Abstract
High-aspect-ratio, porous membrane of vertically-aligned carbon nanotubes (CNTs) were developed through a templated microfabrication approach for electrochemical sensing. Nanostructured platinum (Pt) catalyst was deposited onto the CNTs with a facile, electroless deposition method, resulting in a Pt-nanowire-coated, CNT sensor (PN-CNT). Convective mass transfer enhancement was shown to improve PN-CNT sensor performance in the non‐enzymatic, amperometric sensing of hydrogen peroxide (H2O2). In particular, convective enhancement was achieved through the use of high surface area to fluid volume structures and concentration boundary layer confinement in a channel. Stir speed and sensor orientation especially influenced the measured current in stirred environments for sensors with through-channel diameters of 16μm. Through-flow sensing produced drastically higher signals than stirred sensing with over 90% of the H2O2 being oxidized as it passed through the PN-CNT sensor, even for low concentrations in the range of 50nM to 500μM. This effective utilization of the analyte in detection demonstrates the utility of exploiting convection in electrochemical sensing. For through‐flow at 100μLs−1, a sensitivity of 24,300μAmM−1cm−2 was achieved based on the frontal projected area (871μAmM−1 cm−2 based on the nominal microchannel surface area), with a 0.03μM limit of detection and a linear sensing range of 0.03–500μM.
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