256 × 2 SPAD line sensor for time resolved fluorescence spectroscopy

Nikola Krstajić, James Levitt, Simon Poland, Simon Ameer-Beg, Robert K Henderson

    Research output: Contribution to journalArticlepeer-review

    51 Citations (Scopus)
    299 Downloads (Pure)


    We present a CMOS chip 256 × 2 single photon avalanche diode (SPAD) line sensor, 23.78 µm pitch, 43.7% fill factor, custom designed for time resolved emission spectroscopy (TRES). Integrating time-to-digital converters (TDCs) implement on-chip mono-exponential fluorescence lifetime pre-calculation allowing timing of 65k photons/pixel at 200 Hz line rate at 40 ps resolution using centre-of-mass method (CMM). Per pixel time-correlated single-photon counting (TCSPC) histograms can also be generated with 320 ps bin resolution. We characterize performance in terms of dark count rate, instrument response function and lifetime uniformity for a set of fluorophores with lifetimes ranging from 4 ns to 6 ns. Lastly, we present fluorescence lifetime spectra of multicolor microspheres and skin autofluorescence acquired using a custom built spectrometer. In TCSPC mode, time-resolved spectra are acquired within 5 minutes whilst in CMM mode spectral lifetime signatures are acquired within 2 ms for fluorophore in cuvette and 200 ms for skin autofluorescence. We demonstrate CMOS line sensors to be a versatile tool for time-resolved fluorescence spectroscopy by providing parallelized and flexible spectral detection of fluorescence decay.

    Original languageEnglish
    Pages (from-to)5653-69
    Number of pages17
    JournalOptics Express
    Issue number5
    Publication statusPublished - 9 Mar 2015


    • Artifacts
    • Fluorescein
    • Humans
    • Microspheres
    • Optics and Photonics
    • Photons
    • Skin
    • Spectrometry, Fluorescence
    • Time Factors
    • Journal Article
    • Research Support, Non-U.S. Gov't


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