Photochemically induced motion of liquid metal marbles

We demonstrate photochemically induced actuation of liquid metal marbles, which are liquid metal droplets encased in micro/nanoparticles. The WO3 nanoparticles coated marbles are placed in H2O2 solution, and their surfaces are illuminated with UV light. The semiconducting WO3 coating behaves as a photocatalyst to trigger a photochemical reaction, generating oxygen bubbles that propel the marble. The actuation of the marbles is investigated under different H2O2 concentrations, light intensities, and marble dimensions. Equations describing the fundamentals of such actuations are presented. (C) 2013 AIP Publishing LLC.