Ultrasensitive Wearable Soft Strain Sensors of Conductive, Self-healing, and Elastic Hydrogels with Synergistic “Soft and Hard” Hybrid Networks

作者：Yanjun Liu, Wentao Cao, Ming‐Guo Ma, Pengbo Wan · 发表于：ACS Applied Materials & Interfaces · 年份：2017 · DOI：10.1021/acsami.7b07639 · 被引用次数：547 · 研究领域：Advanced Sensor and Energy Harvesting Materials、Conducting polymers and applications、Electrospun Nanofibers in Biomedical Applications

Robust, stretchable, and strain-sensitive hydrogels have recently attracted immense research interest because of their potential application in wearable strain sensors. The integration of the synergistic characteristics of decent mechanical properties, reliable self-healing capability, and high sensing sensitivity for fabricating conductive, elastic, self-healing, and strain-sensitive hydrogels is still a great challenge. Inspired by the mechanically excellent and self-healing biological soft tissues with hierarchical network structures, herein, functional network hydrogels are fabricated by the interconnection between a “soft” homogeneous polymer network and a “hard” dynamic ferric (Fe 3+ ) cross-linked cellulose nanocrystals (CNCs–Fe 3+ ) network. Under stress, the dynamic CNCs–Fe 3+ coordination bonds act as sacrificial bonds to efficiently dissipate energy, while the homogeneous polymer network leads to a smooth stress-transfer, which enables the hydrogels to achieve unusual mechanical properties, such as excellent mechanical strength, robust toughness, and stretchability, as well as good self-recovery property. The hydrogels demonstrate autonomously self-healing capability in only 5 min without the need of any stimuli or healing agents, ascribing to the reorganization of CNCs and Fe 3+ via ionic coordination. Furthermore, the resulted hydrogels display tunable electromechanical behavior with sensitive, stable, and repeatable variations in resistance upon mechanical defor...