Apparatus to characterize gas sensor response under real-world conditions in the lab

Abstract

The use of semiconducting metal-oxide (MOX) based gas sensors in demanding applications such as climate and environmental research as well as industrial applications is currently hindered by their poor reproducibility, selectivity, and sensitivity. This is mainly due to the sensing mechanism which relies on the change of conductivity of the metal-oxide layer. To be of use for advanced applications metal-oxide (MOX) gas sensors need to be carefully prepared and characterized in laboratory environments prior to deployment. This paper describes the working principle, design, and use of a new apparatus that can emulate real-world conditions in the laboratory and characterize the MOX gas sensor signal in tailor-made atmospheres. In particular, this includes the control of trace gas concentrations and the control of oxygen and humidity levels which are important for the surface chemistry of metal-oxide based sensors. Furthermore, the sensor temperature can be precisely controlled, which is a key parameter of semiconducting, sensitive layers, and their response to particular gas compositions. The setup also allows to determine the power consumption of each device individually which may be used for performance benchmarking or monitoring changes of the temperature of the gas composition. Both, the working principle and the capabilities of the gas measurement chamber are presented in this paper employing tin dioxide (SnO2) based micro sensors as exemplary devices.

Reservoir computing compensates slow response of chemosensor arrays exposed to fast varying gas concentrations in continuous monitoring

“…Such scenarios demand methods and algorithms that can operate on streams of A c c e p t e d M a n u s c r i p t measurements and incorporate information contained on the sensors' dynamics such as RC algorithms, overcoming the requirement of traditional experimental protocols that delay the system prediction until the measurement is finished. Therefore, algorithms based on RC are better suited for open sampling systems, in which the sensors are exposed directly to gas plumes in a turbulent environment, or continuous monitoring and alarm applications, in which large number of volatiles are expected to fluctuate irregularly [47,48]. Previous experimental protocols in open sampling systems also assume control of the gas onset, which happens at specific times from the beginning of the measurement [49,50].…”

Odor-Sensing System to Support Social Participation of People Suffering from Incontinence

“…Furthermore, the results obtained in determining the layer’s resistivity with the time-to-digital conversion are equivalent to that of more sophisticated equipment such as the Keithley 2700, which we use in our fully automated gas measurement apparatus [50]. As a result of these measurements, we can assume that the mobile sensor module is capable of correctly determining the resistivity of the CuO/CTO layers over a wide range of values with high accuracy.…”

“…The device performance of the prototype has been tested using well-defined gas mixtures produced by our custom-built apparatus to simulate real-world conditions in the lab [50]. Taking into account typical environmental conditions in real-world applications, we have opted for a characterization in two humidity regimes at 22% and 47% r.H., respectively.…”

Low-Power Odor-Sensing Network Based on Wake-Up Nodes

“…So far the sensor node has been tested in a laboratory environment using an apparatus to simulate real-world conditions [17] and a sample measurement is shown in Figure 3. During three days the system has been kept in an environment of synthetic air with varying levels of humidity and subject to the ambient temperature.…”