Decision-making by nematodes in complex microfluidic mazes

Nematodes are microscopic, soil-dwelling worms that navigate through soil particles in search of food or a suitable host. Most nematode species employ a myriad of physical and chemical cues that define their navigation strategies. Here, we demonstrate a microfluidic method to observe and characterize the physical aspects of nematode navigation at real-time. The microfluidic devices comprise a series of interconnected T-maze or cylindrical structures of varying geometry. At each physical intersection, nematodes are given the choice to migrate left or right. We found that this decision-making of nematodes is influenced by the angle of intersection of T-maze structures. We further showed that nematodes can be passively directed to move in a linear direction by carefully adjusting the position and spacing of cylindrical obstacles in its path. The experiments were conducted on two nematodes (non-parasitic C. elegans and pigparasitic Oesophagostomum dentatum) and in the absence of any chemical or electrical stimulants.