Recovery and isolation of individual microfluidic picoliter droplets by triggered deposition

Microfluidic emulsion-based droplet systems have a great potential for inexpensive ultrahigh-throughput experimentation. Yet, picking and upscaling single unique picoliter-sized droplets of interest out of million others for deeper analysis is still a fundamental limitation. In order to overcome this missing gap, we present a system in which droplets of interest are collected into a collection chamber (DropLot) in high throughput and then slowly redirected to an agar surface or microtiter plate via a capillary tube passing through an optical sensor before exiting. The signal of each droplet triggers a positioning algorithm that ultimately places the flowing droplet at a defined position on a Petri dish or microtiter plate. Results indicate effective isolation of single droplets giving rise to colonies on agar surface with a recovery rate of over 93%. The possibility to isolate individual droplets provides a critical feature for interfacing droplet microfluidics with standard laboratory analysis and processing.

Automated summary

Microfluidic emulsion-based droplet systems have the potential for inexpensive and high-throughput experimentation. However, selecting and amplifying single droplets of interest from a large number of other droplets is still a challenge. To overcome this limitation, a system is presented where droplets of interest are collected and positioned on agar surface or microtiter plate. Results show effective isolation of single droplets, allowing for further analysis and processing.