Electric field effects on current–voltage relationships in microfluidic channels presenting multiple working electrodes in the weak-coupling limit

Journal Article · Fri May 23 00:00:00 EDT 2014 · Microfluidics and Nanofluidics

DOI:https://doi.org/10.1007/s10404-014-1424-9· OSTI ID:1371878

Contento, Nicholas M. ^[1]; Bohn, Paul W. ^[1]

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1. Univ. of Notre Dame, Notre Dame, IN (United States)

While electrochemical methods are well suited for lab-on-a-chip applications, reliably coupling multiple, electrode-controlled processes in a single microfluidic channel remains a considerable challenge, because the electric fields driving electrokinetic flow make it difficult to establish a precisely known potential at the working electrode(s). The challenge of coupling electrochemical detection with microchip electrophoresis is well known; however, the problem is general, arising in other multielectrode arrangements with applications in enhanced detection and chemical processing. Here, we study the effects of induced electric fields on voltammetric behavior in a microchannel containing multiple in-channel electrodes, using a Fe(CN)₆ ^3/4- model system. When an electric field is induced by applying a cathodic potential at one inchannel electrode, the half-wave potential (E_1/2) for the oxidation of ferrocyanide at an adjacent electrode shifts to more negative potentials. The E_1/2 value depends linearly on the electric field current at a separate in-channel electrode. The observed shift in E_1/2 is quantitatively described by a model, which accounts for the change in solution potential caused by the iR drop along the length of the microchannel. The model, which reliably captures changes in electrode location and solution conductivity, apportions the electric field potential between iR drop and electrochemical potential components, enabling the study of microchannel electric field magnitudes at low applied potentials. In the system studied, the iR component of the electric field potential increases exponentially with applied current before reaching an asymptotic value near 80 % of the total applied potential. The methods described will aid in the development and interpretation of future microchip electrochemistry methods, particularly those that benefit from the coupling of electrokinetic and electrochemical phenomena at low voltages.

• Research Organization: Univ. of Notre Dame, IN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: FG02-07ER15851
• OSTI ID: 1371878
• Journal Information: Microfluidics and Nanofluidics, Vol. 18, Issue 1; ISSN 1613-4982
• Publisher: Springer
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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electric field
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