Evaluation of Graphene and Graphene Derivatives for RF-Impedance Based Sensing
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Evaluation of Graphene and Graphene Derivatives for RF-Impedance Based Sensing Yun Xing1, Hong Huang2 and Yan Zhuang1 1 Department of Electrical Engineering, 2 Department of Mechanical and Materials Engineering, Wright State University, 3640 Colonel Glen Hwy, Dayton, 45435 ABSTRACT Graphene and its derivatives have attracted much attention for potential applications in biological sensing systems because of their unique 2D structural, surface and electronic properties. Reports on graphene - based electrochemical impedance biosensors are emerging rapidly. In this research, we have explored the RF (radio frequency) impedance –based sensing feasibility of graphene and graphene derivative materials on the coplanar waveguide (CPW) device. The transmission line based sensing experiments demonstrated clear and significant blueshifts of resonance frequencies and decrease of the resistance at and beyond resonance frequencies after graphene oxide is absorbed with DNA. The results may lead to an alternative approach in developing graphene based chemical and biosensors. INTRODUCTION Biosensors are experiencing rapid development due to their potential broad applications in detection of disease and infectious agents, and in monitoring of environmental toxins [1-11]. Impedance spectroscopy is an emerging technique for the transduction of events at the surface of an electrode. Due to its label-free feature and effectiveness to directly probe the interfacial properties, such as capacitance and electron transfer resistance, it has become an attractive method for biosensing applications. Impedance sensing in RF /MW frequency region is more attractive in part because bio-molecules exhibit rather large and distinct dielectric properties and in part because the ionic contributed conductivity of water under most physiologically system is greatly diminished [12-16]. It has been reported that tumoral cells exhibited larger values of electrical conductivity and permittivity than normal cells [17-20], which resulted in the significant changes of impedance. The feasibility of RF/microwave-based impedance sensing has recently demonstrated on detecting antibody-antigen complex of only a few nanometers thick [21-25], DNA sequence up to 40GHz [26,27], and biological interaction [28]. The extraordinary electrical properties of graphene, together with the extremely large surface area and adjustable surface chemistry [29-35], make graphene an ideal candidate for chemical/biological sensing with the potentials of high specificity and up to single atom or molecule detection sensitivity. Theoretical modeling predicted that adsorption of atoms or molecules on the graphene surface would lead to a wide range of possible changes in electronic and magnetic properties [36- 40]. A few studies have been explored to graphene-based bio/chemical sensing in the low frequency (< 1MHz) range [6-11], but the overall dynamic responses of various interactions presenting a large spectrum in time domain require impedance measurement covering a broad frequency range. Howeve
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