in-situ detection system for bronze artifacts. It offers the following advantages:

[0029] 1. This invention, through the synergistic effect of its components, utilizes polyvinylidene fluoride (PVDF) and barium titanate nanoparticles to provide flexible support and enhance the piezoelectric effect, respectively. Together, they achieve in-situ, non-destructive, and highly sensitive detection of bronze artifacts, accurately acquiring information on their material composition. It also boasts advantages such as good environmental adaptability, ease of operation, and reliable and accurate test results, thus broadening the scope of its applications. This invention solves the problem of obtaining in-situ, non-destructive information on the material composition of bronze artifacts.

[0030] 2. This invention forms a uniform and stable mixed solution through related steps, where each component plays its corresponding role. For example, barium titanate nanoparticles enhance piezoelectric properties, resulting in consistent microstructure properties of the substrate. This improves detection sensitivity and repeatability, and ensures stable performance when bonded to cultural relics, facilitating in-situ, non-destructive testing of bronze artifacts. It also solves the problem of easy aggregation and uneven distribution of various functional components in polyvinylidene fluoride solutions.

[0031] 3. This invention prepares a uniformly thick and firmly bonded gold film on the surface of a polyvinylidene fluoride (PVDF) composite film. This gold film provides uniform nucleation sites for the growth of silver nanoparticles, ensuring their uniform distribution. It also possesses good conductivity to enhance surface plasmon resonance (SERS) and SERS performance, and facilitates subsequent functional layer modification, laying the foundation for high-sensitivity detection of the surface material composition of bronze artifacts. This invention solves the problems of poor adhesion to the substrate and uneven coating that often occur when preparing high-quality gold films on flexible PVDF composite films.

[0032] 4. This invention utilizes the synergistic effect of its various modules. The flexible piezoelectric SERS substrate module enables non-destructive in-situ detection and identification of the surface composition of cultural relics. The signal acquisition module accurately converts optical signals into electrical signals to provide a data foundation. The signal processing module extracts valuable information to aid in compositional analysis. The power supply module ensures stable power for smooth detection. The positioning module accurately determines the substrate position, improving detection accuracy and repeatability. The data storage module properly stores data for subsequent retrieval and analysis. Overall, this invention is beneficial for in-depth research on the condition of bronze cultural relics and for achieving long-term monitoring and scientific protection. It solves the limitations of traditional detection methods, such as damaging cultural relics and difficulty in detecting trace components. Attached Figure Description

[0033] Figure 1 This is a flowchart of a method for fabricating a flexible piezoelectric SERS substrate proposed in this invention;

[0034] Figure 2 This is a module architecture diagram of an in-situ detection system for bronze artifacts on a flexible piezoelectric SERS substrate proposed in this invention. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Please see the appendix Figure 1 This invention provides a flexible piezoelectric SERS substrate, which, by weight, comprises the following components: 70-90 parts polyvinylidene fluoride, 10-30 parts barium titanate nanoparticles, 7-9 parts gold film, 55-85 parts silver nanoparticles, 1-2 parts graphene oxide, 1-5 parts heat stabilizer, 20-50 parts plasticizer, 5-20 parts magnetic nanoparticles, 1-10 parts quantum dots, and 0.5-2 parts surfactant.

[0037] Specifically, by adding polyvinylidene fluoride, a substrate structure with certain flexibility and basic piezoelectric properties is obtained, which provides initial physical support for the entire flexible piezoelectric SERS substrate and forms the basic framework for subsequent synergistic effects with other components to generate piezoelectric effects.

[0038] By adding barium titanate nanoparticles, a nanophase with a high piezoelectric coefficient is obtained dispersed in polyvinylidene fluoride matrix, thereby enhancing the overall piezoelectric properties of the substrate. This allows the substrate to generate a more significant piezoelectric effect when subjected to external pressure, which in turn helps to improve the adsorption of detection molecules and the Raman signal enhancement effect.

[0039] The addition of a gold film creates a conductive layer on the substrate surface that serves as the basis for the subsequent growth and attachment of silver nanoparticles. This provides a uniform seed layer for the growth of silver nanoparticles, while the gold film itself participates in the conductive process and, to some extent, assists in enhancing the Raman signal, thus helping to improve the surface-enhanced Raman scattering (SERS) effect of the entire substrate.

[0040] By adding silver nanoparticles, a layer of nanoparticles with a polyhedral structure and uniformly distributed on a gold film with a particle size within a specific range is obtained. This enables the creation of abundant Raman signal enhancement hotspots through the surface plasmon resonance effect generated by the nanoparticles themselves, thereby significantly enhancing the substrate's ability to enhance the Raman signal of the molecular surface of the artifact and improving the detection sensitivity.

[0041] By adding graphene oxide, a two-dimensional material layer is obtained covering the surface of a substrate containing silver nanoparticles. This allows for the further enhancement of Raman signal intensity through its own chemical enhancement effect, while effectively preventing the silver nanoparticles from being oxidized, improving the stability of the substrate under different environments, increasing the interaction area between the substrate and the target molecules, and optimizing the detection performance.

[0042] By adding heat stabilizers, a stable system is obtained that can inhibit the degradation of polymer components (such as polyvinylidene fluoride) in the substrate during preparation and use due to thermal effects and other factors. This ensures the chemical stability of the substrate, maintains the integrity of the structure and properties of each component of the substrate, and ensures that the substrate can perform its piezoelectric and SERS effects normally under different temperature environments, thus extending the service life of the substrate.

[0043] The addition of plasticizers creates a softening system that further enhances the flexibility of polyvinylidene fluoride matrix, thereby lowering the glass transition temperature of polyvinylidene fluoride. This allows the substrate to better conform to the complex surface shape of bronze artifacts, preventing damage to the artifacts due to an overly hard substrate. At the same time, it facilitates the dispersion of various functional components in the substrate, ensuring the uniformity of the substrate's performance.

[0044] The addition of magnetic nanoparticles creates a functional phase that imparts magnetic properties to the substrate, enabling convenient positioning, fixation, and recovery of the substrate using a magnetic field. This improves the ease of operation during detection and may also have a synergistic effect with other components, regulating the overall performance of the substrate (such as electric field distribution and signal enhancement).

