Tunable dielectrophoresis for sheathless 3D focusing

We report on a novel tunable insulator-based dielectrophoresis (TiDEP) for three-dimensional, sheathless, single-stream cell and bacteria focusing. For the first time, objects as small as sub-micron sized bacteria are continuously focused in the center of a channel without sheath flows. TiDEP is realized by sandwiching a 3D microfluidic channel with high aspect ratio sidewalls between two conductive, featureless indium tin oxide (ITO) glass substrates. The tunable electric field pattern is realized by deforming the channel´s sidewalls to change its cross-sectional geometry. Compared to prior DEP works, this new TiDEP can provide a long DEP interaction distance to focus small objects into a single stream in the center of a channel in high-speed flows.