Electrically Controlled Aquatic Soft Actuators with Desynchronized Actuation and Light-Mediated Reciprocal Locomotion

Biomedical applications of supramolecular hydrogels with enhanced mechanical properties

Supramolecular hydrogels bound by hydrogen bonding, host-guest, hydrophobic, and other non-covalent interactions are among the most attractive biomaterials available. Supramolecular hydrogels have attracted extensive attention due to their inherent dynamic reversibility, self-healing, stimuli-response, excellent biocompatibility, and near-physiological environment. However, the inherent contradiction between non-covalent interactions and mechanical strength makes the practical application of supramolecular hydrogels a great challenge. This review describes the mechanical strength of hydrogels mediated by supramolecular interactions, and focuses on the potential strategies for enhancing the mechanical strength of supramolecular hydrogels and illustrates their applications in related fields, such as flexible electronic sensors, wound dressings, and three-dimensional (3D) scaffolds. Finally, the current problems and future research prospects of supramolecular hydrogels are discussed. This review is expected to provide insights that will motivate more advanced research on supramolecular hydrogels.

Anti-swellable cellulose hydrogel for underwater sensing

Underwater sensing is of great significance in ocean exploration by divers to monitor their movements and keep in touch with the shore. However, unique sensors are required to apply in the marine environment that is quite different from the land circumstance. Herein, we reported a cellulose-skeleton-based composite hydrogel that is constraint to expand underwater under the effect of hydrogen bonds (H-bonds) and features advantages of high swelling resistance, structural durability, mechanical robustness, medium flexibility, high gauge factor (2.33) and long-term stability in water as a highly efficient wearable underwater sensor. This cellulose-based anti-swellable underwater hydrogel sensor showed tremendous potentials in underwater sensing applications for posture monitoring, communication, and marine biological research, etc.

Organohydrogel Actuators with Adjustable Stimulus Responsiveness for On-Demand Morphing

Hydrogel actuators showing shape morphing in response to external stimuli are of significant interest for their applications in soft robots, artificial muscles, etc. However, there is still a lack of hydrogel actuators with adjustable stimulus responsiveness for on-demand driving. In this study, an organohydrogel actuator was prepared by a two-step interpenetrating method, resulting in the coexistence of poly(N-isopropylacrylamide-co-4-(2-sulfoethyl)-1-(4-vinylbenzyl) pyridinium betaine) (p(NIPAM-SVBP)) hydrophilic networks and poly(lauryl methacrylate) (pLMA) hydrophobic networks with gradient distribution. In the initial state, the organohydrogel actuator can be driven globally under thermal stimulation. Owing to the unique alkali-chromic performance of SVBP, the organohydrogel actuator can be endowed with photothermal properties and actuate locally under the stimulus of NIR light. More importantly, the organohydrogel will return to the original colorless state after being treated with acid solution. Our work provides a new insight into designing and fabricating novel actuators with adjustable stimulus responsiveness for on-demand morphing.