Measurement of local electric field in microdevices for low-voltage electroporation of adherent cells

In this study, we present the measurement of the local electric field in a microdevice designed for electroporation of adherent cells. The microdevice mainly consists of a coverslip that has a transparent conductive layer and an insulating layer. The insulating layer has small cylindrical holes that focus the field lines to reduce the voltage required for electroporation. We estimated the local electric field at the cells by analyzing the ionic current based on a simple equivalent circuit model and investigated the correlation between the field strength and the efficiency of electroporation. We prepared various designs with matrices of electrodes with diameters ranging from 5 to 10 mu m and center-to-center distances between adjacent electrodes ranging from 20 to 75 mu m to perform systematic and statistical investigations. Furthermore, we discussed the efficiency of the electrode design in terms of the degree of field focusing, the applicability of optical observations, and the probability of positioning cells on the electrodes.