Development of embedded system for carbon nano tube (CNT) based Ammonia (NH3) gas sensor

This paper presents a simple, precise, and versatile embedded system for gas concentration measurement of a sensor chip using in-house developed carbon nanotube (CNT) based gas sensor and characterization of packaged device in an ambient. The characterization equation having relation between change in resistance and ppm is obtained by gas sensing measurements and implemented in the embedded system based on MSP430 microcontroller. There is an implementation of a bridge circuit method with instrumentation amplifier to determine the resistance of CNT gas sensor. The proposed signal conditioning circuit is implemented for the prefabricated SWCNT based NH₃ gas sensor and the analysis of NH₃ response at different concentrations and with experimental results is reported in this work.