[0045] By incorporating quantum dots, a quantum doped system with unique optical properties is obtained. This allows the use of the fluorescence properties of quantum dots as an additional signal source to complement and corroborate Raman signals, providing information from different dimensions for analyzing the material composition of bronze artifacts. This further expands the detection capabilities of the substrate and improves the accuracy and comprehensiveness of the detection results.

[0046] By adding surfactants, a dispersion system that can reduce the surface tension between components is obtained, enabling barium titanate nanoparticles, silver nanoparticles, etc. to be more uniformly dispersed in polyvinylidene fluoride solution and matrix, avoiding agglomeration, ensuring the consistency of performance of each part of the substrate, and ensuring the uniform enhancement of Raman signal on the entire substrate surface and the stable performance of piezoelectric effect.

[0047] Through the synergistic effect of its components, polyvinylidene fluoride provides flexible support and basic piezoelectric properties; barium titanate nanoparticles enhance the piezoelectric effect; gold film facilitates the growth and conductivity of silver nanoparticles and enhances Raman signals; silver nanoparticles improve detection sensitivity; graphene oxide strengthens molecular adsorption, signal enhancement, and stability; thermal stabilizers ensure chemical stability; plasticizers improve flexibility; magnetic nanoparticles facilitate positioning and recovery and optimize synergistic performance; quantum dots enrich detection dimensions; and surfactants ensure uniform dispersion of components. This method enables in-situ, non-destructive, and highly sensitive detection of bronze artifacts, accurately acquiring information on material composition. It also possesses good environmental adaptability, ease of operation, and reliable and accurate detection results, broadening the scope of its applications. This method solves the problem of obtaining in-situ, non-destructive information on the material composition of bronze artifacts.

[0048] A method for fabricating a flexible piezoelectric SERS substrate, comprising the following steps:

[0049] S1. Dissolve polyvinylidene fluoride in an organic solvent to form a polyvinylidene fluoride solution.

[0050] S1 specifically includes: accurately weighing 70-90 parts of polyvinylidene fluoride powder, adding it to a three-necked flask containing 500-800 parts of N,N-dimethylformamide organic solvent, placing the three-necked flask on a magnetic stirrer at room temperature, and stirring continuously at a speed of 300-500 rpm for 3-5 hours until the polyvinylidene fluoride powder is completely dissolved, forming a uniform, transparent polyvinylidene fluoride solution without obvious particles or precipitates.

[0051] Specifically, polyvinylidene fluoride (PVDF) is a semi-crystalline polymer with certain intermolecular forces, existing as a solid powder at room temperature and pressure. N,N-dimethylformamide (DMF), as an organic solvent, exhibits good solubility for PVDF. This is because the carbonyl (C=O) and methyl (-CH3) functional groups in the DMF molecule can interact with the fluorine and carbon atoms on the PVDF molecular chains, disrupting the original intermolecular forces and allowing PVDF molecules to gradually disperse in the DMF solvent. During magnetic stirring, the magnetic stir bar moves in a circular motion driven by magnetic force, continuously stirring the solution. This allows newly added PVDF powder to disperse more quickly in the DMF, preventing localized accumulation. Furthermore, the liquid flow generated by stirring accelerates the contact and mixing between PVDF and DMF molecules, facilitating better insertion of DMF molecules into the PVDF molecular chains, further weakening the intermolecular forces and promoting the dissolution process. For example, during stirring, a certain flow rate gradient is formed in the solution area near the stir bar, causing the solution to circulate continuously. PVDF powder particles are entrained in the flowing solution, constantly coming into contact with fresh DMF solvent, thus accelerating dissolution. Controlling the stirring speed at 300-500 rpm and the stirring time at 3-5 hours is a suitable parameter range determined based on the dissolution characteristics of PVDF and the volume of the three-necked flask. If the speed is too low or the time is too short, the PVDF will not be completely dissolved. If the speed is too high, it may cause solution splashing, affecting operation and solution stability. If the time is too long, it will increase unnecessary energy consumption and time costs. By setting these parameters, it is ensured that the PVDF powder is uniformly and completely dissolved in DMF, forming a homogeneous solution system.

[0052] By dissolving polyvinylidene fluoride (PVDF) in an organic solvent, a uniform and transparent solution is formed, providing a homogeneous matrix for the subsequent addition of other components and the preparation of the composite substrate. This ensures that the properties of all parts of the substrate are uniform and consistent, facilitating the preparation of a stable, high-performance flexible piezoelectric SERS substrate through appropriate processes. This improves the accuracy and reliability of detecting the material composition of bronze artifacts. It also solves the problems of ineffective dissolution of PVDF and poor dissolution.

[0053] S2. Add barium titanate nanoparticles, heat stabilizer, plasticizer, magnetic nanoparticles, quantum dots and surfactant to polyvinylidene fluoride solution, stir evenly to form a mixed solution.

[0054] S2 specifically includes: adding 10-30 parts of barium titanate nanoparticles with a particle size of 30-50 nm, 1-5 parts of hindered phenolic heat stabilizer, 20-50 parts of dioctyl phthalate plasticizer, 5-20 parts of magnetite magnetic nanoparticles with a particle size of 10-30 nm, 1-10 parts of cadmium sulfide quantum dots with a particle size of 2-6 nm, and 0.5-2 parts of polyethylene glycol octylphenyl ether surfactant to a polyvinylidene fluoride solution, treating it under ultrasonic power of 60-100 W for 1-2 hours, and then stirring it at a speed of 400-600 rpm for 2-3 hours to form a uniform and stable mixed solution.

