Fabrication of an Electrochemical Sensor for Glucose Detection using ZnO Nanorods
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Fabrication of an Electrochemical Sensor for Glucose Detection using ZnO Nanorods Sanghamitra Mandal1, Mohammed Marie2 and Omar Manasreh1 1 Department of Electrical Engineering, University of Arkansas, Fayetteville, AR 72701, U.S.A. 2 Microelectronics Photonics Program, University of Arkansas, Fayetteville, AR 72701, U.S.A. ABSTRACT An electrochemical glucose sensor based on zinc oxide (ZnO) nanorods is fabricated, characterized and tested. The ZnO nanorods are synthesized on indium titanium oxide (ITO) coated glass substrate, using the hydrothermal sol-gel technique. The working principle of the sensor under investigation is based on the electrochemical reaction taking place between cathode and anode, in the presence of an electrolyte. A platinum plate, used as the cathode and Nafion/Glucose Oxidase/ZnO nanorods/ITO-coated glass substrate used as anode, is immersed in pH 7.0 phosphate buffer solution electrolyte to test for the presence of glucose. Several amperometric tests are performed on the fabricated sensor to determine the response time, sensitivity and limit of detection of the sensor. A fast response time less than 3 s with a high sensitivity of 1.151 mA cm-2mM-1 and low limit of detection of 0.089 mM is reported. The glucose sensor is characterized using the cyclic voltammetry method in the range from -0.8 – 0.8 V with a voltage scan rate of 100 mV/s. INTRODUCTION Today, health issues caused by diabetes have affected 350 million people in the world, causing high rates of illness and deaths [1]. Glucose is the most important form of sugar in the human blood that acts as the prime source of energy for the human body. Monitoring normal blood glucose level prevents the risks of suffering from the chronic disease diabetes. It is reported that zinc oxide (ZnO) nanowires are biodegradable and biocompatible in bio fluids [2]. The isoelectric point of ZnO is 9.5 that makes nanostructured ZnO materials to easily absorb enzymes in buffer solutions [3]. The stability of ZnO in air is high [4]. The oxide layers naturally formed on zinc do not form a passivating film, which prevents its corrosion [5]. In the recent years, one dimensional ZnO nanorods are synthesized using the hydrothermal growth technique [6]. In this paper, an enzyme based amperometric electrochemical glucose sensor is reported. In such sensors, high rate of enzyme mobilization with an appropriate transducer material is desired [7]. The working of amperometric sensors are based on the detection of hydrogen peroxide (H2O2) during the enzymatic reaction by anodic oxidation [8]. Platinum is one of the most commonly used transducer electrodes used in amperometric sensors [8]. A sensitivity of 1151 μA/cm2 mM is reported for the investigated Nafion/GOx/ZnO NRs/ITO coated glass substrate electrode. The sensitivity is derived from the linear response slope obtained for a glucose concentration ranging from 0.01 – 1.6 mM. The acquired sensitivity slope is extremely high compared to peer results reported on glucose sensors based on ZnO nanocombs [11], ZnO nanoro
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