Now,'nanonails' that can repel any liquid

Washington, Jan 30 : University of Wisconsin-Madison engineers and their colleagues from Bell Laboratories have created a material that can repel almost any liquid.

The material is made by sculpting a composed of tightly packed nanostructures that resemble tiny nails.

However, when electricity is applied, the liquid on the surface slips over the heads of the nanonails and spreads out between their shanks, and completely wets the entire surface in the process.

This unique material is developed by UW-Madison mechanical engineers Tom Krupenkin and J. Ashley Taylor and their team, who etched a silicon wafer to create a forest of conductive silicon shanks and non-conducting silicon oxide heads.

This material may have implications in biomedical applications such as "lab-on-a- chip" technology, manufacturing of self-cleaning surfaces, and extending the working life of batteries as a way to turn them off when not in use.

Surprisingly, the ability of the surface of the structure to repel water, oil, and solvents is dependent on the geometry of the nanonail.

"It turns out that what's important is not the chemistry of the surface, but the topography of the surface," explained Krupenkin.

He pointed out that the overhang of the nail head imparts this novel surface its dual personality. He also noted that a surface of posts creates a platform so rough at the nanoscale that "liquid only touches the surface at the extreme ends of the posts. It's almost like sitting on a layer of air."

The discovery was reported recently in Langmuir, a journal of the American Chemical Society.

ANI