Modeling and design of novel photo-thermo-mechanical microactuators

In this paper, an innovative actuation strategy based on a photo-thermo-mechanical energy transformation is introduced. The basic idea is to exploit a new way to get the required actuation energy from light in a highly efficient way by means of micro-machined lenses. The use of micro-lenses provides a way to improve the efficiency of the actuation system, compared with the direct exploitation of the heating produced by light. Furthermore, lenses helps in obtaining localized heating of the micro-actuator, preserving the remaining part of the system. This actuation system can be useful in those application fields where high actuation power is required and an electrical power supply is not accessible or not feasible, for example in autonomous microsystems where on-board power source is strongly limited. In fact, the proposed approach does not require electrical power supply to provide the actuation energy. In this work, the modeling and design of a device based on this novel actuation strategy are presented. A simple thermal microactuator consisting in a bilayer cantilever is taken here into account in order to focus the design on a concrete device. A standard Si technology, coupled with a compatible micromachining post-process, is moreover considered. (C) 2002 Published by Elsevier Science B.V.