Reversible Actuation of Microstructures by Surface-Chemical Modification of Thin-Film Bilayers

Reversible curving of chromium/copper bilayers on exposure to oxidative and reductive environments is described. Bilayers are lithographically patterned as hinges within larger microstructures to enable reversible opening and closing, without the need for any tethers or batteries (see image). Demonstrations suggest a new strategy for coupling chemical reactions and surface modification to mechanical motion to enable autonomous, chemically responsive microstructures.