基于纤维素的空气凝胶因其互联多孔网络、低密度和优异的压缩性，特别适合用于柔性传感器，这些特性使得有效的变形检测和信号传输成为可能。然而，纤维素气凝胶在应变传感应用中的广泛采用受到其有限压缩性和抗疲劳性的限制。为解决这些问题，研究通过协同方法开发了复合气凝胶传感器，该方法将通过TEMPO氧化法制备的竹纤维素纳米纤维（BCNFs）与甲基三甲氧基硅烷（MTMS）改性及氧化石墨烯（GO）掺杂相结合。

所得的BCNF/MTMS/还原石墨烯氧化物（rGO）气凝胶通过冻干和碳化的一体化工艺制备。所制备的压阻式传感器具有弹性、导电的多孔结构，具备卓越的传感性能，展现出高压缩敏感度（在20–30%应变下，应变系数可达2.45）。此外，该传感器在监测人体关节运动方面表现出优异性能，展现出作为下一代健康监测应用中高性能柔性可穿戴应变传感器的潜力。本研究为开发具有增强机械和传感性能的先进纤维素基气凝胶传感器提供了可行策略。

图文导读

图1. Preparation process diagram of BCNF/MTMS/rGO aerogels.

图2. SEM images of BCNF/MTMS/GO-0.5 (A, D), BCNF/MTMS/GO-1 (B, E), BCNF/MTMS/GO-1.5 (C, F), BCNF/MTMS/rGO-0.5 (G, J), BCNF/MTMS/rGO-1 (H, K), and BCNF/MTMS/rGO-1.5 (I, L) aerogels.

图3. (A) TEM image of BCNF. (B) FTIR spectra and (C) XRD spectra of BF, PBF, BCNF, BCNF/MTMS/GO-1 aerogel, and BCNF/MTMS/rGO-1 aerogel. (D) XPS spectra of BCNF, BCNF/MTMS/GO-1 aerogel, and BCNF/MTMS/rGO-1 aerogel, along with (E) C 1s and (F) Si 2p spectra of BCNF/MTMS/rGO-1 aerogel. (G) Nitrogen adsorption–desorption isotherms and (H) pore sizes of BCNF, BCNF/MTMS/GO-1 aerogel, and BCNF/MTMS/rGO-1 aerogel.

图4. (A) Loading and unloading processes of BCNF/MTMS/rGO-1 aerogel. (B) Retention of maximum stresses in BCNF/MTMS/GO-0.5, BCNF/MTMS/GO-1, and BCNF/MTMS/GO-1.5 aerogels at a strain of 50% for 50 cycles. (C) Stress–strain curves of BCNF/MTMS/rGO-1 aerogel at the maximum strains of 10, 30, and 50%, respectively. (D) Fatigue tests of several selected cycles on BCNF/MTMS/rGO-1 aerogel at 50% strain. (E) Retentions of maximum stress and total strain loss of BCNF/MTMS/rGO-1 aerogel during 100 cycles at 50% strain. (F) Comparison of water contact angles for BCNF, BCNF/MTMS/GO-1, and BCNF/MTMS/rGO-1 aerogels.

图5. Electromechanical performance of BCNF/MTMS/rGO-1 aerogels. (A) Mechanism of electrical resistance variation. (B) Current–voltage characteristics under different strains (0, 10, 20, 30, 40, and 50%). Variation of resistance with different applied strains (C) and frequencies (D). (E) Strain-sensing performance of BCNF/MTMS/rGO-1 aerogel. (F) Cycling stability test under 30% strain for 800 cycles.

图6. (A) Schematic representation of the pressure sensor’s structure. (B) Different bending angle signals of the finger. Resistance variation curves during the processes of (C) finger bending, (D) knee bending, and (E) elbow bending.

小结

本研究通过优化溶液混合和冻干工艺，成功制备了BCNF/MTMS/rGO-1气凝胶。竹纤维素纳米纤维（BCNF）、甲基三甲氧基硅烷（MTMS）与还原石墨烯氧化物（rGO）的协同组合，制备出具有坚固三维多孔结构的气凝胶，该结构赋予其机械韧性，同时集成导电网络可实现敏感应变响应（GF在20-30%应变下可达2.45），并展现出卓越的循环稳定性 （压缩循环稳定性可达800次循环）。基于气凝胶的传感器在监测复杂人体运动方面表现出色，包括精细的手指运动和大范围的关节弯曲。这些结果表明，BCNF/MTMS/rGO-1气凝胶在毫米级运动（如手指、肘部和膝盖弯曲）中展现出卓越的机械韧性和可靠的压阻响应，使其成为针对这些关节级变形可穿戴设备的理想候选材料。

文献：

https://doi.org/10.1021/acsaelm.5c01129

审核编辑 黄宇