Membrane potential imaging uses fluorescent voltage-sensitive dyes or genetically encoded voltage indicators (GEVIs) to monitor dynamic changes in cell membrane potential. Depolarization or repolarization induces rapid changes in probe fluorescence intensity or spectrum, enabling optical detection of millisecond-scale electrical signals. This technique provides a noninvasive method for observing electrical activity of single cells and neural networks.

such experiments are typically performed with widefield fluorescence, two-photon, light-sheet, or other high-speed imaging platforms. They require subcellular spatial precision while detecting fluorescence changes of only a few percent (ΔF/F), corresponding to rapid membrane depolarization and repolarization events on the millisecond timescale. Consequently, imaging systems must combine ultra-high temporal resolution excellent signal-to-noise performance, and photostability to minimize phototoxicity during prolonged recordings of excitable cells and neural networks.