Liquid metal-filled magnetorheological elastomer with positive piezoconductivity

• Published in: Nature communications Vol. 10; no. 1; p. 1300
• Main Authors: Yun, Guolin, Tang, Shi-Yang, Sun, Shuaishuai, Yuan, Dan, Zhao, Qianbin, Deng, Lei, Yan, Sheng, Du, Haiping, Dickey, Michael D., Li, Weihua
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.03.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 639/301/1005/1009; 639/301/1023/1025; 639/301/923/1029; Casting; Composite materials; Conductivity; Conductors; Deformation; Deformation effects; Elastomers; Elongation; Fillers; Humanities and Social Sciences; Interfaces; Magnetic fields; Magnetic properties; Metals; Microparticles; multidisciplinary; Robotics; Science; Science (multidisciplinary); Substrates; Tensile strain; Thermal properties; Thermodynamic properties
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09325-4

Conductive elastic composites have been used widely in soft electronics and soft robotics. These composites are typically a mixture of conductive fillers within elastomeric substrates. They can sense strain via changes in resistance resulting from separation of the fillers during elongation. Thus, most elastic composites exhibit a negative piezoconductive effect, i.e. the conductivity decreases under tensile strain. This property is undesirable for stretchable conductors since such composites may become less conductive during deformation. Here, we report a liquid metal-filled magnetorheological elastomer comprising a hybrid of fillers of liquid metal microdroplets and metallic magnetic microparticles. The composite’s resistivity reaches a maximum value in the relaxed state and drops drastically under any deformation, indicating that the composite exhibits an unconventional positive piezoconductive effect. We further investigate the magnetic field-responsive thermal properties of the composite and demonstrate several proof-of-concept applications. This composite has prospective applications in sensors, stretchable conductors, and responsive thermal interfaces. Liquid metal-filled elastic composites for strain sensing devices exhibit reduced conductivity under strain, which limits their usefulness. Here, the authors report a positive piezoconductive effect in liquid metal-filled magnetorheological elastomers and illustrate proof-of concept applications.