GEVIBench › All sensors › FlicR1
FlicR1
Red fluorescent GEVI using the same voltage-sensing domain as ArcLight.
- Category: VSD-single FP
- Published: 2016-02-24 — Journal of Neuroscience 2016
- Derived from: ElectricPk
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 570 nm, emission peak 597 nm (FlicR1)
- Plasmid: Addgene #74142
- Tags: cpmApple, Red, Fast, Positive-going
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 0.34× 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) | 3.4 / 3.7 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 | +6.6% (median of 3 measurements: +5.5%) | 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 | 0.067% (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 | 2.6% (median of 2 measurements: 2%) | 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) | 6.8 ms | Full width at half maximum of the optical spike waveform. |
| Photostability t75% @ 100 mW/mm² | 48 s | 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) | 5 | 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 6.8 ms, τ_off 7.4 ms at 22°C — Abdelfattah 2016, Table 1
- τ_on 3.4 ms, τ_off 3.7 ms at 34°C — Abdelfattah 2016, Table 1
- τ_on 17.4 ms, τ_off 14.2 ms at 25°C — Kannan 2018, Table S1
ΔF/F per 100 mV
- +6.6%, 1P — Abdelfattah 2016, Fig. 3D
- +2.54%, 1P — Milosevic 2020, Fig. 2D
- +5.5%, 1P — Kannan 2018, Fig. S2e
ΔF/F per action potential
- 2.6%, 1P — Abdelfattah 2016, Fig. 5D
- 1.4%, 1P — Beck 2019, Fig. 3d
AP width (FWHM)
- 6.8 ms at 1000 Hz sampling, Cultured rat hippocampal neurons, in vitro, 1P — Abdelfattah 2016, Fig. 5E
Brightness comparisons
- 1458× the brightness of Arch — Monakhov 2020, Table 1
- 0.18× the brightness of Ace2N-mNeon — Kannan 2018, Fig. 1j
Photobleaching
- t75% = 48 s at 100 mW/mm², 1P — Abdelfattah 2016, Fig. 3I
- t50% = 8.6 s at ~1 mW (1120 nm, 2P point scan), 2P — Abdelfattah 2016, Fig. 4C
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: -2%; -80 mV: -1%; -70 mV: 0%; -50 mV: 1%; -20 mV: 3%; 0 mV: 5%; 30 mV: 7%; 50 mV: 8% — Abdelfattah 2016, Fig. 3D
Research papers using FlicR1 (5)
- A bright and fast red fluorescent protein voltage indicator that reports neuronal activity in organotypic brain slices — Abdelfattah AS, et al., Journal of Neuroscience 2016 (HEK293 cells; rat hippocampal neurons, in vitro; rat organotypic brain slices)
- Fast, in vivo voltage imaging using a red fluorescent indicator — Kannan M, et al., Nature Methods 2018 (Mouse hippocampus and cortex, in vivo; Drosophila, in vivo)
- A high-speed, bright, red fluorescent voltage sensor to detect neural activity — Beck C, et al., Scientific Reports 2019 (HEK293T cells; cultured rat hippocampal neurons, in vitro)
- In vitro testing of voltage indicators: Archon1, ArcLightD, ASAP1, ASAP2s, ASAP3b, Bongwoori-Pos6, BeRST1, FlicR1, and Chi-VSFP-Butterfly — Milosevic MM, et al., eNeuro 2020 (HEK293 cells, in vitro)
- Screening and cellular characterization of genetically encoded voltage indicators based on near-infrared fluorescent proteins — Piatkevich KD, et al., ACS Chemical Neuroscience 2020 (HEK293T cells; cultured 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.