Bio-inspired 3D self-patterning of functional coatings for PDMS microfluidics

We report a novel, simple and effective 3D self-patterning method for functional coatings on poly(dimethylsiloxane) (PDMS) microfluidics before bonding, inspired by the wettability-based fast evaporation of water film on superhydrophilic plant leaves. Induced by evaporation, liquid-phase functional coatings are selectively deposited on rough PDMS surfaces, enabling the conventional PDMS-glass bonding. Several control factors are investigated to improve the coating quality including roughness, coverage, uniformity and clogging issues. Teflon-like CYTOP coatings have been demonstrated on PDMS channels with good coverage, uniformity and bonding strength, and significantly reduced the swelling, deformation and collapse of PDMS channels in toluene.