Performance Evaluation of Square Microhotplate with Alternative Membrane Materials

Alternative materials such as Alumina (Al2O3) and Polyimide (PI) have lower thermal conductivity than Si/Si3N4, hence with these materials, low power consumption can be attained even with a thicker membrane. This paper first attempts to determine the convection coefficient by constructing a CFD analysis of microhotplate and then employs the obtained results to investigate the performance of microhotplates with alternative materials, like PI or Al2O3 either as a single material membrane or composite membrane. For attaining same operating temperature (694K) with single material membrane, PI membrane resulted in a lower power consumption compared to Al2O3 membrane. Further, it is found that composite membrane of PI and Al2O3 can bring advantages of both the materials and among the various simulated composite membranes, PI/Al2O3 ( 1/1µm) membrane offers the best response time and thermal uniformity with a power consumption of 19.41mW.