Inlaid Carbon Nanofiber Nanoelectrode Array as Highly Efficient Dielectrophoresis Device for Bacteria Trapping

Dielectrophoresis (DEP) is an effective microelectronic technique for trapping and manipulating biological particles in a microfluidic environment, which relies on the highly asymmetric electric field gradient created by the microelectrodes. Here we demonstrate an AC DEP technique for single-bacteria trapping using nanoelectrode arrays (NEAs) in a "points-and-lid" configuration. The NEA is based on vertically aligned carbon nanofibers (CNFs) embedded in SiO₂ matrix. The miniaturization of the electrode size provides a highly focused electric field with the gradient enhanced by several orders of magnitude. Finite element modeling indicated that the pDEP force using such NEA-based devices can be increased by over 100 times. Experiments indicated that the bacteria can be trapped instantaneously on to the exposed CNF tip with an AC voltage of ~3 V_pp. In most cases, a single E. coli bacterium is trapped at a single CNF site due to the screening effect. Such nano-DEP device allows the integration of millions of nanolectrodes deterministically in lab-on-a-chip devices that can be used for effective cell manipulating and concentration.