Table 1.

Summary of VSD attributes

AttributeElectrochromicFRETPeT
Nature of translocating chargeElectronLipid soluble anionElectron
Forward charge shift occurs whenPhoton absorptionMembrane depolarizationQuenching
Reverse charge shift occurs whenPhoton emission or radiationless decayMembrane repolarizationElectron-hole recombination
Fractional charge x Fraction of total voltage∼0.10.4–0.6∼0.5
Δ energy for 100 mV ΔV0.003–0.02 eV0.06 eV0.05 eV
Comparison energyPhoton energykTkT
1.5–2 eV0.026 eV0.026 eV
Extended rigid fluorophore needed?YesNoNo
Use full ex/em bandNoYesYes
Sensitivity Δ F/F per mVLowHighHigh
Speedfsms–sns–μs
Capacitative loadingNoneSignificantNone