Effects of electrode geometry and cell location on single-cell impedance measurement.

Measurements on single cells provide more accurate and in-depth information about electrical properties than those on pathological tissues. The relationship between electrode geometry and the location of a cell on microfluidic devices greatly affects the accuracy of single-cell impedance measurement. Accordingly, this study presents numerical solutions from the FEM simulation of the COMSOL multiphysics package and experimental measurements to analyze the effects of electrode geometry and cell location on microfluidic devices. An equivalent electrical circuit model is developed to obtain the impedance and sensitivity of various cell locations on various electrode geometries using FEM simulation. According to the simulation results, the parallel electrodes have the largest sensing area (39 microm(2)) and the highest sensitivity (0.976) at a voltage of 0.1 V and a frequency of 100 kHz. Increasing the width of electrodes provides a large sensing area but reduces sensitivity, whereas decreasing the gap between electrodes increases both sensing area and sensitivity. In experiments, the results demonstrate that the magnitude is inversely proportional to the overlap area of the cell and electrodes. Moreover, the impedance of single HeLa cells measured at various cell locations can be modified using equations determined from the modeling and experimental results.