Wrinkled Microelectrode Interface Based on Oil-Pretreated Hyperelastic Substrate

This paper reports a unique fabrication method to obtain wrinkled microelectrodes with different surface morphologies based on different hyperelastic substrates for the first time. The wrinkle microstructures are enhanced by mixture silicone oil in the uncured poly (dimethyl siloxane) (PDMS) or Ecoflex polymer followed by oil-extraction in chloroform and depositing $5\ \mu \mathrm{m}$ Parylene-C film. The wrinkle amplitude of the oil-pretreated PDMS and Ecoflex with Parylene-C top layer show 5-fold and 125-fold increase than the unpretreated ones, respectively. Besides, the wrinkled 3D microelectrode surface distinctly exhibits greater electrochemical properties than the flat 2D one, with impedance decreases of 29.2% and 38.9% for the oil-pretreated PDMS and Ecoflex elastomer.