Label-Free Noninvasive Cell Characterization: A Methodology Using Broadband Impedance Spectroscopy

As an electrical engineer, I like to view everything, large or small, in terms of an equivalent circuit of resistors, capacitors, inductors, and other components. To help me understand cell biology, I attempted to put together a simple equivalent circuit for a cell and validate it by electrical measurements. I soon found sympathy with far-sighted physical scientists and engineers from a century ago whose knowledge of biology was as poor as mine is now?not because they were too lazy to learn but because, back then, the knowledge did not exist. They made me sweat because, despite working with a suspension (mixture) of millions of cells, they gained insight into a single cell with the help of Maxwell [1] and Wagner [2].