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  4. NIR Fluorescence lifetime macroscopic imaging with a time-gated SPAD camera
 
conference paper

NIR Fluorescence lifetime macroscopic imaging with a time-gated SPAD camera

Michalet, X.
•
Ulku, A.
•
Smith, J. T.
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January 1, 2022
Multiphoton Microscopy In The Biomedical Sciences Xxii
Conference on Multiphoton Microscopy in the Biomedical Sciences XXII

The performance of SwissSPAD2 (SS2), a large scale, widefield time-gated CMOS SPAD imager developed for fluorescence lifetime imaging, has recently been described in the context of visible range and fluorescence lifetime imaging microscopy (FLIM) of dyes with lifetimes in the 2.5 - 4 ns range. Here, we explore its capabilities in the NIR regime relevant for small animal imaging, where its sensitivity is lower and typical NIR fluorescent dye lifetimes are much shorter (1 ns or less). We carry out this study in a simple macroscopic imaging setup based on a compact NIR picosecond pulsed laser, an engineered diffuser-based illumination optics, and NIR optimized imaging lens suitable for well-plate or small animal imaging. Because laser repetition rates can vary between models, but the synchronization signal frequency accepted by SS2 is fixed to 20 MHz, we first checked that a simple frequency-division scheme enables data recording for different laser repetition rates. Next, we acquired data using different time gate widths, including gates with duration longer than the laser period, and analyzed the resulting data using both standard nonlinear least-square fit (NLSF) and phasor analysis. We show that the fixed synchronization rate and large gate widths characterizing SS2 (10 ns and over) are not an obstacle to accurately extracting lifetime in the 1 ns range and to distinguishing between close lifetimes. In summary, SS2 and similar very large gated SPAD imagers appear as a versatile alternative to other widefield time-resolved detectors for NIR fluorescence lifetime imaging, including preclinical molecular applications.

  • Details
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Type
conference paper
DOI
10.1117/12.2607833
Web of Science ID

WOS:000831988600005

Author(s)
Michalet, X.
Ulku, A.
Smith, J. T.
Bruschini, C.  
Weiss, S.
Charbon, E.  
Intes, X.
Date Issued

2022-01-01

Publisher

SPIE-INT SOC OPTICAL ENGINEERING

Publisher place

Bellingham

Published in
Multiphoton Microscopy In The Biomedical Sciences Xxii
ISBN of the book

978-1-5106-4802-9

978-1-5106-4801-2

Series title/Series vol.

Proceedings of SPIE

Volume

11965

Start page

1196507

Subjects

Cell Biology

•

Microscopy

•

Optics

•

flim

•

time-resolved

•

time-gated spad imager

•

nir

•

small animal imaging

•

phasor

•

nlsf

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
AQUA  
Event nameEvent placeEvent date
Conference on Multiphoton Microscopy in the Biomedical Sciences XXII

ELECTR NETWORK

Jan 22-Feb 24, 2022

Available on Infoscience
August 15, 2022
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/190039
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