Vision-based automated sorting of C. Elegans on a microfluidic device

This paper reports a vision-based microfluidic system for automated, high-speed sorting of the nematode worm C. elegans. Exceeding the capabilities of conventional worm sorting microfluidic devices purely relying on passive sorting mechanisms, our system is capable of accurate measurement of the worm body length/width and active sorting of worms with the desired sizes from a mixture of worms at different developmental stages. This feature is enabled by the combination of vision-based worm detection and sizing algorithms and automated on-chip worm manipulation. A double-layer microfluidic device with computer-controlled pneumatic valves is developed for sequential loading, trapping, imaging, and sorting of single worms based on vision-based worm size measurement results. To keep the system operation robust, vision-based algorithms for detecting multi-worm loading and worm size measurement failure have also been developed. We conducted sorting experiments on 319 worms and achieve an average sorting speed of 10.4 worms per minute (5.8 s/worm) with an operation success rate of 90.3%. This system will facilitate worm biology studies where body size measurement and size-based sorting of many worms are needed.