Investigation of parallel heat-flow path in electro-thermal microsystems

Due to the miniaturization seen in the last decades, several macro models that neglect parameters have to be revised in order to evaluate the behavior of different types of microsystems. In this paper we present the analysis of one such parameter which affects the thermal functionality, namely, the convection of natural gases. In macro scale this parameter is usually neglected, because the conductivity of gases is several magnitude smaller than that of the base materials. With the advance of microfabrication really good thermal isolation can be achieved and so their values can be evenly compared and the models have to be revised. This effect can be easily modeled on microstructures whose thermal resistance can be compared to the thermal conductivity of natural gases and whose output is temperature dependent. For this purpose different types of cantilevers with embedded thermopiles and heating resistors were used. The modeling and experimental results show that in microsystems that are sensitive to temperature change, the parallel heat flow created by the surrounding gases have significant impact on the operation.