Abstract
A simple, fast, and low-cost process to fabricate arrays of copper microelectrodes (CuMEs) based on disposable electronic microchips is described. Arrays with 8 to 20 CuMEs were characterized by energy-dispersive X-ray spectroscopy and cyclic voltammetry techniques. The closest interelectrode distance in the arrays is 358 ± 22 μm, and the minor radius ranged from 10.6 to 13.5 μm. The microchips with CuMEs were sealed in epoxy resin to fabricate the rod and flat-shaped platforms, allowing the CuMEs to be addressed separately. Glucose, hydrazine, and nitrate were used as analyte models for voltammetric and amperometric detection at CuMEs arrays, showing excellent performance in batch and flow-through cells. Glucose measurements carried out with flow injection analysis system with amperometric detection at an array of 20 CuMEs showed a wide linear range (0.020-4.0 mmol L-1), high sensitivity (734.1 μA L mmol-1 cm-2), and a limit of detection of 1.7 μmol L-1.
Highlights
Copper electrodes have attractive use as electrochemical due to their low cost, good mechanical stability, high electrical conductivity, and easy use in microfabrication processes.[1,2] depending on solution composition, the copper surface can be quickly renewed by electrochemical treatment during the measurements steps to minimize its passivation due to its side-reactions with the sample or electrolyte components.[3,4] Macro and micro-copper electrodes of different shapes have been investigated for applications in environmental, industrial, clinical, and pharmaceutical fields.[5,6,7,8,9] On the other hand, the use of microelectrodes offers significant advantages over large-size electrodes, including the radial diffusion dominance, which yields a sigmoid voltammetric curve, and a reduced capacitive charging current that allows improving the sensitivity of electroanalytical sensors
The CuMEs show a minor radius of 12.4; 10.6 and 13.5 μm in arrays of 8, 14, and 20 microelectrodes, respectively, and the mean center-to-center distance between the two closest electrodes higher than 370 μm, which is more than 27 times higher than the radius in the most density packaged array
The results indicated a 58.6 nA mean anodic current value and a relative standard deviation (RSD) of 1.70%
Summary
Copper electrodes have attractive use as electrochemical due to their low cost, good mechanical stability, high electrical conductivity, and easy use in microfabrication processes.[1,2] depending on solution composition, the copper surface can be quickly renewed by electrochemical treatment during the measurements steps to minimize its passivation due to its side-reactions with the sample or electrolyte components.[3,4] Macro and micro-copper electrodes of different shapes have been investigated for applications in environmental, industrial, clinical, and pharmaceutical fields.[5,6,7,8,9] On the other hand, the use of microelectrodes offers significant advantages over large-size electrodes, including the radial diffusion dominance, which yields a sigmoid voltammetric curve, and a reduced capacitive charging current that allows improving the sensitivity of electroanalytical sensors. Soc. In this work, a low-cost and straightforward process to fabricate platforms of copper microelectrodes arrays with 8 to 20 units obtained from microchips is described.
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