Title: Graduate Student
Email: davidf@ku.edu
Since the introduction of the “lab-on-a-chip” concept, the use of microchip CE systems has grown to include portable devices for uses such as on-site and point-of-care analysis. Electrochemical detection has become more common in a microfluidic platform because the analytical performance is not diminished when the electrodes are miniaturized, as is the case with optical modes of detection. The use of carbon electrodes is of interest in EC detection due to their low cost, large potential widow, and low background noise. Carbon electrodes have previously been employed with microchip CE by inserting a carbon fiber or carbon paste into a microchannel on a polymer substrate. A disadvantage of this approach is that the electrodes are not microfabricated, which prevents the electrode from being mass produced. An improved approach for fabricating carbon electrodes involves pyrolyzing photolithographically patterned photoresist on fused silica plates. This method of fabrication is based on well-established techniques that have been employed for the construction of microelectronics. Fabrication of PPF electrodes in this manner not only allows for high throughput production, but it also produces electrodes that are more rugged and reproducible. The capabilities and analytical performance of the integrated microchip is being evaluated using dopamine (DA), ascorbic acid (AA), and norepinephrine (NE) as model compounds.
Preliminary analysis of DA shows the response of the PPF electrodes to be linear from 10 to 500 µM (r2 = 0.998) while obtaining a LOD of 5 µM (S/N = 3). Further studies involving DA, AA, and NE will evaluate characteristics such as ion selectivity, sensitivity, efficiency and reproducibility. Selectivity will be further enhanced by employing a dual-electrode configuration for selective detection of species exhibiting chemically reversible redox reactions. These characteristics will be directly compared to existing techniques illustrating the abilities of PPF to perform electrochemical detection in microfluidic CE microchips.
