A multifunctional shape-morphing elastomer with liquid metal inclusions

Significance Research in soft robotics and wearable technologies has led to increasing demand for shape-changing materials that can be powered with portable electronics. Liquid crystal elastomers (LCEs) are a promising functional material for these applications but lack the electrical and thermal conductivity required for electrically stimulated shape-memory activation. To address this, LCEs are typically embedded with rigid fillers that enhance conductivity. However, these particles degrade the mechanical properties and shape-morphing capabilities of the LCE matrix. Here, we overcome these limitations with an advanced material architecture in which rigid filler is replaced with deformable liquid metal inclusions. This results in LCE composites that exhibit a combination of high electrical conductivity, high thermal conductivity, and actuation capabilities unlike any other soft composite. Natural soft tissue achieves a rich variety of functionality through a hierarchy of molecular, microscale, and mesoscale structures and ordering. Inspired by such architectures, we introduce a soft, multifunctional composite capable of a unique combination of sensing, mechanically robust electronic connectivity, and active shape morphing. The material is composed of a compliant and deformable liquid crystal elastomer (LCE) matrix that can achieve macroscopic shape change through a liquid crystal phase transition. The matrix is dispersed with liquid metal (LM) microparticles that are used to tailor the thermal and electrical conductivity of the LCE without detrimentally altering its mechanical or shape-morphing properties. Demonstrations of this composite for sensing, actuation, circuitry, and soft robot locomotion suggest the potential for versatile, tissue-like multifunctionality.

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