Film growth of tetragonal SnO2 on glass substrate by dip-coating technique for ethanol sensing applications

Abstract

A thin film sensor based on tetragonal SnO2 nanoparticles was fabricated by combining the sol–gel method and a dip-coating technique on a cylindrical glass substrate. The sensing material was produced through a cycling annealing process at 400 and 600◦ C, using tin chloride (IV) pentahydrate as a precursor in polyethylene glycol (PEG) solution as a surfactant. Materials were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), revealing tetragonal phase formation with no impurities. The sensor′ s assembly was done with low-cost materials such as Cu electrodes, Cu-Ni tube pins, and glass-reinforced epoxy laminate as the base material. For signal variation, an adequate voltage divider circuit was used to detect ethanol′ s presence on the surface of the sensor. The fabricated sensor response to gaseous ethanol at its operating temperature at ambient pressure is comparable to that of a commercial sensor, with the advantage of detecting ethanol at lower temperatures. The sensor response (S = Ra/Rg) to 40 ppm of ethanol at 120◦ C was 7.21. A reported mathematical model was used to fit the data with good results.