Thermal-Responsive Anisotropic Wetting Microstructures for Manipulation of Fluids in Microfluidics
mediaposted on 21.12.2016, 00:00 by Nianzuo Yu, Shuli Wang, Yongshun Liu, Peihong Xue, Peng Ge, Jingjie Nan, Shunsheng Ye, Wendong Liu, Junhu Zhang, Bai Yang
We show morphology-patterned stripes modified by thermal-responsive polymer for smartly guiding flow motion of fluid in chips. With a two-step modification process, we fabricated PNIPAAm-modified Si stripes on silicon slides, which were employed as substrates for fluid manipulation in microchannels. When the system temperature switches between above and below the lower critical solution temperature (LCST) of PNIPAAm, the wettability of the substrates also switches between strong anisotropy and weak anisotropy, which resulted in anisotropic (even unidirectional) flow and isotropic flow behavior of liquid in microchannels. The thermal-responsive flow motion of fluid in the chip is influenced by the applied pressure, the thickness of PNIPAAm, and dimension of the microchannels. Moreover, we measured the feasible applied pressure scopes under different structure factors. Because of the excellent reversibility and quick switching speed, the chip could be used as a thermal-responsive microvalve. Through tuning the system temperature and adding the assistant gas, we realized successive “valve” function. We believe that the practical and simple chip could be widely utilized in medical detection, immunodetection, protein analysis, and cell cultures.
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flow behaviorchipsystem temperature switchesThermal-Responsive Anisotropic Wetting Microstructuresassistant gasthermal-responsive flow motionstructure factorsthermal-responsive microvalveflow motionmicrochannelshow morphology-patterned stripesthermal-responsive polymerprotein analysismodification processsolution temperaturefluid manipulationcell culturesLCSTsubstratePNIPAAm-modified Si stripesanisotropysilicon slidespressure scopessystem temperature