當前的柔性應變傳感器受限于狹窄的應變檢測范圍、脆性特性及較差的環(huán)境適應性。本文，安徽大學郭小輝、Weiqiang Hong，鄭州大學Peng Wang 等研究人員在《Sensors and Actuators B: Chemical》期刊發(fā)表名為“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”的論文，研究提出了一種基于環(huán)保型納米復合材料的離子導電水凝膠。該傳感材料具備自愈合與可降解特性，且能在寬廣范圍內對拉伸應變作出敏感響應。該水凝膠通過將聚乙烯醇（PVA）、硼砂、絲素蛋白（SF）、單寧酸（TA）、氯化鈉和石墨烯（GR）按特定比例混合合成。硼砂與PVA形成的硼酸酯鍵可聚合PVA內部的高分子鏈，賦予水凝膠自愈合能力。

絲素蛋白的引入作為增強劑，穩(wěn)定了硼砂與PVA之間的非牛頓流體行為。絲素蛋白與單寧酸的結合賦予了水凝膠自愈合能力，并提升了其力學性能和粘彈性。作為導電材料，石墨烯可顯著提高水凝膠的導電性?；谒z的傳感器具有良好的拉伸性（>6000%）、超快速響應/恢復時間（12.5 ms）、寬廣的應變檢測范圍（>400%）以及在受到外部力量損壞后良好的自愈合能力。該傳感器的應用示例包括皮膚友好型貼片和人體運動監(jiān)測。對于超大應變監(jiān)測，該設備可成功應用于降落傘下降過程的監(jiān)測。

圖文導讀

圖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.

圖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.

圖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.

圖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.

圖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.

圖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.

圖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.

小結

本文提出了一種具有優(yōu)異拉伸和溫度響應性能的水凝膠。該水凝膠通過將聚乙烯醇（PVA）、硼砂、三羥甲基丙烷（TA）、三氟甲烷（SF）、氯化鈉（NaCl）和聚乙烯吡咯烷酮（GR）混合并攪拌的簡單工藝制備而成。其特點是原料來源廣泛且成本低廉。通過利用硼酸酯鍵與材料間形成的多個氫鍵的協(xié)同作用，該水凝膠實現(xiàn)了高拉伸倍數(shù)比（>6000%）、快速響應/恢復時間（12.5 ms/12.5 ms）及高靈敏度（GF>214，當拉伸倍數(shù)比>300%時）。此外，該水凝膠具有良好的生物相容性和優(yōu)異的降解能力，符合綠色發(fā)展的理念。最后，基于其卓越的拉伸能力，作為概念驗證，我們提出了將水凝膠應用于小型智能保險箱、人體運動訓練及降落傘過程檢測等領域的可能性，從而展示了水凝膠優(yōu)異的拉伸倍數(shù)和拉伸敏感性特性。

文獻：

https://doi.org/10.1016/j.snb.2025.138566

審核編輯 黃宇