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Emerging applications of liquid metals featuring surface oxides.

Dickey MD - ACS Appl Mater Interfaces (2014)

Bottom Line: Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface.The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance.Here, we show that this solid oxide "skin" enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States.

ABSTRACT
Gallium and several of its alloys are liquid metals at or near room temperature. Gallium has low toxicity, essentially no vapor pressure, and a low viscosity. Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface. The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance. Here, we show that this solid oxide "skin" enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects.

No MeSH data available.


Related in: MedlinePlus

Monodisperse,liquid metal microdroplets formed by microfluidic flow focusing. (a)Liquid metal (dark) is pumped through an orifice along with a continuousphase fluid (clear) in a microchannel to produce droplets. Adaptedwith permission from ref (52). Copyright 2012 Wiley. (b) Photograph of the droplets.Adapted with permission from ref (51). Copyright 2012 The Royal Society of Chemistry.(c) Micrograph of oblong liquid metal particles formed using microfluidicsand stabilized by an oxide. Adapted with permission from ref (52). Copyright 2012 Wiley.
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fig6: Monodisperse,liquid metal microdroplets formed by microfluidic flow focusing. (a)Liquid metal (dark) is pumped through an orifice along with a continuousphase fluid (clear) in a microchannel to produce droplets. Adaptedwith permission from ref (52). Copyright 2012 Wiley. (b) Photograph of the droplets.Adapted with permission from ref (51). Copyright 2012 The Royal Society of Chemistry.(c) Micrograph of oblong liquid metal particles formed using microfluidicsand stabilized by an oxide. Adapted with permission from ref (52). Copyright 2012 Wiley.

Mentions: Our group,51 and others,52 have shown it is possible to use microfluidicflow focusing—the coflow of two immiscible fluids through anorifice in a microchannel—to form liquid metal microdroplets.The use of a continuous phase that sheaths the metal prevents it fromsticking to the channel walls. These colloids can form into stableoblong shapes because of the oxide, can be collected, and can be recoveredcompletely into a single sphere of metal by exposure to acid, whichremoves the stabilizing oxide skin from each microdroplet. Figure 6 contains images of a flow-focusing device as wellas spherical and oblong shaped particles of liquid metal that maybe fabricated using this technique. We found that coating the dropletswith a thin layer of polymer (poly(vinyl alcohol)) helped stabilizethem from coalescence. Other groups have made stable liquid metalmarbles53 by coating the surface with smallerparticles, or nanobeads by sonicating the metal in the presence ofligands that bind to the metal.54 Liquidmetal beads and droplets may be useful in self-healing composites,55 for energy harvesting,56 for heat transfer,57 as microfluidicpumps,58,59 actuators,60 asswitches,5 or as electrodes.61,62


Emerging applications of liquid metals featuring surface oxides.

Dickey MD - ACS Appl Mater Interfaces (2014)

Monodisperse,liquid metal microdroplets formed by microfluidic flow focusing. (a)Liquid metal (dark) is pumped through an orifice along with a continuousphase fluid (clear) in a microchannel to produce droplets. Adaptedwith permission from ref (52). Copyright 2012 Wiley. (b) Photograph of the droplets.Adapted with permission from ref (51). Copyright 2012 The Royal Society of Chemistry.(c) Micrograph of oblong liquid metal particles formed using microfluidicsand stabilized by an oxide. Adapted with permission from ref (52). Copyright 2012 Wiley.
© Copyright Policy - editor-choice
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231928&req=5

fig6: Monodisperse,liquid metal microdroplets formed by microfluidic flow focusing. (a)Liquid metal (dark) is pumped through an orifice along with a continuousphase fluid (clear) in a microchannel to produce droplets. Adaptedwith permission from ref (52). Copyright 2012 Wiley. (b) Photograph of the droplets.Adapted with permission from ref (51). Copyright 2012 The Royal Society of Chemistry.(c) Micrograph of oblong liquid metal particles formed using microfluidicsand stabilized by an oxide. Adapted with permission from ref (52). Copyright 2012 Wiley.
Mentions: Our group,51 and others,52 have shown it is possible to use microfluidicflow focusing—the coflow of two immiscible fluids through anorifice in a microchannel—to form liquid metal microdroplets.The use of a continuous phase that sheaths the metal prevents it fromsticking to the channel walls. These colloids can form into stableoblong shapes because of the oxide, can be collected, and can be recoveredcompletely into a single sphere of metal by exposure to acid, whichremoves the stabilizing oxide skin from each microdroplet. Figure 6 contains images of a flow-focusing device as wellas spherical and oblong shaped particles of liquid metal that maybe fabricated using this technique. We found that coating the dropletswith a thin layer of polymer (poly(vinyl alcohol)) helped stabilizethem from coalescence. Other groups have made stable liquid metalmarbles53 by coating the surface with smallerparticles, or nanobeads by sonicating the metal in the presence ofligands that bind to the metal.54 Liquidmetal beads and droplets may be useful in self-healing composites,55 for energy harvesting,56 for heat transfer,57 as microfluidicpumps,58,59 actuators,60 asswitches,5 or as electrodes.61,62

Bottom Line: Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface.The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance.Here, we show that this solid oxide "skin" enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States.

ABSTRACT
Gallium and several of its alloys are liquid metals at or near room temperature. Gallium has low toxicity, essentially no vapor pressure, and a low viscosity. Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface. The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance. Here, we show that this solid oxide "skin" enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects.

No MeSH data available.


Related in: MedlinePlus