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

Area of Science:

• Photonics and Imaging Science
• Biomedical Optics
• Fluorescence Spectroscopy

Background:

• Widefield time-gated SPAD imagers are crucial for fluorescence lifetime imaging (FLI).
• Previous generations like SwissSPAD2 have enabled significant advancements in FLI.
• Optimizing imagers for faster measurements and higher duty cycles remains an active research area.

Purpose of the Study:

• To introduce and evaluate SwissSPAD3, a novel widefield time-gated SPAD imager.
• To demonstrate its capability in measuring short lifetime near-infrared (NIR) dyes using FLI.
• To compare its performance against previous models and theoretical predictions.

Main Methods:

• Utilizing SwissSPAD3 with sub-nanosecond gate widths and high laser repetition rates (up to 80 MHz).
• Employing a dual-gate architecture for a 100% effective duty cycle.
• Performing widefield macroscopic FLI measurements on NIR dyes and analyzing data with the phasor approach.

Main Results:

• SwissSPAD3 successfully performed widefield macroscopic FLI measurements of short lifetime NIR dyes.
• The new imager's performance was validated through comparison with SwissSPAD2 data and theoretical models.
• The enhanced features of SwissSPAD3, including shorter gates and higher repetition rates, were demonstrated.

Conclusions:

• SwissSPAD3 represents a significant advancement in time-gated SPAD imaging for FLI.
• Its capabilities facilitate more accurate and efficient measurements of short lifetime fluorophores.
• The technology holds promise for various applications requiring high-resolution FLI.