A novel approach for detecting HMDSO poisoning of metal oxide gas sensors and improving their stability by temperature cycled operation

Abstract

Abstract. In this paper we study the effect of hexamethyldisiloxane (HMDSO) vapor on an SnO2-based gas sensor (GGS 1330, UST Umweltsensortechnik GmbH, Geschwenda, Germany) in a temperature cycled operation (TCO). We show that HMDSO poisoning can be quantified at early stages (85 to 340 ppm × min) with a resolution of ±85 ppm × min using TCO. This novel approach for sensor self-monitoring provides a simple method for early detection of HMDSO poisoning. It is thereby possible to detect poisoning before the sensor function is strongly impaired. In this paper we show that by using an appropriate normalization of the sensor data, the stability of gas discrimination by linear discriminant analysis (LDA) can be improved, which in turn facilitates a more accurate determination of the poisoning state by a hierarchical LDA discrimination. For a specific temperature cycle and feature extraction approach, we show that identification of ethanol and carbon monoxide is still possible after poisoning with 900 ppm × min HMDSO, i.e. a HMDSO poisoning dose more than twice as high as required by DIN EN 50194-1.

Sensors 4.0 – smart sensors and measurement technology enable Industry 4.0

“…Here, dynamic operation also allows detection of sensor faults, e.g. poisoning of the sensor material (Bastuck et al, 2015;Schüler et al, 2015).…”

New Digital Metal-Oxide (MOx) Sensor Platform

“…Even though the selectivity of MOx sensors can be tuned and notably improved, long-term stability in the presence of siloxanes will deteriorate their accuracy over time or even make it impossible to use sensors in applications with high siloxane loads such as mobile phones [ 6 , 7 , 8 ]. Moreover, most available sensors do only offer a simple analog interface.…”

Self-Test Procedures for Gas Sensors Embedded in Microreactor Systems

“…Problems that have been well-known throughout the entire development of the MOX gas sensor field are that MOX sensors suffer to varying degrees from the effects of baseline resistance drift and from poisoning interactions which make heated MOX surfaces less and less accessible to reactive gases. As during sensor operation such processes are usually slow, and as these do not principally compromise the capability of MOX sensors to detect gases as such, the underlying mechanisms of sensor degradation have not been the subject of intense scientific investigation [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Such degradation processes, however, have always remained a problem of practical concern and precluded MOX gas sensors and sensor arrays from penetrating fields where quantitative measurements need to be made or where safety-critical alarm functionalities are to be provided [ 31 , 32 ].…”

“…In the first part of the paper we consider poisoning interactions of Hexamethyldisiloxane (HMDS) on heated MOX surfaces. In this context, HMDS is taken as a reference substance standing for all kinds of poisons that tend to form passivating overlayers on heated MOX surfaces (silanes, silicones, silicates, lead oxide film formers, sulphides, phosphates, and organic halides [ 21 , 22 , 25 , 26 , 27 , 28 , 30 ]. These first considerations show that HMDS poisoning can have a large impact both on the magnitude of the sensor baseline resistance in clean air and on the gas-induced resistance changes .…”