Search

The present work is a comparative study of cupric oxide (CuO) and tin oxide (SnO2) thin films deposited by spray pyrolysis and their sensitivity towards volatile organic compounds. The film structure and morphology were analyzed by x-ray diffraction, scanning electron microscopy and atomic force microscopy. The obtained results indicate that the synthesized films exhibit small grains size with porous and rough surfaces. This morphology enhances the surface-to-volume ratio necessary for gas sensing efficiency. The prepared CuO and SnO2 films were tested for ethanol and methanol vapor. The organic vapor concentration was varied from 20 ppm to 500 ppm at different temperatures ranging between 20°C and 200°C. The SnO2-based sensor showed good sensitivity, selectivity and repeatability, as well as fast response and recovery towards ethanol gas at room temperature. However, the CuO sensor exhibited high sensitivity and selectivity towards methanol vapor at 50°C operation temperature. The detection limit was in the range of 23–28 ppm for the tested gases. The obtained results suggest the possibility of fabricating a high-performance and low-cost volatile organic sensor using n-type and p-type metal oxide sensitive layers. [ABSTRACT FROM AUTHOR]

Toxic gases are responsible for the loss of many human lives around the world, which is increasing every year. Toxicity can have various biological aspects on the human body. The exposure to its gases leads to harmful consequences for the organism, which leads to metabolic reactions and even death. For this purpose, the initial step is to detect these gases with miniature flexible structures and solid progressed estimation methods using a simulation software tool. The studied sensor is based on the frequency characterization of an RF Planar Resonant Structure, in which the active element is a patch of radiating graphene printed on a polyimide film (Kapton). The objective of this work is to use our Graphene-Kapton sensor for non-invasive testing applications. In our case, the device is tested to detect and recognize several dangerous and toxic gases such as Fluorine azide (F2N), Hydrogen Iodide (HI), Nitrogen (N2), Methane (CH4), and Carbon monoxide (CO). The simulation results indicate that the Graphene-Kapton flexible sensor exhibits an important sensing performance. The sensor is able to detect all the tested gases with a good sensitivity depending on each gas. As well as, the sensor shows a high sensitivity (0.1± 0.01)* 106 [ppm]-1 (0.1 [ppt]-1) of methane (CH4) gas with detection limit of (9±0.1) *10-6 ppm (9 ppt). [ABSTRACT FROM AUTHOR]