Chloride Ion Detection by InN Gated AlGaN/GaN High Electron Mobility Transistors
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1202-I06-05
Chloride Ion Detection by InN Gated AlGaN/GaN High Electron Mobility Transistors Byung-Hwan Chu1, Hon-Way Lin2, Shangjr Gwo2, Yu-Lin Wang3, S. J. Pearton3, J. W. Johnson4, P. Rajagopal4, J. C. Roberts4, E. L. Piner4, and K. J. Linthicum4, and Fan Ren1 1
Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 Department of Physics, National Tsing-Hua University, Hsinchu, 30013 Taiwan 3 Department of Material Science and Engineering, University of Florida, FL 32611 4 Nitronex Corporation, Durham, NC 27703 2
ABSTRACT Chloride ion concentration can be used as a biomarker for the level of pollen exposure in allergic asthma, chronic cough and airway acidification related to respiratory disease. AlGaN/GaN high electron mobility transistor (HEMT) with an InN thin film in the gate region was used for real time detection of chloride ion detection. The InN thin film provided surface sites for reversible anion coordination. The sensor exhibited significant changes in channel conductance upon exposure to various concentrations of NaCl solutions. The sensor was tested over the range of 100 nM to 100 µM NaCl solutions. The effect of cations on the chloride ion detection was also studied. INTRODUCTION Chlorine is a widely used chemical used in the production of paper products, antiseptics, food, insecticides, paints, petroleum products, plastic, medicine, textiles and solvents. One of its main uses includes sanitizing drinking water supplies and waste water. Chlorine readily reacts with organics to form harmful disinfection by-products that may be carcinogenic. Therefore, it is important to effectively monitor chlorine residuals, typically in the form of chloride ion concentration, to ensure public health [1, 2]. Chloride ion is also an essential mineral in our bodies. Our kidneys balance the chloride in body fluids, such as serum, blood, urine, and exhaled breath condensate (EBC). Abnormal chloride ion concentration in serum may serve as an indicator for diseases such as renal diseases, adrenalism, and pneumonia [3]. Much research has been focused on the analysis and collection of EBC to develop a noninvasive method to diagnose patients. Chloride ion concentration can be a biomarker for the level of pollen exposure in allergic asthma, chronic cough and airway acidification related to respiratory disease [4-6]. Also, the Clconcentration in EBC can be used as a reference for the other biomarkers in the EBC to estimate the dilution effect from the humidity in the ambient during the EBC collection [7]. Current analytical methods for measuring chloride ion include colorimetry, ion-selective electrode, X-ray fluorescence spectrometry, activation analysis, and ion chromatography [8-13]. However, these methods involve high expertise levels and require expensive instruments that can’t be readily transported. Therefore, it would be beneficial to develop a fast and accurate sensor that has a low detection limit and low production cost. InN is a small bandgap semiconductor material, which has potential
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