Time-resolved fluorescence measurements using stroboscopic excitation

We report on the development of a simple technique for obtaining time-domain information using dc detection of fluorescence. We show that this is feasible for assays where a change in lifetime of an indicator occurs in reaction to an analyte, in fluorescence resonance energy transfer for example, and could be particularly useful for assays performed in the scaled-down environment of a "lab-on-a-chip", A rate equation model is presented which allows an objective analysis of the relative importance of the key measurement parameters: optical saturation of the fluorophore and excitation pulse characteristics. We present a comparison of the model with a cuvette based analysis of a carbocyanine dye where the excitation source is a 650 nm wavelength, self-pulsing AlGaInP laser diode. © 2005 SPIE and OSA.