Robust Conductive Hydrogels with Ultrafast Self-Recovery and Nearly Zero Response Hysteresis for Epidermal Sensors

Abstract

Robust conductive hydrogels are in great demand for the practical applications of smart soft robots, epidermal electronics, and human–machine interactions. We successfully prepared nanoparticles enhanced polyacrylamide/hydroxypropyl guar gum/acryloyl-grafted chitosan quaternary ammonium salt/calcium ions/SiO2 nanoparticles (PHC/Ca2+/SiO2 NPs) conductive hydrogels. Owing to the stable chemical and physical hybrid crosslinking networks and reversible non-covalent interactions, the PHC/Ca2+/SiO2 NPs conductive hydrogel showed good conductivity (~3.39 S/m), excellent toughness (6.71 MJ/m3), high stretchability (2256%), fast self-recovery (80% within 10 s, and 100% within 30 s), and good fatigue resistance. The maximum gauge factor as high as 66.99 was obtained, with a wide detectable strain range (from 0.25% to 500% strain), the fast response (25.00 ms) and recovery time (86.12 ms), excellent negligible response hysteresis, and good response stability. The applications of monitoring the human’s body movements were demonstrated, such as wrist bending and pulse tracking.

High-Performing Conductive Hydrogels for Wearable Applications

“…Nanoparticle-enhanced polyacrylamide/hydroxypropyl guar gum/acryloyl-grafted chitosan quaternary ammonium salt/calcium ions/SiO 2 nanoparticles (PHC/Ca 2+ /SiO 2 NPs) conductive hydrogels were prepared [46]. The hydrogels exhibited good conductivity, toughness, stretchability, self-recovery, and fatigue resistance.…”

Wearable Electrochemical Sensors Based on Nanomaterials for Healthcare Applications

“…F.J. Martinez-Tabares [2] has developed a garment for dynamic electrocardiogram monitoring, a smart T-shirt with conductive textile electrodes coated with silica nanoparticles to maintain electrical conductivity and give superhydrophobic properties. Xu group [128] prepared conductive hydrogels of nanoparticle reinforced polyacrylamide, hydroxypropyl Guar gum, acrylyl grafted chitosan quaternary ammonium salt, calcium ion and silica nanoparticle (PHC/Ca 2 + /SiO 2 NPs) for monitoring human movement. Based on Morpho Menelaus (M.Menelaus) wearable sensors integrated with microfluidic systems and electronic networks, He et al [129].…”

Electrospun Nanofibers Hybrid Wrinkled Micropyramidal Architectures for Elastic Self-Powered Tactile and Motion Sensors

“…However, they normally exhibit poor extensibility and are quite rigid. Conductive hydrogels are good candidates for their softness, large elasticity, and excellent conductivity [ 15 , 16 ]. On the other hand, various high-dielectric materials such as nylon 6′6, polytetrafluoroethylene (PTFE), and PVDF have been studied to enhance the output sensing performance of triboelectric devices [ 13 , 17 ].…”