An actuator includes a bistable mechanism having a tension beam and a compression beam defined by a relief slit in a flexible substrate; and a first shape memory element that upon heating actuates the actuator from a first position to a second position. A heat source can be thermally coupled to actuate the first shape memory element, or the first shape memory element can be heated by passing current through the element. The actuators can be formed in an array. Such arrays can be useful for tactile displays, massagers, and the like. Also included are methods of operation and manufacturing.