Sponge-like, semi-interpenetrating self-sensory hydrogel for smart photothermal-responsive soft actuator with biomimetic self-diagnostic intelligence

Abstract

Actuators based on hydrogels are good candidates for biomimetic soft robots due to their excellent mechanical properties and flexibility. Despite great efforts in hydrogel-based actuators, their actuation process still differs from the “recognition-judgment-execution” process that conscious intelligent beings go through owing to the lack of perceptive capacity. Herein, to imitate the intelligent actuation process of conscious organisms, a fast photo-thermal responsive and self-sensory soft actuator is proposed based on sponge-like hydrogel with semi-interpenetrating (semi-IPN) polymer network of thermosensitive poly (N-isopropylacrylamide) (PNIPAM) and electronically conductive polyaniline (PANI). The proposed actuator exhibits excellent photo-thermal responsiveness enabling remotely triggered actuation controlled by near infrared light (NIR), covering all azimuths with ultrafast response rate (within 2 s) and recover rate (within 1 s). Meanwhile, the conformational transition of PNIPAM networks during the course of actuation also lead to accompanying migration of the interpenetrated PANI chains and significant variation of local conductivity (>15%), endowing the actuator with self-sensing capacity to monitor its deformations. Eventually, a smart self-adaptive actuator is designed inspired by neuromuscular in intelligent organisms, which can actively perceive external environmental stimuli and consciously regulate its own shape transformation by monitoring and analyzing electrical signal. This sensory actuating hydrogel can provide insights into the development of artificial intelligent soft robotics with higher levels of autonomy and complexity.