Carbon nanotube-enhanced nanocomposite organohydrogel based on a physically cross-linked double network for sensitive wearable sensors

Abstract

Conductive hydrogels have attracted tremendous research interest in wearable sensing electronics. However, it is still a great challenge to develop hydrogels with robust mechanical properties, long-term stability, and good conductivity for highly sensitive hydrogel-based wearable strain sensors. Here, a nanocomposite organohydrogel (NOH) based on a physically cross-linked double network is prepared by a combination of simple one-pot polymerization and a solvent displacement process. By introducing carbon nanotubes (CNTs) into the cross-linked network, the prepared NOH demonstrates an enhanced mechanical performance (a fracture stretchability of 1871%, and a tensile strength of 1.56 MPa). Meanwhile, the NOH exhibits outstanding freezing and drying tolerance to ensure a long-term stability and high mechanical and electrical performances. Furthermore, sodium chloride is introduced into the organic solvents in the solvent displacement process and it penetrated the organohydrogel to greatly improve its conductivity, which is about 6 times higher than that without sodium chloride. Finally, the NOH demonstrates good strain sensitivity with a broad working range as a wearable strain sensor and can be attached to different parts of the human body to monitor various human activities successfully. This work provides a strategy to balance the different properties of a hydrogel to meet the requirements of next-generation wearable electronics for practical applications.