CONTROLLED FOLDING OF MICROMETER-SIZE STRUCTURES

Several types of microactuators have been fabricated, from simple padd les to self-assembling and -disassembling cubes. Conducting bilayers m ade of a layer of polymer and a layer of gold were used as hinges to c onnect rigid plates to each other and to a silicon substrate. The bend ing of the hinges was electrically controlled and reversible, allowing precise three-dimensional positioning of the plates. The structures w ere released from the substrate with a technique based on differential adhesion. This method, which avoids the use of a sacrificial layer an d allows the actuators to pull themselves off the surface, may have ge neral applications in micromachining. Possibilities include the manufa cture of surfaces whose light reflection or chemical properties can be switched.