High-throughput time-correlated single photon counting.

We demonstrate time-correlated single photon counting (TCSPC) in microfluidic droplets under high-throughput conditions. We discuss the fundamental limitations in the photon acquisition rate imposed by the single photon detection technique and show that it does not preclude accurate fluorescence lifetime (FLT) measurements at a droplet throughput exceeding 1 kHz with remarkable sensitivity. This work paves the way for the implementation of innovative biomolecular interaction assays relying on the FLT detection of nanosecond-lived fluorophores for high-throughput biotechnological applications, including high-throughput screening or cell sorting potentially allowed by droplet microfluidics or other fast sample handling facilities.