MP21:Sinkala:Electrode Calibration with a Microfluidic Flow Cell for Fast Scan Cyclic Voltammetry
Elly Sinkala1 James E. McCutcheon2 Mitchell F. Roitman2 David T. Eddington1
1. Department of Bioengineering and 2. Department of Psychology, University of Illinois at Chicago
Fast-scan cyclic voltammetry (FSCV) is a common analytical electrochemistry tool used to measure chemical species. It has recently been adapted for measurement of neurotransmitters such as dopamine in awake and behaving animals (in vivo). Electrode calibration is an essential step in FSCV to relate observed current to concentration of a chemical species. However, existing methods require expensive components and more importantly produce inconsistent calibrations. To this end, a microfluidic flow cell (µFC) was developed as a simple device to switch between buffer and buffer with a known concentration of the analyte of interest – in this case dopamine - in a microfluidic Y-channel. The ability to quickly switch solutions reduced variability in current responses, which yielded better electrode calibrations for concentration measurements. The µFC reduced the noise in the electrochemical recordings with the removal of external electrical components and produced linear calibrations over a range of concentrations. To demonstrate this, an electrode calibrated with the µFC was used in FSCV recordings from a rat during the delivery of food reward – a stimulus that reliably evokes a brief increase in current due to the oxidation of dopamine. Using the linear calibration, dopamine concentrations were determined from the current responses evoked during the behavioral task. The µFC is an inexpensive device with the ability to calibrate FSCV electrode responses to chemical species for both in vitro and in vivo experiments with superior response times and accuracy.
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