During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors' knowledge and experience. Abstract:During last decades, magnetorheological (MR) elastomer has attracted significant amount of attention for its enormous potentials in engineering applications. Being a solid counterpart of MR fluids, MR elastomers exhibit unique field-dependent material property when being exposed to magnetic field, in meanwhile overcoming major issues faced in magnetorheological fluids, e.g. deposition of iron particles, sealing problem and environmental contamination. Such advantages offer great potentials for designing intelligent devices to be used in various engineering fields, especially for vibration reduction and isolation. This paper presents a state-of-the-art review on the recent progress of MR elastomer technology, with special emphasis on research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, the review includes a brief introduction of the MR elastomer materials and follows by discussion of critical issues in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices and so on. Summary of research on modeling mechanical behavior for both material and devices are presented. Finally, challenges and potentials facing ...

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.

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