Liquid Metal Enabled Soft Electronics and E-textiles

Gallium-based liquid metals have remarkable properties: melting points below room temperature, water-like viscosity, low-toxicity (unlike Hg), and effectively zero vapor pressure (they don’t evaporate). They also have, by far, the largest interfacial tension of any liquid at room temperature. Yet, these liquid metals can be patterned into non-spherical shapes (cones, wires, etc) due to a thin, oxide skin that forms rapidly on its surface. We have harnessed this oxide to pattern and manipulate metal into shapes—such as wires and particles—that are useful for applications that call for soft and deformable metallic features, such as wearables. It is possible to pattern the metal in a number of ways, including injection into microchannels or by direct-write 3D printing at room temperature, to form ultra-stretchable wires, deformable antennas, and microelectrodes. In addition, recently we have shown that liquid metals can be used in textiles that are highly conductive, breathable, and most interestingly, can “self-heal” autonomously when cut.
Furthermore, we have recently demonstrated for the first time the creation of stretchable gas barrier materials. Normally, stretchable materials are inherently permeable, which means it is not possible to encapsulate air sensitive electronic devices. We have used liquid metal, combined with elastomer, to create nearly perfect hermetic seals that can block water or oxygen from entering or leaving devices. Such materials can be used to encase stretchable batteries to prevent leakage of electrolyte (and thus, battery degradation) with respect to time. The talk will discuss the implications of these materials for soft and stretchable electronics; that is, devices with desirable mechanical properties for human-machine interfacing, soft robotics, and wearable electronics.