Materials that change their properties in response to external stimuli could have applications in electronics, sensing and catalysis. In the past, such switchable nanomaterials have relied on changes of shape to modify their properties, but now Bartosz Grzybowski and co-workers have shown that the electrical conductance of a film made of gold nanoparticles coated with charged ligands can be controlled by applying an electric field. This applied field sets up long-range gradients of both electrons (in the nanoparticle cores) and negative counterions (around the nanoparticles). Moreover, these gradients and the internal electric fields they create can be reconfigured to create different electronic elements. In this abstract representation, the nanoparticles are cubes, the currents between them are yellow and the conducting paths that have been switched off are copper coloured.
Article p740; News & Views p693
IMAGE: DAVID A. WALKER AND MARK SENIW
COVER DESIGN: ALEX WING