Multiphysics modelling of a resistive polymeric sensor for VOC

A smart ASIC chip was previously designed, fabricated and tested for monitoring of volatile organic compounds (VOC), with both signal processing electronics and resistive sensors integrated within a single CMOS device. The ASIC has been successfully tested using different types of sensitive materials, including carbon black-polymer composites and bi-functional linker molecules with gold nanoparticles. Different geometries and configurations have been designed for each generation of the device. In the interest of getting a better understanding of the sensor behaviour, which is affected by a number of physical phenomena, namely temperature, humidity, chemical properties of the sensing materials, and geometry of the electrodes, among others, a novel multiphysics model of the device has been developed and simulation results are reported in this paper. The model explores coupled electrical and thermal behaviour of the resistive microsensors obtained after depositing sensing materials upon the electrodes built in the second metal layer of a CMOS process. The results show the distribution of electric potential and the distribution of temperature obtained for a set of resistive sensors made out of carbon black-polymer composites.