Figure 8

Schematic drawing of an ECIS array and principle of the electric cell-substrate impedance sensing (ECIS) method. Cell layers are grown to confluence on integrated gold-film electrodes. An applied AC current flows between small working electrodes and the larger counter electrode using normal culture medium as an electrolyte. By a variation of the frequency ω, a spectrum can be obtained. Applying higher frequencies the current flow is dominated by the capacity of the total system, at mid-range frequencies the ohmic resistance of the total system is mirrored. Adapted from Applied BioPhysics, Inc [28].