Phase-Change Materials in Optically Triggered Microactuators

Phase-change materials have been extensively used for optical data storage in commercial rewritable compact disks and digital video disks. These materials are also widely considered for next-generation phase-change random access memories to replace current Flash memories. We suggest a different application of phase-change materials in optically triggered microactuators. The suggested device consists of a thin film of a phase-change material deposited on a microfabricated cantilever. A laser-induced phase transformation in the film initiates a cantilever deflection since the transformation is accompanied by a large density change. We analyze quantitative criteria for material selection and optimization of device dimensions for the largest possible actuation angles and deflections. The resulting analytical model is both verified numerically and applied experimentally. Furthermore, we show that these cantilevers offer a convenient way to measure film stresses and film strains associated with laser-induced phase transformations.