Fluorescence lifetime-based sensing is now recognized as a valuable methodology in clinical and analytical chemistry. For clinical chemistry, or for non-invasive sensing through skin, it is often necessary to obtain quantitative information in highly scattering media. Lifetime-based sensing can be used to obtain quantitative measurements in turbid media. We describe frequency-domain lifetime measurements in intralipid suspension, and present a reliable technique which allows phase-modulation lifetime measurements of fluorophores dispersed within or localized within intralipid. Lifetimes can be measured using an intensity decay law which accounts for the time delays and pulse-broadening effects of multiple light scattering events occurring in the intralipid. Alternatively, the phase and modulation measurements can be performed relative to a reference fluorophore of known lifetime. This approach provided reliable lifetime data for a pH-sensitive fluorophore contained within a microcuvette 4 mm under the surface of an intralipid suspension.

Date Published: 8 May 1995
PDF: 12 pages
Proc. SPIE 2388, Advances in Fluorescence Sensing Technology II, (8 May 1995); doi: 10.1117/12.208549

Published in SPIE Proceedings Vol. 2388:
Advances in Fluorescence Sensing Technology II
Joseph R. Lakowicz, Editor(s)