[0055] Specifically, the dispersion and mixing of barium titanate nanoparticles, heat stabilizers, plasticizers, magnetic nanoparticles, quantum dots, and surfactants in polyvinylidene fluoride (PVDF) solutions depends on a variety of physicochemical processes. During ultrasonic treatment, the cavitation effect generated by ultrasound in the liquid forms microbubbles. The rapid expansion and collapse of these bubbles generate a strong impact force, dispersing aggregated nanoparticles (such as barium titanate, magnetite magnetic nanoparticles, and cadmium sulfide quantum dots) into individual particles or small aggregates. For example, under ultrasonic cavitation, the surface energy of barium titanate nanoparticles with a diameter of 30-50 nm decreases, reducing the tendency for aggregation due to van der Waals forces. The amphiphilic structure of the surfactant (polyethylene glycol octylphenyl ether) causes its hydrophilic groups to face the solvent, while its lipophilic groups adsorb onto the surface of the nanoparticles, forming an electrostatic or steric stabilizing layer that prevents the particles from re-aggregating. Dioctyl phthalate plasticizer molecules insert into the PVDF molecular chains, weakening interchain forces, reducing solution viscosity, improving fluidity, and facilitating the dispersion of other components. During subsequent stirring, mechanical force further promotes the uniform distribution of the components, ensuring that small molecules such as heat stabilizers (hindered phenols) and plasticizers dissolve uniformly in the solution. Magnetic nanoparticles and quantum dots maintain a stable dispersion under the protection of surfactants. For example, a stirring speed of 400-600 rpm provides sufficient shear force to ensure thorough mixing of the components in the solution without damaging the structure of the nanoparticles. Throughout the process, the synergistic effect of ultrasonic power (60-100W), processing time (1-2 hours), and stirring speed and time is an optimal combination of parameters determined based on the physicochemical properties of each component (such as density, particle size, and surface properties) and the rheological properties of the solution system, to achieve uniform dispersion and stable mixing of the components.

[0056] Through these steps, a homogeneous and stable mixed solution is formed, enabling barium titanate nanoparticles to enhance the piezoelectric properties of the substrate, a heat stabilizer to ensure the substrate's resistance to thermal degradation, a plasticizer to impart flexibility, magnetic nanoparticles to provide magnetic response, quantum dots to supplement fluorescence signals, and surfactants to maintain stable dispersion of each component. Overall, this ensures consistent performance across the substrate's microstructure, improving detection sensitivity, repeatability, and ensuring stable performance when the substrate adheres to the surface of the artifact. This facilitates in-situ, non-destructive testing of bronze artifacts. It also solves the problem of easy aggregation and uneven distribution of various functional components in polyvinylidene fluoride solutions.

[0057] S3. Coat the mixed solution onto the substrate and dry to form a polyvinylidene fluoride composite film.

[0058] S3 specifically includes: pouring the mixed solution into a polytetrafluoroethylene mold by solution casting, air drying in a fume hood at room temperature for 24-48 hours, and then vacuum drying at 50-70℃ and 5-10Pa for 12-24 hours to form a polyvinylidene fluoride composite film with a thickness of 50-200μm.

[0059] Specifically, solution casting is a method for preparing polyvinylidene fluoride (PVDF) composite films based on the rheological properties of the solution and the evaporation characteristics of the solvent. First, when the mixed solution is poured into a PTFE mold, its own fluidity allows it to spread evenly within the mold, filling the space defined by the mold. This is thanks to the good flow state formed by the uniform mixing of the components, allowing the solution to flow naturally under gravity and cover the entire bottom surface of the mold. During the air-drying process in a fume hood at room temperature, the solvent (such as N,N-dimethylformamide) gradually evaporates from the solution into the air. As the solvent continues to evaporate, the concentration of the solute in the solution (including PVDF, various dispersed nanoparticles, and additives) gradually increases, the intermolecular distance gradually decreases, and they begin to aggregate and form a continuous solid network structure, which is the initial film morphology. Room temperature is chosen for this stage because it avoids unnecessary chemical reactions or performance degradation of the solute components due to excessively high temperatures, while ensuring a suitable solvent evaporation rate, allowing the film to form uniformly and slowly. The ventilation function of a fume hood is to accelerate solvent evaporation, promptly remove the evaporated solvent, and maintain an environment conducive to continuous solvent evaporation.

[0060] Then, vacuum drying is performed at 50-70℃ and 5-10Pa. Increasing the temperature further accelerates the evaporation of the remaining solvent, while the vacuum environment lowers the partial pressure of the solvent in the gas phase, making it easier for the solvent to escape from the solid film and more thoroughly removing residual solvent. Moreover, within this temperature and vacuum range, polyvinylidene fluoride and other functional components (such as barium titanate nanoparticles and heat stabilizers) maintain their structural stability and do not decompose or deform due to excessively high temperatures or low pressures. By controlling the vacuum drying time to 12-24 hours, it is ensured that the solvent in the film is fully evaporated, allowing the film to reach the set thickness range (50-200μm). The thickness control depends on both the initial amount of mixed solution poured into the mold and the degree of solvent evaporation. Under suitable drying conditions, as the solvent decreases, the film thickness gradually stabilizes within the target range, ultimately forming a polyvinylidene fluoride composite film.

[0061] By preparing polyvinylidene fluoride (PVDF) composite films with thicknesses ranging from 50 to 200 μm, the internal components are uniformly distributed and structurally stable. These films possess good flexibility, allowing them to adhere to artifact surfaces. Furthermore, the functional components they contain endow them with various properties such as piezoelectricity, chemical stability, and magnetic field manipulation, laying the foundation for subsequent construction of complete flexible piezoelectric SERS substrates, precise control of substrate performance, and standardized testing procedures. This process solves the problem of transforming a mixed solution containing multiple functional components into a composite film with uniform thickness, stable structure, and no solvent residue.

[0062] S4. Gold films are prepared on the surface of polyvinylidene fluoride composite films by physical vapor deposition or chemical plating.

[0063] S4 specifically includes: cutting the polyvinylidene fluoride composite film into a size of 5cm×8cm, rinsing it alternately with anhydrous ethanol and deionized water 3-5 times, fixing it on the sample stage of the magnetron sputtering instrument with a distance of 6-10cm between it and the gold target; evacuating to below 0.05-0.1Pa, introducing high-purity argon gas to the working pressure of 0.3-0.6Pa, and sputtering at a power of 100-180W for 6-10 minutes to deposit a gold film with a thickness of 7-9nm.

