Highly selective and sensitive DNA measurement by microelectrical impedance spectroscopy

A novel μ-EIS (microelectrical impedance spectroscopy) device for label free analysis of DNA are developed and experimentally demonstrated. The feature of μ-EIS system is not only detecting DNA without any labelling, but also controlling the conformation that would enhance the EIS signal. The μ-EIS system is fully integrated with a microfluidic network made of polydimethylsiloxane (PDMS), a micromeasurement electrode and a micropump in order to conduct a semiautomated measurement controlled by an external PC system. The micro EIS system is capable of detecting the DNA concentration of a few nM in aqueous solution of a few pl in volume by virtue of the conformation enhanced impedance response. As a first demonstration of conformational change induced DNA analysis, the frequency and the electric field strength dependence of various length and concentrations of DNA were evaluated.