当前的柔性应变传感器受限于狭窄的应变检测范围、脆性特性及较差的环境适应性。本文，安徽大学郭小辉、Weiqiang Hong，郑州大学Peng Wang 等研究人员在《Sensors and Actuators B: Chemical》期刊发表名为“Polyvinyl Alcohol/Silk Fibroin/Graphene Hydrogel-Based Flexible Sensor with Self-Healing, Ultra-Stretchable, and Eco-Friendly Properties for Advanced Wearable Electronics and Human-Machine Interaction Applications”的论文，研究提出了一种基于环保型纳米复合材料的离子导电水凝胶。该传感材料具备自愈合与可降解特性，且能在宽广范围内对拉伸应变作出敏感响应。该水凝胶通过将聚乙烯醇（PVA）、硼砂、丝素蛋白（SF）、单宁酸（TA）、氯化钠和石墨烯（GR）按特定比例混合合成。硼砂与PVA形成的硼酸酯键可聚合PVA内部的高分子链，赋予水凝胶自愈合能力。
丝素蛋白的引入作为增强剂，稳定了硼砂与PVA之间的非牛顿流体行为。丝素蛋白与单宁酸的结合赋予了水凝胶自愈合能力，并提升了其力学性能和粘弹性。作为导电材料，石墨烯可显著提高水凝胶的导电性。基于水凝胶的传感器具有良好的拉伸性（>6000%）、超快速响应/恢复时间（12.5 ms）、宽广的应变检测范围（>400%）以及在受到外部力量损坏后良好的自愈合能力。该传感器的应用示例包括皮肤友好型贴片和人体运动监测。对于超大应变监测，该设备可成功应用于降落伞下降过程的监测。
图文导读
图1.(a) Preparation process of hydrogel. (b) Multiple complexations among components within the hydrogel. (c) Formation mechanism of dynamic reversible boronic ester bonds between PVA chains and borax.
图2.Characterization of hydrogels. (a-d) Internal 3D network structure and micro-morphology of hydrogel. (e) Small networks extend from hydrogel networks. (f,g) EDS images of hydrogel. (h) FTIR images of hydrogel and its components. (i) XRD images of hydrogel and its components.
图3.(a) Resistive response of hydrogel at different strains. (b)I-Vvariation of hydrogel within the strain range of 0-800%. (c) Response/recovery time of hydrogel at 2% strain. (d) Experimental results of hydrogel under cyclic tests at 5%, 20%, and 50%. (e) Signal output curves of hydrogels at different stretch/release rates (25mm/min, 50mm/min, 100mm/min, 200mm/min). (f) Relative resistance change of hydrogel under gradually applied strain ranging from 0-10%. (g) Tensile loading-unloading curve at 30% strain. (h) Continuous cycling test of hydrogel at 30% stretch for 2500 cycles.
图4.(a) Effect of presence or absence of SF on the response properties of hydrogels. (b) Effect of NaCl on the tensile properties of hydrogels in a cold environment. (c) Comparison of response properties of hydrogels before and after being pulled apart. (d) Tensile properties of the samples in this paper before and after placing them in a cold environment. (e) Comparison of tensile multiplicity and sensitivity of this study with other references. (f) Comparative demonstration of hydrogel skin-friendly properties. (g) Demonstration of hydrogel degradation properties.
图5.(a) Conceptual diagram of a small smart combination box. (b) Set the knob to the “off” position. (c) Input “00” to the knob. (d) Invalid interval between " OFF" and "00" (e) Input the correct combination. The safe opens. (f) Input the wrong password. Trigger the error reminder.
图6.(a) Conceptual diagram for signal acquisition during shooting motion. (b) The hydrogel was damaged during exercise and quickly repaired itself. (c) Volunteer makes a shooting motion. (d) Wrist signal response when a shot is successful. (e) Wrist signal response when the volunteer is in a designated shooting position. (f) Elbow signal response when a shot is successful. (g) Elbow signal response when the volunteer is in the spotting position. (h) Knee signal response when a shot is successful. (i) Knee signal response when the volunteer is in the spot-up shooting position. (j) Categorization of 40 shots according to the magnitude of the gap between the shooting motion and the hitting motion. (k) Shots with an accuracy gesture between shooting motion and hitting motion. (l) Hits when there is an inaccuracy gesture between shooting motion and hitting motion.Fig. 6j shows that 24 of the 40 sets of movements have a small difference from the movements at the time of the hit, and 16 of the 40 sets of movements have a large difference from the movements at the time of the hit.Fig. 6k demonstrates that the hitting situation in the movements with a small gap and hitting time. There are 8 hits in 24 shots, and the hitting rate is about 33%.Fig. 6l reveals the hitting situation in the movements with a large gap and hitting time. There are 0 hits in 16 shots, and the hitting rate is 0. It can be seen that the sensor has a certain effect on shooting training for beginner basketball players. In addition, the hydrogel has low cost and is harmless to the environment, and can be rapidly degraded after being discarded without causing harm to the environment.
图7.(a) Three main stages of parachute descent, (I) Free fall stage (II) Parachute opening fall stage (III) landing stage. (b) Schematic diagram of assembly position of each component of the detection system. (c) Schematic diagram of synchronization and analysis of landing data. (d) Curve of tensile power over time at low temperature. (e) Curve of output signal over stretch power at low temperature. (f) Output curve of underwater gel signal at 35 °C temperature difference. (g) Hydrogel output signal curve during simulated parachute descent.
小结
本文提出了一种具有优异拉伸和温度响应性能的水凝胶。该水凝胶通过将聚乙烯醇（PVA）、硼砂、三羟甲基丙烷（TA）、三氟甲烷（SF）、氯化钠（NaCl）和聚乙烯吡咯烷酮（GR）混合并搅拌的简单工艺制备而成。其特点是原料来源广泛且成本低廉。通过利用硼酸酯键与材料间形成的多个氢键的协同作用，该水凝胶实现了高拉伸倍数比（>6000%）、快速响应/恢复时间（12.5 ms/12.5 ms）及高灵敏度（GF>214，当拉伸倍数比>300%时）。此外，该水凝胶具有良好的生物相容性和优异的降解能力，符合绿色发展的理念。最后，基于其卓越的拉伸能力，作为概念验证，我们提出了将水凝胶应用于小型智能保险箱、人体运动训练及降落伞过程检测等领域的可能性，从而展示了水凝胶优异的拉伸倍数和拉伸敏感性特性。
文献：
https://doi.org/10.1016/j.snb.2025.138566
审核编辑 黄宇
