Haptically assisted chemotaxis for odor source localization

Film Growth of Tetragonal SnO2 on Glass Substrate by Dip-Coating Technique for Ethanol Sensing Applications

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.