Microbubble powered actuator

Abstract

A micromechanical, bubble-powered actuator is presented which can produce mechanical displacements as large as 140 mu m of a polysilicon actuator plate in a direction perpendicular to the substrate with as little as 8.4 mA input current. This device has been designed, fabricated, and successfully tested to have controllable displacement in a nonconducting liquid (Fluorinert FC43). The principle of actuation is the local heating of a polysilicon line resistor (immersed in liquid) in order to create a single, controllable microbubble that expands and lifts the actuator plate formed at the end of a microcantilever beam. The displacement of this actuator is stable and is controllable by adjusting the input current, which changes the bubble size and, subsequently, changes the actuator plate displacement. Linear beam theory has been used to calculate the displacement of the actuator plate and a simplified model has been used to explain the thermal behavior of the bubble.<>