Abstract
In this work, we report the analysis of the electrochemical detection of electroactive species with band microelectrodes that operate under controlled convection. The study focuses on the determination of the collection efficiency of the analyte as a function of inlet flow velocity and microband geometry (inlaid, bumped and recessed), also providing a straightforward method for the theoretical determination of the lower detection limit. The analysis has been carried out by simulating the dimensionless mass transport with the finite element method, delivering the stationary limiting current density. Simulations have been performed on systems consisting of single and double band electrodes to investigate the trail effect on the electrochemical detection. We show that the obtained dimensionless results can be easily turned into dimensional data, providing a tool for the design of devices. The proposed method is general and can easily be extended to systems with different geometry.
Highlights
Electrochemical detection with microelectrodes can either complement other analytical techniques or be used as a stand-alone analytical solution [1–8]
Flow microelectrodes can be schematically represented as a channel with electroactive species solution flowing in, and with electrodes lying at the bottom; three major geometries are usually encountered: bumped, inlaid, and recessed [29–31]
It is necessary to consider how physical or geometrical parameters, such as fluid velocity, channel geometry, electrode shape and length, affect the current flowing at the electrode, the equilibration time, and the amount of analyte that is collected at the electrode [20,24,31–39]
Summary
Electrochemical detection with microelectrodes can either complement other analytical techniques (e.g., chromatography) or be used as a stand-alone analytical solution [1–8]. The use of microelectrodes allows high signal to noise ratio and short electrodic current equilibration times compared to macroelectrodes. Microelectrodes can be implemented in electro-analytical instrumentation where the μL scale must be used, as is the case with lab-on-chip devices [9–28]. Flow microelectrodes can be schematically represented as a channel with electroactive species solution flowing in, and with electrodes lying at the bottom; three major geometries are usually encountered: bumped, inlaid, and recessed [29–31]. It is necessary to consider how physical or geometrical parameters, such as fluid velocity, channel geometry, electrode shape and length, affect the current flowing at the electrode, the equilibration time, and the amount of analyte that is collected at the electrode [20,24,31–39]. Theoretical models have been proposed along with numerical computations, mainly based on the finite elements analysis
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