Temperature Modulation with Specified Detection Point on Metal Oxide Semiconductor Gas Sensors for E-Nose Application

Temperature modulation technique, some called dynamic measurement mode, on Metal-Oxide Semiconductor (MOS/MOX) gas sensor has been widely observed and employed in many fields. We present its development, a Specified Detection Point (SDP) on modulated sensing element of MOS sensor is applied which associated to its temperature modulation, temperature modulation-SDP so-named. We configured the rectangular modulation signal for MOS gas sensors (TGSs and FISs) using PSOC CY8C28445-24PVXI (Programmable System on Chip) which also functioned as acquisition unit and interface to a computer. Initial responses and selectivity evaluations were performed using statistical tool and Principal Component Analysis (PCA) to differ sample gases (Toluene, Ethanol and Ammonia) on dynamic chamber measurement under various frequencies (0.25 Hz, 1 Hz, 4 Hz) and duty-cycles (25 %, 50 %, 75 %). We found that at lower frequency the response waveform of the sensors becomes more sloping and distinct, and selected modulations successfully increased the selectivity either on singular or array sensors rather than static temperature measurement.