Printing EGaIn nanodroplets out of liquid metal

Abstract We report a method to fabricate surfactant-free eutectic gallium-indium (EGaIn) sessile nanodroplets out of liquid metal. The method takes advantage of weak adherence between the liquid metal and its ultrathin surface oxide layer. During the van der Waals exfoliation process of transferring the ultrathin oxide layer to a desired substrate, nanoscale liquid metal droplets could form due to dynamic wetting failure. Here we have prepared EGaIn nanodroplets on the surface of transferred Ga2O3 ultrathin films. Surface morphology measured by atomic force microscope shows the vast majority of nanodroplets are isolated and randomly distributed, with mean radius below 100 nm. This preparation method is facile, low cost and can be applied in fields such as Ga-catalyzed nanostructures growth and gallium plasmonics.