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Imidazole-based Ionogel as Room Temperature Benzene and Formaldehyde Sensor

Authors:
N. Gil-González, F. Benito-Lopez, E. Castaño, M. C. Morant-Miñana
Year:
2020
Journal:
Microchim. Acta
Impact Factor:
6.232
Quartile:
Q1
Volume:
187:638
Initial page - Ending page:
1 - 8
ISBN/ISSN:
1436-5073
DOI:
http://dx.doi.org/10.1007/s00604-020-04625-9
Description:

A room temperature benzene and formaldehyde gas sensor system with an ionogel as sensing material is presented. The sensing layer is fabricated employing poly(N-isopropylacrylamide) polymerized in the presence of 1- ethyl-3-methylimidazolium ethyl sulfate ionic liquid onto gold interdigitated electrodes. When the ionogel is exposed to increasing formaldehyde concentrations employing N2 as a carrier gas, a more stable response is observed in comparison to the bare ionic liquid, but no difference in sensitivity is observed. On the other hand, when air is used as carrier gas the sensitivity of the system towards formaldehyde is decreased in one order of magnitude. At room temperature, the proposed sensor exhibited in air higher sensitivities to benzene, at concentrations ranging between 4 and 20 ppm resulting, in a limit of detection of 47 ppb, which is below the standard permitted concentrations. The selectivity of the IL towards HCHO and C6H6 is demonstrated by the absence of response when other IL is employed. Humidity from the ambient slightly affects the resistance of the system proving the protective role of the polymeric matrix. Furthermore, the gas sensor system showed fast response/recovery times considering the thickness of the material, suggesting that ionogel materials can be used as novel and highly efficient volatile organic compounds sensors operating at room temperature.

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