Plasma Etching of Poly(dimethylsiloxane): Roughness Formation, Mechanism, Control, and Application in the Fabrication of Microfluidic Structures
Résumé
Etching of PDMS in SF6 plasmas is investigated as planar technology for the fabrication of microfluidic devices with simultaneous control of surface topography and wettability. Plasma conditions were optimized for high etch rate, which was achieved at high plasma powers and bias voltages, where PDMS microstructures exhibited good anisotropy. Depending on the etcher wall and the mask material, topography can be controlled from very rough to almost smooth. Independent control of the topography was achieved by treating the rough surfaces with wet etchants. Open microchannels of controlled surface roughness and wettability were fabricated. Subsequently, such microchannels were irreversibly sealed with a PDMS cover plate, for fabrication of enclosed microchannels. Plasma etching of PDMS is proven to be a reliable and indispensable method for the fabrication of microfluidic devices with desired wall roughness and wettability.