![]() Nanograins structure is obtained due to addition of glycerine in the sol solution, which also leads to porosity enhancement of the sensing layer. High response of the sensor at RT is attributed due to porous nanograins (with average particle size ~50 nm) based SnO2 thin film layer. Upon exposure to 500 ppb and 1 ppm of NH3, sensor manifests appreciable response ~28% and ~31.5%, respectively. High response and good selectivity towards ammonia are observed with very fast response and recovery time at RT, for extreme low concentrations. ammonia (NH3) solution, acetone (C3H6O), methanol (CH3OH) and 2-propanol (C3H8O) at room temperature (RT) with humidity level ~55% RH for concentration range 500 ppb-500 ppm. The performance of the fabricated sensor has been investigated for analytes viz. SnO2 nanostructured thin film based gas sensor is fabricated by sol-gel spin coating technique. ![]() monoethanolamine (MEA), diethanol amine (DEA), triethanolamine (TEA), ethanol, methanol, 2-propanol and acetone along with target analyte ammonia. The selectivity of the sensor was analyzed against other competing analytes viz. 3365% for 1000 ppm at RT, with appreciable response and recovery times. The response of the sensor was analyzed for ammonia concentration ranging from 100 ppb to 1000 ppm and utterly high % response was observed i.e. Under exposure to 100 ppb of ammonia at RT, the sensor showed ˜57% response with fast response (18 s) and recovery times (30 s). Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) results were used to analyze the surface morphology and chemical composition. Fourier transform infrared spectroscopy (FTIR) results were used for structural analysis and to confirm the SnO2/polypyrrole composite formation. The mean crystallite size of the composite was calculated using X-ray diffractometer (XRD) and found to be ˜ 13 nm, which is comparable with the 2LD (Debye length) of SnO2. Porous SnO2 nanofibers having diameter in range ˜70–150 nm were deposited using electrospinning technique, followed by vapor phase polymerization of pyrrole to develop SnO2/polypyrrole (PPy) composite. Ultra-sensitive, highly selective, fast responsive and extreme low-ppb ammonia (NH3) sensor working at room temperature (RT) has been developed using SnO2/polypyrrole nanocomposite. Compared with other dopant levels, the 3wt.% Al-ZnO nanorods unveiled the uppermost retort when tested to 100 ppm ammonia (NH3) gas concentration at room temperature. The gas sensing analysis showed that Al doping content was made to drastically increase the gas sensing response. ![]() It was shown that the estimated values of the energy gap are enlarged to 3.12 from 3.01 on rising the Al content till 3wt.% and finally decreased for 5wt.% Al content. The photoluminescence study revealed that due to Al doping the PL intensity was quenched which signifies the reduction of defects in the films. ![]() Surface morphological tests through SEM presented the formation of nanoparticles and nanorods with a variation of Al content. EDX study approves the presence of Al doping in ZnO. XRD examination disclosed polycrystalline nature with the hexagonal system of all films and crystallite size was noticed between 37 and 51 nm. A systematic evolution of structural, surface morphology, composition, photoluminescence and ammonia gas sensing behaviour of the system was investigated with a variation of Al dopant. In this present research work, we report the preparation of successfully synthesized ZnO films as pristine and doped with Al(Al-ZnO) on glass via facile, eco-friendly, and controllable SILAR method. Fabrication techniques included coating techniques, printing techniques, spinning techniques, and transferring techniques are discussed in detail, respectively. Here, recent advances in the fabrication techniques of wearable gas sensors are presented. Therefore, fabrication techniques for wearable gas sensors are extremely limited, thus a summary of which is necessary. However, some traditional fabrication techniques of gas sensors such as lithography and chemical vapor deposited, are incompatible with most flexible substrates due to the flexible substrates cannot endure the harsh fabricated conditions, for instance, high temperature. To ensure the gas sensors can be worn and carried easily, most of them were fabricated on flexible substrates. Among them, wearable gas sensors, which can detect both gas markers from the human body and hazardous gas from the environment, are particularly gaining tremendous interest. With the progress of intelligent and digital healthcare, wearable sensors are attracting considerable attention due to their portable and real-time monitoring capabilities.
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