Selectivity enhancement of SiC-FET gas sensors by combining temperature and gate bias cycled operation using multivariate statistics, 2014, Sensors and actuators. B, Chemical, (193) In this paper temperature modulation and gate bias modulation of a gas sensitive field effect transistor based on silicon carbide (SiC-FET) are combined in order to increase the selectivity. Data evaluation based on extracted features describing the shape of the sensor response was performed using multivariate statistics, here by Linear Discriminant Analysis (LDA). It was found that both temperature cycling and gate bias cycling are suitable for quantification of different concentrations of carbon monoxide. However, combination of both approaches enhances the stability of the quantification, respectively the discrimination of the groups in the LDA scatterplot. Feature selection based on the stepwise LDA algorithm as well as selection based on the loadings plot has shown that features both from the temperature cycle and from the bias cycle are equally important for the identification of carbon monoxide, nitrogen dioxide and ammonia. In addition, the presented method allows discrimination of these gases independent of the gas concentration. Hence, the selectivity of the FET is enhanced considerably.

Hence, the suggested strategy is suitable for on demand ventilation control in indoor air quality application systems.

Abstract. Applications like air quality, fire detection and detection of explosives require selective and quantitative measurements in an ever-changing background of interfering gases. One main issue hindering the successful implementation of gas sensors in real-world applications is the lack of appropriate calibration procedures for advanced gas sensor systems. This article presents a calibration scheme for gas sensors based on statistically distributed gas profiles with unique randomized gas mixtures. This enables a more realistic gas sensor calibration including masking effects and other gas interactions which are not considered in classical sequential calibration. The calibration scheme is tested with two different metal oxide semiconductor sensors in temperature-cycled operation using indoor air quality as an example use case. The results are compared to a classical calibration strategy with sequentially increasing gas concentrations. While a model trained with data from the sequential calibration performs poorly on the more realistic mixtures, our randomized calibration achieves significantly better results for the prediction of both sequential and randomized measurements for, for example, acetone, benzene and hydrogen. Its statistical nature makes it robust against overfitting and well suited for machine learning algorithms. Our novel method is a promising approach for the successful transfer of gas sensor systems from the laboratory into the field. Due to the generic approach using concentration distributions the resulting performance tests are versatile for various applications.

Abstract. We present DAV3E, a MATLAB toolbox for feature extraction from, and evaluation of, cyclic sensor data. These kind of data arise from many real-world applications like gas sensors in temperature cycled operation or condition monitoring of hydraulic machines. DAV3E enables interactive shape-describing feature extraction from such datasets, which is lacking in current machine learning tools, with subsequent methods to build validated statistical models for the prediction of unknown data. It also provides more sophisticated methods like model hierarchies, exhaustive parameter search, and automatic data fusion, which can all be accessed in the same graphical user interface for a streamlined and efficient workflow, or via command line for more advanced users. New features and visualization methods can be added with minimal MATLAB knowledge through the plug-in system. We describe ideas and concepts implemented in the software, as well as the currently existing modules, and demonstrate its capabilities for one synthetic and two real datasets. An executable version of DAV3E can be found at http://www.lmt.uni-saarland.de/dave (last access: 14 September 2018). The source code is available on request.