An autonomously electrically self-healing liquid metal–elastomer composite for robust soft-matter robotics and electronics

Abstract

Large-area stretchable electronics are critical for progress in wearable computing, soft robotics and inflatable structures. Recent efforts have focused on engineering electronics from soft materials-elastomers, polyelectrolyte gels and liquid metal. While these materials enable elastic compliance and deformability, they are vulnerable to tearing, puncture and other mechanical damage modes that cause electrical failure. Here, we introduce a material architecture for soft and highly deformable circuit interconnects that are electromechanically stable under typical loading conditions, while exhibiting uncompromising resilience to mechanical damage. The material is composed of liquid metal droplets suspended in a soft elastomer; when damaged, the droplets rupture to form new connections with neighbours and re-route electrical signals without interruption. Since self-healing occurs spontaneously, these materials do not require manual repair or external heat. We demonstrate this unprecedented electronic robustness in a self-repairing digital counter and self-healing soft robotic quadruped that continue to function after significant damage.

Fast and Efficient Electric‐Triggered Self‐Healing Shape Memory of CNTs@rGO Enhanced PCLPLA Copolymer

“…MWCNTs could enhance shape memory effect of poly( l ‐lactide‐ co ‐ε‐caprolactone) biodegradable copolymer . However, to date most of these polymers are only thermo‐sensitive, which cannot be precisely controlled and locally responsive, so they dissatisfy the growing practical requirements . Hence, it is expected to not only explore more channel stimuli‐responsive smart polymers, but also to design multifunctional materials including shape memory and self‐healing behaviors …”

Light‐Induced Shape Morphing of Liquid Metal Nanodroplets Enabled by Polydopamine Coating

“…Compared to the well‐known LM mercury, gallium, and its alloys, for example, eutectic gallium‐indium (EGaIn) and gallium‐indium‐tin (GaInSn), have received considerable more attention in recent years due to their low toxicity and negligible vapor pressure. The gallium‐based LMs have been widely used for reconfigurable electronics, soft robotics, and conformable medical devices . These devices can retain their functions under various mechanical deformations or adopt shape transformation for specific tasks when exposing to external stimuli.…”

Ultrauniform Embedded Liquid Metal in Sulfur Polymers for Recyclable, Conductive, and Self‐Healable Materials

“…Interestingly, different from previous LM composites based on crosslinked elastomers and rubbers, the LMESP materials are solvent-/thermal-processable and recyclable. [17,23] However, LMESP showed remarkable conductivity (0.43-1.8 × 10 3 S m −1 ) at low volume percentage of 30-50% (Figure 2e), even outperforming many metal powder/fiber-polymer composites required much higher metal content (typically >65%) for conductivity. Besides, the bulk materials are also capable to be hot-pressed into certain shapes (Figure 1b), indicating the remarkable thermal processability and recyclability (Figure 2f, no obvious change in electrical property (ranging from 1.12 to 1.91 Ω) after 100 cycles of thermal processing).…”

“…Representative engineering stress versus strain curves were plotted in Figure 4a,b and results were summarized in Tables S5 and S6 of the Supporting Information. [2,[18][19][20]23,24] f) The values of resistance for LMESP-50% composites during thermal processing in 100 times. As shown in Figure 4a and Table S5 (Supporting Information) c) Fourier transform infrared (FT-IR) spectrum for sulfur polymer.…”

“…[18,23,[38][39][40] For pure sulfur polymer, external thermal annealing at 100 °C was necessary for complete healing of the pure sulfur copolymer materials as reported in previous work. In previous reports, self-healing of liquid metals based materials required delicate structural design such as microcapsuling or microfluidic tools to achieve the self-healing feature in bulk LM-based composites.…”