Thermal-Responsive Anisotropic Wetting Microstructures for Manipulation of Fluids in Microfluidics.
writer：Nianzuo Yu, Shuli Wang, Yongshun Liu, Peihong Xue, Peng Ge, Jingjie Nan, Shunsheng Ye, Wendong L
keywords：none
source：期刊
specific source：Langmuir
Issue time：2017年
We show morphology-patterned stripes modi-
?ed by thermal-responsive polymer for smartly guiding ?ow
motion of ?uid in chips. With a two-step modi?cation process,
we fabricated PNIPAAm-modi?ed Si stripes on silicon slides,
which were employed as substrates for ?uid 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)
?ow and isotropic ?ow behavior of liquid in microchannels.
The thermal-responsive ?ow motion of ?uid in the chip is
in?uenced by the applied pressure, the thickness of PNIPAAm, and dimension of the microchannels. Moreover, we measured the
feasible applied pressure scopes under di?erent 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.