"Lock-and-Key" Geometry Effect of Patterned Surfaces: Wettability and Switching of Adhesive Force

A strategy to create a superhydrophobic surface by employing microlens and microbowl arrays without a thin fluorinated carbon film coating was described. The wettability and switching of adhesive force was checked by fabricating PDMS microbowl arrays with imprinted inverse microlens structure following the lock-and-key domains. No distortion is observed on the array surface, suggesting that this approach eliminates significant drawbacks encountered with conventional bottom-up techniques. The variation of the contact angles measured at different sites imply that the PDMS microlens-arrayed surface has hydrophobity with a high adhesive force. The results also show that the 10×6 PDMS microbowl-arrayed surface exhibits perfect superhydrophobicity with a contact angle of approximately 164.6°, owing to the hollow structures in the surface.