Frequency-Amplitude Dual-Parameter-Modulated on a Single WE-QCM‑D for VOCs Discrimination and Analysis

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.