In the paper a new implementation of a compact smart resistive sensor based on a microcontroller with internal ADCs is proposed and analysed. The solution is based only on a (already existing in the system) microcontroller and a simple sensor interface circuit working as a voltage divider consisting of a reference resistor and a resistive sensor connected in parallel with an interference suppression capacitor. The measurement method is based on stimulation of the sensor interface circuit by a single square voltage pulse and on sampling the resulting voltage on the resistive sensor. The proposed solution is illustrated by a complete application of the compact smart resistive sensor used for temperature measurements, based on an 8-bit ATxmega32A4 microcontroller with a 12-bit ADC and a Pt100 resistive sensor. The results of experimental research confirm that the compact smart resistive sensor has 1°C resolution of temperature measurement for the whole range of changes of measured temperatures.

This paper analyses the effectiveness of determining gas concentrations by using a prototype WO3 resistive gas sensor together with fluctuation enhanced sensing. We have earlier demonstrated that this method can determine the composition of a gas mixture by using only a single sensor. In the present study, we apply Least-Squares Support-Vector-Machine-based (LS-SVM-based) nonlinear regression to determine the gas concentration of each constituent in a mixture. We confirmed that the accuracy of the estimated gas concentration could be significantly improved by applying temperature change and ultraviolet irradiation of the WO3 layer. Fluctuation-enhanced sensing allowed us to predict the concentration of both component gases.