Thermal optimization of a micro valve array

Abstract

This paper describes the thermal optimization of an array of thermopneumatically actuated microvalves. The valve density achieved in the current prototype amounts to 100 valves per square inch. Thin valve membranes of less than 3 μm thickness allow for low temperature actuation. In order to reduce thermal cross talk between adjacent valves, cooling channels and insulating trenches have been introduced. It could be shown that these features reduce thermal cross talk and thus enhance array performance. The effectiveness of the cooling channels was characterized both experimentally and by means of finite element simulations. Since available theories for convective heat transfer showed some discrepancies for the examined device, the average heat transfer coefficient was determined experimentally. The comparison of computational simulation results and infra-red measurements showed good agreement. Finite element models allow reliable prediction and optimization of the performance of high-density valve arrays.