Cell polarization and DEP response. Light green circle represents a cell and the dark green circle is the nucleus. (A) When the electric field is off ions are randomly oriented around the cell (no polarization). (B) Turning on the electric field causes ions to redistribute and align around the cell (polarization). The nucleus is not expected to reorient in the cell with polarization. (C) After polarization, cell movement toward the low strength part of the AC electric field, away from electrodes, is negative DEP (nDEP). (D) In positive DEP (pDEP), cells move toward the high strength part of the electric field, attracted to electrode edges. Yellow rectangles in (C) and (D) represent electrodes and dashed lines are the electric field lines. (C) and (D) adapted with permission from [33].