Liu Jingfeng, Liu Jintao, Zhang Xuan, Liu Xingang, Zhang Chuhong
State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China.
ACS Appl Mater Interfaces. 2023 Nov 15;15(45):52631-52640. doi: 10.1021/acsami.3c12921. Epub 2023 Oct 31.
Piezoelectric energy harvesters (PEHs) with porous structures, such as piezoelectric elastic sponges, exhibit high force-to-electricity conversion efficiencies owing to their excellent compression recovery properties. However, conventional preparation methods are limited to producing bulk-form sponge-like PEHs and fail to create more elaborate three-dimensional (3D) structures that could enhance conversion efficiency. Herein, we invent a composite ink consisting of waterborne polyurethane (WPU), barium titanate (BTO), and cellulose nanofibers (CNFs) that is suitable for direct ink writing (DIW) 3D printing. This ink, when coupled with freeze-drying, allows the customization of piezoelectric sponges with functional 3D structures. The printed lattice sponge exhibits remarkable compression recovery of 70% and a notably high relative sensitivity of 9.83 mV/kPa*wt % (where *wt % denotes the BTO content) across a wide pressure range of 2.98-37 kPa, which is approximately three times broader than those of other composite piezoelectric pressure sensors based on BTO or piezoceramic (PZT) materials. Furthermore, a customized 3D piezoelectric sponge with a "boomerang" configuration is utilized as an anisotropic bending sensor on the wrist for intelligently monitoring the stroke posture and programming scientific training for table tennis players. This study highlights a versatile strategy for constructing elastic sponges with high piezoelectricity and designing 3D PEH functional structures that can be applied to flexible self-powered intelligent sensing systems.
具有多孔结构的压电能量收集器（PEH），如压电弹性海绵，由于其优异的压缩恢复性能而表现出高的力电转换效率。然而，传统的制备方法仅限于生产块状海绵状PEH，无法制造出能提高转换效率的更精细的三维（3D）结构。在此，我们发明了一种由水性聚氨酯（WPU）、钛酸钡（BTO）和纤维素纳米纤维（CNF）组成的复合墨水，适用于直接墨水书写（DIW）3D打印。这种墨水与冷冻干燥相结合，可定制具有功能性3D结构的压电海绵。打印的晶格海绵在2.98 - 37 kPa的宽压力范围内表现出70%的显著压缩恢复率和9.83 mV/kPawt%（其中wt%表示BTO含量）的显著高相对灵敏度，这比其他基于BTO或压电陶瓷（PZT）材料的复合压电压力传感器的压力范围宽约三倍。此外，一种具有“回旋镖”构型的定制3D压电海绵被用作手腕上的各向异性弯曲传感器，用于智能监测乒乓球运动员的击球姿势并规划科学训练。这项研究突出了一种通用策略，用于构建具有高压电性的弹性海绵并设计可应用于柔性自供电智能传感系统的3D PEH功能结构。
