Contactless actuation of giant magnetostriction thin-film alloy bimorphs for two-dimensional scanning application

Giant magnetostriction appears to be very promising for contactless actuation. However, very few attempts have been made to actually exploit that advantage in sensors and actuators. The 2D scanning actuator that is being developed is a cantilever based structure that benefits from another unique features of the magnetostrictive materials: the ability to produce both bending and torsion at the same time with two AC magnetic fields. The ability to drive bending and torsion modes has been proven but never on a micro- structure. The actuators are processed and released from SOI wafers and all the micromachining process is done before the deposition of the active layer. A two-cantilever-based actuator has been designed i) to decrease the resonant frequency of the first rank of the torsion mode ii) to achieve a good decoupling between the bending and the torsion motion iii) to enhance the displacement. The actuation is performed using one DC 60mT and two AC 3-12 mT magnetic fields. Depending on the size of the actuator, resonant frequencies from 1 kHz to 30 kHz have been investigated for both the bending and the torsion motion.