All-in-one strain-triboelectric sensors based on environment-friendly ionic hydrogel for wearable sensing and underwater soft robotic grasping

Juntian Qu, Qiangjing Yuan, Zhenkun Li, Ziqiang Wang, Feng Xu, Qigao Fan, Min Zhang, Xiang Qian, Xueqian Wang, Xiaohao Wang, Minyi Xu; Nano Energy.


Hydrogel-based wearable devices and soft robotics have become a research hotspot. However, due to hydrogels’ poor anti-dehydration and susceptibility to breakage, issues of recycling and waste stream contamination risks have severely limited large-scale applications. Moreover, the practical monitoring of robotic grasping is rather limited due to the complex underwater environment. In this work, an environment-friendly high-performance ionic hydrogel with fracture toughness (146.5 kJ/m3) capable of strain and triboelectric sensing is developed. As a strain sensor, it owns good sensitivity (gauge factor: 4.30), a quick response time (70 ms), outstanding stability (~ 1000 cycles), low-temperature resistance, and well reproducibility (within one month). The hydrogel was also employed in the development of a flexible triboelectric sensor (200 % strain), which could respond sensitively to abundant types of materials (including water droplets). Due to these advantageous properties, the developed strain-triboelectric sensors can detect real-time human motion and grasping states of the soft gripper simulta- neously. Thanks to the good degradability (~ 12 h), it may well address potential problems of high cost and risks during the underwater recycling process. To summarize, the developed all-in-one strain-triboelectric sensors have demonstrated great potentials in enhancing the actively perceiving capabilities during underwater soft robotic grasping.