Reconfigurable hydrophobic/hydrophilic surfaces in microelectromechanical systems (MEMS)

Abstract

Fully reconfigurable hydrophobic–hydrophilic surfaces were achieved by reversibly adsorbing and removing avidin from a hydrophobic self-assembled monolayer. The adsorption process was characterized using surface plasmon resonance, while contact angle measurements were used to monitor the resulting wetting behavior. This reconfigurable approach was demonstrated in micromachined silicon channels coated with a 25 nm layer of SiO2. Hydrophilic surfaces led to spontaneous flow while pressurized flow was required along hydrophobic surfaces. By controlling the surface modification process, spatially selective flow was achieved.