Key Performance:
1)    Negative polarity (fluorescence decreases with depolarization);
2)    >6-fold improved photostability compared to state-of-the-art eFRET GEVIs (pAce, Ace-mNeon2) under one-photon illumination;
3)    14.5% ΔF/F per action potential with SNR of ~9.20 in cultured neurons (comparable to Ace-mNeon2);
4)    ~1.6-fold brighter than Ace-mNeon2 in mammalian cells;
5)    Fast kinetics (τ_on = 1.75 ± 0.32 ms; τ_off = 1.14 ± 0.25 ms);
6)    3-to >10-fold extension in functional recording duration for spike detection;
7)    Exceptionally slow SNR decay (only 13% loss over 30 minutes at 5 mW/mm²);
8)    Ultra-stable in vivo – routinely >30 minutes, occasionally up to 80+ minutes in behaving mice;
9)    4.6-fold slower SNR decrease compared to Ace-mNeon2 in vivo;
10)  Functional under scanless two-photon excitation (~18% ΔF/F with SNR 5-10).

Applications:
1)    Ultra-long voltage imaging in behaving mammals (30-80+ minutes continuous trials);
2)   Extended in vivo recordings across multiple neuron types (pyramidal neurons, PV+ interneurons, VIP+ interneurons, cholinergic interneurons);
3)    Multi-region voltage imaging (hippocampus CA1, visual cortex, striatum);
4)    Long-term synaptic plasticity studies and circuit dynamics during behavior;
5)    Intracranial electrical stimulation studies and neuromodulation research;
6)    Trial-based sensory adaptation and skill learning experiments;
7)    Widefield population voltage imaging with minimal photobleaching;
8)    Two-photon voltage imaging in deep brain tissues;
9)    Chronic neuronal activity monitoring in disease models.