UV-driven microvalve based on a micro–nano TiO 2 /SiO 2 composite surface for microscale flow control

This paper presents a novel ultraviolet (UV)-driven microvalve based on the concept of inserting a trimethyl chlorosilane (CTMS) modified TiO 2 /SiO 2 composite patch of switchable wettability in a microfluidic system. A unique micro–nano hierarchical structure was designed and used to enhance the overall wetting contrast with the aim of improving the wetting-based valve performances. Field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and chemical composition of the surface. UV-driven wettability conversion on the patched microchannel was investigated using water column relative height tests, and the results confirmed the significant improvement of the hierarchical structure with the surface hydrophobic/hydrophilic conversion, which produced enhancements of 276% and 95% of the water-repellent and water-sucking pressures, respectively, compared with those of the single-scale Ti...

Ting Guo, Tao Meng, Wei Li, Jilong Qin, Zhiping Tong, Qing Zhang and Xueru Li

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