A novel actuation mechanism based on ferromagnetic SMA thin films

A novel actuation mechanism is presented, which makes use of the antagonism of intrinsic magnetic and shape recovery forces acting on a ferromagnetic shape memory alloy (SMA) microactuator in a magnetic field. This mechanism is associated with large actuation and small biasing forces in each actuation direction resulting in a large stroke. Since no external biasing elements are required, extremely compact designs are possible. As a demonstrator, an optical microscanner of 9/spl times/3/spl times/5 mm/sup 3/ size is presented showing large scanning angles up to 75 deg in off-resonance mode. The scanning performance keeps frequency-independent below a critical frequency, which is determined by heat-transfer times.