Authors: F.A. Shaikh and V.M. Ugaz
Affilation: Texas A&M University, United States
Pages: 632 - 635
Keywords: DNA concentration, focusing, collection, metering, electric field, microfabricated, electrophoresis, lab-on-a-chip
Microfluidic technology is a key component in the development of microfabricated lab-on- a-chip systems for use in bioanalytical and biosensing applications. These devices continue to be developed to perform a variety of DNA analysis assays, however many of these applications deal with such minute amounts of DNA that it must first be preconcentrated to a detectable level. On the macroscale, this pre-concentration is typically performed using centrifugation processes which are difficult to miniaturize and interface with other microfluidic components. In order to address this issue, we have developed microfluidic devices incorporating arrays of on-chip electrodes to locally increase the concentration of DNA in solution. By applying a low voltage (~1-2V) between neighboring microfabricated electrodes positioned inside a microfluidic channel, the intrinsically negatively charged DNA fragments are induced to migrate toward and collect at the anode, thereby allowing the quantity of accumulated DNA to be precisely metered. We demonstrate the application of this technique in electrophoresis microchips to inject a narrow and well-defined DNA plug into an electrophoresis gel. This loading scheme both increases the concentration of the sample to be separated and significantly reduces the degradation in separation resolution due to the size of the injected sample plug.