Material Selection for Photothermal Driving of Micromachine Elements

Abstract

The photothermal effect, which changes light into heat, can be used to generate driving force from thermal stress. Micro-cantilevers, the simplest micromachine element, are driven using a modulated laser diode and the frequency response characteristics and deflection are measured. By applying photothermal driving to a micro-disk on a central pivot, a standing wave is generated. The optimum disk material parameters to maximize the driving force are investigated. The amplitude of the standing wave is found to increase as the thickness of the micro-disk is decreased and the amplitude increases with the ratio of the coefficient of thermal expansion and thermal conductivity. The amplitude also increases with laser output. It is found that stainless steel is the most suitable disk material.

Keywords

• micromachine
• photothermal effect
• standing wave