Assessing the diagnostic information in the response patterns of a temperature-modulated tin oxide gas sensor

Abstract

The transient response patterns of a tin oxide chemoresistive gas sensor, temperature-modulated by the application of staircase voltage waveforms to its microheater, to five different volatile organic compounds were compared with respect to their target gas discriminating features. These patterns were divided into a number of segments, each corresponding to a temperature transition at the surface of the tin oxide pallet. The effectiveness of the gas discriminating information content of each segment was quantitatively assessed utilizing Fisher's discriminant ratio calculations in a 3D feature space. It was established that the amount of the useful information in a response segment depended on the corresponding temperature transition; larger pallet temperature transitions rendered more diagnostic information. Similar assessments were carried out for the different combinations of these segments. The results facilitated, for the first time, a comparative analysis of the levels of the correlated (redundant) and uncorrelated information in the different response segments. It was shown that the response segments occurring at or near the nominal operating temperature of the sensor contained most of the effective information, while those at low temperatures contained mostly the redundant or indiscriminative information. The results help minimize the temperature modulation duration required for gas recognition.

Comparison of different feature reduction methods in the improvement of gas diagnosis of a temperature modulated resistive gas sensor

“…In order to compare measured output and the output of a trained network, fitness criterion is computed for each segment [9]. Based on the results of fitness computations, the smallest and best model order for each five defined systems is selected.…”

“…Attempts have been made to create selectivity in a single sensor [8]. One of the techniques that's commonly used for creating the capability of selectivity in single sensors is the modulation of sensor temperature [9][10]. Various studies have shown that gas sensors with modulated working temperature yield more discriminant features.…”

Design of a Breath Analysis System for Diabetes Screening and Blood Glucose Level Prediction

“…MOS sensors under TM are believed to provide richer information and have better selectivity than those operated in the ordinary way [36], [37]. In the proposed system, we applied a staircase modulation voltage [36], [37] to three MOS sensors. Experiments with real breath samples show that sensor arrays with these TM sensors have higher accuracy.…”

Diffusive Representation: A Powerful Method to Analyze Temporal Signals from Metal-Oxide Gas Sensors Used in Pulsed Mode

“…Metal-oxide thin film sensors have been widely used for gas sensing applications thanks to their sensitivity toward a large variety of gases [1]. Modulating the temperature of a micro-hotplate gas sensor allows increasing the sensitivity and/or selectivity toward various gases [2][3][4][5][6][7][8][9][10][11][12][13][14]. In some cases, the transient behavior of the sensing resistance, located just after a temperature change, is used to discriminate gases by comparing signal shapes [10,11].…”