Fluorescence lifetime spectroscopy in multiply scattering media

In vivo analytical sensing using fluorescence spectroscopy is complicated not only by the scattering of tissue, but also by the fact that most sensing fluorophores do not exhibit single exponential decay lifetime. Herein, we present a study that underscore the sensitivity of lifetime spectroscopy in tissue-like scattering media by comparisons of measurements made on a mixture of two dyes in Intralipid solution to the predictions incorporating optical diffusion equation and various decay kinetics model. In addition, this work extends fluorescence sensing to dyes whose relaxation kinetics are described not only by first order kinetics but by more complex kinetics owing to quenching and multiple activated states of the sensing dye.