Transverse electrodes for improved DNA hybridization in microchannels

The present study examines the modality, in which localized transverse electric fields can be successfully employed, to augment the rate of DNA hybridization at the capturing probes that are located further downstream relative to the inlet section of a rectangular microchannel. This is in accordance with an enhanced strength of convective transport that can be achieved, on account of increments in the wall zeta potential at the transverse electrode locations. In the present model, the overall convective transport, which is an implicit function of the magnitude and the location of the transverse electrical field being employed, is essentially coupled with the surface kinetics of the bare silica wall and also the kinetics that are involved in the dual mechanisms of DNA hybridization. Parameters that govern the overall transport phenomena, such as the pH of the inlet buffer, the length of the transverse electrodes, and the voltages at which these electrodes are maintained are critically examined, in an effort to obtain an optimized wall pH distribution, which in turn can ensure favorable DNA hybridization rates at the capturing probe locations. Practical constraints associated with the upper limits of the strength of the transverse electrical fields that can be employed are also critically analyzed, so as to ensure that an optimized rate of DNA hybridization can be achieved from the bio-microfluidic arrangement, without incurring any adverse effects associated with the overheating of the DNA molecules leading to their thermal denaturation. (c) 2007 American Institute of Chemical Engineers.