The advocacy of smart living results in a high demand for wearable and flexible sensors to monitor human motions. Among these, sensors based on strain–optics conversion are attractive due to their inherent electrical safety and electromagnetic immunity in comparison to strain–electricity conversion sensors. Particularly, hydrogel-based optical fiber sensors are biocompatible, flexible, and stretchable and thus are potentially applicable to health monitoring, human–machine intelligence, and soft robots. Nonetheless, hydrogel-based optical fibers still demonstrate challenges such as limited stretch ratios from chemical cross-linking networks and insufficient light transmittance from dehydration or nucleation of water. Herein, flexible and stretchable strain sensors based on glycerol-introducing nanocomposite hydrogel fibers (GN-Fibers) were achieved via dynamic stretching of a reactive pregel from monomer/nanoparticle hybrid precursors in a glycerol–water cosolvent. The resultant GN-Fibers evolved with anisotropic microstructures, displaying excellent tensile strength (9.76 MPa), high elastic modulus (32.63 MPa), low light propagation attenuation (0.26 dB cm^–1), and broad strain range. Owing to the use of glycerol–water, such GN-Fibers also exhibited long-term moisture-retaining and antifreezing properties. In addition, GN-Fibers functioned well as sensors based on strain–optics conversion to monitor stretching and compressing behaviors. It is believed that such an optical fiber based strain sensor is a gateway to fabrication of next-generation wearable and flexible devices for health monitoring or artificial intelligence.

中文翻译：

---

基于各向异性结构演化引起的应变-光学转换的坚硬凝胶纤维作为应变传感器

倡导智能生活导致对可穿戴和灵活的传感器进行监控的需求很高。其中，与应变-电转换传感器相比，基于应变-光转换的传感器具有固有的电气安全性和电磁抗扰性，因此具有吸引力。特别是，基于水凝胶的光纤传感器具有生物相容性，柔性和可伸缩性，因此可能适用于健康监测，人机智能和软机器人。然而，基于水凝胶的光纤仍然表现出挑战，例如化学交联网络的拉伸比有限以及水的脱水或成核导致光透射率不足。在这里 通过将甘油/水助溶剂中的单体/纳米颗粒杂化前体中的反应性预凝胶动态拉伸，从而实现了基于甘油引入的纳米复合水凝胶纤维（GN-Fibers）的灵活，可拉伸的应变传感器。所得的GN纤维具有各向异性的微观结构，具有出色的拉伸强度（9.76 MPa），高弹性模量（32.63 MPa），低光传播衰减（0.26 dB cm）^–1），应变范围广。由于使用了甘油水，这种GN纤维还表现出长期的保水和防冻性能。此外，GN光纤作为基于应变-光学转换的传感器，可以很好地发挥作用，以监控拉伸和压缩行为。据信，这种基于光纤的应变传感器是制造用于健康监测或人工智能的下一代可穿戴和柔性设备的门户。