Microcapillary-assisted dielectrophoresis for single-particle positioning.

Here, we demonstrate microcapillary-assisted dielectrophoresis (μC-DEP), a new capability for precise positioning of particles or biological cells in applications such as dynamic assays. The method largely derives from a need to evade the challenges faced with hydrodynamic trapping of particles or cells at microcapillaries typically realized through brief application of suction. Microcapillaries here serve a dual purpose by firstly squeezing field lines to define localized positive DEP traps and then establishing an exclusive access to the trapped cell for probing. Strength of the traps is presented through numerical results at various excitation frequencies. Their effectiveness is shown experimentally against relevant solution conductivities using 10 μm polystyrene microspheres. Usefulness of the method for positioning individual cells is demonstrated via experimental results on cell viability and single-cell impedance spectroscopy.