Since the increase in the emission of various Volatiles Organic Compounds, gas and formaldehyde gas have had a harmful effect on the human body, and gas sensors that can measure those gases were fabricated in this study. After Pt coating was performed on the alumina substrate, Zn seed layers were fabricated. Nanostructures were formed through sonochemical synthesis by varying the ratio of ZnO and TiO2. Thereafter, the reactivity and recovery properties were compared and evaluated according to the concentrations of formaldehyde and toluene gas. The ZnO(99%)-TiO2(1%) gas sensor showed meaningful selectivity of about 40% or more at a concentration ranging from 5 to 20 ppm (high concentration) of formaldehyde and toluene gas, and showed a low selectivity of about 5% or more for a concentration ranging from 0.1 to 1 ppm (low concentration) of formaldehyde and toluene gas. This sensor can be optimized to have a meaningful selectivity of formaldehyde gas compared to other Volatiles Organic Compounds gases by optimizing the ZnO-TiO2 nanostructure.

Owing to the increasing construction of new buildings, the increase in the emission of formaldehyde and volatile organic compounds, which are emitted as indoor air pollutants, is causing adverse effects on the human body, including life-threatening diseases such as cancer. A gas sensor was fabricated and used to measure and monitor this phenomenon. An alumina substrate with Au, Pt, and Zn layers formed on the electrode was used for the gas sensor fabrication, which was then classified into two types, A and B, representing the graphene spin coating before and after the heat treatment, respectively. Ultrasonication was performed in a 0.01 M aqueous solution, and the variation in the sensing accuracy of the target gas with the operating temperature and conditions was investigated. As a result, compared to the ZnO sensor showing excellent sensing characteristics at 350 °C, it exhibited excellent sensing characteristics even at a low temperature of 150 °C, 200 °C, and 250 °C.

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In this study, graphene oxide (GO) was coated on the surface of a large-area polystyrene film using spray coating. To analyze the possibility of developing a large-area cell culture vessel from this material, the mechanical properties of the coated surface as well as the cell compatibility and cell proliferation in the vessel were evaluated. Step measurements confirmed a curve of 100 nm or larger on the cell culture vessel surface. The surface was composed of GO (as determined from Raman spectroscopy) and its measured transmittance was ~90% or higher. The coated surface was rendered hydrophilic with an increase in surface energy. Although the cells hardly grew on the general polystyrene film, they attached and proliferated on the polystyrene film coated with GO. Zero cytotoxicity was reported, particularly in the sample that was spray-coated three times at 93.75 mm/s. Note that the cell viability was 1.43 times higher than that in the conventional cell culture vessel. Economic and efficient large-area cell culture vessels can be developed if the GO coating establishes an appropriate surface roughness and surface energy.

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