A frequency-based signature gas identification circuit for SnO2 gas sensors

This paper presents a gas identification circuit for tin oxide (SnO₂) gas sensors. The proposed circuit uses 2 gas sensors with different characteristics to achieve gas identification. A spike train is generated during operation, with the frequency of spike occurrence being gas dependent but concentration invariant. As a result, the spike firing frequency can be used to achieve gas identification. The calibration of this readout technique requires only a single exposure to the target gases to extract the sensor resistances. The low complexity processing is suitable for on-chip implementation. The functionality of this circuit has been validated with real data from our in-house fabricated sensors.