Soft/Hard Controllable Conversion Galactomannan Ionic Conductive Hydrogel as a Flexible Sensor

Abstract

A galactomannan hydrogel has the characteristics of renewability and biodegradability. It has good prospects in flexible sensors and soft robot technology. However, it is still a challenge to prepare galactomannan hydrogel sensors with soft/hard controllable conversion and conductivity properties. In this paper, galactomannan, borax, and NaCl were introduced into a poly-N-isopropylacrylamide network to obtain a hydrogel with a double network structure. This hydrogel has a higher compressive strength (3.80 MPa), higher elongation (1370%), and higher conductivity (4.40 S/m). In addition, the hydrogel exhibits soft/hard controllable conversion and shape memory properties. It can be used as a flexible underwater gripper. The resistance curve shows that the prepared hydrogel can be used as a sensor to monitor and distinguish all kinds of small movements and sound changes of the human body through the change of the resistance signal. This hydrogel shows great potential in the fields of sustainable wearable sensors, artificial skin, flexible sensors, and soft robots.