Impedance Spectroscopy Of Biological Cells

Abstract

ABSTRACTA six-electrode impedance chamber is used to perform wide-bandwidth (10 Hz − 3 MHz), sensitive impedance measurements to evaluate the electrical properties of living cells under normal physiologic conditions. The high sensitivity in these measurements, compared to cell suspension techniques, is accomplished by embedding the cells into the pores of a filter, creating a “pseudoepithelium” and markedly reducing the current shunt pathways around the cells. The shunt resistance for each cell is between 6 − 7 × 107 Ω. The cellular geometry and the portion of cell membrane under measurement are precisely controlled in this method. This technique produces a multi-parallel, whole-cell, patch-clamp like structure for 3.3 × 105 cells. The advantages of this technique, general insights, and improvements in impedance measurements will be discussed. Effects of bandwidth mismatch between high-input impedance amplifiers, reference point drift due to solution resistivity changes, and the use of porous electrodes will be covered. Lastly, the ability to electroporate the cell membrane contributes another unique way to study the impedance of living cells.