Micro impact drive mechanisms using optically excited thermal expansion

The physical phenomenon of thermal expansion of solid materials is useful for microdisplacement actuators because of the scale effect. The response speed of thermally excited actuators is directly coupled with the thermal emission speed, and its value is quite low for mechanisms of the macroscale. However, this speed becomes considerably higher as the actuator becomes smaller. Various methods exist to supply thermal energy to the actuator in order to accomplish thermal expansion. Among them, thermal expansion by means of optical excitation proves to be a good candidate. Major advantages of optical excitation is that it enables noncontact thermal energy supply and remote operation in a special environment such as vacuum and at high environmental temperatures. The structure of the microactuator is simple, and it can be made from various materials using easy fabrication processes. Supported by these advantages, thermally driven micro impact drive mechanisms were developed and fabricated. The global size of the realized micromechanisms is approximately 1.7×0.6×0.4 mm³. All are made of aluminum alloy by precision-cutting techniques, which is suitable for the fabrication of three-dimensional (3-D) shapes. The maximum travel speed and minimum displacement of the developed mechanisms are about 30 mm/s and 1 μm, respectively