Changle Pei,Muhammad Hamza Nadeem,Nan Li,Jun Fu,Nan Xu,You Wang,Adrian Carl Stevenson,Guang Li,Ruifen Hu
The complexity of in situ volatile organic compounds (VOCs) detection demands high selectivity and anti-interference capability of electronic noses (E-noses). Multivariant virtual sensor array (VSA) is a new generation of E-noses under research to overcome the insufficient VOCs selectivity limitation of existing electronic noses and alleviate the issue of sensor drifts. In this paper, a frequency-amplitude dual-parameter modulation strategy is presented on a wireless electrodeless quartz crystal microbalance with dissipation (WE-QCM-D) to realize the recognition and analysis of VOC mixtures and complex real-world analytes with a single multivariant VSA E-nose, by probing the gas dynamic sorption in a sensitive film at various scales of oscillating shear displacements and obtaining multiple partially independent responses to VOCs. Ten VOC analytes from alcohols, esters, and aromatic hydrocarbons were classified with accuracies of above 95% for both interclass and intraclass discriminations. Additionally, a discriminating accuracy of 95% has been achieved on VOC mixtures, and their component concentrations were predicted with coefficients of determination above 0.9. For practical testing, the system was exposed to the headspace VOCs of banana, pineapple, and mango under different concentrations. It recognized different fruits and identified the ripen state of bananas based on the detection of their volatiles. The dual-parameter modulated WE-QCM-D paves a promising multivariant way to realize online real-time VOCs monitoring with high performance on selectivity and quantitative analysis.
Xuefei Su,Daqi Chen,Nan Li,Adrian Carl Stevenson,Guang Li,Ruifen Hu
Wireless sensor technology is a facile way of realizing low cost and miniaturized device for the detection of the volatile organic compounds (VOCs). A wireless electrodeless quartz crystal microbalance with dissipation (WE-QCM-D) sensor array was developed by using a single sensor working in a multi-resonance mode, which obtained an acoustic spectra of the quartz crystal at four harmonics (6 MHz, 18 MHz, 30 MHz and 42 MHz). Multi-responses (frequency shift, and energy dissipation) of WE-QCM-D sensor array were obtained via a ring-down mode and employed as discrimination factors for VOCs. The gas discrimination capability of the WE-QCM-D sensor array has been tested by coating a 100 μ g polyvinylpyrrolidone film on the quartz disc and achieved an optimal recognition rate of 97.5 % with K nearest neighbor algorithm. The results indicate that the single element WE-QCM-D sensor array could be a promising way to realize compact and low-cost VOCs monitoring systems.
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