My lab has developed the label-free electrochemical impedance spectrum (EIS) technique to quantitatively detect the DNA hybridization of virus, such as Geminivirus and Dengue virus, small molecules, such as salbutamol and progesterone, and large molecules, such as specific antibodies. Furthermore, the EIS-based biosensors can integrate AC electrokinetics (ACEK)-controlled flow to concentrate analytes and promote the hybridization efficiency and immunoreactive reaction between antigens and antibodies or between target DNA and probe DNA fragments. The chip of patterning a double ring-single disk electrode array integrated with a DC-biased ACEK vortex can reach the hybridization plateau in 2.5 min when using a 20 mer thiolated DNA fragment as a probe. The limit of detection (LOD) was as low as 0.5 aM, which is sensitive enough to perform the nucleic acid detection without polymer chain reaction. Furthermore, multi-double ring electrodes and a single disk elec-trode integrated with a DC-biased ACEK vortex can reach the immunoreactive plateau in 8 min with the LOD of 32 pg/mL for the detection of protein. The bioaffinity impedimetric sensing chips integrated with the ACEK vortex show great promise for the fast, sensitive and easy detection of different analytes.

DNA and Biomarker DetectionElectrochemical Impedance Spectrum (EIS)AC Electrokinetic Vortexes