The Search of Cell Positioning in Electrorotation Measurements

Electrorotation (ROT) is a wide-used technique to measure the dielectric properties of cells. But the position of the cell in the measurement brings the error for the non-uniform of the ROT torque. In this paper, The Schwarz-Christoffel mapping (SCM) method was used for obtaining the accurate analytical solution of the ROT torque and the dielectrophoretic (DEP) force distribution in the circular electrode structure. A roughly uniform electric field in the near central region of the circular electrode structure for ROT measurement was defined, which the radius is about 36% of the circular electrode structure´s radius. The more, we found that before the ROT measurement, an additional conventional negative dielectrophoretic (nDEP) step can assist the cells well positioning. The analysis of the distribution of the DEP force at nDEP step was described in the paper also using SCM method.