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Time-gated Sensors for FLIM

  • FLIM image of a Convallaria sample taken with a custom SPAD sensor

Fluorescence Lifetime Imaging Microscopy (FLIM) is a powerful tool for the analysis of biological samples, enabling the extraction of more information by detecting not only the intensity of the fluorescence but also its lifetime.

Time-gating is one of the possible approaches for measuring the flurescence decay lifetime: the sample is illumintaed with a short laser pulse and then it reacts with a fluorescent emission with a lifetime in the nanosecond range. By opening 2 or more subsequently delayed observation windows it is possible to acquire several points of the decay and therefore extract the needed information. Due to the intrinsic nature of the fluorescence phenomena, very sensitive and fast detectors must be used.

The IRIS research unit developed, in these years, several sensors aimed either at confocal or wide-field FLIM by employing time-gated single-photon avalanche diode (SPAD), using digital or analog approaches, in linear or 2D arrays from 32x32 [1] up to 160x120-pixels resolution [2].

[1] L. Pancheri, N. Massari, and D. Stoppa, “SPAD Image Sensor With Analog Counting Pixel for Time-Resolved Fluorescence Detection,” IEEE Transactions on Electron Devices, vol.60, no.10, pp.3442-3449, October 2013.

[2] M. Perenzoni, N. Massari, D. Perenzoni, L. Gasparini, and D. Stoppa, “A 160×120-pixel analog-counting single-photon imager with Sub-ns time-gating and self-referenced column-parallel A/D conversion for fluorescence lifetime imaging,” IEEE International Solid-State Circuits Conference (ISSCC), 22-26 February 2015.

Application cases: 
  • Scientific imaging for research purposes
  • Point-of-care diagnostics
Research topics: