Light-Driven Actuator with Energy Conversion Efficiency in the Order of 1%

We propose a light-driven actuator capable of actuating macroscopic objects using pre-tensioned wire of NiTi shape memory alloy of a diameter of 50 pm. The use of pre-tensioned wire made it possible to avoid concentration of stress, and enabled large load to be applied. With 1.0 W Argon-ion laser beam, this actuator produced work of 3.7 mJ with 0.5 s response time. The efficiency was 0.97% when a load of 0.98 N was applied. High efficiency can be ascribed to use of shape memory alloy, suitable coupling of a material's state change with the actuating mechanism, and low heat dissipation. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/APEX.2.034502