Electrical molecular focusing for laser induced fluorescence based single DNA detection

This paper details an electrokinetic focusing technique that significantly enhances the detection efficiency for laser induced fluorescence (LIF) based molecular sensing by concentrating fluorescence labeled molecules in a tiny probe region. 3-D electrodes were fabricated to generate wider and denser electric fields toward the probe region in the microchannel. The generated electric field is able to focus flowing DNA molecules to widths as narrow as 3 /spl mu/m in a 120 /spl mu/m wide channel. A single molecule detection technique is developed and the enhancement of detection efficiency by using the focusing method is demonstrated.