title: Influence of water on the interfacial behavior of gallium liquid metal alloys.
abstract: Eutectic gallium indium (EGaIn) is a promising liquid metal for a variety of electrical and optical applications that take advantage of its soft and fluid properties. The presence of a rapidly forming oxide skin on the surface of the metal causes it to stick to many surfaces, which limits the ability to easily reconfigure its shape on demand. This paper shows that water can provide an interfacial slip layer between EGaIn and other surfaces, which allows the metal to flow smoothly through capillaries and across surfaces without sticking. Rheological and surface characterization shows that the presence of water also changes the chemical composition of the oxide skin and weakens its mechanical strength, although not enough to allow the metal to flow freely in microchannels without the slip layer. The slip layer provides new opportunities to control and actuate liquid metal plugs in microchannels-including the use of continuous electrowetting-enabling new possibilities for shape reconfigurable electronics, sensors, actuators, and antennas.
authors.affiliation: Department of Chemical and Biomolecular Engineering, NC State University , Raleigh, North Carolina 27695, United States.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Khan
authors.forename: Chris
authors.initials: C
authors.lastname: Trlica
authors.forename: Ju-Hee
authors.initials: JH
authors.lastname: So
authors.forename: Michael
authors.initials: M
authors.lastname: Valeri
authors.forename: Michael D
authors.initials: MD
authors.lastname: Dickey
keywords: EGaIn; continuous electrowetting; fluidic antenna; rheology; slip layer; wetting