Fabrication of polymeric dry microneedle electrodes coated with nanoporous parylene

In this study, we demonstrate the fabrication of polymeric dry microneedle electrodes covered with nanoporous parylene film that can be applicable as flexible electrodes for biopotential measurements. For the application, polymer microneedles must be stiff enough to penetrate through the high-impedance stratum corneum without reaching the dermis. We successfully manufactured a 20 × 20 polymer microneedle electrode, with a needle length of 200 μm and a tip curvature radius of 15 μm. We experimentally verified that sufficiently low electric impedance was achieved at the pressure of 8 N without the skin preparation and electrolytic gel.