الفهرس 
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Abstract
Nowadays in order to enhance environmental and safety regulation of gases, there is a great need to introduce a gas sensor (GS) device. In the developing transport industry, in domestic and industrial applications, there is also a great need for this form of sensor. GSs are used to detect gases, discriminate odours or generally monitor change of gas atmosphere. The development of GSs to monitor combustible gases are imperative due to the concern for safety requirements in homes and for industries. Among the various techniques used in industry for gas detectors and sensors, the Metal oxide semiconductor (MOS) GS offers the best capabilities for gas sensing in this environment. The MOS sensors have attracted a lot of attention due to their cheap and easy-to-use gas monitoring capabilities. The main drawback of MOS is that high sensitivity occurred at high temperature. The main objective of this thesis is to fabricate MOS GS with high sensitivity at low temperature by doping the MOS material. The ZnO is the MOS which is used here. The integration of nanoscale chemical sensors with wireless device is an approach to improve device applications in personal healthcare, environmental monitoring and chemical agent detection. So, here the fabricated ZnO nanomaterials are integrated with Radio Frequency Identification (RFID) tag to form wireless GSs. The thesis based on four main stages; firstly the preparation of fabricated nanomaterials, a solution of .25 M of zinc nitrate ((Zn(NO3)2), Diethanolamine (DEA) and different weight ratios of Ruthenium chloride hydrate (RuCl3) are successfully synthesized using hydrothermal technique places in an autoclave at 70 °C for 24h to fabricate a Zinc oxide (ZnO) and ZnO:Ru nanopowders. Different weight ratios (1, 5 and 10 %) of Ru-doped ZnO GSs are fabricated which are sensitive to different low gases concentrations. Secondly the nanomaterials are examined to study their characterization. Field Emission Scanning Electron Microscopy (FESEM) is used to investigate the surface structure of the nanopowder. Also, Fourier-Transform Infrared (FTIR) Spectroscopy is applied to declare the chemical bound of the formed material. The crystalline structures are examined by X-ray Diffraction (XRD) and atomic structure of the samples using High-Resolution Transmission Electron Microscopy (HRTEM). The EDX spectra detect the presence of Zinc and Ruthenium. Also, the electrical I-V curves properties of the doped and undoped gas sensors are studied Thirdly the formation of RFID GS, a nanopowder` of pure ZnO and doped ZnO are dropped on a certain portion of a commercial Ultra High Frequency (UHF) RFID antenna tag to fabricate RFID GSs. For the 13.56 MHz RFID tag the overall antenna is covered by sensitive material. The S parameters and resonance frequency are measured for all prepared tag sensors at room temperature exposed to ammonia gas to show the sensitivity of the fabricated wireless sensor. Finally, the results for the fabricated GSs, a maximum variation of the resonance frequency reaches to 940 MHz for UHF RFID tag with ZnO doped 5% Ru at low concentration of ammonia gas (NH3) with low reflectance at room temperature. The Fabricated RFID GS is more sensitive of RFID tag combined carbon black/ (PEVA) sensor for ammonia gas detection. The fabricated RFID GS tag has a stability under twisting deformations and mechanical bending. The fabricated pure ZnO and doped gas sensors have a good response for different gas like Oxygen, Liquified petroleum gas (LPG) and NH3 specially for 5% Ru doped ZnO. For O2 the gas response is higher than the tin oxide (SnO) sensor. At room temperature the response time and recovery time of ZnO doped 5% Ru to ammonia is less than the wireless gas sensor which is fabricated by integration a reduced graphene oxide (RGO) decorated with silver nanoparticles (AgNPs) with a commercial near-feld communication (NFC) tag. The I-V characteristic curve show that the 5% doped Ru has better conductivity than others. It consumes low power ratings preferers in application than others fabricated ones. Pure ZnO and 1% doped Ru compound exhibit ohmic behavior but the ZnO doped 5% and 10% Ru compound act as a reversible nonlinear device.