Real-time Image-based Sorting of Picoliter Droplets

Picoliter droplets containing Actinobacteria are sorted using real-time image analysis, which in contrast to most available sorting approaches is independent of fluorescent labels. Images are triggered by changes in brightness due to total internal light reflection at the interface of each droplet, which is detected by a photodiode with a reduced field of view. The time interval between triggered imaging of single droplets and sorting is in average 0.5 ms for 5-fold magnification (72 × 72 px) and 1.6 ms for 10-fold (144 ×144 px), enabling sorting rates higher than 100 Hz.