Wearable Flexible Sensors for Human Motion Detection with Self-Healing, Tough Guar Gum-Hydrogels of GO-P4VPBA/PDA Janus Nanosheets

Flexible and wearable sensors based on nanocomposite hydrogels have been used to monitor human physiological signals. However, it is still a challenge to develop flexible sensors using self-healing hydrogels with the properties of biocompatibility and flexibility. In this manuscript, Janus nanosheets were implanted into guar gum (GG)/poly(vinyl alcohol) (PVA) 3-dimensional network structure. The obtained flexible sensor with nanocomposite hydrogels had outstanding flexibility, high sensitivity, and excellent durability. In typical oil-in-water (O/W) Pickering emulsion, GO-poly(4-vinylphenylboronic acid)/polydopamine Janus nanosheets (JNs) were surface-initiated with 4-vinylphenylboronic acid (4VPBA) on the side of GO by RAFT polymerization and self-polymeriztion of dopamine (DA) on the other side by mussel-inspired chemistry, respectively. The JNs hydrogels had the preferable mechanical strength (1.0 MPa) and self-healing efficiency (93.1%) in the presence of reversible interaction. The resistive-type hydrogels sensor with these JNs hydrogels exhibited high sensitivity (gauge factor (GF) = 12.5) and antifatigue sensing performance (100% strain, 600 cycles). The sensor could monitor different human movements, which includes both large-scale (wrist bending, elbow bending, and running) and small-scale (cough vibrations, pulse rates, and finger bending) motion precisely. These nanocomposite hydrogels will provide strategies for wearable flexible sensors with superior stability and repeatability.