Impedance Spectroscopy

Abstract Impedance spectroscopy (IS), also referred to as electrochemical impedance spectroscopy (EIS), is a versatile approach to investigate and characterize dielectric and conducting properties of materials or composite samples. The technique is based on measuring the impedance (i.e., the opposition to current flow) of a system that is being excised with weak alternating current or voltage. The impedance spectrum is obtained by scanning the sample impedance over a broad range of frequencies, typically covering several decades. This article starts with providing a general introduction to the theoretical background of IS and the methodology connected to impedance measurement. Then, the focus will be on applications of IS, particularly devises for in vitro monitoring of cultured cell systems that have attracted widespread interest due to demand for noninvasive, marker‐free, and cost‐effective methods.