Key Laboratory of Optoelectronic Material and Device, Department of Physics , Shanghai Normal University , Shanghai 200234 , China.
ACS Appl Mater Interfaces. 2019 Feb 20;11(7):7379-7386. doi: 10.1021/acsami.8b19824. Epub 2019 Feb 6.
Piezoelectric polymers with good flexibility have attracted tremendous attention in wearable sensors and energy harvesters. As the piezoelectricity of polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] is lower than that of their ceramic counterparts, various approaches have been employed to improve the piezoelectric output of PVDF-based sensors, such as electrospinning, heat annealing, nanoconfinement, polymer blending, and nanoparticle addition. Here, we report two strategies to improve the piezoelectric sensing performance of polymer-based piezoelectric nanofibers, which include the formation of barium titanate (BTO)/P(VDF-TrFE) composite nanofibers and fabrication of penetrated electrodes to enlarge the interfacial area. BTO/P(VDF-TrFE) nanofibers with a BTO weight fraction of 5 wt % exhibit the maximum β-phase crystallinity and piezoelectricity. The piezoelectric output of the BTO/P(VDF-TrFE) nanofiber mat is significantly improved compared with that of pristine P(VDF-TrFE), which is confirmed by piezoresponse force microscopy (PFM) and compression loading tests. In order to form the penetrated electrodes, oxygen (O) plasma treatment is employed, followed by an electroless plating process. The BTO/P(VDF-TrFE) nanofibers with penetrated electrodes demonstrate increased dielectric constants and enhanced piezoelectric outputs. A BTO/P(VDF-TrFE) nanofiber-based sensor with penetrated electrodes is capable of discerning the energy of a free-falling ball as low as 0.6 μJ and sensing the movement of a walking ant.
具有良好柔韧性的压电聚合物在可穿戴传感器和能量收集器中引起了极大关注。由于聚偏二氟乙烯（PVDF）和聚偏氟乙烯-三氟乙烯（P（VDF-TrFE））等聚合物的压电性低于其陶瓷对应物，因此已经采用了各种方法来提高基于 PVDF 的传感器的压电输出，例如静电纺丝、热退火、纳米约束、聚合物共混和纳米颗粒添加。在这里，我们报告了两种提高聚合物基压电纳米纤维的压电传感性能的策略，包括形成钛酸钡（BTO）/P（VDF-TrFE）复合纳米纤维和制造穿透电极以扩大界面面积。BTO/P（VDF-TrFE）纳米纤维中 BTO 的重量分数为 5wt%时表现出最大的β相结晶度和压电性。与原始 P（VDF-TrFE）相比，BTO/P（VDF-TrFE）纳米纤维垫的压电输出得到了显著提高，这一点通过压电力显微镜（PFM）和压缩加载测试得到了证实。为了形成穿透电极，采用了氧气（O）等离子体处理，然后进行化学镀工艺。具有穿透电极的 BTO/P（VDF-TrFE）纳米纤维的介电常数增加，压电输出增强。具有穿透电极的 BTO/P（VDF-TrFE）纳米纤维传感器能够辨别低至 0.6 μJ 的自由落体球的能量，并感测行走蚂蚁的运动。
