Patent ID: 7312043

Claim:
A method of characterizing the biological activity of a candidate compound comprising: placing one or more cells into an area of observation in a sample well; exposing said one or more cells to said compound; repetitively exposing said one or more cells to a series of biphasic electric fields at a rate of approximately 20 to 100 pulses per second; producing a limited spatial variation in intensity in said electric field in said area of observation of within ±10% from a mean intensity in that area; producing a controlled change in transmembrane potential predominantly in a single direction away from a starting transmembrane potential during said series of biphasic electric fields due to a continuing and additive accumulation of charge in said one or more cells over the course of said series of electric fields; and detecting said controlled change in transmembrane potential of said one or more cells by detecting fluorescence emission of a FRET based voltage sensor from an area of observation containing said one or more cells.