Facile fabrication of carbon nanocolloids reinforced hydrogels for the application of high-performance strain sensors

Conductive hydrogels have attracted extensive attention in the application of wearable devices due to their excellent flexibility, biocompatibility, and stability. However, it is still a significant challenge to facilely fabricate the conductive hydrogels with high strength, high sensitivity and stable conductivity for wearable strain sensors. Herein, carbon nanoparticles based conductive hydrogels were prepared by a facile one-pot method of combining dispersant-free carbon nanocolloids with PVA/TA/PAM. When a small amount of carbon nanoparticles (0.45 wt%) were added into the hydrogel, the conductivity was significantly enhanced. Due to the synergetic effects from the PVA/TA/PAM polymers and carbon nanoparticles, the as-synthesized composites exhibited large mechanical strength (11.9 MPa) and failure strain (476 %), good sensitivity (GFmax = 1.41), great stability (over 500 cycles). In addition, the strain sensor made from the conductive hydrogel could sensitively detect human movements such as finger bending, arm bending, wrist bending, and leg bending. This hydrogel preparation strategy exhibits potential applications in low-cost wearable devices with high mechanical strength and sensitivity.