Healing, flexible, high thermal sensitive dual-network ionic conductive hydrogels for 3D linear temperature sensor

A temperature sensor based on muti-wall carbon nanotubes (MWCNTs) composite polyacrylamide/Fe³⁺-polyacrylic acid (PAM/Fe³⁺-PAA) double network (DN) hydrogels that combines flexibility, thermal sensitivity and self-healing ability is fabricated through in situ polymerization and maceration. Due to the excellent thermal conductivity of carbon nanotubes, the temperature sensitivity of the DN hydrogels are improved and therefore can be exploited as a novel channel material for a temperature sensor. This temperature sensor can be stretched from 0 to 750% strain with the sensitivity as high as 9.4%/°Cat extreme 200% strain. Importantly, the DN hydrogels have excellent self-healing properties that it can still be stretched after cutting and healing. Similarly, the electrical and thermal sensing properties of the DN hydrogels can be self-healed analogous to the self-healing capability of human skin. In addition, DN hydrogels have high stability for bending and torsion, which can avoid errors caused by deformation in the temperature measurement. In order to attaching on nonplanar curvilinear surfaces for practical temperature detection, we designed a linear-shaped hydrogels temperature sensor, which can improve the accuracy by wrapping the surface of the measured object completely in a way that eliminates the influence of air in the holes, enabling it to be potentially integrated in soft robots to grasp real-world information for guiding their actions.