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

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 widesprea...

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Bibliographic Details
Published in:Advanced electronic materials 2018-01, Vol.4 (1), p.n/a
Main Authors: Secor, Ethan B., Cook, Alexander B., Tabor, Christopher E., Hersam, Mark C.
Format: Article
Language:English
Subjects:
conductive inks
eGaIn
printed electronics
reconfigurable circuits
stretchable electronics
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Summary: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 circuits and systems. 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 eutectic gallium‐indium (eGaIn) functionality with conventional electronics. Here, printed graphene is demonstrated as a reliable and high‐performance interfacial layer to enable electrical connections to eGaIn. A thin film (≈100 nm) of graphene 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 contacts offer excellent durability, with thermal stability to 300 °C, robust tolerance to mechanical bending, and chemical inertness. By leveraging this unique strategy to stabilize liquid metal contacts, a reconfigurable liquid metal electrical switch is fabricated with significantly improved longevity. Robust electrical contacts to liquid metal are demonstrated using printable graphene inks. A thin film of graphene effectively suppresses alloy formation between eutectic gallium‐indium and silver, enabling reliable electrical junctions with thermal, mechanical, and chemical stability. Detailed optimization and characterization of this strategy is leveraged to enable a reconfigurable liquid metal electrical switch operating in 2 m HCl.
ISSN:2199-160X
2199-160X
DOI:10.1002/aelm.201700483