GEVIBench › All sensors › Mermaid2
Mermaid2
Improved CFP/YFP FRET variant of Mermaid engineered for larger ratiometric response and submillisecond activation, enabling single-trial detection of action potential trains up to 150 Hz.
- Category: VSD-FRET GEVI
- Published: 2013-08-09 — J. Physiol. 2013
- Derived from: Mermaid
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 435 nm, emission peak 529 nm (Mermaid2)
- Tags: Ci-VSP, FRET, CFP/YFP, Positive-going
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_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) | 3.5 / 10 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 | +48.5% | 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 | 0.35% (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 | 2.57% | 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) | — | 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 3.46 ms, τ_off 10.3 ms at 33°C — Tsutsui 2013, Fig. 4C
ΔF/F per 100 mV
- +48.5%, 1P — Tsutsui 2013, Fig. 4B
ΔF/F per action potential
- 2.57%, 1P — Tsutsui 2013, Fig. 6B
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -90 mV: -5%; -80 mV: -3%; -70 mV: 0%; -60 mV: 4%; -50 mV: 9%; -40 mV: 15%; -30 mV: 21%; -20 mV: 27%; -10 mV: 32%; 0 mV: 37%; 10 mV: 40%; 20 mV: 43%; 30 mV: 45%; 40 mV: 46%; 50 mV: 47% — Tsutsui 2013, Fig. 4B
Research papers using Mermaid2 (1)
- Improved detection of electrical activity with a voltage probe based on a voltage-sensing phosphatase — Tsutsui H, Jinno Y, Tomita A, Niino Y, Yamada Y, Mikoshiba K, Miyawaki A, Okamura Y, The Journal of Physiology 2013 (HEK293 cells, rat hippocampal neurons, in vitro; mouse auditory cortex, in vivo (1P); Xenopus oocytes, 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.