Highly Sensitive and Stretchable CNT‐Bridged AgNP Strain Sensor Based on TPU Electrospun Membrane for Human Motion Detection

Abstract

simplicity of design. [10,11] Several requirements such as high stretchability, flexibility, a wide working strain range from a subtle region to a large region, durability, lightweight, and low energy consumption should be fulfilled for wearable devices. [12] To achieve the stretchable flexible devices, studies on stretchable elastomeric substrates consisting of highly conductive fillers have been reported. [13,14] Ding et al. demonstrated a scalable and facile preparation of the electrospun polyurethane (PU) nonwoven dip-coated with the conducting polymer poly(3,4-ethylened ioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), which possessed adjustable electrical conductivity in the range of 30-200 S m −1 and large stretchability of 400%. [15] Lu et al. reported a sandwich-structured strain sensor with a gauge factor (GF) of 12.9 (at 20% strain) and a sensing range of 0-50% based on attaching the silver nanowires (AgNWs) on the thermoplastic polyurethane electrospun membrane (TPUEM) by filtration, followed by spin-coating using the liquid polydimethylsiloxane (PDMS). [16] Recently, electrospinning has become an effective, facile, and scalable technique for preparation of micro/nanofibers applied in wide applications. [17][18][19] The electrospun fibers own numerous advantages such as large specific surface area, high porosity, fine diameter, and commendable mechanical flexibility, which is an ideal base material for functional composites. [20,21] Especially, thermoplastic polyurethane (TPU) was easily electrospun into fibrous membrane which displayed outstanding stretchability, flexibility, and mechanical strength. [22,23] However, the pristine TPUEM has no conductivity and cannot be serving as sensing materials solely. Diverse conductive fillers incorporate into TPUEM to be developed as stretchable strain sensors. Yan et al. fabricated electrospun TPU fiber yarns successively decorated with multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) for wearable strain sensors. [24] Wang et al. developed a novel strain sensor with an excellent 3D conductive network based on reduced graphene oxide (RGO)-decorated TPU mats. [25] Tian fabricated electrospun PU/polyaniline nanofibrous mat by in situ chemical polymerization of aniline monomers on the surface of electrospun PU nanofiber substrate for wearable device. [26] However, it is quite difficult to Highly stretchable, conductive, and sensitive strain-sensing materials have aroused wide interest owing to their potential in wearable devices. A facile and scalable method to fabricate a carbon-nanotube-(CNT-) bridged silver nanoparticles (AgNPs) strain sensor based on thermoplastic polyurethane electrospun membrane (TPUEM), which exhibits a large strain range with a high gauge factor simultaneously, is demonstrated. It exhibits a high stretchability with large workable strain range of up to 550%, high gauge factor of 7066, good durability over 1000 cycles, and comparable stability under various strains. Importantly, it can be used for human mo...

Core–Sheath Fiber‐Based Wearable Strain Sensor with High Stretchability and Sensitivity for Detecting Human Motion

“…After several stretching and releasing processes, the destruction and reconstruction of the conductive network reached equilibrium, leading to a stable change in the relative electrical resistance. [17,25,42]…”

Highly Stretchable and Sensitive SBS/Graphene Composite Fiber for Strain Sensors

“…When an external force was applied to induce a relatively small deformation, the compact graphene network had disconnection at some Gr–Gr junctions, resulting in a gentle increase in the resistance and a low GF, as illustrated schematically in Figure a,b (red dotted square). [ 32 ] Upon applying a higher tensile strain, the tunnel distance of Gr–Gr became larger and the conductive pathways experienced irreversible destruction, which resulted in the rapid and sharp change of Δ R/R 0 , as shown in Figure 7b,c (red dotted square). [ 5,20 ]…”

Recent Advances in Natural Functional Biopolymers and Their Applications of Electronic Skins and Flexible Strain Sensors

“…Flexible strain sensors have attracted growing attentions owing to their valuable applications in monitoring of human physiological signals, the interaction between human and machine, as well as wearable sensors [ 54 , 55 ]. Compared with synthetic polymers, biopolymers are biocompatible and innoxious, which contribute to the improvement of the recycling performance for flexible sensors.…”