Nanaostructure integrated microfluidic based biosensors
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A novel continuous monitoring electrochemical biosensor with enhanced sensitivity was developed. This biosensor exhibited high current response compared to that of a conventional channel biosensor. Present channel biosensors exhibit very low current response in detecting electroactive species, which is caused by a small electrode area available for sensing and poor electrode design. For example, these types of biosensor were fabricated on a MEMs platform, so the electrode area available for enzyme immobilization and species detection is small. In the conventional design, an enzyme electrode is placed upstream and a working or detector electrode is placed next to the enzyme surface downstream. Analyte flowing through the channel reacts with the enzyme, and the product is produced at the enzyme electrode is detected at the detector electrode. During sensing, some of the product diffuses out of the channel without being detected at the detector electrode causing low current. In this project, we combined experimental and computational approach to address the two critical issues for the development of a high sensitive channel biosensor. In an experimental approach, the surface area of the electrodes was increased by incorporating vertically aligned nanopillars onto the electrodes. The nanopillars were incorporated by combining techniques such as anodization, photolithography and electrodeposition. In computational approach, various electrode designs were evaluated with respect to the current response using a finite element method with COMSOL Multiphysics. The experimental results showed that the developed channel biosensor incorporated with nanopillars exhibited enhanced current response than the conventional device. Simulation results showed that the interdigitated array electrode design has significantly improved the current response compared to the conventional electrode design. Moreover, the width and spacing of the interdigitated arrays affected the current response and the maximum current response was found when the width and spacing were much minimized.