Superhydrophobic membranes with electrically controllable permeability and their application to smart microbatteries

Electrically tunable membranes with controllable permeability have been experimentally demonstrated by combining nanostructured and microstructured superhydrophobic surfaces with the phenomenon of electrowetting. Electrowetting allows dynamical tuning of the contact angle that the liquid forms with the membrane nanofeatures and microfeatures, thus controlling the flow of the liquid through the membrane and, therefore, tuning the permeability of the entire structure. Smart electrochemical energy storage cells that can be activated on demand have been built by combining these membranes and microfabricated Zn/MnO2 electrodes. A typical open-circuit voltage of 1.55 V and capacity of 200 mu A h/cm(2) have been demonstrated. (C) 2008 American Institute of Physics.