Electrochemical Sensing with High Aspect Ratio Carbon Nanotube Platforms

Increased sensitivity of electrochemical sensors is important for detection of low analyte concentrations. A unique flow-through sensor is demonstrated by depositing nanostructured platinum catalyst onto high aspect ratio, porous membranes of vertically-aligned carbon nanotubes (CNTs). Convective mass transfer enhancement was shown to improve the platinum-nanowire-coated CNT (PN-CNT) sensor performance in amperometric sensing of hydrogen peroxide (H2O2). Over 90% of the H2O2 was oxidized as it passed through the PN-CNT sensor, even for low concentrations in the range of 50 nM to 500 μM. This effective utilization of the analyte in detection demonstrates the utility of exploiting convection in electrochemical sensing. At a 100 μL s-1 flow rate, a sensitivity of 24,300 μA mM-1 cm-2 was achieved based on the frontal projected area, with a 0.03 μM limit of detection and a linear sensing range of 0.03-500 μM. Glucose oxidase was also functionalized unto the surfaces of PN-CNT sensors by polymer entrapment to enable detection of low glucose concentrations.