An efficient way to save the lives from flash floods in the Himalayan Rivers by using ZnO sensors Jibish Mathew 1, * and Deepu Thomas 2 1 Prajyoti Niketan College, Pudukad,Thrissur, Kerala, India - 680 301. 2 Research and Development Centre, Bharathiar University, Coimbatore, India-641046. Abstract The Himalayan Rivers are notorious for their flash flood. Due to the flash flood, hundreds of lives were washed away through the Himalayan Rivers every year. This paper proposes an innovative idea to save such lives by appropriate precautions with the proper operation of ZnO sensors. In this paper, we are using the light and temperature sensitivity property of the ZnO material. Keywords :ZnO, Irradiation, Sensor, Himalayan Rivers, Flash flood 1. Introduction The Himalaya is full of snow in most of the time. Compared to other rivers, the Himalayan Rivers have a speciality they are flooded at summer season. These high flash floods affect the lives of the people who are staying not only in the banks of the rivers but also in the rivers. Number of human lives flashed in such currents. A proper warning at proper time will save their lives. In this paper we are proposing a novel method to save the lives of the above mentioned people. ZnO is a photo-sensitive material. Its resistance may vary from few kilo ohms to several mega ohms as the light falls on it [1-2]. Its resistance is also sensitive to temperature variations. The other speciality of ZnO is that it has no reaction with any form of H 2 O ( including ice). Moreover it is a robust material by nature. There are also different types of photo sensors, humidity sensors and temperature sensors are available in the market [3-11]. However their performance in ice covered mountains are very weak. In this paper we are presenting ZnO as a photo conductive sensor. As the sun rays fall on the surface of the sensor, its resistance decreases. Another interesting thing of ZnO is that its resistance is inversely proportional temperature. That is as temperature increases the resistance of ZnO is decreases. There is another relationship in between intensity of the Sun rays and the temperature of the Sun rays affected area. Temperature of an area is proportional to the intensity 246
of the Sun rays hit on that area. That is the resistance of the sensor decreases as the intensity of light or temperature increases. If such sensors are connected to a battery, current through the sensor increases as intensity of light increases, temperature increases or both. 2. Design The flowchart in figure 1 shows the basic idea of the system. Seven ZnO sensors are arranged upon a semi circle rubber ring (30 degree apart from each other), which is oriented towards the east- west direction. Since they are equally spaced, one of the sensor output is always higher than the others in every day time. When the output from any sensor is higher than the permissible limit, wait for a known time( say x ), then increase another time variable i which was initialized by 0. When the variable i reaches a maximum limit( which is assumed to melt ice), send alarm to the banks of Himalayan rivers. Otherwise read inputs from the sensors. In this say we can save hundreds of life. 3. Experimental Fig.1 Flow chart of the system ZnO thin films were prepared by microwave assisted Successive Ionic Layer Adsorption Reaction (msilar) method, in which, the ZnO thin film was coated on a glass substrate (26 76 mm) by alternately dipping it in a sodium zincate bath at room temperature and then in hot water maintained at 90-95 o C. The well-cleaned substrates were immersed in the chemical bath for 10 second followed by immersion in hot water for an equal duration and 247
the process was repeated for 100 times. Then the sample was microwave irradiated and annealed in a micro controlled annealing chamber at 400 o C for half an hour. The electrical resistance of ZnO thin film was measured by Keithley 2100 Digital Multimeter. 4. Results and discussion The thin film resistivity depends on the interaction of the conduction electrons with the surface. It can be also defined as the measure of the material s inherent surface resistance to current flow. The resistance of sample is measured in the presence of sunlight and by varying the temperature. Figure 2 shows the effect of resistance with the Sun rays intensity on ZnO in a sunny day. It is quite evident that its resistance decreases as the intensity of light increases. Figure 3 describes the relationship between electrical resistance of ZnO and temperature. Here also the resistance of ZnO decreases as temperature increases. From the plots it is clearly noticed that resistance found to be minimum at high sunlight intensity and also at maximum temperature. So ZnO samples can b e used to detect the intensity of sunlight and temperature variation. Fig. 2 shows the variation of resistance with Sunlight 248
Fig. 3 shows the variation of resistance with Temperature 4. Conclusion This is an innovative idea to save the lives of the people who stay in the banks of the Himalayan Rivers. The key part of this system is ZnO. ZnO sensors are simple to construct but powerful and strong enough to handle the Himalayan circumstance. Here we used the electrical properties if ZnO. The electrical resistance values of the samples were noticed to be varied with sunlight irradiation and temperature. Hence synthesized sample can be employed as light sensors and temperature sensors. References [1] Periasamy C and Chakrabarti P (2011) J. Electron. Mater. 40 259 [2] Thomas C, Vattappalam S. C, Mathew S and Augustine S (2014) Journal of Optoelectronics and Biomedical Materials 6(3) 75 83. [3]Maddanimath T, Mulla I.S.Sainkar S.R, Vijayamohanan K et.al (2002) Sensors and Actuators B, 81 ( 2002) 141-151. [4] Jain S, Chakane S, Samui A.B et. al, (2003) Sens. Actuators B: Chem. 96, 124. [5] Albrecht B.A, Benson C.H. and Beuermann S (2003) Geotech. Test J. 26 3-11. [6]Hijikigawa M, Miyoshi S. Sugihara T and Jinda A (1983) Sens. Actuators, 4 (1983) 249
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