Composite metal oxide based thin film based sensors are proposed to eradicate the problems faced by the single phase materials. The composite thin films of ZnO and SnO2 are expected to have significantly enhanced humidity sensing properties. In the present work, pure and composite thin films of ZnO and SnO2 are prepared by sol-gel based spin coating. The structural, optical and morphological properties of the films were studied by X-ray diffraction, Ultraviolet-Visible absorption spectroscopy and the scanning electron microscopy. The composite films with different compositions of ZnO and SnO2 phase were studied for their impedometric humidity sensing characteristics. Among the proposed sensors, the zinc rich composite sensors exhibit the maximum sensor response of 95% and sensitivity of 8.6 ± 0.5 kΩ/RH%. Further, the composite metal oxide based humidity sensors exhibit better transient characteristics and significantly lower hysteresis compared to their pure counterparts. © 2019 Elsevier B.V.

Samir Ranjan Meher

Department of Physics

School of Advanced Sciences

Vellore Campus

Zachariah C Alex

Department of Sensor and Biomedical Technology

School of Electronics Engineering

Velumani M

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Sensors and Actuators B: Chemical

SnO2 thin films and ZnO–SnO2 composite thin films were grown by reactive magnetron sputtering. Optical emission spectra was used to monitor the sputtered Sn and Zn species in the plasma. The structural and morphological characteristics of the films were studied using X-ray diffraction and scanning electron microscopy. The films were investigated for their humidity sensing characteristics using impedance spectroscopy in the frequency range 100 Hz–5 MHz. The sensing mechanism was evaluated by fitting the impedance spectra with the corresponding equivalent circuit. The composite ZnO–SnO2 based sensors exhibit faster response time (~21 s) compared to that of pure SnO2. The pure SnO2 based humidity sensors possess better sensitivity ((1.10 ± 0.079) kΩ/%RH) whereas the ZnO–SnO2 based sensors exhibit better sensor response (~ 24%). The enhancement in the sensor response is attributed to the dissociative adsorption of water molecules at the Sn and Zn lattice sites resulting in increased protonic conduction. © 2017, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Materials Science: Materials in Electronics

Impedometric humidity sensing characteristics of SnO2 thin films and SnO2–ZnO composite thin films grown by magnetron sputtering

Pristine and amine functionalized ZnO nanoflakesbased fiber-optic sensors were investigated towards different volatile compounds (VCs) for environmental monitoring applications. The ZnO nanoflakes synthesized through co-precipitation method was subjected to X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectrometer, and optical absorption studies to examine the structural, morphological, elemental, and optical properties. The analysis confirms the formation of ZnO nanoflakes with wurtzite structure. The spectral response of the ZnO and amine functionalized ZnO nanoflakes-based fiber-optic gas sensors were studied at ambient temperature for various concentrations (0C300 ppm) of acetone, ammonia, ethanol, methanol, hexane, and chloroform in clad modification technology. The analysis revealed that the pristine ZnO nanoflakes have selectivity towards acetone and amine functionalized nanoflakes have enhanced sensitivity towards all VCs and high selectivity (∼ four times) toward ammonia with fast response and recovery. Further, the pristine ZnO-based sensor shows selectivity towards acetone above 150 ppm with the response and recovery time of 19 s and 23 s, whereas the sensor based on amine functionalized ZnO shows enhanced selectivity towards ammonia above 50 ppm with fast response and recovery time of 14 s and 17 s, respectively. © 2017 IEEE.

IEEE Sensors Journal

Fiber-Optic Ammonia Sensor Based on Amine Functionalized ZnO Nanoflakes

In recent years, issues on greenhouse pollution and power consumption related to the operation of information communication technology (ICT) devices have triggered a huge amount of research work towards green radio communication. Many of the power efficient solutions will introduce cost performance trade-offs. The energy efficient solution which also takes care of the quality requests of the mobile customer is really required for the 5G based green radio communication. It is identified that enhanced nodeBs (eNB) are power inefficient and not suited for many deployment scenarios. Multihop relay (MHR) network is the suitable alternate for eNB especially in the coverage holes and cell edges. But MHR network suffers by various quality issues like site planning and path selection. Many of the site planning and path selection schemes will fail under network imbalance conditions. In this work, we have proposed a hybrid throughput oriented (TO) - load aware spectral efficient routing (LASER) scheme which offers high performance even under network load imbalance conditions. The simulation results proved that the proposed scheme is more suited for future green radio communication. © 2015 River Publishers.

Fulltext

Journal of Green Engineering

Quality of Service Aware Multi-Hop Relay Networks for Green Radio Communication

QCM-based humidity sensor and sensing properties employing colloidal SnO2 nanowires

Superior humidity sensor and photodetector of mesoporous ZnO nanosheets at room temperature

Composite metal oxide thin film based impedometric humidity sensors

Journal	Data powered by TypesetSensors and Actuators B: Chemical
Publisher	Data powered by TypesetElsevier BV
ISSN	0925-4005
Open Access	0