Daphnia: A Master in Microfluidics

Extracting particles such as live cells from a fluid, sorting those cells in a microflow, and adding small concentrations of info-chemicals to create a minute chemical landscape in the flow, are current research topics both for researchers in microfluidics and for biologists interested in the biomechanics of aquatic and marine zooplankton. Our model animal, Daphnia spp., a microcrustacean of 1 to 3 mm (about 0.12 in) size, features four pairs of appendages that are covered by the carapace. These appendages move at around 10 Hz and generate an in/out-current system to extract algae for food.

These animals operate at the same spatial and temporal scales as microfluidic devices; that challenges our group to compare the mechanical and fluid dynamical procedures for 1) fast extraction of particles from flows and 2) sorting the particles according to a criterion (e.g., size).

After a brief introduction to the morphology of Daphnia, we will demonstrate Daphnia’s dynamic flow system using high-speed video with tracer particles and dyes. In the discussion we will touch on the biology-inspired engineering aspect, since Daphnia are ecologically successful self-contained “microfluidic devices.”