Kim Min-Gi, Nam Kun-Woo, Kim Won-Jin, Park Sung-Hoon
Department of Mechanical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-Gu, Seoul 06978, Republic of Korea.
Micromachines (Basel). 2024 Nov 30;15(12):1467. doi: 10.3390/mi15121467.
Gallium-based liquid metals remain in a liquid state at room temperature and exhibit excellent electrical and thermal conductivities, low viscosity, and low toxicity, making them ideal for creating highly stretchable and conductive composites suitable for flexible electronic devices. Despite these benefits, conventional single-layer liquid metal composites face challenges, such as liquid metal leakage during deformation (e.g., stretching or bending) and limited elongation due to incomplete integration of the liquid metal within the elastomer matrix. To address these limitations, we introduced a bilayer structure into liquid metal composites, comprising a lower polydimethylsiloxane (PDMS) layer and an upper PDMS-liquid metal mixed layer. In the mixed layer, the liquid metal precipitates, forming a conductive network spanning both layers. This bilayer composite structure demonstrated significantly improved stretchability and elongation compared to pure PDMS or single-layer composites. Additionally, by adjusting the size and content of the liquid metal particles, we optimized the composite's mechanical and electrical properties. Under optimal conditions, spherical liquid metal particles deform into elliptical shapes under tensile stress, increasing conductive pathways and reducing electrical resistance. The combined effects of the bilayer structure and particle shape deformation enhanced the composite's stretchability and elongation, supporting its potential for flexible electronics applications.
镓基液态金属在室温下保持液态，具有优异的导电性和导热性、低粘度和低毒性，使其成为制造适用于柔性电子设备的高拉伸性导电复合材料的理想选择。尽管有这些优点，但传统的单层液态金属复合材料面临挑战，例如在变形（如拉伸或弯曲）过程中液态金属泄漏，以及由于液态金属在弹性体基质中不完全整合导致的伸长受限。为了解决这些限制，我们在液态金属复合材料中引入了双层结构，包括下层的聚二甲基硅氧烷（PDMS）层和上层的PDMS-液态金属混合层。在混合层中，液态金属沉淀，形成跨越两层的导电网络。与纯PDMS或单层复合材料相比，这种双层复合结构表现出显著提高的拉伸性和伸长率。此外，通过调整液态金属颗粒的尺寸和含量，我们优化了复合材料的机械和电学性能。在最佳条件下，球形液态金属颗粒在拉伸应力下变形为椭圆形，增加了导电路径并降低了电阻。双层结构和颗粒形状变形的综合作用增强了复合材料的拉伸性和伸长率，支持其在柔性电子应用中的潜力。
