Aquavert: Imaging and Microfluidics for Vertical Swimming of Microorganisms

Investigating aquatic microorganisms' swimming and feeding behaviors under well-controlled conditions is of great interest across multiple disciplines. Thus, broader access to resources that enable these investigations is desirable. Given the organisms' microscopic dimensions, an ideal system should combine microscopy to visualize and fluidics to control and modulate their environments. We report an integrated device (Aquavert) that combines DIY microscopy and microfluidics for biomechanical investigations of marine microorganisms, emphasizing vertical swimming. The DIY microscope was developed for modularity, and imaging chambers were secured in vertical orientations (either in portrait or landscape mode). Fluid channels were used to introduce flow and fluid segmentation while remaining upright. Fluid segmentation established two distinct environments (e.g., with and without algae) in neighboring regions inside a chamber. System application with multiple marine larvae (sand dollars, sea urchins, and starfish) and introduction of unicellular algae were demonstrated. Finally, the device's capabilities were extended to fluorescence imaging to visualize tracer beads. The role of gravity is often ignored in conventional plate or microfluidic experiments. Beyond the current application, Aquavert enables investigations of the behavior and physiology of microorganisms where the role of gravity is critical.