Fully compliant double tensural tristable micromechanisms (DTTM)

Numerous possible micromechanism applications (e.g. three-way switches, mechanical memory and multiplex optical switches) could benefit from a device with three stable equilibrium positions. In this paper, we present a new class of tristable mechanisms called double tensural tristable mechanisms (DTTMs) which are fully compliant (i.e. they are monolithic and get their motion from the deflection of elastic components) and can be fabricated at the micro scale. A pseudo-rigid-body model (PRBM) for the DTTM has been developed. DTTMs were fabricated in polysilicon using the SUMMiT V process and tested for tristability and force-deflection characteristics. The results successfully demonstrate tristable behavior and show that the PRBM can be used to identify tristable configurations and predict their performance.