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CN-122015688-A - Preparation method and application of flexible strain sensor based on SERS technology

CN122015688ACN 122015688 ACN122015688 ACN 122015688ACN-122015688-A

Abstract

A preparation method and application of a flexible strain sensor based on SERS technology belong to the field of optical strain sensing. The invention aims to solve the technical problems that the current mainstream optical strain sensing technology is limited in measuring range and difficult to consider both precision and measuring range, and is difficult to adapt to the large strain detection requirement of flexible structures such as low-altitude aircrafts. The flexible strain sensor based on the SERS technology forms a compact 4-MBa-au NPs single-layer film through a three-phase interface self-assembly method and is successfully transferred to the adhesive surface of the VHB adhesive tape with ultra-high flexibility, the manufactured sensor can realize wide-range strain detection of 0-24%, the measurement precision is +/-2% FS, the limitation of the existing optical sensing technology on the detection range is broken through, the excellent adhesiveness of the VHB adhesive tape is benefited, the sensor is easy to integrate to the surface of a material to be detected, and the application prospect is good.

Inventors

  • SUN YE
  • ZHANG KEXIN
  • YU MIAO
  • ZHANG CHENGGANG
  • WANG CHAOTONG

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. A preparation method of a flexible strain sensor based on a SERS technology is characterized by comprising the following steps of preparing a gold nanoparticle aqueous solution by adopting a sodium citrate reduction method, centrifuging, re-suspending a precipitate obtained by centrifugation in absolute ethyl alcohol to obtain an Au NPs ethanol solution, adding the ethanol solution of 4-mercaptobenzoic acid and the Au NPs ethanol solution into absolute ethyl alcohol, carrying out ultrasonic treatment, stirring, centrifuging, re-suspending the precipitate obtained by centrifugation in absolute ethyl alcohol to obtain a 4-MBa-Au NPs ethanol solution, forming a compact 4-MBa-Au NPs monolayer film by adopting a three-phase interface self-assembly method, transferring the 4-MBa-Au NPs monolayer film to a paper-free adhesive surface of a hydrophilized VHB adhesive tape, and naturally drying to obtain the flexible strain sensor based on the SERS technology.
  2. 2. The preparation method of the flexible strain sensor based on the SERS technology is characterized in that the preparation method of the gold nanoparticle aqueous solution in the first step comprises the steps of uniformly mixing chloroauric acid aqueous solution, silver nitrate aqueous solution, sodium citrate aqueous solution and Tris aqueous solution, then injecting the mixture into hot water, and reacting for 0.5-1 h at 100 ℃ to obtain the gold nanoparticle aqueous solution.
  3. 3. The preparation method of the flexible strain sensor based on the SERS technology, which is characterized in that the concentration of the chloroauric acid aqueous solution is 50mg/mL, the concentration of the silver nitrate aqueous solution is 2mg/mL, the concentration of the sodium citrate aqueous solution is 60 mg/mL-200 mg/mL, and the concentration of the Tris aqueous solution is 2mol/L.
  4. 4. The preparation method of the flexible strain sensor based on the SERS technology, which is disclosed in claim 2, is characterized in that the volume ratio of chloroauric acid aqueous solution, silver nitrate aqueous solution, sodium citrate aqueous solution, tris aqueous solution and hot water is 400 mu L/85 mu L/200 mu L/400 mu L/200 mL.
  5. 5. The method for preparing a flexible strain sensor based on SERS technology according to claim 1, wherein the concentration of the ethanol solution of 4-mercaptobenzoic acid in the second step is 50mg/mL.
  6. 6. The preparation method of the flexible strain sensor based on the SERS technology is characterized by comprising the specific operation of sequentially adding dichloromethane, 4-MBA-Au NPs ethanol solution and water into a centrifuge tube, placing the centrifuge tube into a vortex oscillator, 10-gear vortex vibration for 10s, adding n-hexane, spontaneously assembling the 4-MBA-Au NPs into a film at the interface of water and n-hexane, and sucking the n-hexane to form a compact 4-MBA-Au NPs single-layer film.
  7. 7. The method for preparing the flexible strain sensor based on the SERS technology, as claimed in claim 1, wherein the 4-MBA-Au NPs single-layer film in the fourth step is transferred onto the paper-free adhesive surface of the hydrophilized VHB adhesive tape by a pulling method.
  8. 8. The application of the SERS technology-based flexible strain sensor prepared by the preparation method according to any one of claims 1-7, wherein the flexible strain sensor is suitable for strain detection of deformable materials.
  9. 9. The application of the flexible strain sensor based on the SERS technology as claimed in claim 8, wherein the strain detection method is as follows: Step one, mounting a flexible strain sensor based on SERS technology on an electric stretching table, recording the initial gauge length before stretching as L 0 , wherein the unit is mm, detecting the Raman spectrum of a deformable material surface sensor in an initial state by using a Raman spectrometer, step two, carrying out quasi-static stretching test on the deformable material with the sensor on the surface by using the electric stretching table, using a graded loading mode, gradually applying the stretching strain with a displacement control step length of 50 mu m, recording the length of the gauge length after stretching of the deformable material with the sensor on the surface as L ε , wherein the unit is mm, and according to a formula Calculating strain epsilon until the strain reaches 24%, synchronously detecting Raman spectra of the surface sensor of the deformable material under different tensile strains in the process, performing data processing on the obtained Raman spectra under the tensile strains by adopting SERS spectrum data processing, extracting fitting intensity of characteristic peaks of 1588cm -1 and 1076cm -1 under the tensile strains, calculating a bimodal intensity ratio H ε of characteristic peaks of 1588cm -1 and 1076cm -1 under the tensile strains, The data processing in the step III ① comprises the steps of carrying out Raman spectrum smoothing, baseline correction and Raman peak fitting, extracting intensity information of characteristic peaks of 1588cm -1 and 1076cm -1 after fitting, the step IV of constructing a function relation of strain epsilon and bimodal intensity ratio H ε , wherein the strain epsilon is taken as an abscissa, the bimodal intensity ratio H ε is taken as an ordinate, a calibration curve is drawn, the curve is subjected to function fitting to obtain a fitting linear function H ε =0.797+0.159 epsilon, a coefficient R 2 =0.999 is determined, the step V of removing isolation paper on the other side of a flexible strain sensor based on the SERS technology, pasting the isolation paper on the surface of a deformable material to be measured, applying strain to the material to be measured, detecting the Raman spectrum of the surface sensor of the material to be measured, carrying out data processing, extracting the fitting intensities of the characteristic peaks of 1588cm -1 and 1076cm -1 , calculating the bimodal intensity ratio H ε , and substituting the fitting intensities into the H ε =0.797+0.159, and calculating the strain generated on the surface of the material to be measured.
  10. 10. The use of a SERS-based flexible strain sensor according to claim 9, wherein the deformable material to be measured in step five comprises carbon fiber composite, thermoplastic polyurethane film, polydimethylsiloxane film, 3MW8751 film, 3MW8607 film and silicone film.

