This talk will discuss recent progress in utilizing liquid metals as conductors for stretchable, soft, and reconfigurable components for electroactive polymeric devices. Alloys of gallium are noted for their low viscosity, low toxicity, and near-zero vapor pressure. Despite the large surface tension of the metal, it can be patterned into non-spherical 2D and 3D shapes due to the presence of an ultra-thin oxide skin that forms on its surface. Because it is a liquid, the metal is extremely soft and flows in response to stress to retain electrical continuity under extreme deformation. By embedding the metal into elastomeric or gel substrates, it is possible to form soft, flexible, and conformal electrical components, stretchable antennas, and ultra-stretchable wires that maintain metallic conductivity up to ~800% strain. Thus, these materials are well-suited for soft robotics, stretchable electronics, and actuators because they can maintain metallic properties during deformation. In addition to introducing the advantages of these materials for such applications (e.g. conductive and self-healing electrodes in electroactive polymers), this talk will focus on recent work to utilize liquid metal for (2) tough energy absorbing materials1, stretchable embedded sensors and antennas[2], and soft materials logic3. This latter work is exciting because it suggests a way for materials to perform logic without the need of a centralized processor. Here, the deformation of a material (by touch or actuation) can be used as a logic input, which in turn ‘calculates’ a response. These advances have implications for soft machines and robots that have ultra-soft mechanical properties.
References
1. Cooper, C. B. et al. Toughening stretchable fibers via serial fracturing of a metallic core. Sci. Adv. 5, eaat4600 (2019).
2. Dickey, M. D. Stretchable and Soft Electronics using Liquid Metals. Adv. Mater. 29, 1606425 (2017).
3. Jin, Y. et al. Materials Tactile Logic via Innervated Soft Thermochromic Elastomers. Nat. Commun. 10, 4187 (2019).
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