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MP20:Improving the Versatility of Microchip-Based Electrochemical Detection: Use of Compact Discs for Electrode Fabrication and Integration of Segmented Flow

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Douglas Kirkpatrick, Christiana Antwi, Laura A. Filla, and R. Scott Martin

Saint Louis University


This poster will present two different strategies to increase the versatility of electrochemical detection in microchip-based systems. First, the integration of electrodes fabricated from gold-layered compact discs (CDs) for amperometric detection in microchip-based systems will be presented. This approach greatly reduces the device cost when compared to commonly used gold-sputtered glass plates. A unique fabrication procedure was developed that allows for electrodes as small as 10 microns to be patterned. These electrodes show wide versatility in electrochemical applications. Unmodified single and dual electrodes used with microchip-based flow analysis were able to detect the oxidation and reduction of catechol. The ability to form a mercury amalgam is also demonstrated, which selectively detects thiols at low potentials. Lastly, palladium was electrodeposited on the surface of an electrode, which allowed for the integration of a decoupler for microchip capillary electrophoresis.
This poster will also describe how an increase in temporal resolution was obtained using droplets of aqueous analyte suspended in an immiscible oil phase. In microdialysis, temporal resolution is lost by dispersion of analyte throughout the capillary while in transit to the detector. The utilization of an additional phase maintains a concentration gradient for long periods by preventing dispersion outside of the aqueous phase. Droplets were created off-chip in a simple micro-tee, connected by perfluoroalkoxy (PFA) tubing to a microchip using a unique transfer method. Once on chip, droplets were desegmented via a hydrophilic/hydrophobic interface created prior to chip operation by a one second corona discharge. Hydrophilic droplets travel down a special tapered channel completely isolated from any oil, allowing analysis with electrochemical detection.


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