Conformation dependent non-linear impedance response of DNA in nanofluidic device

Applying high intensity electric field (>MV/m), a non-linear measurement of DNA was conducted by impedance spectroscopy. Low alternate voltage was enough to generate high field strength (0.5 MV/m) in the nanometer gap to several micrometer gap and providing non-faradaic condition. With high field strength, DNA was subjected to electrostatic forces, which induced the conformational change and motion. DNA interaction with alternated field would reflect to the non-liner responses of the impedance signal. We could differentiate the DNA characteristic based on length and conformation of 100, 500, 1000, 5000, 10000bp and λ DNA (48kbps). With this format, we obtained 4 times higher sensitivity than the conventional impedance measurement. Furthermore, the mechanism was qualitatively proofed by the visualized behavior of DNA by fluorescent microscopy.