Transient perfusion through a microfluidic dragonfly wing vein model*

Insect wings include a network of tubular veins through which hemolymph (blood) flows to provide the sensory organs and other tissues with water and nutrients and to remove waste products. Thus, hemolymph flow through veins is important for stability and functionality of the fragile wing blade. However, the perfusion through wing venation has been poorly studied because tracing hemocytes (blood cells) in veins of living specimen provides limited information about flow patterns. To characterize transient perfusion through complex wing venation, we created a microfluidic wing vein model of the dragonfly, Anax junius. Hemolymph flow was simulated by injecting red dye into the device filled with water at a range of flow rates. Visualized perfusion patterns suggested that the perfused area in the device logarithmically increased with time. When water was injected into the device filled with the dye, perfusion occurred slower with different patterns, and the time dependence of the perfused area was not logarithmic. The observed difference suggests that perfusion does not occur uniformly throughout the wing vein network.