With a jolt, 'nanonails' go from repellant to wettable

Jan 29, 2008
With a jolt, 'nanonails' go from repellant to wettable
Liquid beads on a surface composed of silicon "nanonails." Made by Tom Krupenkin and J. Ashley Taylor of University of Wisconsin-Madison's Department of Mechanical Engineering, the surface repels virtually all liquids, including water, oil, solvents and detergents. When an electrical current is applied, the liquid slips past the nail heads and between the shanks to wet the entire surface. According to Krupenkin, the nails create such a rough surface at the nanoscale that liquids only touch the surface at the extreme ends of the forest of nails, so the liquid is like sitting on a bed of air. Photo by: courtesy Tom Krupenkin/University of Wisconsin-Madison

Sculpting a surface composed of tightly packed nanostructures that resemble tiny nails, University of Wisconsin-Madison engineers and their colleagues from Bell Laboratories have created a material that can repel almost any liquid.

Add a jolt of electricity, and the liquid on the surface slips past the heads of the nanonails and spreads out between their shanks, wetting the surface completely.

The new material, which was reported this month in Langmuir, a journal of the American Chemical Society, could find use in biomedical applications such as "lab-on-a-chip" technology, the manufacture of self-cleaning surfaces, and could help extend the working life of batteries as a way to turn them off when not in use.

UW-Madison mechanical engineers Tom Krupenkin and J. Ashley Taylor and their team etched a silicon wafer to create a forest of conductive silicon shanks and non-conducting silicon oxide heads. Intriguingly, the ability of the surface of the structure to repel water, oil, and solvents rests on the nanonail geometry.

"It turns out that what's important is not the chemistry of the surface, but the topography of the surface," Krupenkin explains, noting that the overhang of the nail head is what gives his novel surface its dual personality.

A surface of posts, he notes, 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."

Source: University of Wisconsin-Madison

Explore further: Graphene reinvents the future

add to favorites email to friend print save as pdf

Related Stories

Move over, silicon, there's a new circuit in town

Jun 17, 2014

(Phys.org) —When it comes to electronics, silicon will now have to share the spotlight. In a paper recently published in Nature Communications, researchers from the USC Viterbi School of Engineering descri ...

Recommended for you

Tiny graphene drum could form future quantum memory

4 hours ago

Scientists from TU Delft's Kavli Institute of Nanoscience have demonstrated that they can detect extremely small changes in position and forces on very small drums of graphene. Graphene drums have great potential ...

Graphene reinvents the future

Aug 27, 2014

For many scientists, the discovery of one-atom-thick sheets of graphene is hugely significant, something with the potential to affect just about every aspect of human activity and endeavour.

Catalytic gold nanoclusters promise rich chemical yields

Aug 25, 2014

(Phys.org) —Old thinking was that gold, while good for jewelry, was not of much use for chemists because it is relatively nonreactive. That changed a decade ago when scientists hit a rich vein of discoveries ...

User comments : 0