Template-Free and Stretchable Conductive Fiber with a Built-In Helical Structure for Strain-Insensitive Signal Transmission

Abstract

With the rapid development of intelligent electronic devices, conductive fibers have become very critical to signal transmission devices. However, metal-based rigid conductive wires, such as high-modulus copper and silver wires, are prone to signal failure owing to tensile breakage under large strain conditions. Therefore, strain-insensitive stretchable conductive fibers for signal transmission are critical for next-generation wearable devices. Herein, a stretchable conductive fiber with a built-in helical structure is constructed by a "speed discrepancy" fiber-coating strategy with mass scalable production (60 cm/min). Such a "speed discrepancy" strategy is the key mechanism to template-free fabricate a built-in helical structure of the stretchable conductive fiber. The resultant fiber exhibits high conductivity (873 S/cm), stable insensitive signal transmission with a high quality factor (47.4), and a low relative resistance change (∼6%) under large strain. The built-in helical structure inspired by loofah whiskers endows the fiber with excellent strain insensitivity, and it can withstand large strains. On the proof of concept, our fiber can be seamlessly knitted, woven, and braided into smart textiles as an ideal signal transmission device under large strains, which will undoubtedly promote the development of intelligent electronic textiles and next-generation wearable devices.

Double‐Helical Carbon Nanotube‐Wrapped Elastomeric Mandrel for Electrical Shortage‐Free, One‐Body Multifunctional Fiber Systems

“…Table 1 compares the structural configuration, deformability, and functionality of the DHB fiber system and prior-art various predeformationbased 1D device systems for clarifying the novelty of this work. [35][36][37][38][39][40][41] Benefitting from the torsion-/strain-mismatch coupling and resulting torque-balance structure design principle, the electrical shortage-free DHB fiber exhibits outstanding electromechanical stability with an intimate interfacial contact between the electrode layer and rubber substrate. With these features, we demonstrate three potential applications of the DHB fiber system as (1) a dielectric-based capacitive sensor of tensile, torsional, and compressive strains, (2) a deformable supercapacitor with pseudocapacitive effects of the electrochemically introduced oxygen-containing groups, and (3) a tensile actuator through electrothermally driven mandrel-core expansion under load tension.…”

“…[35][36][37][38][39] Helical fibers (Figure S1b, Supporting Information) have also been reported to be utilized as stretchable conductors and transmission lines. [40,41] Notwithstanding the numerous achievements of these pioneered studies, most predeformation-based 1D device systems are still unsatisfactory because they are mainly focused on obtaining stretching-tolerance. Particularly, they did not demonstrate the torsional deformability presented in this work, which may be ascribed to their deformable strategy being only prestretch (prestrain).…”