The stop-flow mode of operation applied to a single chemiresistor

The stop-flow mode of operation was characterized as applied to a chemiresistor. In this mode, the main factor causing the alteration of exposure and operation conditions was the flow of gas. A chemiresistor was represented by the pool of 15 different TGS sensors. They were exposed to samples of air containing an analyte together with an interfering compound. The characteristics of the mode consisted of the following elements: (1) the analysis of sensor output signal, (2) the analysis of time variability of classification performance regarding the interfering compounds (3) the analysis of time variability of quantification error regarding the analyte. In order to characterize stop-flow mode the single-sensor perspective was adopted, i.e., classification and quantification models utilized time-point responses of single sensors. It was shown that exposure and operation conditions were well reflected in chemiresistor response, which showed a specific time-pattern. Interestingly, the distribution of classification useful information in sensor response was not related to sensor operation conditions in a fixed manner. It differed between sensors and gases. Contrarily, the distribution of quantification-useful information in sensor response was found specific for the stop-flow mode, irrespective of the sensor and the analyte. It was concluded that the operating conditions may be used as a means of shaping the content of quantification and classification useful information in sensors responses. The obtained results may serve as a guideline when considering the application of stop-flow as the mode of sensor operation.