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New Reconfigurable Biosensor Technique in a Microfluidic System
Keywords: BioMEMS, Biosensors, Reconfigurable
Many MEMS biosensors are designed to be disposable, taking advantage of low cost materials and batch fabrication. Disposable MEMS biosensor chips are very attractive for medical applications where it is difficult to wash all residues in microfluidic channels and sensing surfaces. On the other hand, reusable and reconfigurable biosensors are useful where detail calibration of sensors is required such as in biochemical science and analytical chemistry. Electrochemical desorption of SAMs has been studied to immobilize different receptors or to reuse biosensors and its theoretical mechanism has been well established. However, no one has demonstrated SAM desorption can be practically useful as reusable and reconfigurable biosensors in microfluidic systems. That is because i) when reductive potential is applied to the SAM-coated electrode, the opposite electrode peels off and ii) electrolysis occurs at similar voltage of the SAM desorption. Several reseach groups desorbed SAM in a strong alkaline electrolyte to prevent hydrogen evolution; however, most biosensors need to operate in a physiologically relevant medium such as PBS (pH=7.4) and few research have been active in such physiological solutions. In this paper, we present a technique to form reconfigurable biosensors in microfluidic systems overcoming aforementioned limitations. We report a reconfigurable biosensor platform in microfluidic systems using electrochemical desorption of self-assembled monolayers (SAMs). By applying a low DC voltage (0.9V) between two electrodes, the sensing surface resets to be reusable and reconfigurable; streptavidin-bound COOH-SAM completely desorbs and CH3-terminated SAM forms on the sensing surface to capture fibrinogen in a microfluidic device. The bio-molecular interactions are monitored by SPR (Surface Plasmon Resonance) in real time and ellipsometry and cyclic voltammetry are used to evaluate the results. This technique is useful when a biosensor needs to be reconfigured to capture different molecules.
Seokheun Choi, Research Assistant
Arizona State University
Tempe, AZ

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