Fabrication And Sensing Application Of Composite Thin Films Based On Gold And Silver Nanostructures

Plasma metal(gold,silver)nanomaterials have attracted attention in the fields of surface-enhanced Raman scattering(SERS)sensing and wearable stress sensing due to their unique physical and chemical characteristics.Among them,SERS is a detection technology that uses plasma metal nanomaterials to enhance Raman scattering signals,which has the characteristics of high sensitivity and high efficiency,etc.Wearable sensing elements based on noble metal nanomaterials have high sensitivity for sensing micro-stress and micro-strain of the human body.Based on the above background,two kinds of rigid composite films prepared in this thesis are that rambutan-like Au@Ag alloy nanoparticle film supported by silicon wafers and rambutan-like Au@Ag alloy nanoparticle film support by island nano-silver film.A flexible composite film is a multi-layer paper-based flexible conductive composite film(the upper and lower layers are paper-based silver nanowire composite films,and the middle layer is paper-based silver/carbon ball composite film),which is applied to SERS sensing and wearable stress sensing detection respectively.1.In this thesis,the seed-mediated growth method was selected as the preparation method,inorganic alkaline hydrogen peroxide was used as a“clean”reducing agent to reduce and prepare a kind of rambutan-like Au@Ag alloy nanoparticles.The effects of reaction temperature,reaction time and the amount of silver seeds on the surface morphology were discussed by designing the experimental scheme and optimizing the experimental parameters with control variates method.The finite difference time domain method is used to calculate the distribution of electromagnetic field intensity on the surface of a single nanoparticle.The results showed that the rambutan-like Au@Ag alloy nanomaterial composite film exhibited low limit of detection(LOD=1×10^–10M),high enhancement factor(EF=1.2×10⁶),high repeatability(RSD=6.7%),and strong anti-interference ability in SERS detection,indicating that the rambutan-like Au@Ag alloy nanoparticle film supported on a silicon wafer has excellent SERS enhancement performance.2.Silver nanowires and silver/carbon ball composites were prepared by the solvothermal method.Paper-based silver nanowire/carbon ball silver composite conductive composite film was prepared by dipping and drying method.The multi-layer paper-based flexible composite film was prepared by a layer-by-layer superposition method and applied to a wearable flexible pressure sensor.Through analysis and calculation,the sensor shows high sensitivity(0.65 k Pa^-1),the fast response time(0.14/0.16 seconds),and it can still show relative stability after up to 1000 times of repeated detection.Through bending,twisting and the application of combining sensor with the mouse,the composite film also shows excellent sensing performance.