Magnetically Engineered Conductivity of Soft Liquid Metal Composites for Robotic, Wearable Electronic, and Medical Applications

Abstract

Stretchable composites comprising liquid metal (LM) inclusions and silicone elastomers (LME composites) are of great interest for soft electronics and wearable devices. LME composites consisting of highly deformable materials and low conductive filler ratios offer high stretchability and good strain‐tolerant conductance, while not compromising the functionality of their host systems. Despite advances, actively achieving electrical conductivity for LME composites with a low ratio of fillers is challenging, especially in highly deformable elastomers. Herein, a new fabrication strategy that turns nonconductive LME composites with highly deformable elastomers into conductive ones using a small amount of magnetic Ni‐doped LM is introduced. By actively manipulating conductive fillers with an external magnetic field, electrically conductive traces can sustainably be achieved at any desired location. Experimental results show that conductive traces have high conductivity of 2.55 × 105 S m−1, high stretchability (>450%), good strain‐tolerant conductance (R/R0 ≈ 1.56 at 250% strain), and especially a tensile modulus as low as 60.1 kPa at a very low loading ratio (9.7% by volume). The noncontacting magnetic fabrication also enables the creation of diverse configurations in 1D, 2D, and 3D, offering a broad range of potential applications from robotics, stretchable electronics, wearable devices, smart garments to biomedical systems.

Keywords

• 3D fabrication
• biomedical devices
• liquid metal elastomer composites
• magnetic particles
• smart garments
• soft functional materials