HVI+

Positive-going variant of chemigenetic voltage indicator HVI.

Category: Chemigenetic GEVI
Published: 2025-08-08 — Science Advances 2025
Derived from: HVI
Response polarity: positive-going (fluorescence increases on depolarization)
Spectrum: excitation peak 556 nm, emission peak 571 nm (HVI+ (Cy3b))
Tags: Ace opsin, Cy3b, Positive-going

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_EGFP)	1.11× 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)	6.8 / 5.5 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	+55%	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	0.22%	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	22.3%	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)	9.5 ms	Full width at half maximum of the optical spike waveform.
Photostability t75% @ 100 mW/mm²	3.2 min	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 6.77 ms, τ_off 5.48 ms at 25°C — Liu 2025, Table S2

ΔF/F per 100 mV

+55%, 1P, dye Cy3b — Liu 2025, Fig. 2E

ΔF/F per mV (subthreshold)

0.22%/mV — Liu 2025, Fig. 2G

ΔF/F per action potential

22.3%, 1P, dye Cy3b — Liu 2025, Fig. 2C

AP width (FWHM)

5 ms at 1000 Hz sampling, Rat, cultured hippocampal neurons, in vitro, 1P, 25°C — Liu 2025, Fig. 3B
14 ms at 200 Hz sampling, Mouse, pancreatic islet β cells, ex vivo, 1P, 37°C — Liu 2025, Fig. 6F

Brightness comparisons

0.53× the brightness of HVI — Liu 2025, Fig. S5C

Photobleaching

t75% = 381 s at 50 mW/mm², 1P — Liu 2025, Fig. S7

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: -10%; -80 mV: -5%; -70 mV: 0%; -60 mV: 6%; -40 mV: 15%; -20 mV: 25%; 0 mV: 37%; 20 mV: 47%; 40 mV: 57%; 60 mV: 67%; 80 mV: 78%; 100 mV: 88% — Liu 2025, Fig. 2E

Research papers using HVI+ (1)

Positive-going hybrid indicators for voltage imaging in excitable cells and tissues — Liu S, et al., Science Advances 2025 (Rat, hippocampal neurons, in vitro; rat, cardiomyocytes, in vitro; mouse, pancreatic islets, ex vivo)

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.