Study On Fabrication Of SiO₂Microspheres In Microfluidics

Nowadays energy is a major social theme. Compared with the traditionalsynthesis methods, microfluidics is simple, low energy. In this paper, weinvestigate the preparation of SiO₂microspheres and SiO₂hollow microspheresin microfluidic devices. Scanning electron microscopy （SEM）, opticalmicroscope are used for characterizing its performance.Firstly, Y and dubble Y-junction microfluidic chips are prepared at60℃inpoly（dimethylsiloxane）（PDMS）. In order to satisfy the the preparation ofmicrospheres, surface modification is fabricated on PDMS using UV irradiation.Then, as aqueous phase, TEOS solution is prepared of dimethylactamide,tetraethyl orthosilicate and ammonia, and their volume ratio is8:4:1. Dimethylsilicone oil is selected as the oil phase. The monodispersed SiO₂microspheresranged from40μm to220μm were prepared in Y-junction microfluidic device in60℃. These microspheres are high sphericity, smooth surface and their density is918.9mg/cm3. Multaneously, fluid flow is simulated by using fluent software inY-junction microchannel.At last, in double Y-junction microfluidic device，SiO₂hollow microspheresare synthesized in40℃. Aqueous phase is composed of DMAC, ethanol, TEOSand ammoniawith volume ratio is6:2:4:1. Dimethyl silicone oil is choosed as theoil phase. Particle size of these hollow microspheres is1100²400μm andthickness is30¹30μm. These spheres are high sphericity and concentricity,smooth surface and the surface area is697.77cm²/g.