A video-rate fluorescence lifetime (FLT) imaging system is presented featuring in-pixel lifetime calculation based on the center of mass of the times of arrival (ToAs) of photons received by the single-photon avalanche diode of the pixel. The ToAs of photons received during a gating window placed in the decay of the returned fluorescent emission are averaged by a switched-capacitor circuit, implementing the center-of-mass method (CMM) in a compact pixel circuit. Binning of ToAs or complex time-to-digital circuits are avoided, and instead, optimal use of all received photons is achieved on a small pixel area with low communication and computational overhead. The system is validated through analytical modeling, Monte Carlo simulations, and real-world experiments using fluorophores with known lifetimes, demonstrating agreement with the analytical model and achieving accurate FLT estimations across a large range of photon counts. A dedicated quarter video graphics array (QVGA) (320 × 240 pixel) image sensor that includes all necessary circuitry for the CMM currently reaches 10 frames per second and demonstrates the real-time FLT imaging capability of the system.
Nevens, W, Lapauw, T, Vrijsen, J, Dries, TVD, Ingelberts, H & Kuijk, M 2025, 'Video-Rate Fluorescence Lifetime Imaging System Using a Novel Switched Capacitor QVGA SPAD Sensor', IEEE Sensors Letters, vol. 9, no. 8, 3502704. https://doi.org/10.1109/LSENS.2025.3585198
Nevens, W., Lapauw, T., Vrijsen, J., Dries, T. V. D., Ingelberts, H., & Kuijk, M. (2025). Video-Rate Fluorescence Lifetime Imaging System Using a Novel Switched Capacitor QVGA SPAD Sensor. IEEE Sensors Letters, 9(8), Article 3502704. https://doi.org/10.1109/LSENS.2025.3585198
@article{d9cbd26cfd244c229fb164389b2f2460,
title = "Video-Rate Fluorescence Lifetime Imaging System Using a Novel Switched Capacitor QVGA SPAD Sensor",
abstract = "A video-rate fluorescence lifetime (FLT) imaging system is presented featuring in-pixel lifetime calculation based on the center of mass of the times of arrival (ToAs) of photons received by the single-photon avalanche diode of the pixel. The ToAs of photons received during a gating window placed in the decay of the returned fluorescent emission are averaged by a switched-capacitor circuit, implementing the center-of-mass method (CMM) in a compact pixel circuit. Binning of ToAs or complex time-to-digital circuits are avoided, and instead, optimal use of all received photons is achieved on a small pixel area with low communication and computational overhead. The system is validated through analytical modeling, Monte Carlo simulations, and real-world experiments using fluorophores with known lifetimes, demonstrating agreement with the analytical model and achieving accurate FLT estimations across a large range of photon counts. A dedicated quarter video graphics array (QVGA) (320 × 240 pixel) image sensor that includes all necessary circuitry for the CMM currently reaches 10 frames per second and demonstrates the real-time FLT imaging capability of the system.",
keywords = "fluorescence lifetime, fluorescence lifetime imaging, single-photon avalanche diode, SPAD, sensor systems",
author = "Wannes Nevens and Thomas Lapauw and Jonathan Vrijsen and Dries, {Thomas Van den} and Hans Ingelberts and Maarten Kuijk",
note = "Publisher Copyright: {\textcopyright} 2017 IEEE.",
year = "2025",
month = jul,
day = "3",
doi = "10.1109/LSENS.2025.3585198",
language = "English",
volume = "9",
journal = "IEEE Sensors Letters",
issn = "2475-1472",
publisher = "IEEE",
number = "8",
}