Washington: A butterfly's proboscis resembles a straw -- long, slender used for sipping -- but works more like a paper towel. Inspired by this design, a researcher has developed tiny probes that can sample fluids inside cells.

At the scales at which a butterfly or moth lives, liquid is so thick that it is able to form fibres. The insects' liquid food -- drops of water, animal tears, and the juice inside decomposed fruit -- spans nearly three orders of magnitude in viscosity.

Pumping liquid through its feeding tube would require an enormous amount of pressure. "No pump would support that kind of pressure," says Konstantin Kornev of Clemson University. "The liquid would boil spontaneously."

Instead of pumping, Kornev's findings suggest that butterflies draw liquid upwards using capillary action -- the same force that pulls liquid across a paper towel.

The proboscis resembles a rolled-up paper towel, with tiny grooves that pull the liquid upwards along the edges, carrying along the bead of liquid in the middle of the tube. This process is not nearly as affected by viscosity as pumping.

Kornev has been recently awarded an National Science Foundation grant to develop artificial probes made of nano fibers that use a similar principle to draw out the viscous liquids inside cells and examine their contents, said a Clemson release.

Kornev presented his work on Sunday at the 62nd annual meeting of the American Physical Society's (APS) Division of Fluid Dynamics. IANS