[0064] Specifically, magnetron sputtering is a process for depositing gold thin films based on plasma physics principles. High-purity argon gas is introduced into a high-vacuum environment (below 0.05-0.1 Pa) and an electric field is applied. The argon gas is ionized to form plasma, where argon ions are accelerated and bombard the surface of a gold target under the influence of the electric field. Gold atoms are sputtered from the target surface due to energy transfer, flying towards the surface of the polyvinylidene fluoride composite film in the form of atoms or atomic clusters, and depositing to form a continuous film. The sputtering power (100-180W) and time (6-10 minutes) determine the sputtering rate and deposition amount of gold atoms, thereby controlling the film thickness (7-9 nm). The working pressure (0.3-0.6 Pa) affects the mean free path and energy distribution of argon ions. A suitable pressure ensures that the argon ions have sufficient energy to bombard the target and that gold atoms can successfully reach the substrate surface. The target-substrate distance (6-10 cm) needs to balance the deposition rate of gold atoms with energy loss, ensuring that the gold atoms reaching the substrate have sufficient energy to form a dense and uniform film. During this process, the polyvinylidene fluoride composite film is alternately rinsed with anhydrous ethanol and deionized water to remove surface impurities and organic matter, ensuring that gold atoms can directly bond with the substrate surface and improve adhesion. The film is cut to a size of 5cm × 8cm for easy fixation and handling in the sputtering apparatus, while also meeting the area requirements for subsequent preparation of the silver nanoparticle layer.

[0065] By preparing a uniformly thick and firmly bonded gold film on the surface of a polyvinylidene fluoride (PVDF) composite film, a uniform nucleation site can be provided for the growth of silver nanoparticles, ensuring their uniform distribution. It also possesses good conductivity to enhance surface plasmon resonance (SERS) and SERS performance, and facilitates subsequent functional layer modification, laying the foundation for high-sensitivity detection of the material composition on the surface of bronze artifacts. This method solves the problems of poor adhesion to the substrate and uneven coating that are common when preparing high-quality gold films on flexible PVDF composite films.

[0066] S5. Silver nanoparticles are prepared on the surface of gold thin films by chemical reduction or electrochemical deposition.

[0067] S5 specifically includes: preparing a 0.02-0.05 mol / L silver nitrate solution and an equal concentration of sodium citrate solution; adding 5-10 ml of silver nitrate solution to a substrate container containing a gold film; adding an equal volume of sodium citrate solution; and reacting in an oil bath at 50-70℃ with magnetic stirring at 300-500 rpm for 3-5 hours; after the reaction is completed, naturally cooling to room temperature; rinsing with deionized water 5-8 times; and then vacuum drying at 40-60℃ and 5-8 Pa for 8-12 hours to form polyhedral silver nanoparticles with a particle size of 55-85 nm.

[0068] Specifically, in the chemical reduction method for preparing silver nanoparticles, sodium citrate is used as the reducing agent and silver nitrate as the silver source. When a sodium citrate solution is added dropwise to a silver nitrate solution, under specific temperature (50-70℃ oil bath) and stirring (300-500 rpm magnetic stirring) conditions, the reducing groups in sodium citrate react with the silver ions in silver nitrate in a redox reaction. Specifically, electrons from functional groups such as the carboxyl groups in sodium citrate are transferred to silver ions, gradually reducing the silver ions to silver atoms. The chemical reaction formula is approximately: Ag... + +Reducing agent (sodium citrate) → Ag (atom) +Oxidation product.

[0069] As the reaction continues, newly formed silver atoms continuously aggregate and grow on the surface of the gold film. Due to the unique lattice structure and surface energy of the gold film, it adsorbs silver atoms, serving as nucleation sites for their aggregation and growth. This promotes preferential nucleation and gradual growth of silver atoms on its surface. Simultaneously, the synergistic effect of oil bath heating and magnetic stirring ensures that, on the one hand, the uniform and stable heating environment provided by the oil bath maintains the reaction system within a suitable temperature range, allowing the reaction to proceed continuously and stably. Excessive temperature may lead to an overly vigorous reaction, resulting in uneven silver nanoparticle size; conversely, excessively low temperature results in a slow reaction rate. On the other hand, magnetic stirring ensures uniform mixing of the reaction solution, preventing localized excessively high or low reactant concentrations. This guarantees sufficient contact and reaction between silver ions and the reducing agent, and also helps to uniformly disperse the generated silver nanoparticles in the solution, preventing their aggregation.

[0070] After the reaction, the system was allowed to cool naturally to room temperature to ensure a stable reaction process and prevent adverse effects on the structure of the resulting silver nanoparticles due to sudden temperature changes. The nanoparticles were then rinsed multiple times with deionized water to remove unreacted reactants, byproducts, and other impurities remaining on the substrate surface and around the silver nanoparticles, ensuring their purity. Finally, the nanoparticles were dried under vacuum at 40-60℃ and 5-8 Pa. Increasing the temperature lowered the saturated vapor pressure of the solvent (water), while simultaneously reducing the partial pressure of solvent molecules in the gas phase under vacuum accelerated solvent evaporation, ensuring complete removal of water and other solvents from the silver nanoparticles. This temperature and vacuum range did not damage the structure of the silver nanoparticles or their bonding with the gold film substrate, ultimately forming polyhedral silver nanoparticles with a diameter of 55-85 nm. The particle size is mainly influenced by the reactant concentration, reaction temperature, stirring rate, and reaction time. Strict control of these parameters allows for the regulation of the silver nanoparticle size and morphology.

[0071] By preparing polyhedral silver nanoparticles with a particle size of 55-85 nm on the surface of a gold thin film, a strong surface plasmon resonance effect is generated, significantly enhancing the Raman scattering signal and improving the sensitivity for detecting the material composition of bronze artifacts. Furthermore, the uniform distribution on the gold thin film surface ensures consistent Raman signal enhancement, aiding in the accurate detection of trace components on the artifact surface. This method solves the problems of uneven particle size and distribution that often occur when preparing silver nanoparticles on a gold thin film substrate.

[0072] S6. Graphene oxide is applied to the surface of silver nanoparticles by drop coating, spin coating or spray coating.

[0073] S6 specifically includes: adding 10-20 mg of graphene oxide, with a sheet thickness of 1-2 nm and a lateral dimension of 1-5 μm, to 10-20 ml of deionized water, and treating it under ultrasonic power of 40-60 W for 2-3 hours to form a homogeneous solution; using a pipette to take 0.1-0.3 ml of the graphene oxide solution and drop it onto the surface of a substrate containing silver nanoparticles, drying it under vacuum at 30-50 °C and 3-6 Pa for 6-10 hours, and then placing it in a vacuum tube furnace, introducing argon gas at a flow rate of 30-50 ml / min, and heating it to 180-220 °C at 3-5 °C / min and holding it for 1-2 hours to allow the graphene oxide to form a chemical bond with the silver nanoparticles.

