Research On The Fabrication Of Nanosphere-based Flexible SERs Substrate And Its Detection Applications

The Raman scattering signal intensity of substances adsorbed on the rough metal surface will be significantly enhanced,this effect is named as surface-enhanced Raman scattering(SERS).Due to the effect of SERS,the application of Raman spectroscopy technology in biology,chemistry,medicine,and food safety has become a reality.The development of Raman spectroscopy technology strongly relies on the high-performance SERS substrates,which have evolved from rough metal electrodes and metal sols to rigid substrates with periodic metal nanostructures.Nowadays,researchers have paid more attention to flexible SERS substrates which have high flexibility and better light transmittance.However,it still faces great challenges to fabricate a low-cost,high-repeatability,high-sensitivity and anti-bending flexible SERS substrate.In order to obtain a high-performance flexible SERS substrate through a simple and low-cost fabrication method,transparent adhesive tape was used to transfer the SiO2 nanosphere array to fabricate flexible SERS substrate.First,we let the transferred SiO2 nanosphere array sink into the adhesive layer of the tape,and then introduced oxygen plasma to etch the adhesive layer in order to expose SiO2 nanosphere array again.In this way,it could significantly improve the controllability and repeatability of the flexible SERS substrate fabrication process.After depositing Au on the surface of re-exposed nanosphere array,a low-cost flexible SERS substrate with high sensitivity and strong anti-bending ability has been obtained.The main research content and results of the thesis are as follows:1.SiO2 nanospheres with different diameters(300 nm,500 nm,700 nm)have been assembled on the surface of one quarter of 2 inch Si substrate through spin coating.By adjusting the concentration of the nanosphere dispersion,spin coating speed,spin coating time and other conditions,SiO2 nanospheres with different diameters have been self-assembled into large-area monolayer close-packed ordered arrays on the entire Si substrate,and there were only a few defective areas in the array structures.2.Flexible transparent adhesive tape was covered on the surface of above Si substrate and SiO2 nanosphere array was fully buried into the adhesive layer via the gravity of the tape.Then the tape was peeled off so that SiO2 nanosphere array could be transferred simply and efficiently from the rigid substrate to the surface of flexible tape.Furthermore,oxygen plasma was introduced to etch away the adhesive layer that wraps SiO2 nanosphere,to ensure that the nanosphere array could be re-exposed on the surface of the tape.The exposure degree of nanosphere arrays with different diameters could be controlled by optimizing the etching time,so as to realize the controllable fabrication of the rigid patterned structures on the surface of flexible transparent adhesive tape.3.60 nm thick Au was deposited on the surface of the above flexible transparent adhesive tape by electron beam evaporation to obtain a flexible SERS substrate.A large number of Au nanoclusters formed on the top of SiO2 nanosphere act as SERS hot-spots,significantly enhancing the Raman signal intensity of the probe molecules.The Raman spectrum of Rhodamine(R6G)probe molecule with concentration as low as 10-10 M could still be detected.After bending the flexible SERS substrate 500 times,the average signal intensity of the 10-7 M R6G Raman spectrum characteristic peaks detected by the above flexible SERS substrate was only 36%lower than that without bending,which shows the strong anti-bending ability of the flexible SERS substrate based on SiO2 nanospheres.