Study On Controllable Synthesis Of Gold Nanobipyramids In Microfluidic Channels

In this paper,a microfluidic platform is designed to prepare gold nanobipyramids(Au NBPs).Under the precise control of the flow rate of reactants,Au NBPs with various shapes and aspect ratios can be obtained through seed-mediated method in the microfluidic chip.By changing the flow rate of silver nitrate,ascorbic acid and gold seeds in microchannels,the effect of reactant concentration on the synthesis of Au NBPs was systematically studied,and the mixing mechanism inside the microfluidic chip was analyzed and simulated by COMSOL.The main research contents of this topic are as follows: 1)A microfluidic chip with S-shaped microchannels is designed for passive mixing of various reactants in Au NBPs synthesis.2)Preparation of a microfluidic chip.Firstly,SU-8 2075 negative photoresist is used for spin coating on single crystal silicon wafers,then polydimethylsiloxane(PDMS)is used to complete the mold inversion,finally oxygen plasma bonding is used to obtain the required microfluidic chip.This molding method is relatively simple and the lithographic template can be used repeatedly.3)Using the fabricated microfluidic chip to investigate controllable synthesis of Au NBPs in microchannels.The results show that adjusting the ascorbic acid flow rate can effectively reduce the production of by-products such as spherical nanoparticles and square nanoparticles;Gold seed flow rate plays an important role in the length and aspect ratio of the synthesized Au NBPs;Optimized flow rate of silver nitrate can be obtained to improve the yield of Au NBPs.