Zhu Wei-Bin, Li Yuan-Qing, Wang Jun, Wang You-Yong, Huang Pei, Hu Ning, Liao Kin, Fu Shao-Yun
College of Aerospace Engineering, Chongqing University, Chongqing 400044, P. R. China.
State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044, P. R. China.
ACS Appl Bio Mater. 2020 Dec 21;3(12):8748-8756. doi: 10.1021/acsabm.0c01128. Epub 2020 Nov 11.
Bamboo, one of the most abundant biomaterials, has been used as a building material since ancient times; however, its application in functional materials has been rarely explored. Herein, a highly robust and conductive carbonized bamboo aerogel (CBA) is obtained from the natural bamboo through a simple three-step process of pulp oxidization, freeze-drying, and carbonization. The CBA obtained shows not only a low density of 0.02 g/cm but also a high conductivity of 6.42 S/m and remarkable elasticity with a maximum recoverable compressive strain of 60% due to its unique three-dimensional (3D) network randomly stacked with the hybrid structure of carbonized bamboo fibers and films. After encapsulation with silicone resin, the CBA/silicone composite prepared exhibits excellent flexibility and stretchability with a low Young's modulus (0.09 MPa) and a large failure strain (275%). Importantly, the CBA/silicone composite also offers remarkable strain-sensing performance with a maximum gauge factor of 30.6, a short responsive time of 50 ms, and a stable response to cyclic loading over 1000 cycles, which is comparable to those of the piezoresistive composites based on expensive nanomaterials. Moreover, the CBA/silicone composite demonstrates the capability as a wearable strain sensor for human motion recognition comprising finger bending, breathing, and throat movement. Considering the green and sustainable nature of bamboo as a raw material, combined with the excellent piezoresistive performance, low production cost, and simple preparation process, the flexible strain sensors with CBA/silicone composite as a sensing element are promising in wearable electronic devices, personalized healthcare, and artificial intelligence systems.
竹子是最丰富的生物材料之一，自古以来就被用作建筑材料；然而，其在功能材料中的应用却鲜有探索。在此，通过纸浆氧化、冷冻干燥和碳化这一简单的三步工艺，从天然竹子中获得了一种高度坚固且导电的碳化竹气凝胶（CBA）。所获得的CBA不仅密度低至0.02 g/cm，而且具有6.42 S/m的高电导率以及显著的弹性，由于其独特的三维（3D）网络由碳化竹纤维和薄膜的混合结构随机堆叠而成，其最大可恢复压缩应变达60%。用硅树脂封装后，制备的CBA/硅树脂复合材料表现出优异的柔韧性和拉伸性，杨氏模量低（0.09 MPa）且破坏应变大（275%）。重要的是，CBA/硅树脂复合材料还具有出色的应变传感性能，最大应变系数为30.6，响应时间短至50 ms，对1000次以上的循环加载具有稳定响应，这与基于昂贵纳米材料的压阻复合材料相当。此外，CBA/硅树脂复合材料展示了作为可穿戴应变传感器用于人体运动识别的能力，包括手指弯曲、呼吸和喉咙运动。考虑到竹子作为原材料的绿色可持续性，结合其优异的压阻性能、低生产成本和简单的制备工艺，以CBA/硅树脂复合材料为传感元件的柔性应变传感器在可穿戴电子设备、个性化医疗保健和人工智能系统中具有广阔前景。