Description

Preparation method and application of flexible strain sensor based on SERS technology Technical Field The invention belongs to the field of optical strain sensing, and particularly relates to a preparation method and application of a flexible strain sensor based on a SERS technology. Background At the technical front of low-altitude aircrafts, the deformable material is a core driving force for realizing aerodynamic shape self-adaption and structure intellectualization. The material endows the self-adaptive wing, intelligent skin and other structures with key deformability, however, the material needs to repeatedly bear large-strain cyclic load in service, fatigue damage and even sudden failure are extremely easy to cause, and serious potential safety hazard is formed. Therefore, the development of a reliable large-strain detection technology realizes the accurate sensing and evaluation of the strain state of the material, becomes a key link for early warning risk and guaranteeing safety, and is a technical challenge to be broken through currently. The ideal detection technology needs to have a wide range to represent large-scale deformation and high precision to capture early damage signals of tiny strain, which is important for realizing reliable fatigue life prediction and health early warning. However, the existing mainstream optical strain sensing methods have obvious limitations in meeting the requirements of wide range and high precision at the same time. The measurement range of FBG sensors is usually limited by the fiber material itself, typically not exceeding ± 1500 με, corresponding to a strain of about ± 0.15%. If the strain exceeds this range, damage to the optical fiber may be caused. Digital Image Correlation (DIC) is highly dependent on the texture characteristics of the surface being measured. The surface texture is insufficient or the quality is not up to standard, and the strain measurement precision can be directly influenced. In addition, conventional raman spectroscopy strain sensing methods are generally based on the characteristic peak shift effect of low dimensional materials (e.g., graphene), which have limited effective strain measurement ranges (typically less than 2%), and are difficult to cope with large strain measurement requirements. Therefore, the technical limitation that the existing optical sensing technology cannot realize wide-range and high-precision measurement simultaneously is broken through, a novel large-strain detection technology adapting to the flexible structure of the low-altitude aircraft is developed, and key data support can be provided for structural health management and maintenance work of the low-altitude aircraft. Meanwhile, the large strain detection scheme has important leading and supporting significance for the development of next generation variant aircrafts. Disclosure of Invention The invention aims to solve the technical problems that the measuring range is limited, the precision and the measuring range are difficult to consider in the current mainstream optical strain sensing technology, and the large strain detection requirement of flexible structures such as low-altitude aircrafts is difficult to adapt, and provides a preparation method and application of a flexible strain sensor based on the SERS technology. The invention constructs a linear function relation between the SERS signal characteristic parameter H ε and the strain epsilon, and quantitatively detects the strain by detecting the change of the bimodal intensity ratio H ε of 1588cm -1 to 1076cm -1 in the SERS spectrum. The method expands the effective strain measurement range to 24%, significantly surpasses the existing optical technology level, provides a new solution for large strain measurement, and significantly improves the practicality. According to the invention, a bimodal intensity ratio detection strategy is adopted, and the intensity ratio H ε of 1588cm -1 and 1076cm -1 characteristic peaks is used as a core sensing parameter, so that systematic commonality errors can be effectively inhibited, the inherent defect that a single characteristic peak signal is easily influenced by systematic noise is overcome, and the measurement reliability and data accuracy of the SERS strain sensing method are remarkably improved. A preparation method of a flexible strain sensor based on an SERS technology comprises the following steps of firstly preparing a gold nanoparticle aqueous solution by adopting a sodium citrate reduction method, centrifuging, re-suspending a precipitate obtained by centrifugation in absolute ethyl alcohol to obtain an Au NPs ethanol solution, secondly adding the ethanol solution of 4-mercaptobenzoic acid and the Au NPs ethanol solution into absolute ethyl alcohol, carrying out ultrasonic treatment, stirring, centrifuging, re-suspending the precipitate obtained by centrifugation in absolute ethyl alcohol to obtain the 4-MBa-Au NPs ethanol solution, thirdly, enab