No abstract

The three-dimensional wetting phenomena in a T-shaped microchannel made of a SU-8 photoresist accompanying with a pillar sub-pattern are analyzed by using an environmental scanning electron microscopy (ESEM). By lowering the sample temperature in the ESEM chamber at constant the H 2 O pressure, the water condensation occurs under H 2 O dew point and the liquid propagation in the microchannel can be observed. The experimental results show that the pinning angle of water flow at T-junction is 58 degrees in the T-shaped microchannel. In the case of the T-shaped microchannel with the sub-pattern, it is found that the pinning angle becomes low by adhering the water around the sub-pattern. These results can realize to the smooth flow at the channel junction without any water trapping for the three-dimensional microfluidic devices.