MSE Seminar Series: Paula Mellado
Friday, March 13, 2015
1:00 p.m.-2:00 p.m.
Room 2110, Chemical and Nuclear Engineering Bldg.
301 405 5240
Bio-inspired microfluidics: The case of the velvet worm
School of Engineering and Sciences
Adolfo Ibañez University, Santiago, Chile
The rapid squirt of a proteinaceous slime jet endows the ancient velvet worms (Onychophora) with a unique mechanism for defense from predators and for capturing prey [1–6] by entangling them in a disordered web that immobilizes their target. However, to date neither qualitative nor quantitative descriptions have been provided for this unique adaptation [1, 2, 7, 8]. We have investigated the mechanism that allows velvet worms the fast oscillatory motion of their oral papillae and the exiting liquid jet that oscillates with frequencies ƒ ~ 30 – 60 Hz. Using anatomical images and high speed videography, we show that even without fast muscular action of the papilla, a strong contraction of the slime reservoir and the geometry of the reservoir-papilla system suffices to accelerate the slime to speeds up to ν ~ 5 m/s in about ∆t ~ 60 ms. A theoretical analysis and a physical simulacrum allow us to infer that this fast oscillatory motion is the result of an elastohydrodynamic instability driven by the interplay between the elasticity of oral papillae and the fast unsteady flow during squirting. Inspired by the physics of the velvet worm squirting system we propose several applications that can be implemented using this instability. Ranging from high-throughput droplet production, printing, micro-nanofiber production between others  .