A microfluidic device for automated, high-speed microinjection ofCaenorhabditis elegans

The nematode worm Caenorhabditis elegans has been widely used as a modelorganism in biological studies because of its short and prolific life cycle, relativelysimple body structure, significant genetic overlap with human, and facile/inexpensivecultivation. Microinjection, as an established and versatile tool for delivering liquidsubstances into cellular/organismal objects, plays an important role in C.elegans research. However, the conventional manual procedure of C.elegans microinjection is labor-intensive and time-consuming and thus hinderslarge-scale C. elegans studies involving microinjection of a large numberof C. elegans on a daily basis. In this paper, we report a novelmicrofluidicdevice that enables, for the first time, fully automated, high-speedmicroinjection of C. elegans. The device is automaticallyregulated by on-chip pneumatic valves and allows rapid loading, immobilization, injection,and downstream sorting of single C. elegans. For demonstration, weperformed microinjection experiments on 200 C. elegans worms anddemonstrated an average injection speed of 6.6 worm/min (average worm handling time:9.45 s/worm) and a success rate of 77.5% (post-sorting success rate: 100%), both muchhigher than the performance of manual operation (speed: 1 worm/4 min and success rate:30%). We conducted typical viability tests on the injected C. elegans andconfirmed that the automated injection system does not impose significant adverse effecton the physiological condition of the injected C. elegans. We believethat the developed microfluidicdevice holds great potential to become a useful tool for facilitatinghigh-throughput, large-scale worm biology research.