A label-free impedimetric DNA sensing chip integrated with AC electroosmotic stirring

AC electroosmosis (ACEO) flow and label-free electrochemical impedance spectroscopy are employed to increase the hybridization rate and specifically detect target DNA (tDNA) concentrations. A low-ionic-strength solution, 6.1 μS/cm 1 mM Tris (pH 9.3), was used to produce ACEO and proved the feasibility of hybridization. Adequate voltage parameters for the simultaneous ACEO driving and DNA hybridization in the 1 mM Tris solution were 1.5 Vpp and 200 Hz. Moreover, an electrode set with a 1:4 ring width-to-disk diameter ratio exhibited a larger ACEO velocity above the disk electrode surface to improve collecting efficiency. The ACEO-integrated DNA sensing chips could reach 90% saturation hybridization within 117 s. The linear range and detection limit of the sensors was 10 aM–10 pM and 10 aM, respectively. The label-free impedimetric DNA sensing chips with integrated ACEO stirring can perform rapid hybridization and highly-sensitive detections to specifically measure tDNA concentrations.

► We developalabel-free impedimetric DNA biosensor integrated with ACEO stirring.
► 1 mM Tris can compromise the electrolyte requirements for DNA hybridization and ACEO stirring.
► Under ACEO stirring of 1.5 Vpp and 200 Hz, 90% saturation hybridization is achieved within 117 s.
► The hybridization is estimated by the change in electron transfer resistance in 10 mM TES (pH 7.0).
► The linear range and detection limit of the sensing chips is 10 am–10 pm and 10 am, respectively.