Dynamic characteristics of micro-optothermal expansion and optothermal microactuators

Abstract

The dynamic characteristics of micro-optothermal (OT) expansion and novel OT microactuators are theoretically analysed using a heat transient model and finite element modelling thermal simulation. Three different-shaped microactuators are machined by an excimer laser micromachining system using a single layer material; first with a single OT expansion arm; second with a bi-direction microactuator (BDMA); and third with a bi-direction microswitch (BDMS). A red laser diode (650 nm) with a maximum power output of 30 mW and an adjustable frequency of 0–20 Hz is used as an irradiation light source. The experimental results show that the maximum response frequency of the OT microactuators can be at least 15 Hz, and the deflections of the BDMA (about 13 µm at 10 mW, 2 Hz) and the BDMS (about 10 µm at 8 mW, 2 Hz) are significantly magnified compared with the OT expansion (1.32 µm at 10 mW, 2 Hz) of the single arm, proving the feasibility of the enlarged bi-direction deflection/vibration of the microactuators. The expansion and deflection amplitude of the microactuators decrease as the laser frequency increases, and the experimental data and curves greatly agree with the theoretical predictions. The new method of OT microactuators can be widely applied in the fields where simple structure, easy fabrication, large displacement and wireless controlling are required.