An Electrokinetically Controlled DNA Hybridization Chip

Biosensors and more specifically biochips exploit the interactions between a target analyte and an immobilized biological recognition element to produce a measurable signal. Systems based on surface phase nucleic acid hybridization, such as modern microarrays, are particularly attractive due to the high degree of selectivity in the binding interactions. One drawback of this reaction is the relatively long time required for complete hybridization to occur, as a result of the diffusion limited reaction kinetics. In this work an electrokinetically controlled DNA hybridization microfluidic chip will be introduced. The electrokinetic delivery technique provides the ability to dispense controlled sample sizes to the hybridization array while serving to increase the mass transfer rate and therefore the reaction speed. The focus of this paper will be on the design and microfabrication of the chip, the unique H-type channel structure and electrokinetic sample delivery and washing technique, and development of the on-line hybridization scanning. Initial hybridization results presented here demonstrate that less than 5 minutes and 4.9nL of 0.5μM ssDNA sample was required (35s dispensing period followed by a 4 minute wash) for complete hybridization.