A 10 ms-readout Interface For Experimental Resistive Sensor Characterization
Alessandro Depari, Alessandra Flammini, D. Marioli, Emiliano Sisinni, Elisabetta Comini, Andrea Ponzoni, Matteo Pardo, Giorgio Sberveglieri · AIP conference proceedings · 2009
Metal oxide gas sensors exhibit resistance values varying over a wide range, from tens of kilohms to tens of gigohms, depending on the chosen oxide and on the excitation parameters (voltage, temperature, gas exposure). Resistance‐to‐time converters (RTC) are widely used in electronic interfaces to such sensors thanks to the low‐cost, low‐noise and high‐range characteristics. RTC main limit is in the variable and long measuring time, ranging from microseconds (tens of kilohms) to several seconds (tens of gigohms), impeding a fine analysis of fast transients. This work proposes a new approach based on combination of the RTC method with a new technique based on the least means square algorithm. The implemented prototype allows the sensor resistance estimation with 100 sample/s (Tmeas = 10 ms) over the range 10 kΩ÷10 GΩ with relative estimation error below 10% (below 1% in the range 47 kΩ÷2 GΩ). Fast thermal transients of a SnO2 nanowire sensor have been finely analyzed thanks to the new interface system.