The ECIS 9600 monitors cell grown in arrays having a standard 96-well plate configuration and footprint. The consumable arrays, easily connect to the instrument, using a single lever to make electrical contact. The instrument can scan all 96 wells in approximately 30 seconds, making impedance measurements at a fixed AC frequency (three frequencies are available). Using very weak current, the impedance of a small active electrode in each well is measured in real time to provide nearly immediate indications of cell activity and response to agents. The ECIS 9600 can also be programmed to applied elevated fields for cell migration measurements via an automated wound-healing assay (PNAS 101; 1554-1559 (2004)). The same high fields can also be used at shorter duration to electroporate membrane-impermeable compounds into cells for analysis. Assays can also be devised for many ECIS applications, including signal transduction, cell invasion, cell integrin-ECM interactions and in vitro toxicology.