[0074] Specifically, firstly, graphene oxide (GO) is added to deionized water and subjected to ultrasonic treatment, utilizing the cavitation effect of ultrasound. At an ultrasonic power of 40-60W, the high-frequency vibrations generated in the liquid create countless tiny cavitation bubbles. These bubbles, during their growth and collapse, generate strong impact forces and microjets that act on the graphene oxide sheets, breaking their agglomeration and allowing them to disperse uniformly in the water, thus forming a homogeneous solution. Because graphene oxide has a large specific surface area and strong interlayer interactions, it is prone to stacking and agglomeration. Ultrasonic treatment effectively overcomes this problem, ensuring that it exists in a monodisperse state in the solution, facilitating subsequent operations.

[0075] Next, a pipette is used to draw up a graphene oxide solution and drop it onto the surface of the silver nanoparticle-containing substrate. The fluidity of the solution allows the graphene oxide to cover the substrate surface. As the solvent (deionized water) evaporates naturally, the graphene oxide will gradually deposit on the silver nanoparticles.

[0076] Then, vacuum drying is performed. Under conditions of 30-50℃ and 3-6Pa, by reducing the ambient pressure and appropriately increasing the temperature, the evaporation rate of the solvent is accelerated, so that the graphene oxide deposited on the substrate adheres more firmly. At the same time, excess water is removed to avoid moisture residue interfering with subsequent chemical bonding and other processes.

[0077] Finally, the substrate was placed in a vacuum tube furnace, and argon gas was introduced as a protective gas to maintain an inert atmosphere within the furnace at a flow rate of 30-50 ml / min, preventing oxidation of the substrate and graphene oxide during the high-temperature process. The temperature was slowly increased to 180-220℃ at a rate of 3-5℃ / min and held for 1-2 hours. During this process, the abundant oxygen-containing functional groups (such as hydroxyl and carboxyl groups) on the surface of graphene oxide react chemically with the atoms on the surface of silver nanoparticles under high temperature, forming chemical bonds. For example, this may be achieved through coordination bonds between oxygen and silver atoms, resulting in a tight bond between the two. This chemical bonding enhances the adhesion stability of graphene oxide on the substrate and allows graphene oxide to better exert its synergistic function with silver nanoparticles.

[0078] By uniformly and stably modifying the surface of silver nanoparticles with graphene oxide and forming chemical bonds, the adsorption capacity of analyte molecules is increased by utilizing the oxygen-containing functional groups of graphene oxide. This also enhances the Raman signal by synergistically utilizing the plasmon resonance effect of silver nanoparticles, while preventing the oxidation of silver nanoparticles. This improves detection sensitivity, extends the substrate's lifespan, and ensures reliable detection results, meeting the requirements for the detection of bronze artifacts. This method solves the problem of the difficulty in uniformly and stably modifying the surface of silver nanoparticle-containing substrates with graphene oxide.

[0079] Please see the appendix Figure 2 An in-situ detection system for bronze artifacts on a flexible piezoelectric SERS substrate, comprising the following modules:

[0080] The flexible piezoelectric SERS substrate module is used in the in-situ detection system for bronze artifacts. By utilizing the surface-enhanced Raman scattering effect and the piezoelectric effect, it can identify the copper rust, corrosion products and organic residues on the surface of bronze artifacts without damaging their original appearance.

[0081] The signal acquisition module is used in the in-situ detection system for bronze artifacts to receive Raman scattered light signals generated by a flexible piezoelectric SERS substrate. With the help of fiber optic probes and Raman spectrometer components, the light signals are converted into processable electrical signals, providing raw data for subsequent signal analysis and processing, and enabling the understanding of the material composition information on the surface of bronze artifacts.

[0082] The signal processing module is used to process the electrical signal data corresponding to the Raman scattering light signal on the surface of the bronze artifact acquired by the signal acquisition module. Through noise reduction, characteristic peak identification, and component identification, valuable information is extracted, and the material composition and related conditions of the surface of the bronze artifact are analyzed.

[0083] The power module is used to provide stable power to the flexible piezoelectric SERS substrate in the in-situ detection system for bronze artifacts, so that its piezoelectric effect can be performed normally, ensuring that the entire detection process can proceed smoothly and that the surface composition of bronze artifacts can be effectively detected.

[0084] The positioning module is used in the in-situ detection system for bronze artifacts to determine the position of the flexible piezoelectric SERS substrate on the surface of the bronze artifact by magnetic or optical positioning methods.

[0085] The data storage module is used in the in-situ detection system for bronze artifacts to store the raw Raman signal data acquired by the signal acquisition module and the result data after analysis and processing by the signal processing module.

[0086] Specifically, the flexible piezoelectric SERS substrate contains various functional components such as polyvinylidene fluoride (PVDF) and barium titanate nanoparticles. When subjected to minor external pressure (such as pressure changes when adhering to the surface of a bronze artifact), a corresponding piezoelectric electric field is generated within the substrate based on the piezoelectric effect of the piezoelectric material. Simultaneously, structures such as silver nanoparticles on the substrate surface, under light irradiation, significantly enhance the local electromagnetic field through their surface plasmon resonance effect. When detection light shines on the surface of the bronze artifact, molecules of copper rust, corrosion products, and organic residues adsorb onto the substrate surface. The Raman scattering signal of these molecules is significantly enhanced through the synergistic effect of surface plasmon resonance and the piezoelectric electric field. Specifically, the piezoelectric electric field influences the orientation and distribution of molecules, making them more conducive to interaction with the substrate surface and enhancing the adsorption effect, while the surface plasmon resonance effect directly enhances the intensity of the Raman scattering light, thereby amplifying the weak Raman signal for subsequent identification and analysis.

[0087] Utilizing the optical transmission characteristics of fiber optic probes, Raman scattered light signals generated by flexible piezoelectric SERS substrates can be efficiently transmitted to the Raman spectrometer components. The Raman spectrometer contains key components such as gratings and detectors. The gratings separate the incident Raman scattered light according to its wavelength, separating light of different wavelengths. Then, based on the photoelectric effect, the detector converts the light signals of different wavelengths into corresponding electrical signals. Specifically, when light shines on the photosensitive material of the detector, electrons within the material gain sufficient energy to escape, thereby generating a current. This conversion from optical signal to electrical signal ultimately provides identifiable and quantifiable raw data for subsequent analysis and processing.

