Stretchable and Soft Electronics using Liquid Metals

Dickey, Michael D.

doi:10.1002/adma.201606425

Cited by 1,340 publications

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References 218 publications

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“…In particular, stable electrical contacts have been identified as a critical challenge for the integration of GaLMAs in electronic circuits and systems. [4] Since gallium alloys rapidly with most metals, GaLMAs lead to unstable or mechanically sensitive interfaces when combined with metal electrodes or interconnects, thereby preventing the reliable integration of eGaIn functionality with conventional electronics. In a recent dramatic demonstration of this effect, Dickey and coworkers exploited the aggressive alloying of eGaIn with silver to direct the motion of liquid metal droplets across a surface, completely removing the silver in the process.…”

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confidence: 99%

“…This configuration exhibits clear alloying between the silver and eGaIn, as expected from prior reports. [4,24] To establish the ability of graphene to stabilize this interface, a similar sample is fabricated with a thin film (≈100 nm) of graphene printed between the silver and eGaIn. The graphene ink and printing methods are adopted from recent work, [30] resulting in a continuous film of few-layer graphene flakes with a dense microstructure, functioning as a physical barrier between the eGaIn and silver (Figures S1 and S2, Supporting Information).…”

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Wiring up Liquid Metal: Stable and Robust Electrical Contacts Enabled by Printable Graphene Inks

Secor

Cook

Tabor

et al. 2017

Adv Elect Materials

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electronic materials. By leveraging these unique characteristics, researchers have recently demonstrated advances in reconfigurable, responsive, and stretchable electronic devices. [5][6][7][8] Select applications of liquid metals include soft electronic skins, [9,10] dynamic and flexible antennas, [11][12][13][14] and self-healing and elastic electronics. [15,16] Moreover, the fluid nature of GaLMAs such as eutectic gallium-indium (eGaIn) enables broad process compatibility with additive printing methods such as direct write, inkjet, transfer, and 3D printing. [17][18][19][20][21][22][23] As such, research toward the control and integration of GaLMAs for printed, stretchable, and reconfigurable electronics has attracted broad scientific and practical interest.Despite their promise, the development of liquid metal electronics must overcome several challenges for widespread application. In particular, stable electrical contacts have been identified as a critical challenge for the integration of GaLMAs in electronic circuits and systems. [4] Since gallium alloys rapidly with most metals, GaLMAs lead to unstable or mechanically sensitive interfaces when combined with metal electrodes or interconnects, thereby preventing the reliable integration of eGaIn functionality with conventional electronics. In a recent dramatic demonstration of this effect, Dickey and coworkers exploited the aggressive alloying of eGaIn with silver to direct the motion of liquid metal droplets across a surface, completely removing the silver in the process. [24] Therefore, to enable broader application of eGaIn with conventional circuits, interfacial alloying needs to be suppressed without compromising electrical or mechanical properties.Here, we demonstrate printed graphene as a reliable and high-performance interfacial layer to enable electrical connections to eGaIn. In contrast to conventional metals, sp 2 -bonded carbon materials are stable to alloy formation with liquid metals. [25,26] To leverage this property in a platform that is suitable for printed GaLMAs, graphene inks based on cellulose derivatives are used for robust contacts to liquid metal. This class of graphene inks has shown broad process compatibility with excellent electrical conductivity, mechanical durability, and environmental stability. [27][28][29][30] A thin film (≈100 nm) of fewlayer graphene flakes printed between conventional silver leads and eGaIn acts as a physical barrier, effectively passivating the surface against alloying while retaining the ability to conduct current across the interface. Moreover, graphene interfacial Gallium-based liquid metal alloys (GaLMAs) are a unique class of advanced materials with the potential to offer unprecedented opportunities in stretchable and reconfigurable electronics. Despite their promise, the development of liquid metal electronics must overcome several challenges for widespread application. In particular, stable electrical contacts have been identified as a critical challenge for the integration of GaLMAs in electronic...

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Wiring up Liquid Metal: Stable and Robust Electrical Contacts Enabled by Printable Graphene Inks

Secor

Cook

Tabor

et al. 2017

Adv Elect Materials

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“…The use of gallium-based liquid-metal alloys confined in elastomeric enclosures provides intrinsically stretchable properties that maintain bulk electrical conductivity with high stretchability. 6 Additionally, unlike mercury, gallium is safe to use in ambient environment due to its low vapor pressure. 7,8 By taking full advantage of the deformability and nontoxicity of the liquid metal, many research groups have utilized liquid metal for wearable applications.…”

Section: Introductionmentioning

confidence: 99%

A skin-attachable, stretchable integrated system based on liquid GaInSn for wireless human motion monitoring with multi-site sensing capabilities

et al. 2017

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This paper introduces a liquid-metal integrated system that combines soft electronics materials and engineering designs with advanced near-field-communication (NFC) functionality for human motion sensing. All of the active components, that is, strain sensor, antenna and interconnections, in this device are made of liquid metal, and the device has unique gel-like characteristics and stretchability. Patterning procedures based on selective wetting properties of the reduced GaInSn enable a skin-attachable, miniaturized layout, in which the diameter of the device is less than 2 cm. Electromechanical characterization of the strain sensor and antenna reveals their behaviors under large uniaxial tensile and compressive strains, as well as more complex modes of deformation. Demonstrations of these devices involve their use in monitoring various human motions in a purely wireless fashion; examples include wrist flexion, movements of the vocal cord and finger motion. This simple platform has potential for use in human-machine interfaces for prosthetic control and other applications. NPG Asia Materials (2017) 9, e443; doi:10.1038/am.2017.189; published online 27 October 2017 INTRODUCTION Skin-mounted, deformable devices capable of sensing various signals such as strain, pressure and temperature can be used in a variety of applications ranging from health monitoring systems and personal diagnostics to human-machine interfaces. 1 Advanced concepts in stretchable materials and mechanics principles form the basis for devices that can gently laminate onto the soft and curvilinear surfaces of human skin or conformally wrap onto internal organs of the body. 2-5 Gallium-based liquid metals are highly suitable candidates for such applications due to their unlimited deformability while maintaining excellent metallic conductivity. The use of gallium-based liquid-metal alloys confined in elastomeric enclosures provides intrinsically stretchable properties that maintain bulk electrical conductivity with high stretchability. 6 Additionally, unlike mercury, gallium is safe to use in ambient environment due to its low vapor pressure. 7,8 By taking full advantage of the deformability and nontoxicity of the liquid metal, many research groups have utilized liquid metal for wearable

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“…Gallium-based room temperature liquid metals (eutectic gallium-indium, or eGaIn, and eutectic gallium-indium-tin, or galinstan, alloys) are often used in highly stretchable and flexible soft electronics (Dickey, 2016(Dickey, , 2017. Their unique properties allow for a variety of soft systems to be developed that are not available in solid-metal electronics.…”

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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Stretchable and Soft Electronics using Liquid Metals

Cited by 1,340 publications

References 218 publications

Wiring up Liquid Metal: Stable and Robust Electrical Contacts Enabled by Printable Graphene Inks

Wiring up Liquid Metal: Stable and Robust Electrical Contacts Enabled by Printable Graphene Inks

A skin-attachable, stretchable integrated system based on liquid GaInSn for wireless human motion monitoring with multi-site sensing capabilities

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

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