Thermal and electrical behaviour of PVDF infrared matrix sensors

The thermal behaviour of layered sensor structures (with and without heat sinks) is analysed. It is found that the structure with heat sink, for instance a sensor consisting of a PVDF foil glued on a silicon chip, can be accurately described by a higher-order RC analog. This is due to the fact that the heat sink reduces the lateral heat spread thereby reducing the three-dimensional thermal problem to a one-dimensional one. In the proposed analog the thermal parameters of the different layers and the effect of the thermal diffusion length in the sensing PVDF layer are included. However, when there is significant lateral heat flow, for instance when a piece of PVDF is freely suspended and the onfalling infrared radiation is modulated at low frequencies, a full 3D analysis is needed. Based on the results from that analysis the low-frequency results from the RC analog can be corrected. Also an analysis of the (pyro)electrical behaviour of the sensors is performed. The results of these combined analyses, describing the sensor response to infrared stimulation, are compared to measured sensor responses from two types of sensors. A good agreement was found.