Reusable,Long-life 3D Array Sers Substrate Research And Spectral Analysis

Under the concept of Miniaturized Total Analysis System(μ-TAS)or Lab On a Chip,the biochip is limited to the miniaturization of the spectrum detection and the micro and trace samples in the micro channel,making the micro detection spectrum signal weak.Under the concepts of"volume miniaturization and functional integration",to explore a new and effective micro-detection technology is currently widely concerned by countries but is still in the exploring stage,becoming a"bottleneck"problem that hinders the development of biochips.To solve this problem,this thesis studies the Raman spectral trace detection.However,because the Raman scattering cross-section is extremely small,Raman signals are usually weak in trace detection,so it is critical for the development of surface enhanced Raman scattering(SERS)substrates with superior performance.For conventional SERS substrates or SERS sensors,they are expensive to manufacture,non-reusable and have a short life.Meanwhile,the Raman spectroscopy needs to be collected by a huge confocal Raman instrument.In order to meet the requirements of functional integration,structure miniaturization and portability and as well as overcoming the deficiencies of conventional SERS substrates,this thesis proposes two new methods to prepare 3D SERS substrates suitable for portable or micro-Raman instruments and perform spectral analysis.For the research and design of Raman spectroscopy miniaturization detection,we provide a new SERS substrate technology scheme that can enhance Raman signal.At present,harmful microorganisms in the spacecraft cabin seriously threaten the health of astronauts and corrode the materials in the cabin.This technology provides a technical reference for the spectrum detection of biohazard warning systems for space applications.The main research work and achievements of this thesis are as follows:(1)Silicon nanowire arrays were prepared using a metal-assisted chemical etching method,and a long-life silver nanoparticle was prepared by green chemical synthesis.The silver nanoparticles coated Si nanowire array using a simple nanotechnology to form a three-dimensional SERS substrate.Finally,the used SERS substrate was pickled for reuse.The main exploration is to load an appropriate amount of silver nanoparticle colloid on a super-hydrophilic silicon nanowire array substrate to form 3D SERS substrate with high"hot spot".The reusability,long life,SERS performance,and mechanism of SERS substrates were explored.Finite element simulation of the electric field distribution of silver nanoparticles was performed,and XRD,TEM,SEM,UV-Vis,EDS and various SERS molecular probes were used to characterize and analyze the performance of SERS substrates.The enhancement factor of 3D Ag nanoparticles coated Si nanowires array SERS substrate was about 1×10~5 and its relative standard deviation is 9.85%.The substrate can be used for more than ten times and the lifetime was longer than seventy days.(2)On the basis of the technology proposed in(1),further study on the preparation of Ag-NPs and the cleaning method of the substrate is proposed.A 3D SERS substrate was prepared using metal-assisted chemical etching and photonic reduction.The substrate consists of silver nanoparticles preparing in situ on silicon nanowires.This thesis mainly studies the morphology and growth mechanism of SERS substrate,explores the photodegradation of SERS substrate residues during repeated use,and tests the performance of SERS substrates with rhodamine 6G and dopamine hydrochloride.The data show that this new substrate provides an enhancement factor of nearly 1×10~8.The results show that the 3D SERS substrate is highly sensitive and sufficiently robust to allow repeated reuse.