PDMS double casting method enabled by plasma treatment and alcohol passivation

•A simple and efficient PDMS double casting method using plasma treatment followed by alcohol passivation is described.•Two-step surface treatment ensures double casting performance at a single micron scale resolution.•The method is capable of micron level reproduction of objects featuring high aspect ratios and complex 3D microstructures. We propose a simple and efficient polydimethylsiloxane (PDMS) double casting method using plasma treatment followed by methanol or ethanol treatment. The plasma treatment oxidizes the functional groups on the surface of the PDMS mold, showing an increase in the concentration of hydroxyl functional groups (OH); subsequent exposure to the alcohols prevents adherence of the second PDMS casting. This process effectively passivates the surface of the PDMS master mold to suppress further chemical bonding. This two-step surface treatment ensures excellent double casting performance at a single micron scale resolution to yield micron level reproduction of objects featuring high aspect ratios, two-dimensional surface micropatterns, and complex three-dimensional microstructures.