Nanonails repel liquids

4 February 2008

Using tightly packed nanostructures University of Wisconsin-Madison and Bell Laboratory engineers have created a material that can repel almost any liquid.

The surface of the material resembles tiny nails and when a jolt of electricity is added the liquid on the surface passes the heads of the nails and wets the surface completely.

Wisconsin-Madison mechanical engineering associate, Professor Tom Krupenkin, and senior scientist, J. Ashley Taylor, led the team to etch a silicon wafer with a ‘forest of conductive silicon shanks and non-conducting silicon oxide heads’. The team discovered that the ability to repel liquids rested in the geometry of the surface.

‘It turns out that what’s important is not the chemistry of the surface, but the topography of the surface,’ said Krupenkin. ‘It’s almost like sitting on a layer of air.’

The team believe the overhang of the nail head is what gives the surface its dual personality and could allow it to be used in biomedical applications such as 'lab-on-a- chip' technology and the manufacture of self-cleaning surfaces.