Real-Time Fluorescence Lifetime Imaging

Dr Day-Uei Li


ST Mircoelectronics,
Fondazione Bruno Kessler (FBK),
University of Pavia


Despite the fact that fluorescence lifetime imaging microscopy (FLIM) technology has matured in recent years, typical confocal FLIM imaging is still slow. For a laboratory confocal FLIM setup, pulsed lasers (either Ti-Sapphire laser for mutiphoton excitation or pulsed laser diodes for direct excitation) have to be coupled into the microscope and typically need to be scanned across the sample with a photomultiplier tube (PMT) coupled to a time-correlated single-photon counting card. Often, the fluorescence lifetime is not displayed immediately but only extracted from the recorded fluorescence decay histograms by a separate piece of software. Although the imaging is accurate with a high resolution, it is limited to image stationary objects. Clinical and commercial applications, on the other hand, increasingly demand compact, high-speed, and portable system-on-chip FLIM solutions which are robust, easy to operate, and high-speed. Thanks to the progress of semiconductor technology it is now possible to achieve high accuracy time resolution, high sensitivity, low cost, compactness, and high-throughput with parallelism by exploiting low dark count CMOS SPAD arrays to replace PMTs.