[0088] First, to address the noise signals mixed in with the acquired electrical signals, noise reduction algorithms such as digital filtering are employed. Based on the differences between the noise signals and the effective signals in terms of frequency, amplitude, etc., appropriate filtering parameters are set to filter out the noise signals, making the effective signals clearer. Then, by analyzing the processed signals, the positions and intensities of characteristic peaks in the Raman spectrum are compared with known Raman spectral databases to identify the corresponding characteristic peaks. Because different substances have unique Raman characteristic peaks, this method is used to determine the composition present on the surface of the artifact. Simultaneously, by combining the characteristic peaks of multiple components and related data, the content and distribution of each component are comprehensively identified, thus completing the analysis of the material composition and related conditions on the surface of the bronze artifact.

[0089] The power module contains key components such as a voltage regulator circuit and a power management chip. The voltage regulator circuit regulates the input voltage, utilizing the characteristics of transistors and other electronic components. Based on a set voltage value, when the input voltage fluctuates (e.g., due to changes in the external power supply environment), it automatically adjusts the current in the circuit to maintain a stable output voltage. The power management chip intelligently controls the entire power supply process, such as monitoring the power output status and controlling the power supply's on / off state. This provides a stable and suitable power supply to the flexible piezoelectric SERS substrate, ensuring that the piezoelectric materials in the substrate (such as barium titanate nanoparticles) can normally exert their piezoelectric effect under a stable power supply, maintaining the substrate's performance stability during the testing process.

[0090] If a magnetic positioning method is used, the magnetic components (such as permanent magnets or electromagnets) in the positioning module will generate a magnetic field. The flexible piezoelectric SERS substrate contains magnetic nanoparticles (such as magnetite nanoparticles), which interact with the external magnetic field. By detecting changes in the strength and direction of the magnetic field, the position of the substrate on the surface of the bronze artifact can be determined. If an optical positioning method is used, optical sensors (such as CCD cameras) are employed to identify and locate pre-set optical marks (such as specific patterns or reflective materials) on the substrate. By analyzing the coordinates of the marks in the optical image, the precise position of the substrate can be determined, facilitating accurate placement and repeated positioning during the inspection process.

[0091] The data storage module is equipped with high-capacity storage chips (such as flash memory chips) and a corresponding data management system. Based on semiconductor storage technology, the storage chips encode and store electrical signals, saving the raw Raman signal data acquired by the signal acquisition module and the processed data from the signal processing module in binary form. The data management system is responsible for classifying, indexing, and backing up the stored data. For example, it classifies and stores data according to different dimensions such as detection time and detection location, facilitating subsequent quick retrieval, access, and data integration and analysis, ensuring data integrity and security.

[0092] Through the coordinated operation of its various modules, the flexible piezoelectric SERS substrate module enables non-destructive in-situ detection and identification of artifact surface components. The signal acquisition module accurately converts optical signals into electrical signals, providing a data foundation. The signal processing module extracts valuable information to aid in compositional analysis. The power supply module ensures stable power for smooth detection. The positioning module precisely determines the substrate location, improving detection accuracy and repeatability. The data storage module properly stores data for subsequent retrieval and analysis. Overall, this approach facilitates in-depth research into the condition of bronze artifacts, enabling long-term monitoring and scientific preservation. It overcomes the limitations of traditional detection methods, such as damaging artifacts and difficulty in detecting trace components.

[0093] The following is a further description with reference to specific embodiments:

[0094] Example 1:

[0095] A flexible piezoelectric SERS substrate, characterized in that, by weight, it comprises the following components: 90 parts polyvinylidene fluoride, 30 parts barium titanate nanoparticles, 9 parts gold film, 85 parts silver nanoparticles, 2 parts graphene oxide, 5 parts heat stabilizer, 50 parts plasticizer, 20 parts magnetic nanoparticles, 10 parts quantum dots, and 2 parts surfactant.

[0096] A method for fabricating a flexible piezoelectric SERS substrate, characterized in that, for use with the flexible piezoelectric SERS substrate of claim 1, the method comprises the following steps:

[0097] S1. Dissolve polyvinylidene fluoride in an organic solvent to form a polyvinylidene fluoride solution;

[0098] S2. Add barium titanate nanoparticles, heat stabilizer, plasticizer, magnetic nanoparticles, quantum dots and surfactant to polyvinylidene fluoride solution, stir evenly to form a mixed solution;

[0099] S3. Coat the mixed solution onto the substrate and dry to form a polyvinylidene fluoride composite film;

[0100] S4. Gold films are prepared on the surface of polyvinylidene fluoride composite films by physical vapor deposition or chemical plating.

[0101] S5. Silver nanoparticles were prepared on the surface of a gold thin film by chemical reduction or electrochemical deposition.

[0102] S6. Graphene oxide is applied to the surface of silver nanoparticles by drop coating, spin coating or spray coating.

[0103] S1 specifically includes: accurately weighing 90 parts of polyvinylidene fluoride powder, adding it to a three-necked flask containing 800 parts of N,N-dimethylformamide organic solvent, placing the three-necked flask on a magnetic stirrer at room temperature, and stirring continuously at 500 rpm for 5 hours until the polyvinylidene fluoride powder is completely dissolved, forming a uniform, transparent polyvinylidene fluoride solution without obvious particles or precipitates.

[0104] S2 specifically includes: adding 30 parts of barium titanate nanoparticles with a particle size of 50 nm, 5 parts of hindered phenolic heat stabilizer, 50 parts of dioctyl phthalate plasticizer, 20 parts of magnetite magnetic nanoparticles with a particle size of 30 nm, 10 parts of cadmium sulfide quantum dots with a particle size of 6 nm, and 2 parts of polyethylene glycol octylphenyl ether surfactant to a polyvinylidene fluoride solution in sequence. The solution is treated with 100 W ultrasonic power for 2 hours, and then stirred at 600 rpm for 3 hours to form a uniform and stable mixed solution.

