A method for label-free electrical impedance sensing
of DNA is proposed, and experimentally demonstrated
using a micro Electrical Impedance Spectroscopy (μ-
EIS) device. The method features not only the detection
of DNA without any labelling, but also the control
of the conformation that would enhance the electrical
impedance signal. In order to conduct semiautomated
measurements controlled by an external
PC, a microfluidic chip made of a silicone elastomer
of polydimethylsiloxane (PDMS), a measurement chip
embedded with micro-electrodes, and a micropump
chip are fully integrated in the μ-EIS device. The
μ-EIS device is capable of detecting DNA concentrations
of a few nM in aqueous solution of a few pL in
volume by virtue of the conformation-enhanced nonlinear
impedance response. As a first demonstration
of conformational-change-induced DNA analysis, the
frequency and the electric field strength dependence
of various lengths of DNA are evaluated.
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