An electrically tunable nanomaterial that changes its strength from hard to soft at the touch of a button has been developed by researchers at the Technical University of Hamburg and the Helmholtz Center Geesthacht.

The researchers placed either gold or platinum in an acidic solution. As the metal corroded, minute ducts and holes were formed, creating a network of pore channels. The pores were impregnated with a conductive liquid, either a simple saline solution or diluted acid.

A hybrid material of metal and liquid was created that, when triggered by an electric signal, changed the properties of the material from hard to soft, literally at the touch of a button, the researchers said.

As ions dissolved in the liquid, the surfaces of the metal were electrically charged: the mechanical properties of the metallic partner were changed by the application of an electric potential in the liquid partner. This produced a strengthening or weakening of the atomic bonds in the surface of the metal when extra electrons were added to (or withdrawn from) the surface atoms.

The researchers found that the the strength of the material could be doubled when required. Alternatively, the material could be switched to a weaker, but a more damage-tolerant, energy-absorbing, and malleable state.

Ref.: H.-J. Jin, J. Weissmuller, A Material with Electrically Tunable Strength and Flow Stress, Science, 2011; 332 (6034): 1179 [DOI: 10.1126/science.1202190]