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Proceedings Paper

Spitting cobras: fluid jets in nature as models for technical applications
Author(s): Alexander Balmert; David Hess; Christoph Brücker; Horst Bleckmann; Guido Westhoff
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Paper Abstract

Spitting cobras defend themselves by ejecting rapid jets of venom through their fangs towards the face of an offender. To generate these jets, the venom delivery system of spitting cobras has some unique adaptations, such as prominent ridges on the surface of the venom channel. We examined the fluid acceleration mechanisms in three spitting cobra species of the genus Naja. To investigate the liquid-flow through the venom channel we built a three-dimensional 60:1 scale model. First we determined the three-dimensional structure of the channel by using microcomputer tomography. With help of the micro computer tomographical data we then created a negative form out of wax. Finally, silicon was casted around the wax form and the wax removed, resulting in a completely transparent model of the cobra´s venom channel. The physical-chemical properties of the cobra venom were measured by micro rheometry and tensiometry. Thereafter, an artificial fluid with similar properties was generated. Particle image velocimetry (PIV) was performed to visualize the flow of the artificial liquid in the three-dimensional model. Our experiments show how the surface structure of the venom channel determines the liquid flow through the channel and ultimately the form of the liquid jet. Understanding the biological mechanisms of venom ejection helps to enhance industrial processes such as water jet cutting and cleaning as well as injection methods in technical and medical sectors, e.g. liquid microjet dissection in microsurgery.

Paper Details

Date Published: 23 March 2011
PDF: 7 pages
Proc. SPIE 7975, Bioinspiration, Biomimetics, and Bioreplication, 797514 (23 March 2011); doi: 10.1117/12.880392
Show Author Affiliations
Alexander Balmert, Univ. Bonn (Germany)
David Hess, Technische Univ. Freiberg (Germany)
Christoph Brücker, Technische Univ. Freiberg (Germany)
Horst Bleckmann, Univ. Bonn (Germany)
Guido Westhoff, Univ. Bonn (Germany)

Published in SPIE Proceedings Vol. 7975:
Bioinspiration, Biomimetics, and Bioreplication
Raúl J. Martín-Palma; Akhlesh Lakhtakia, Editor(s)

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