A massively parallel microfluidic device for long-term visualization of isolated motile cells

Visualizing the natural behavior of motile cells over many hours is a challenge, as cells can leave the field of view of a microscope in a matter of minutes. Many interesting cell behaviors—such as cell division, motility phenotype, cell–cell interactions, and multicellular colony formation—require hours of observation to characterize. We present a microfluidic device that traps hundreds of single motile cells in isolated chambers, thereby allowing observation over several days. This polydimethylsiloxane device features 400 circular chambers, connected to a central serpentine channel. Motile cells are loaded into these chambers through the serpentine channel. The channel is then purged with air, fluidically isolating the chambers from each other and effectively trapping the cells. We applied the device to observe the behavior of the choanoflagellate Salpingoeca rosetta. Because of its ability to live in both solitary and colonial forms, S. rosetta is a useful model organism for the study of the evolutionary origins of multicellularity. In particular, S. rosetta can take on two distinct colonial forms: chain colonies and rosette colonies. With our device, we are able to observe the formation of these colonies from single cells more easily and with higher throughput than ever before. This device has the potential to be a powerful tool for studying the long-term behavior of motile cells.