Anna Strzelczyk

Determination of toxic gases based on the responses of a single electrocatalytic sensor and pattern recognition techniques

A response from an electrocatalytic gas sensor contains fingerprint information about the type of gas and its concentration. As a result, a single gas sensor can be used for the determination of different gases. However, information about the type of gas and its concentration is hidden in the unique shape of the current–voltage response and it is quite difficult to explore. One of the ways to get precise information about the measured gas is to use multivariate data analysis and pattern recognition techniques. In this paper we present the results of an investigation based on a combination of the cyclic voltammetry measurement technique and chemometric analysis methods such as principal components analysis, linear discriminant analysis and the k-nearest neighbors algorithm classifier for distinguishing different types of toxic gases. The responses of the single electrocatalytic gas sensor to 20 ppm of ammonia, nitrogen dioxide, sulfur dioxide and various concentrations of hydrogen sulfide in balance with synthetic air have been measured and analyzed. The reduction of measurement points in the data set used for multivariate analysis was evaluated.

Low cost electrochemical sensor module for measurement of gas concentration

This paper describes a low cost electrochemical sensor module for gas concentration measurement. A module is universal and can be used for many types of electrochemical gas sensors. Device is based on AVR ATmega8 microcontroller. As signal processing circuit a specialized integrated circuit LMP91000 is used. The proposed equipment will be used as a component of electronic nose system employed for classifying and distinguishing different levels of air contamination.

Gas sampling system for matrix of semiconductor gas sensors

Semiconductor gas sensors are popular commercial sensors applied in numerous gas detection systems. They are reliable, small, rugged and inexpensive. However, there are a few problem limiting the wider use of such sensors. Semiconductor gas sensor usually exhibits a low selectivity, low repeatability, drift of response, strong temperature and moisture influence on sensor properties. Sample flow rate is one of the parameters that influence sensors response what should be considered in the measurement system. This paper describes low cost module for controlling measured gas flow rate. The proposed equipment will be used as a component of electronic nose system employed for classifying and distinguishing different levels of contamination in air.

Investigation of solid polymer electrolyte gas sensor with different electrochemical techniques

In this work solid polymer electrolyte (SPE) amperometric sulphur dioxide sensor is investigated. Nafion was used as a membrane electrode and 1M sulphuric acid as an internal electrolyte. Sensor response to sulphur dioxide was measured. Besides traditional constant voltage amperometry also different electrochemical techniques were used. Results obtained by these methods are compared.

Techniques of acquiring additional features of the responses of individual gas sensors

Gas sensors usually exhibit lack of selectivity, require frequent calibration, exhibit drift of the response and a lot of factors, such as humidity or ambient temperature, influence their performance. Different approaches can be used to overcome this shortcomings. Building arrays of different sensors and usage of pattern recognition methods to analyze responses of elements in array is a popular approach. In this paper the approach of using a single sensor and special measurement techniques will be presented. Instead of increasing the number of sensors an additional information, needed to improve the properties of the sensor, is obtained from the response signal of a single sensor.