ElectricPk

Early voltage indicator using a cpGFP inserted into a voltage-sensing domain.

Category: VSD-cpGFP GEVI
Published: 2012-09-06 — PLoS ONE 2012
Response polarity: negative-going (fluorescence decreases on depolarization)
Spectrum: excitation peak 489 nm, emission peak 511 nm (ElectricPk)
Plasmid: Addgene #40314
Tags: cpEGFP, Fast

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_EGFP)	0.32× EGFP	Molecular brightness relative to EGFP (extinction coefficient × quantum yield, or a measured ratio). Sensors not measured against EGFP directly are placed through a chain of pairwise brightness comparisons, combined by geometric mean.
Kinetics τ_on / τ_off (ms)	2.2 / 36 ms	Activation / decay time constants in ms (amplitude-weighted mean τ for multi-exponential fits). The value shown averages the measurements made at physiological temperature (≥33 °C); if there are none, it is the measurement closest to 33 °C.
ΔF/F per 100 mV	-1.2%	Steady-state fluorescence change for a 100 mV depolarization step (−70 → +30 mV); the sign gives the polarity. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting.
ΔF/F per mV	0.02% (estimated from the F–V curve)	Subthreshold sensitivity: fluorescence change per mV near rest (−90 to −50 mV). Where no value is reported directly, it is estimated from the F–V curve.
ΔF/F per AP	0.7%	Fluorescence change per single action potential in neurons. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting.
AP width (FWHM, ms)	4.4 ms	Full width at half maximum of the optical spike waveform.
Photostability t75% @ 100 mW/mm²	—	Time for fluorescence to fall to 75% of its initial value under one-photon illumination, linearly dose-scaled to 100 mW/mm² (t50% is used where the 75% crossing falls inside a fast initial transient). Two-photon curves are not dose-scaled and are excluded.
Papers using it (N_used)	1	Number of published research papers, tracked by GEVIBench, that used the sensor for an experiment (a popularity / track-record measure).

Measurements and sources

Kinetics

τ_on 2.24 ms, τ_off 35.6 ms at 35-37°C — Barnett 2012, Fig. 5A

ΔF/F per 100 mV

-1.2% (peak), 1P — Barnett 2012, Fig. 4A

ΔF/F per action potential

0.7%, 1P — Barnett 2012, Fig. 7C

AP width (FWHM)

4.4 ms at 2000 Hz sampling, Mouse, hippocampal neurons, in vitro, 1P, 35-37°C — Barnett 2012, Fig. 7B

Brightness comparisons

0.32× the brightness of EGFP — doi:estimated from cpEGFP (GCaMP3) EC×QY vs EGFP

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -150 mV: 1.4%; -120 mV: 1%; -100 mV: 0.6%; -70 mV: 0%; -50 mV: -0.4%; 0 mV: -1%; 30 mV: -1.4% — Barnett 2012, Fig. 6B

Research papers using ElectricPk (1)

A Fluorescent, Genetically-Encoded Voltage Probe Capable of Resolving Action Potentials — Barnett L, Platisa J, Popovic M, Pieribone VA, Hughes T, PLoS ONE 2012 (HEK293 cells, mouse hippocampal neurons, in vitro)

Data and citation

llms.txt — summary for language models
llms-full.txt — every sensor in full (Markdown)
gevis.json — all values and measurements with sources (JSON)
gevis.csv — one row per sensor (CSV)

Cite GEVIBench as: Adam E. Cohen and Daozheng Gong (2026). Voltage imaging: A practical guide. Neuron. https://doi.org/10.1016/j.neuron.2026.08.002

Generated from the GEVIBench database on 2026-10-12.