Nanoparticle-coated liquid-metal droplets: interfacial tension and electron transport across the interface

We form stable droplets of molten metal, investigate their stability, and demonstrate their potential for forming electronic devices. Droplets of liquid Ga, 0.1-100 microns in diameter, are suspended in water and stabilized by Au or Fe$_{3}$O$_{4}$ nanoparticles. We measure a large reduction of the surface tension of the Ga droplets when nanoparticles assemble at the interface. To investigate electron transport through the Ga-nanoparticle-Ga junction, we deposit coated droplets on substrates with patterned electrodes. We apply a bias voltage to the electrodes and measure the current after evaporation of the solvent. The nonlinear I-V curve shifts with a gate voltage and indicates a transistor is formed in the junction. Improved understanding of the electrical characteristics may allow inexpensive assembly of a large number of functional devices. We acknowledge support from the Center for UMass/Industry Research on Polymers (CUMIRP) and from NSF NIRT program (CTS-0609107).