Synthesis of Nano Gas Sensor Arrays H. Shokry Hassan*, A.B.Kashyout*, A. A. A. Nasser**, I. Morsi**, and A. Rafaat** *Advanced Technology and New Materials Research Institute, City for Scientific Research and technology application, new Borg el Arab City, Alexandria **Arab Academy for Science, and Technology, and Maritime Transport Correspondence should be addressed to at menem_1954@yahoo.com. Abstract:- The paper presents novel structures of Nano gas sensor arrays by using ZnO and doped with aluminum . ZnO Nanomaterial are successfully prepared using sol-gel technique . These include, similar and dissimilar structures. All used sensors are composed of zinc oxide doped with aluminum at different concentrations for dissimilar structures, and with the same concentration for similar structures. The first array (double sensor array) based on doping with percentages of 5% and 1%, while the second array (quadrature sensor array) uses 5% doping only. The resulting Nano array characterization is carried out using the scanning electron microscopy (SEM). This characterization determines the structure of the Nano element (dot, rod or wire). This is followed by the X-Ray Diffraction (XRD) characterization which indicates the purity and intensity of the Nano element within the structure. The electrical characteristic of the sensor is determined by measuring the two terminal sensor’s resistance at different concentrations of the gas, for different temperature ranges. More than order of magnitude change in the resistance is found to occur in response more than 100% change in temperature for different doping concentration, which indicates that arraying results in a more than unity array factor. This is a good measure for pollution in industrial applications. 1. Introduction Recently, there is a large need for low-cost production of transparent conducting films e.g.,( ZnO, SnO2, In2 O3, and Cd2SnO4) [1-3] because of their applications in various energy Efficiency specializations such as Piezoelectric devices, multilayer thermal image converter Systems, thin film transistor (TFT) ,window layer in heterojunction Solar cells, dye sensitization solar cells, heat mirrors, and gas sensors Solid State [4]. The film metal oxide gas sensors used widely because of their excellent characteristics such as low Cost, and small size, high sensitivity and fast response, and speed recovery. Greater selectivity, sensitivity and improve Stability [5]. Zinc oxide (ZnO) is not a newly discovered compound and research on its preparation and characterization has continued for several decades. However, a renewed interest of the scientific community in ZnO can be measured by the very large number of publications which have appeared on this compound in the past few years. ZnO is an oxide of group II metallic zinc [6] that exists between semiconductors and ionic materials, which gives ZnO the electrical amphoteric property as n-type semiconductor in most preparation procedures, although p-type conductivity is also reported under certain conditions [7,8].ZnO is a large band gap n-type Semiconductor which combines several advantages over its competitors such as GaN used today for production of short wavelength light- emitting devices. Its excitation energy (60 mV) is larger than the room-temperature thermal energy, and high-excitation near-UV luminescence and laser emissions can be expected. ZnO is stable under high-energy radiation and can be easily etched in acidic or alkaline solutions. The preparation of nanostructured ZnO in a large variety of shapes is an emerging field. One-dimensional (1D) ZnO nanostructures such as nanorods, nanowires, nanobelts, nanotubes and nanowhiskers are important for their physical properties arising from quantum confinement (such as electronic quantum transport and enhanced radiative recombination of carriers). Nanowires have promising potentials in extensive applications and are the fundamental building blocks for fabricating short-wavelength nanolaser, field effect transistors (FET), ultrasensitive nanosized gas sensors, nanoresonators, transducers, actuators, nanocantilevers and field emitters [8–14]. These properties could have numerous applications in various areas such as nanoscale electronics, optoelectronic devices and high-density magnetic memories [15] .Several techniques have been stated to grow doped and nondoped ZnO films as vapor condensation, thermal evaporation, spray pyrolysis, magnetron sputtering, metalorganic, chemical vapor deposition, and sol- gel among others [16–20].In this paper two structure of gas sensor array are developed by using ZnO doped with aluminum with different doping concentration , the array can sense different gases with high selectivity and sensitivity.