On-chip parylene-C microstencil for simple-to-use patterning of proteins and cells on polydimethylsiloxane.

Polydimethylsiloxane (PDMS) is widely used as a substrate in miniaturized devices, given its suitability for execution of biological and chemical assays. Here, we present a patterning approach for PDMS, which uses an on-chip Parylene-C microstencil to pattern proteins and cells. To implement the on-chip Parylene-C microstencil, we applied SiOx-like nanoparticle layers using atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) of tetraethyl orthosilicate (TEOS) mixed with oxygen. The complete removal of Parylene-C from PDMS following application of SiOx-like nanoparticle layers was demonstrated by various surface characterization analysis, including optical transparency, surface morphology, chemical composition, and peel-off force. Furthermore, the effects of the number of AP-PECVD treatments were investigated. Our approach overcomes the tendency of Parylene-C to peel off incompletely from PDMS, which has limited its use with PDMS to date. The on-chip Parylene-C microstencil approach that is based on this Parylene-C peel-off process on PDMS can pattern proteins with 2-μm resolution and cells at single-cell resolution with a vacancy ratio as small as 10%. This provides superior user-friendliness and a greater degree of geometrical freedom than previously described approaches that require meticulous care in handling of stencil. Thus, this patterning method could be applied in various research fields to pattern proteins or cells on the flexible PDMS substrate.