A poling-free PVDF nanocomposite via mechanically directional stress field for self-powered pressure sensor application. (July 2022)

• Record Type: Journal Article
• Authors: Yuan, Xiaoting; Yan, Ao; Lai, Ziwei; Liu, Zhenghao; Yu, Zhonghui; Li, Zhanmiao; Cao, Yan; Dong, Shuxiang
• Is Part Of: Nano energy. Volume 98(2022)
• Publication Date: 2022-07
• Subjects: Strong electromechanical coupling -- Large poling-free piezoelectricity -- Mechanically directional stress field -- PVDF nanocomposite -- Self-powered sensor; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2022.107340
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: It is well known that Poly(vinylidene fluoride) (PVDF) polymer and its composites exhibit limited piezoelectricity only after strong electric field poling (SEFP) to align randomly oriented molecular dipoles inside. Here, we report that a (Pb, Zr)TiO3 (PZT) particles doped PVDF-polymer nanocomposite shows a large poling-free piezoelectric (PFP) coefficient and strong electromechanical coupling after experiencing mechanically directional stress field (MDSF). Analyses based on WAXD, FTIR, and HRTEM reveal that the MDSF actives and then induces a crystal phase transformation (CPT) from disordered star-shape nanocrystals to ordered, self-poled chain-shape high-β nanocrystalline fibers. PFM scanning images further show the existence of well-defined polarization. Furthermore, a 7-layer series-connected, self-powered circular pressure sensor was fabricated using multi-material 3D-printing technology, which exhibits a high sensitivity of 235 mV/kPa and a high-power density of 0.9 mW/cm 2 under a dynamic pressure of 255 kPa, and it is near 8 times higher than that of a conventional, poled single-layer PVDF sensor. Finally, a (3 × 3) real-time lighting tactile sensor array is 3D printed, confirming its feasibility for practical application. The MDSF-induced CPT and large PFP effect are significant because it may open a way to fabricate piezopolymer integrated devices without SEFP. Graphical Abstract: ga1 Highlights: Here, we report that dual mechanically directional stress field induces a crystal phase transformation from disordered star-shape nanocrystals to ordered, self-poled chain-shape high-β nanocrystalline fibers in PVDF and shows a large poling-free piezoelectric coefficient and strong electromechanical coupling. Based on the poling-free PVDF, a self-powered circular pressure sensor was fabricated using multi-material 3D-printing technology, which exhibits a high sensitivity of 235 mV/kPa and a high-power density of 0.9 mW/cm 2 under a dynamic pressure of 255 kPa. The power density is near 8 times higher than that of a conventional, poled single-layer PVDF sensor. Finally, a (3 × 3) real-time lighting tactile sensor array is 3D printed, confirming its feasibility for practical application. This work further expands on the potential applications of future flexible, smart, wearable devices, especially in integrated microelectronic systems.