Feedback-enabled discrimination enhancement for temperature-programmed chemiresistive microsensors

Temperature cycling can be used to enrich signal streams in gas phase sensing, however drift that can occur when repeatedly applying such cycles can degrade target recognition over time. A method for correcting heater drift through operational feedback has been implemented specifically to examine the level of performance improvement introduced for a single microhotplate-based chemiresistive sensing element exposed to multiple gas compositions. The element included ≈30 nm chemical vapor-deposited thin film of SnO2 formed over the interdigitated Pt electrodes, which acted as the transduction interface. Gas exposure experiments were performed using concentrations of methanol and ethane less than 100 μmol/mol in backgrounds of dry air and 15% relative humidity air. Removing temperature drift is shown to significantly decrease sensing signal drift, thereby facilitating enhanced target identification. Since this approach represents an operational adjustment, similar performance benefits are expected for sensing devices based upon other chemiresistive materials.