Microfluidic Wet-Spun Core-Shell Elastomer Fibers with Integrated Sensing and Actuation Capabilities

The rapid developments of textile engineering and flexible electronics have driven the designs of functional fibers for smart sensing and soft robotics. However, it remains a great challenge to integrate multiple functions simultaneously in a single fiber system. Here, a core-shell elastomer fiber consists of a conductive core and an actuating shell is designed and prepared by microfluidic wet spinning. The fiber core provides stable strain-dependent resistive sensing via interconnected pathways of liquid metal (LM) nanodroplets (80% resistance change at 150% strain), and the fiber shell enables efficient electrothermal actuation through the nematic-isotropic phase transition of liquid crystal (LC) mesogens (30% actuation strain at 1.2 V applied voltage). The prepared LM-LCE fibers demonstrate good reproducibility, repeatability, tunability, controllability and multi-functionality. By integrating multiple functions in a single fiber system, a closed-loop control system is developed to maintain a target fiber length under different weights via real-time resistive sensing, Joule heating, actuation regulation and automatic control. The structure-function design of core-shell fibers is well-suited for the development of multi-functional fibers and would pave the way for their applications in diverse areas.