[0105] S3 specifically includes: pouring the mixed solution into a polytetrafluoroethylene mold by solution casting, air-drying it in a fume hood at room temperature for 48 hours, and then vacuum drying it at 70°C and 10Pa for 24 hours to form a polyvinylidene fluoride composite film with a thickness of 200μm.

[0106] S4 specifically includes: cutting the polyvinylidene fluoride composite film into a size of 5cm×8cm, rinsing it 5 times alternately with anhydrous ethanol and deionized water, fixing it on the sample stage of the magnetron sputtering instrument with a distance of 10cm from the gold target; evacuating to below 0.1Pa, introducing high-purity argon gas to the working pressure of 0.6Pa, and sputtering at 180W power for 10 minutes to deposit a gold film with a thickness of 9nm.

[0107] S5 specifically includes: preparing a 0.05 mol / L silver nitrate solution and an equal concentration of sodium citrate solution; adding 10 ml of silver nitrate solution to a substrate container containing a gold film; adding an equal volume of sodium citrate solution; and reacting in a 70°C oil bath with magnetic stirring at 500 rpm for 5 hours; after the reaction is completed, naturally cooling to room temperature; rinsing 8 times with deionized water; and then drying under vacuum at 60°C and 8 Pa for 12 hours to form polyhedral silver nanoparticles with a particle size of 85 nm.

[0108] S6 specifically includes: adding 20 mg of graphene oxide with a sheet thickness of 2 nm and a lateral dimension of 5 μm to 20 ml of deionized water and treating it under ultrasonic power of 60 W for 3 hours to form a homogeneous solution; using a pipette to take 0.3 ml of graphene oxide solution and drop it onto the surface of a substrate containing silver nanoparticles, drying it under vacuum at 50 °C and 6 Pa for 10 hours, and then placing it in a vacuum tube furnace, introducing argon gas at a flow rate of 50 ml / min, and heating it to 220 °C at 5 °C / min and holding it therefore for 2 hours to allow the graphene oxide to form a chemical bond with the silver nanoparticles.

[0109] An in-situ detection system for bronze artifacts on a flexible piezoelectric SERS substrate, characterized in that it is used on a flexible piezoelectric SERS substrate as described in claim 1, and comprises the following modules:

[0110] The flexible piezoelectric SERS substrate module is used in the in-situ detection system for bronze artifacts. By utilizing the surface-enhanced Raman scattering effect and the piezoelectric effect, it can identify the copper rust, corrosion products and organic residues on the surface of bronze artifacts without damaging their original appearance.

[0111] The signal acquisition module is used in the in-situ detection system for bronze artifacts to receive Raman scattered light signals generated by a flexible piezoelectric SERS substrate. With the help of fiber optic probes and Raman spectrometer components, the light signals are converted into processable electrical signals, providing raw data for subsequent signal analysis and processing, and enabling the understanding of the material composition information on the surface of bronze artifacts.

[0112] The signal processing module is used to process the electrical signal data corresponding to the Raman scattering light signal on the surface of the bronze artifact acquired by the signal acquisition module. Through noise reduction, characteristic peak identification, and component identification, valuable information is extracted, and the material composition and related conditions of the surface of the bronze artifact are analyzed.

[0113] The power module is used to provide stable power to the flexible piezoelectric SERS substrate in the in-situ detection system for bronze artifacts, so that its piezoelectric effect can be performed normally, ensuring that the entire detection process can proceed smoothly and that the surface composition of bronze artifacts can be effectively detected.

[0114] The positioning module is used in the in-situ detection system for bronze artifacts to determine the position of the flexible piezoelectric SERS substrate on the surface of the bronze artifact by magnetic or optical positioning methods.

[0115] The data storage module is used in the in-situ detection system for bronze artifacts to store the raw Raman signal data acquired by the signal acquisition module and the result data after analysis and processing by the signal processing module.

[0116] Example 2:

[0117] The difference between this embodiment and Embodiment 1 above is that:

[0118] A flexible piezoelectric SERS substrate, characterized in that, by weight, it comprises the following components: 70 parts polyvinylidene fluoride, 10 parts barium titanate nanoparticles, 7 parts gold film, 55 parts silver nanoparticles, 1 part graphene oxide, 1 part heat stabilizer, 20 parts plasticizer, 5 parts magnetic nanoparticles, 1 part quantum dot, and 0.5 parts surfactant.

[0119] Example 3:

[0120] The difference between this embodiment and Embodiment 1 above is that:

[0121] A flexible piezoelectric SERS substrate, characterized in that, by weight, it comprises the following components: 80 parts polyvinylidene fluoride, 20 parts barium titanate nanoparticles, 8 parts gold film, 70 parts silver nanoparticles, 1.5 parts graphene oxide, 3 parts heat stabilizer, 35 parts plasticizer, 12.5 parts magnetic nanoparticles, 5.5 parts quantum dots, and 1.25 parts surfactant.

[0122] Table 1:

[0123]

[0124]

[0125] The comparison in the table above is with existing materials. Through the comparison of the data in the table above, it can be seen that the flexible piezoelectric SERS substrate of the present invention is superior to the existing flexible piezoelectric SERS substrate in terms of detection sensitivity, substrate flexibility and stability. It can be seen that it has a stronger signal capture and amplification capability for detecting trace components on the surface of bronze artifacts, is easier to fit the complex shape of artifacts, and has more stable performance over long-term use. Thus, it achieves high sensitivity, in-situ non-destructive bonding and long-term stable detection, and solves the problem of obtaining information on the material composition of the surface of artifacts in in-situ and non-destructively in the detection of bronze artifacts.

Claims

1. A flexible piezoelectric SERS substrate, characterized in that, By weight, it contains the following components: 70-90 parts polyvinylidene fluoride, 10-30 parts barium titanate nanoparticles, 7-9 parts gold film, 55-85 parts silver nanoparticles, 1-2 parts graphene oxide, 1-5 parts heat stabilizer, 20-50 parts plasticizer, 5-20 parts magnetic nanoparticles, 1-10 parts quantum dots, and 0.5-2 parts surfactant.

