Abstract
In this paper, the UV illumination effect for microwave gas sensors based on the tin dioxide was verified. A UV LED with emission wavelength close to the absorption edge of the SnO2 gas-sensing layer was selected as the UV source. The developed gas sensors were tested under exposure to acetone in the 0–200 ppm range at room temperature. The sensor’s complex reflection coefficient corresponding to target gas concentration was measured with the use of a five-port reflectometer system exhibiting enhanced uncertainty distribution, which allows for the detection of low gas concentration. The UV illumination significantly emphasizes the sensors’ response in terms of both magnitude and phase for low gas concentrations, in contrast to previously reported results, in which only the reflection coefficient’s phase was affected. The highest responses were obtained for modulated UV illumination.
Highlights
Acetone (C2H5OH) is a colorless, mobile, flammable liquid that serves as an important solvent in chemistry and industry. It has become attractive for biomedical applications, where it is considered a biomarker of diabetes, due to its presence in exhaled breath in various concentrations for healthy and diabetic patients [1,2,3,4,5]
In the last few years, a number of papers have focused on enhanced acetone detection, utilizing various methods, such as optical detection [8,9,10], electrochemical sensors [11,12,13], metal oxides (MOXs)-based sensors [14,15,16,17,18,19,20], and analytical systems [21,22,23,24,25]
The recently obtained results have shown that microwave gas sensors based on metal oxides can be utilized for acetone detection in the ppm range at room temperature [28,29,30]
Summary
Acetone (C2H5OH) is a colorless, mobile, flammable liquid that serves as an important solvent in chemistry and industry. The recently obtained results have shown that microwave gas sensors based on metal oxides can be utilized for acetone detection in the ppm range at room temperature [28,29,30]. For such sensors, the response/recovery time(s) at room temperature is longer than for conventional applications, where the operating temperature is usually in the 300–500 ◦C range. A linear relationship between acetone concentration and magnitude/phase changes of the sensor’s reflection coefficient was observed
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