From carbon nanotubes to ultra-sensitive, extremely-stretchable and self-healable hydrogels

Bearing several merits including resemblance to tissues, tunable conductivity, and mechanical flexibility, conductive hydrogels have been widely applied in wearable sensors, implantable bioelectronics, artificial skins, etc. However, the fragile nature, lack of self-healing capability, and insufficient sensitivities at low strains of traditional conductive hydrogels cannot meet the increasing demands of flexible electronics. Here, carbon nanotubes (CNTs) were dispersed in water with the assistance of bis benzyl-modified polyethylene glycol (B-PEG(181)), which served as additional cross-linkers to prepare hydrogel by introducing acrylamide (AM) and N,N'-methylene bisacrylamide (MBAA). The synergy of physical entanglements and pi-pi interactions led to extreme stretchability (0 similar to 132 mm/mm) and self-healable capability. In addition, the introduction of CNTs and lithium chloride endowed the hydrogel with ultra-high sensitivity (GF = 122.7, at 6.0 similar to 8.0 mm/mm strain), superior to present sensors. Consequently, the obtained sensor could detect various human motions. It is envisioned that the remarkable performances empower the obtained gel promising applications in strain sensors, human-machine interfaces, and soft robots.