AC dielectrophoretic manipulation and electroporation of vaccinia virus using carbon nanoelectrode arrays

This paper reports the capture and detection of vaccinia virus particles based on AC dielectrophoresis (DEP) and electrochemical impedance measurements employing an embedded vertically aligned carbon nanofiber (VACNF) nanoelectrode array (NEA) versus a macroscopic indium-tin-oxide (ITO) transparent electrode in a "points-and-lid" configuration. The nano-DEP device was fabricated by bonding two SU-8 covered electrodes patterned using photolithography. The bottom electrode contains a 200 × 200 μm² active region on a randomly distributed NEA and the top electrode contains a microfluidic channel in SU-8 spin-coated on ITO to guide the flow of the virus solution. The real-time impedance change was measured during DEP capture and validated with fluorescence microscopy measurements. The NEA was able to capture virus particles with a rather low AC voltage (∼8.0 V peak-to-peak) at 1.0 kHz frequency as the particles were passed through the fluidic channel at high flow velocities (up to 8.0 mm/s). A concentration detection limit as low as ∼2.58 × 10³ particles/mL was obtained via impedance measurements after only 54 sec of DEP capture. At the low AC frequencies (50.0 Hz or less), the high electric field at the exposed VACNF tips induced electroporation of the DEP-captured virus particles, which was validated by fluorescence emission from the dyes staining lipophilic membrane and internal nucleic acid, respectively. This study suggests the possibility of integration of a fully functional electronic device for rapid, reversible and label-free capture and detection of pathogenic viruses, with a potential of generating electroporation to the captured the virus particles for further biochemical study.