Fabrication and performance of a flextensional microactuator

A flextensional microactuator has been designed and fabricated for the amplification of the small strain of the piezoelectric materials to achieve large displacements. Bulk PZT material available in the form of 500 νm thick polished substrate has been integrated with a precision micromachined silicon beam structure to achieve the clamped-clamped flextensional microactuator. A high strength, high precision (alignment) and low temperature (∼200 °C) In/Sn solder bonding process has been developed and used for the fabrication of the flextensional microactuators. Actuators with physical dimensions of the flextensional structure ranging from 350 to 600 νm in length, 50 to 100 νm in width and 5 to 6 νm in thickness were fabricated. The measured static deflection characteristics of the silicon micromachined beam show a flextensional gain factor of 20 with a large amplitude stroke of ∼8 νm when actuated using -100 V to 100 V. The bandwidth of the actuator was experimentally measured to be 265 kHz. The fabricated devices show good repeatability with a hysteresis pattern arising from the PZT characteristics. The bonding technique described here can be used for the precision integration of heterogeneous materials for MEMS device fabrication and their packaging.