Trimorph actuation based on shape memory alloys

Trimorph and bimorph martensitic actuators have been designed and produced by sputter-depositing NiTi shape memory alloys films on one or both sides of heated Si cantilever-type substrates. The phase transformation temperatures and specific sequence of the shape memory alloy films was induced by appropriately selecting the deposition temperature. Thus, the deflection of the trimorph cantilever recorded as a function of temperature reflects the phase transformation associated features of the corresponding films. Various actuation signals obtained by selecting the composition and the deposition temperatures of the films are discussed and models for the behavior of such trimorphs have been proposed.