Design and fabrication of quick responsive and highly sensitive LPG sensor using ZnO/SnO2 heterostructured film

Highly efficient LPG sensor working at room temperature was developed using a simple and cost-effective route. For this purpose, ZnO/SnO _2 heterostructure was synthesized using the hydrothermal route and thin films of the material were prepared. X-ray Diffraction revealed all the crystal parameters including grain size, texture coefficient, dislocation densities, surface area which are necessary for a sensor. Also, particle size, zeta potential, and conductivity were observed using nanozetasizer. Heterojunctions at the surface of the film were viewed by Scanning electron microscopy. An optical band-gap of ∼3.85 eV was measured using UV–vis absorption spectrum. Further, the film was used as room ambient sensor for different concentrations of LPG. Among them, the best sensor response and sensitivity of 276.51 and 3.78 respectively were obtained for 2.0 vol% of LPG whereas minimum response and recovery time of 10 s and 15 s were obtained for 0.5 vol% of LPG

Review on pressure sensors for structural health monitoring

Abstract This paper reports the state of art in a variety of pressure and the detailed study of various matrix based pressure sensors. The performances of the bridges, buildings, etc. are threatened by earthquakes, material degradations, and other environmental effects. Structural health monitoring (SHM) is crucial to protect the people and also for assets planning. This study is a contribution in developing the knowledge about self-sensing smart materials and structures for the construction industry. It deals with the study of self-sensing as well as mechanical and electrical properties of different matrices based on pressure sensors. The relationships among the compression, tensile strain, and crack length with electrical resistance change are also reviewed

Hydrothermally Synthesized ZnSnO3 Nanoflakes Based Low-Cost Sensing Device for High Performance CO2 Monitoring

This work reports a room temperature operative ZnSnO _3 nanoflakes-based CO _2 gas sensor. The perovskite ZnSnO _3 nanoflakes are synthesized by a one-pot hydrothermal technique. The prepared material was characterized via XRD, SEM, UV-visible spectroscopy, and DLS measurement for confirming the crystal structure, surface morphology, optical properties, and size distribution. The X-ray diffraction pattern revealed that ZnSnO _3 was in the orthorhombic phase and average crystallite size examined by the Scherrer formula was 8.05 nm. Optical studies were done by the UV–vis spectroscopy and a direct optical band gap was found to be 3.27 eV. The surface morphology of ZnSnO _3 was found to nanoflakes are almost uniform dimensions. The fabricated sensor device of ZnSnO _3 detected the CO _2 gas at room temperature (RT) for different concentrations. The best sensor response was found to be 4.93 for 1000 ppm of CO _2 whereas at 200 ppm the response and recovery times were found to be 5.92 s and 7.23 s respectively. HOMO-LUMO gap energy of ZnSnO _3 without and with interaction from CO _2 molecule was found 1.165 eV and 1.577 eV, respectively. DFT studies are used for a better understanding of sensing mechanisms

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices

Chemically Functionalized Gold Nanosphere-Blended Nematic Liquid Crystals for Photonic Applications

A demand for functional materials that are capable of tailoring light-emissive properties has apparently been rising nowadays substantially for their utilization in organic optoelectronic devices. Motivated by such promising characteristics, we present highly emissive as well as aggregation-induced emission (AIE) electroluminescent composite systems composed of a nematic liquid crystals (NLC) blended with polyethylene-functionalized gold nanospheres (GNSs). The major findings of this study include superior electro-optical properties such as threshold voltage reduction by around 24%. The fall time is reduced by 11.50, 30.33, 49.33, and 63.17% respectively, and rotational viscosity is reduced by 13.86, 32.77, 36.97, and 49.58% for 5.0 × 1011, 5.0 × 1012, 2.5 × 1013, and 5.0 × 1013 number of GNS-blended liquid crystal (LC) cells. The increased UV absorbance and greatly enhanced luminescence properties have been attributed to surface plasmon resonance near the surface of GNSs and AIE effect risen due to agglomeration of the capping agent with the NLC molecules respectively, and these characteristics make them suitable for new-age display applications