Elastic Multifunctional Liquid–Metal Fibers for Harvesting Mechanical and Electromagnetic Energy and as Self‐Powered Sensors

Abstract

Future wearable technologies and personal electronics may benefit from e‐textiles that simultaneously possess high elasticity and multiple capabilities such as energy harvesting and sensing. Here, the first elastic multifunctional fiber that can scavenge mechanical energy from body motion and electromagnetic energy from surrounding electrical appliances is presented. In addition to converting multiple sources of waste energy into electricity, the fibers can also serve as self‐powered tactile and biomechanical sensors. The fibers consist of hollow elastomeric fibers filled with liquid metal. The fibers harvest energy by the combination of triboelectricity (160 V m−1, 5 µA m−1, and ≈360 µW m−1) and induced electrification of the liquid metal (±8 V m−1 (60 Hz), ±1.4 µA m−1, and ≈8 µW m−1). The fibers are characterized and their utility for powering electronics and sensing biomechanical information is demonstrated. These fibers are further demonstrated as completely soft and stretchable components for human–machine interfaces, including keypads and wireless music controllers.

Multifunctional liquid metal polymer composites

“…The means of achieving these self-powered devices are through TEGs and TENGs, which are small enough to be integrated into LMPCs without completely sacrificing the soft and stretchable characteristics of the composites (Figure 12E). 79,177,178 These devices have shown promising potential for powering wearable low power devices and have been extensively covered in a recent review. 43 Another type of sensor that has seen some attention in recent research is electrochemical sensing LMPCs.…”

Smart Textile Triboelectric Nanogenerators: Prospective Strategies for Improving Electricity Output Performance

“…The poor interface stability can be effectively avoided by directly injecting flowing liquid electrodes into dielectric elastomeric tubes. For example, a triboelectric fiber consists of an elastomeric SEBS hollow fiber filled with metallic EGaIn liquid, fabricated with melt extrusion and injection methods (Figure 5e) [87]. Similarly, a coaxial wet spinning process is used to continuously manufacture inherently stretchable, high conductivity, and stable conductivity liquid metal core microfibers (Figure 5f) [88].…”

“…(e) Multifunctional liquid-metal triboelectric fibers with metallic EGaIn liquid filled in SEBS hollow fiber. Reproduced with the permission of [87], copyright 2021, Wiley-VCH. (f) Liquid-metal sheath-core microfibers consisting of double-network fluoroelastomer as the sheath and that percolated EGaIn alloy nanoparticles as the core.…”

Progress in the Triboelectric Human–Machine Interfaces (HMIs)-Moving from Smart Gloves to AI/Haptic Enabled HMI in the 5G/IoT Era

“…To further enrich the function of the glove-based HMI, Zhu et al integrated TENGbased finger bending sensors, palm sliding sensors, and also piezoelectric mechanical stimulators onto one 3D-printed glove which realizes the multidirectional bending sensing, sliding event detecting, as well as haptic stimulation simultaneously for augmented AR/VR experiences (Figure 2d) [132]. By attaching multiple elastomer-based TENG tactile sensors onto different joints of each finger, the perception of motions of each phalanx with multiple degrees of freedoms (DOFs) could be achieved, where these sensors provide more useful subtle features regarding the finger bending compared with other common solutions that installing one sensor node per finger [136][137][138][139]. In the meanwhile, the sensory information of the normal and shear force could also be collected by the TENG palm sliding sensor to realize diversified sensing, especially for grasping-related tasks, revealing a new possibility of multifunctional HMI solution based on TENGs for VR entertainment and training applications.…”