Characterization of a logarithmic spike timing encoding scheme for a 4×4 tin oxide gas sensor array

In this paper, the performance of a logarithmic spike timing encoding scheme for gas sensor is analyzed. Utilizing the non-linear (power law) relationship between tin oxide (SnO₂) gas sensor sensitivity and gas concentration, we designed and fabricated a time domain readout circuit for a 4×4 SnO₂ gas sensor array. A unique pattern is generated by the readout scheme for each gas, irrespective of the gas concentration. This pattern is used as the signature of the gas. Gas identification is achieved by matching the generated signature with pre-stored reference signatures. The design was implemented in standard CMOS technology. Reported experimental results demonstrate the fabricated gas sensor exhibits the detection accuracy comparable to computationally expensive classifiers.