Emerging Applications of Liquid Metals Featuring Surface Oxides

Dickey, Michael D.

doi:10.1021/am5043017

Cited by 557 publications

(509 citation statements)

References 116 publications

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“…Microchannels of these materials embedded in flexible and stretchable elastomers can be used to create intrinsically soft sensors 98 or connect pre-packaged IC components 99 . EGaIn is particularly desirable for these applications because of its high conductivity, stable surface oxides, low toxicity and low viscosity 100 . The fabrication and filling of these liquid-metal microchannels has been a persistent challenge, with numerous techniques proposed in the literature, including injection 101 , freeze placement 102 and direct writing 103 .…”

Section: Nature Electronicsmentioning

confidence: 99%

Untethered soft robotics

2018

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Research in soft matter engineering has introduced new approaches in robotics and wearable devices that can interface with the human body and adapt to unpredictable environments. However, many promising applications are limited by the dependence of soft systems on electrical or pneumatic tethers. Recent work in soft actuation and electronics has made removing such cords more feasible, heralding a variety of applications from autonomous field robotics to wireless biomedical devices. Here we review the development of functional untethered soft robotics. We focus on recent advances in soft robotic actuation, sensing and integration as they relate to untethered systems, and consider the key challenges the field faces in engineering systems that could have practical use in real-world conditions.

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Section: Nature Electronicsmentioning

confidence: 99%

Untethered soft robotics

2018

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“…First, when encapsulated in channels in a silicone elastomer, the liquid metal flows readily, maintaining continuity as the channel changes geometry due to external extension or compression. Furthermore, when galliumbased liquid metals are exposed to air, the liquid metal forms a stabilizing oxide layer that prevents unwanted flow (Dickey, 2014). These two properties make these alloys ideal for use in damage resilient electronics: the stabilizing oxide prevents the conductive liquid from leaking out any punctures/holes, but the liquid-like behavior allows it to seal circuit breaks.…”

Section: Room Temperature Liquid Metal-based Electronicsmentioning

confidence: 99%

“…One potential challenge facing this system is the non-conductive oxide layer that builds up each time the liquid metal is exposed to air (during multiple self-healing events), which results in overall decreasing conductance. However, liquid metal oxidation has also been shown to prevent the liquid metal from leaking during healing events by creating an encapsulating seal at the location of failure (Dickey, 2014). Therefore, while highly advantageous in simple applications, implementation of liquid metal as a selfhealing conductor may be limited in applications where stable conductance is necessary, such as resistive sensors.…”

Section: Room Temperature Liquid Metal-based Electronicsmentioning

confidence: 99%

Self-Healing and Damage Resilience for Soft Robotics: A Review

Bilodeau

Kramer

2017

Front. Robot. AI

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Advances in soft robotics will be crucial to the next generation of robot-human interfaces. Soft material systems embed safety at the material level, providing additional safeguards that will expedite their placement alongside humans and other biological systems. However, in order to function in unpredictable, uncontrolled environments alongside biological systems, soft robotic systems should be as robust in their ability to recover from damage as their biological counterparts. There exists a great deal of work on self-healing materials, particularly polymeric and elastomeric materials that can self-heal through a wide variety of tools and techniques. Fortunately, most emerging soft robotic systems are constructed from polymeric or elastomeric materials, so this work can be of immediate benefit to the soft robotics community. Though the field of soft robotics is still nascent as a whole, self-healing and damage resilient systems are beginning to be incorporated into three key support pillars that are enabling the future of soft robotics: actuators, structures, and sensors. This article reviews the state-of-the-art in damage resilience and self-healing materials and devices as applied to these three pillars. This review also discusses future applications for soft robots that incorporate self-healing capabilities.

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“…The ability to control the surface tension of liquid metal could enable new opportunities for creating shape reconfigurable structures with metallic properties for electronic, thermal, and optical applications [9][10][11][12][13][14] . The most common liquid metal is Hg, which is noted for its toxicity.…”

Section: Introductionmentioning

confidence: 99%

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Eaker

Khan

Dickey

2016

JoVE

Self Cite

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Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( ̴ 500 mN/m to near zero). Furthermore, this method requires only a very modest potential (< 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests. Video LinkThe video component of this article can be found at

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Emerging Applications of Liquid Metals Featuring Surface Oxides

Cited by 557 publications

References 116 publications

Untethered soft robotics

Untethered soft robotics

Self-Healing and Damage Resilience for Soft Robotics: A Review

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

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