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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

3D printing of free-standingliquid metal structures. (a) Sudden burst of pressure forces liquidmetal out of the tip of a syringe, which extends as a fiber to thesubstrate. The fiber is stabilized by the oxide layer. (b) Resultingfibers are strong enough to span a gap. (c) Extruded wire that isbent into the shape of an arch. (d) Stacks of liquid metal droplets.(e) Liquid metal injected into microchannels remains mechanicallystable after dissolving all of the channel walls except the substrate.Scale bars are all 500 μm. Adapted with permission from ref (24). Copyright 2013 Wiley.
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fig4: 3D printing of free-standingliquid metal structures. (a) Sudden burst of pressure forces liquidmetal out of the tip of a syringe, which extends as a fiber to thesubstrate. The fiber is stabilized by the oxide layer. (b) Resultingfibers are strong enough to span a gap. (c) Extruded wire that isbent into the shape of an arch. (d) Stacks of liquid metal droplets.(e) Liquid metal injected into microchannels remains mechanicallystable after dissolving all of the channel walls except the substrate.Scale bars are all 500 μm. Adapted with permission from ref (24). Copyright 2013 Wiley.

Mentions: Figure 4 shows imagesof freestanding liquid metal structures resting on a substrate. Thesestructures may be generated in four different ways: (i) By rapidlyapplying a burst of pressure to the syringe, a fine fiber of metal(diameters as small as 10 μm) emerges from the syringe, as shownin Figure 4a. These fibers are stabilized againstcapillary instabilities by the presence of the oxide, as shown inFigure 4b. (ii) By drawing a liquid metal cylinderfrom a syringe to form wires, as shown in Figure 4c. The process begins by contacting a droplet on the end ofa syringe to a substrate. If the droplet sticks to the substrate,increasing the distance between the syringe tip and the substrategenerates a tensile force that yields the oxide. Simultaneously applyingpressure to the metal keeps the resulting wire from necking (i.e.,collapsing) during formation. This same approach may be used for direct-writingthe metal in 2D.41 (iii) By stacking dropletson top of each other, as shown in Figure 4d.The droplets form at the tip of a syringe by applying small burstsof pressure inside the syringe to expel the metal. A motorized x-y-z stage positionsthe droplets, which stick to each other and release from the syringetip. The presence of the oxide stabilizes these structures and thusprevents them from collapsing into a single bead. (iv) By injectingthe metal into microchannels and then dissolving away the microchannels,as shown in Figure 4e.


Emerging applications of liquid metals featuring surface oxides.

Dickey MD - ACS Appl Mater Interfaces (2014)

3D printing of free-standingliquid metal structures. (a) Sudden burst of pressure forces liquidmetal out of the tip of a syringe, which extends as a fiber to thesubstrate. The fiber is stabilized by the oxide layer. (b) Resultingfibers are strong enough to span a gap. (c) Extruded wire that isbent into the shape of an arch. (d) Stacks of liquid metal droplets.(e) Liquid metal injected into microchannels remains mechanicallystable after dissolving all of the channel walls except the substrate.Scale bars are all 500 μm. Adapted with permission from ref (24). Copyright 2013 Wiley.
© Copyright Policy - editor-choice
Related In: Results  -  Collection

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

fig4: 3D printing of free-standingliquid metal structures. (a) Sudden burst of pressure forces liquidmetal out of the tip of a syringe, which extends as a fiber to thesubstrate. The fiber is stabilized by the oxide layer. (b) Resultingfibers are strong enough to span a gap. (c) Extruded wire that isbent into the shape of an arch. (d) Stacks of liquid metal droplets.(e) Liquid metal injected into microchannels remains mechanicallystable after dissolving all of the channel walls except the substrate.Scale bars are all 500 μm. Adapted with permission from ref (24). Copyright 2013 Wiley.
Mentions: Figure 4 shows imagesof freestanding liquid metal structures resting on a substrate. Thesestructures may be generated in four different ways: (i) By rapidlyapplying a burst of pressure to the syringe, a fine fiber of metal(diameters as small as 10 μm) emerges from the syringe, as shownin Figure 4a. These fibers are stabilized againstcapillary instabilities by the presence of the oxide, as shown inFigure 4b. (ii) By drawing a liquid metal cylinderfrom a syringe to form wires, as shown in Figure 4c. The process begins by contacting a droplet on the end ofa syringe to a substrate. If the droplet sticks to the substrate,increasing the distance between the syringe tip and the substrategenerates a tensile force that yields the oxide. Simultaneously applyingpressure to the metal keeps the resulting wire from necking (i.e.,collapsing) during formation. This same approach may be used for direct-writingthe metal in 2D.41 (iii) By stacking dropletson top of each other, as shown in Figure 4d.The droplets form at the tip of a syringe by applying small burstsof pressure inside the syringe to expel the metal. A motorized x-y-z stage positionsthe droplets, which stick to each other and release from the syringetip. The presence of the oxide stabilizes these structures and thusprevents them from collapsing into a single bead. (iv) By injectingthe metal into microchannels and then dissolving away the microchannels,as shown in Figure 4e.

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