2. A method for fabricating a flexible piezoelectric SERS substrate, characterized in that, The method for using a flexible piezoelectric SERS substrate as described in claim 1 includes the following steps: S1. Dissolve polyvinylidene fluoride in an organic solvent to form a polyvinylidene fluoride solution; S2. Add barium titanate nanoparticles, heat stabilizer, plasticizer, magnetic nanoparticles, quantum dots and surfactant to polyvinylidene fluoride solution, stir evenly to form a mixed solution; S3. Coat the mixed solution onto the substrate and dry to form a polyvinylidene fluoride composite film; S4. Gold films are prepared on the surface of polyvinylidene fluoride composite films by physical vapor deposition or chemical plating. S5. Silver nanoparticles were prepared on the surface of a gold thin film by chemical reduction or electrochemical deposition. S6. Graphene oxide is applied to the surface of silver nanoparticles by drop coating, spin coating or spray coating.

3. The method for preparing a flexible piezoelectric SERS substrate according to claim 2, characterized in that, S1 specifically includes: accurately weighing 70-90 parts of polyvinylidene fluoride powder, adding it to a three-necked flask containing 500-800 parts of N,N-dimethylformamide organic solvent, placing the three-necked flask on a magnetic stirrer at room temperature, and stirring continuously at a speed of 300-500 rpm for 3-5 hours until the polyvinylidene fluoride powder is completely dissolved, forming a uniform, transparent polyvinylidene fluoride solution without obvious particles or precipitates.

4. The method for preparing a flexible piezoelectric SERS substrate according to claim 2, characterized in that, S2 specifically includes: sequentially adding 10-30 parts of barium titanate nanoparticles with a particle size of 30-50 nm, 1-5 parts of hindered phenolic heat stabilizer, 20-50 parts of dioctyl phthalate plasticizer, 5-20 parts of magnetite magnetic nanoparticles with a particle size of 10-30 nm, 1-10 parts of cadmium sulfide quantum dots with a particle size of 2-6 nm, and 0.5-2 parts of polyethylene glycol octylphenyl ether surfactant to a polyvinylidene fluoride solution, treating it under ultrasonic power of 60-100 W for 1-2 hours, and then stirring it at a speed of 400-600 rpm for 2-3 hours to form a uniform and stable mixed solution.

5. The method for preparing a flexible piezoelectric SERS substrate according to claim 2, characterized in that, S3 specifically includes: pouring the mixed solution into a polytetrafluoroethylene mold by solution casting, air drying in a room temperature fume hood for 24-48 hours, and then vacuum drying at 50-70℃ and 5-10Pa for 12-24 hours to form a polyvinylidene fluoride composite film with a thickness of 50-200μm.

6. The method for preparing a flexible piezoelectric SERS substrate according to claim 2, characterized in that, S4 specifically includes: cutting the polyvinylidene fluoride composite film into a size of 5cm×8cm, rinsing it alternately with anhydrous ethanol and deionized water 3-5 times, fixing it on the sample stage of the magnetron sputtering instrument with a distance of 6-10cm between it and the gold target; evacuating to below 0.05-0.1Pa, introducing high-purity argon gas to the working pressure of 0.3-0.6Pa, and sputtering at a power of 100-180W for 6-10 minutes to deposit a gold film with a thickness of 7-9nm.

7. The method for preparing a flexible piezoelectric SERS substrate according to claim 2, characterized in that, S5 specifically includes: preparing a 0.02-0.05 mol / L silver nitrate solution and an equal concentration of sodium citrate solution; adding 5-10 ml of silver nitrate solution to a substrate container containing a gold film; adding an equal volume of sodium citrate solution; and reacting in an oil bath at 50-70℃ with magnetic stirring at 300-500 rpm for 3-5 hours; after the reaction is completed, naturally cooling to room temperature; rinsing with deionized water 5-8 times; and then vacuum drying at 40-60℃ and 5-8 Pa for 8-12 hours to form polyhedral silver nanoparticles with a particle size of 55-85 nm.

8. The method for preparing a flexible piezoelectric SERS substrate according to claim 2, characterized in that, S6 specifically includes: adding 10-20 mg of graphene oxide, with a sheet thickness of 1-2 nm and a lateral dimension of 1-5 μm, to 10-20 ml of deionized water, and treating it under ultrasonic power of 40-60 W for 2-3 hours to form a homogeneous solution; using a pipette to take 0.1-0.3 ml of the graphene oxide solution and drop it onto the surface of a substrate containing silver nanoparticles, drying it under vacuum at 30-50 °C and 3-6 Pa for 6-10 hours, and then placing it in a vacuum tube furnace, introducing argon gas at a flow rate of 30-50 ml / min, and heating it to 180-220 °C at 3-5 °C / min and holding it for 1-2 hours to allow the graphene oxide to form a chemical bond with the silver nanoparticles.

9. An in-situ detection system for bronze artifacts on a flexible piezoelectric SERS substrate, characterized in that, A flexible piezoelectric SERS substrate according to claim 1 includes the following modules: The flexible piezoelectric SERS substrate module is used in the in-situ detection system for bronze artifacts. By utilizing the surface-enhanced Raman scattering effect and the piezoelectric effect, it can identify the copper rust, corrosion products and organic residues on the surface of bronze artifacts without damaging their original appearance. The signal acquisition module is used in the in-situ detection system for bronze artifacts to receive Raman scattered light signals generated by a flexible piezoelectric SERS substrate. With the help of fiber optic probes and Raman spectrometer components, the light signals are converted into processable electrical signals, providing raw data for subsequent signal analysis and processing, and enabling the understanding of the material composition information on the surface of bronze artifacts. The signal processing module is used to process the electrical signal data corresponding to the Raman scattering light signal on the surface of the bronze artifact acquired by the signal acquisition module. Through noise reduction, characteristic peak identification, and component identification, valuable information is extracted, and the material composition and related conditions of the surface of the bronze artifact are analyzed. The power module is used to provide stable power to the flexible piezoelectric SERS substrate in the in-situ detection system for bronze artifacts, so that its piezoelectric effect can be performed normally, ensuring that the entire detection process can proceed smoothly and that the surface composition of bronze artifacts can be effectively detected. The positioning module is used in the in-situ detection system for bronze artifacts to determine the position of the flexible piezoelectric SERS substrate on the surface of the bronze artifact by magnetic or optical positioning methods. The data storage module is used in the in-situ detection system for bronze artifacts to store the raw Raman signal data acquired by the signal acquisition module and the result data after analysis and processing by the signal processing module.

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