Anil D. Garje; Manoj Mayaji Ovhal; Shweta Mishra; Namrata Bagwe
Abstract
Nano-crystalline tin (II) oxide (SnO2) was successfully synthesized by a simple and cost-effective surfactant assisted solution precipitation technique. The structural, optical, and morphological characterization of as synthesized nano-crystalline SnO2 was confirmed by X-Ray diffraction (XRD), ultraviolet-visible ...
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Nano-crystalline tin (II) oxide (SnO2) was successfully synthesized by a simple and cost-effective surfactant assisted solution precipitation technique. The structural, optical, and morphological characterization of as synthesized nano-crystalline SnO2 was confirmed by X-Ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy (TEM). The nano-crystalline SnO2 possesses tetragonal lattice structure (rutile phase) with preferential growth along (101) plane and average crystallite size of 8 ±2 nm were confirmed by XRD Rietveld refinement. The TEM images were showed quasi spherical particles with average particle size of 10 ±2 nm. The optical energy band gap of 3.76 eV confirms the electronic conduction mechanism in SnO2. Furthermore, the synthesized nano-crystalline SnO2 with 15 wt % glass frit was used as a functional material to fabricate thick film sensors using cost-effective screen printing method. The sensor shows high sensitivity towards H2, CO, and LPG selectively at optimal operating temperatures of 120, 150 and 70 o C respectively for 100 ppm concentration of each gas. The improvement in sensitivity, selectivity, and stability at low operating temperature and their correlation with the nano-crystalline SnO2 (101) plane, small particle size and optical band gap were also envisaged along with repeatability, reproducibility, calibration, and aging effect.
Andrew F. Zhou; Xinpeng Wang; Peter Feng
Abstract
Diamond-based sensors have shown great potential in the past few years due to their unique physicochemical properties. We report on the development of high-performance nitrogen-doped ultrananocrystalline diamond (UNCD) nanowire-based methane (CH4) gas sensors, taking advantage of a large surface-to-volume ...
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Diamond-based sensors have shown great potential in the past few years due to their unique physicochemical properties. We report on the development of high-performance nitrogen-doped ultrananocrystalline diamond (UNCD) nanowire-based methane (CH4) gas sensors, taking advantage of a large surface-to-volume ratio and a small active area offered by the 1D nanowire geometry. The morphologic surface and crystalline structures of UNCD are also characterized by using scanning electron microscopy (SEM) and Raman scattering, respectively. By using synthesized nanowire arrays combined with 4-pin electrical electrodes, prototypic highly sensitive CH4 gas sensors have been designed, fabricated and tested. Various parameters including the sensitivity, response and recovery times, and thermal effect on the performance of the gas sensor have also been investigated in order to quantitate the sensing ability. Enhanced by the small grain size and porosity of the nanowire structure, fabricated nanowire UNCD sensors demonstrated a high sensitivity to CH4 gas at room temperature down to 2 ppm, as well as fast response and recovery times which are almost 10 times faster than that of regular nanodiamond thin film based sensors.
Gounder Thangamani J.; Kalim Deshmukh; Kishor Kumar Sadasivuni; K. Chidambaram; M. Basheer Ahamed; Deepalekshmi Ponnamma; Mariam Al-Ali AlMaadeed; S. K. Khadheer Pasha
Abstract
Graphene and carbon nanotubes (CNTs) based sensors have been extensively studied because of their applications in the detection of various chemicals and biomolecules. From an application point of view, high sensitivity and selectivity is a promising tool for fast detection of gas leakage and early diagnosis ...
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Graphene and carbon nanotubes (CNTs) based sensors have been extensively studied because of their applications in the detection of various chemicals and biomolecules. From an application point of view, high sensitivity and selectivity is a promising tool for fast detection of gas leakage and early diagnosis of diseases for health care. In the present review article, we provide a comprehensive overview on the recent advances in the development of graphene and CNT based electrochemical biosensors and gas sensors. From the future point of view, special attention is paid to the synthesis techniques for high-performance biosensors and gas sensors. This article focuses on detecting mechanism for various volatile organic compounds (VOCs) gas sensing behavior of the graphene and CNT based sensors. A comparative study of the sensing behavior of pure metal oxide nanoparticles as well as their hybrids with graphene and CNTs has been reported.
Deepak Kumar; R. P. Tandon ;Partap K Chaudhury; Poornendu Chaturvedi; Abhilasha Chouksey
Abstract
The recovery of single wall nanotube (SWNT) based gas sensors have been investigated in the presence of Ultraviolet (UV) light at ambient conditions by real time monitoring. The rate of recovery is same for low concentration upto 5 ppm, but decreases with increase in concentration of NO2. It is observed ...
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The recovery of single wall nanotube (SWNT) based gas sensors have been investigated in the presence of Ultraviolet (UV) light at ambient conditions by real time monitoring. The rate of recovery is same for low concentration upto 5 ppm, but decreases with increase in concentration of NO2. It is observed that the response of thick film resistor (CNT-TFR) remains 7.5 and 25.4 % with multiple exposures of 5 ppm and 20 ppm NO2 concentration, respectively. But the recovery rate decreases with multiple exposures. Both the response and recovery rate changes in case of micro resistor (CNT-µR). To study the significant effect of absorbed O2 in recovery behavior, the analyte is exposed to gas sensor with and without regeneration in the presence of UV light. The gas sensor response increases 1.5 times but it does not recover to its base line when regenerated in the presence of UV light.
Megha P. Mahabole; Ravindra U. Mene;Rajendra S. Khairnar
Abstract
This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange ...
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This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange process is carried out for the partial substitution of cobalt ions in HAp matrix. Hydroxyapatite thick films, prepared using screen printing technique, are used as samples for gas sensing and dielectric measurements. The structural identification of HAp thick films is carried out using X-ray diffraction and the presence of functional groups in pure and doped HAp is confirmed by means FTIR spectroscopy. The surface morphology of these films is visualized by means of SEM and AFM analysis. Detailed study on CO2 gas sensing performance of pure and Co-HAp thick films is carried out wherein operating temperature, response/recovery times and gas uptake capacity are determined. It is remarkable to note that Co-HAp film with 0.01M cobalt concentration shows maximum sensitivity to CO2 gas at relatively lower operating temperature of 135 o C in comparison with pure HAp as well as other concentrations of cobalt doped HAp films. The frequency dependent variation of dielectric constant (K) and dielectric loss (tan δ) of HAp thick films are also studied in the range of 10 Hz-1MHz at room temperature. The result shows that increase of cobalt concentration in HAp matrix leads to increase in dielectric constant. The study reveals clear influence of cobalt substitution on dielectric properties and gas sensing properties HAp matrix.
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