title: UV-driven microvalve based on a micro-nano TiO₂/SiO₂ composite surface for microscale flow control.
abstract: This paper presents a novel ultraviolet (UV)-driven microvalve based on the concept of inserting a trimethyl chlorosilane (CTMS) modified TiO₂/SiO₂ 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 TiO₂ nanopatterned structure. Accordingly, a good reversible and repeated on-off performance was identified by the valve tests, highlighting the potential application of the novel microvalve in the efficient control of microscale flow.
authors.affiliation: School of Life Sciences and Engineering, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Guo
authors.forename: Tao
authors.initials: T
authors.lastname: Meng
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Jilong
authors.initials: J
authors.lastname: Qin
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Tong
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xueru
authors.initials: X
authors.lastname: Li