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Sensors (Basel)

Title:		Volatile Organic Compound Monitoring during Extreme Wildfires: Assessing the Potential of Sensors Based on LbL and Sputtering Films
Author(s):		Magro C; Goncalves OC; Morais M; Ribeiro PA; Serio S; Vieira P; Raposo M;
Address:		"Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Almada, Portugal. School for International Training, World Learning Inc., Brattleboro, VT 05302, USA. Centro de Quimica Estrutural, Institute of Molecular Sciences, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal. Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL), Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Almada, Portugal"
Journal Title:		Sensors (Basel)
Year:		2022
Volume:		20220903
Issue:		17
Page Number:		-
DOI:		10.3390/s22176677
ISSN/ISBN:		1424-8220 (Electronic) 1424-8220 (Linking)
Abstract:		"A new theory suggests that flammable gases generated by heated vegetation, in particular the volatile organic compounds (VOC) common to Mediterranean plants, may, under certain topographic and wind conditions, accumulate in locations where, after the arrival of the ignition source, they rapidly burst into flames as explosions. Hence, there is a need for the development of a system that can monitor the development of these compounds. In this work, a sensor's array is proposed as a method for monitoring the amount of eucalyptol and alpha-pinene, the major VOC compounds of the Eucalyptus and Pine trees. The detection of the target compounds was assessed using the impedance spectroscopy response of thin films. Combinations of layers of polyelectrolytes, such as poly(allylamine hydrochloride) (PAH), polyethyleneimine (PEI), poly(sodium 4-sytrenesulfonate) (PSS) graphene oxide (GO), and non/functionalized multiwall nanotubes (MWCNT-COOH or MWCNT), namely, PAH/GO, PEI/PSS, PEI/GO, PAH/MWCNT, PAH/MWCNT-COOH, films, and TiO(2) and ZnO sputtered films, were deposited onto ceramic supports coated with gold interdigitated electrodes. The results showed that concentrations of the target VOCs, within the range of 68 to 999 ppm(v), can be easily distinguished by analyzing the impedance spectra, particularly in the case of the ZnO- and PAH/GO-film-based sensors, which showed the best results in the detection of the target compounds. Through principal component analysis (PCA), the best set of features attained for the ZnO and PAH/GO based sensor devices revealed a linear trend of the PCA's first principal component with the concentration within the range 109 and 807 ppm(v). Thus, the values of sensitivity to eucalyptol and alpha-pinene concentrations, which were (2.2 +/- 0.3) x 10(-4) and (5.0 +/- 0.7) x 10(-5) per decade, respectively, as well as resolutions of 118 and 136 ppb(v), respectively, were identified"
Keywords:		Electrodes Eucalyptol Polyethyleneimine/chemistry *Volatile Organic Compounds/analysis *Wildfires *Zinc Oxide electronic nose extreme wildfires impedance spectroscopy layer-by-layer sputtering volatile organic compounds alpha-pinene;
Notes:		"MedlineMagro, Catia Goncalves, Oriana C Morais, Marcelo Ribeiro, Paulo A Serio, Susana Vieira, Pedro Raposo, Maria eng PCIF/GFC/0078/2018/Fundacao para a Ciencia e Tecnologia/ UIDP/FIS/04559/2020/Fundacao para a Ciencia e Tecnologia/ Switzerland 2022/09/10 Sensors (Basel). 2022 Sep 3; 22(17):6677. doi: 10.3390/s22176677"