Interface Circuit for Three-Electrode Metal-Oxide (MOX) Gas Sensor

This paper proposes an interface circuit for a three-electrode metal-oxide (MOX) gas sensor. The proposed interface circuit adopts a pulse width modulation (PWM) signal to control the heater and to measure the sensor resistance almost simultaneously. Furthermore, to measure the resistance of the sensing material, our circuit adopts a scheme that works regardless of the asymmetry of the sensor geometry and an opamp-based integrator to provide a wide input dynamic range. Our circuit also introduces an additional noise and offset reduction technique. Therefore, it is highly suitable for accurate data acquisition.