Highly sensitive and reusable Pt-black microfluidic electrodes for long-term electrochemical sensing

Abstract

Highly sensitive, long-term stable and reusable microfluidics electrodes have been fabricated and evaluated using H 2O 2 and hydroquinone as model analytes. These electrodes composed of a 300 nm Pt-black layer situated on a 5 μm thick electrodeposited Au layer, provide effective protection against electrooxidation of an underlying chromium adhesion layer. Using repeated cyclic voltammetric (CV) sweeps in flowing buffer solution, highly sensitive Pt-black working electrodes were realized with five- (four-) decade linear dynamic range for H 2O 2 (hydroquinone) and low detection limit of 10 nM for H 2O 2 and 100 nM for hydroquinone. Moreover, high sensitivity for H 2O 2 was demonstrated at low (0.3 V vs. Ag/AgCl) oxidation potentials, together with long-term stability and reusability for at least 30 days. Microfluidic flow was employed for desorption and reactivation of the nominally planar Pt-black electrodes. Such electrocatalytic surface architecture should be appropriate for long-term electrochemical detection of various molecules and biomolecules as well as in reusable immunoassay configurations.