An out-of-plane electro-thermal polymer actuator

An out-of-plane micro thermal polymer actuator, which is designed with the bimorph effect, is presented. This actuator has a bi-layer structure, which consists of SU-8 photoresist encapsulating meandering nickel heater and passive Ni top layer. The actuator has a symmetric configuration. This paper demonstrates its design, simulation, fabrication and device tests. This actuator bends vertically when energized. With a size of 0.38 mm times 0.23 mm, it demonstrated a maximal vertical displacement of 24 mum at 1.4 V driving voltage and at 20 mW input power, at an average temperature of 95degC. The stiffness of the actuator is of 36 N/m along perpendicular direction, and it can generate a vertical force of 0.98 mN in this direction.