Tunable Multiplanar Nanowrinkled Surface Platform

Abstract Wrinkled surfaces have extraordinary characteristics, such as enlarged surface area and enhanced adhesion, which form the basis of several emerging applications in electrical, mechanical, and biological processes. Furthermore, wrinkles at a nanoscale display additional ultrahigh functions offering enhanced Raman scattering and superhydrophobicity; however, artificial nanowrinkled morphology is mostly limited to simple planar surfaces. Here, a microfluidics‐based approach to create tunable nanowrinkles on nonplanar surfaces is developed. In this approach, polyethylene glycol microposts using photolithography in a polydimethylsiloxane microfluidic channel are first fabricated. A syringe pump is then used with a washing solvent, ethanol, to remove the excess unpolymerized monomer from the microfluidic channel. In combination with nonuniform photopolymerization, this washing postprocess results in microposts with a fully cured inner layer and a partially cured outer layer. The partially cured layer spontaneously forms nanowrinkles upon plasma treatment. Their wavelengths are tunable by controlling the thickness of the partially cured layer during the washing process. The effect of the flow rate and duration of the washing fluid on the wavelength of nanowrinkle formed is investigated.