Super-hydrophobic microfluidic channels fabricated via xurography-based polydimethylsiloxane (PDMS) micromolding

Abstract

The facile and rapid fabrication of super-hydrophobic microfluidic channels has numerous bio- and physico-chemical applications. In this study, we present a simple, fast, and inexpensive method to fabricate a super-hydrophobic polydimethylsiloxane (PDMS) microchannel. The method involves using xurography-based PDMS micromolding with a silicon carbide paper. The microchannel exhibited a micro-textured surface with a water contact angle of 152° and minimum feature size of 300 μm. To demonstrate the utility of our method, we generated water-in-oil droplets over a wide range of input flow rates. Compared to conventional PDMS microchannels of the same size, our super-hydrophobic channels produced the droplets at four times faster rate with higher size uniformity. This method was further used for the gelation of alginate droplets, which can be broadly utilized in drug delivery and biosensing applications. Furthermore, spatially selective formation of super-hydrophobic surfaces was used to passively control the two merging flows via capillary action.