Wafer-level mechanical and electrical integration of SMA wires to silicon MEMS using electroplating

This paper reports on the wafer-level fixation and electrical connection of pre-strained SMA wires on silicon MEMS using electroplating, providing high bond strength and electrical connections in one processing step. The integration method is based on standard micromachining techniques, and it potentially allows mass production of microactuators having high work density. SEM observation showed an intimate interconnection between the SMA wire and the silicon substrate, and destructive testing performed with a shear tester showed a bond strength exceeding 1 N. The first Joule-heated SMA wire actuators on silicon were fabricated and their performance evaluated. Measurements on a 4.5 x 1.8 mm² footprint device show a 460 μm stroke at low power consumption (70 mW).