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Electrothermal Actuators Fabricated from Single Crystal Silicon

John M. Maloney, Don L. DeVoe, and David S. Schreiber
IMECE 2000 (ASME Annual Winter Meeting), Orlando, FL.

Thermal actuators that deflect laterally by resistive heating have been fabricated in single crystal silicon (SCS) by deep reactive ion etching. With heights of 50 microns, these high-aspect actuators produce significantly larger forces than similar polysilicon devices. Problems with stiction are also avoided through the use of silicon-on-insulator (SOI) technology. An analytical model is applied to U-beam and V-beam actuator shapes fabricated on SOI wafers. The electrothermal component of the analysis uses an axial conduction model to predict temperature distribution; the thermomechanical component employs elastic beam theory to calculate deflection due to thermal strain. Experimental results are compared to analytical predictions. Deflections of 29 microns for a 1200 micron long, 12 micron wide actuator were observed, corresponding to a predicted force of 7.6 mN.

 

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