An ultrasensitive label-free electrochemical impedimetric DNA biosensing chip integrated with a DC-biased AC electroosmotic vortex

Abstract

A label-free electrochemical impedance spectroscopy (EIS)-based DNA biosensing chip is integrated with DC-biased AC electroosmotic (ACEO) stirring using concentric double ring-single disk electrodes to greatly promote the hybridization efficiency of 20-base target DNA (tDNA) fragments. The +0.7V-biased ACEO flow of 3Vpp and 380Hz applied at the outer ring electrode (ORE) and inner ring electrode (IRE) can drive the tDNA-containing 1mM Tris solution from the ORE to the probe's DNA-modified disk electrode (DE) to achieve 90% saturation hybridization within 141s. The DNA biosensor used Pd-deposited ORE as the pseudo-reference electrode and IRE as the counter electrode for on-chip-type three-electrode EIS measurement, and presented good linearity and repeatability in the range of 1aM–10pM and exhibited an ultrasensitive detection limit of 0.5aM. The label-free EIS-based DNA sensing chips with integrated DC-biased ACEO vortex can achieve rapid hybridization, high selectivity and ultrasensitive detection for different tDNA samples.