Liu Shiyuan, Hong Ying, Hong Wang, Zheng Yi, Yang Xiaodan, Li Xuemu, Zhang Zhuomin, Yan Xiaodong, Shan Yao, Lin Weikang, Peng Zehua, Zhang Xingqi, Yao Xi, Wang Zuankai, Yang Zhengbao
Thrust of Smart Manufacturing, System Hub, The Hong Kong University of Science and Technology, Guangzhou, China.
Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
Nat Commun. 2024 Dec 2;15(1):10136. doi: 10.1038/s41467-024-54412-w.
The thickness of film materials is a critical factor influencing properties such as energy density, optical performance, and mechanical strength. However, the long-standing challenge of the intrinsic thermodynamic limit on maximum thickness often leads to detrimental cracking, compromising these desirable properties. In this study, we present an approach called the stress-eliminated liquid-phase fabrication (SELF) method. The SELF method eliminates the need for substrates to support the precursor solution used for film fabrication. We harness the intrinsic surface tension of the solution by confining it within specifically designed grids in a framework, forming suspended liquid bridges. This technique enables fabrication of crack-free ceramic films within a broad thickness range from 1 to 100 μm. Furthermore, the fabricated PZT films exhibit a high piezoelectric coefficient (d) of 229 pC N. The customizable grids not only offer design freedom for film topologies but also facilitate the fabrication of diverse film arrays without the need for destructive cutting processes. Moreover, the freestanding nature of these films enhances their adaptability for MEMS processing, and the "capillary bridge" topology allows the PZT films to be used in ultrasound focusing transmitter, providing possibilities in the medical imaging.
薄膜材料的厚度是影响能量密度、光学性能和机械强度等性能的关键因素。然而，最大厚度存在固有的热力学极限这一长期挑战常常导致有害的开裂，从而损害这些理想性能。在本研究中，我们提出了一种称为应力消除液相制造（SELF）法的方法。SELF法无需使用基板来支撑用于薄膜制造的前驱体溶液。我们通过将溶液限制在框架内专门设计的网格中，利用溶液固有的表面张力，形成悬浮的液桥。该技术能够在1至100μm的宽厚度范围内制造无裂纹的陶瓷薄膜。此外，所制备的PZT薄膜表现出229 pC/N的高压电系数（d）。可定制的网格不仅为薄膜拓扑结构提供了设计自由度，还便于制造各种薄膜阵列，而无需进行破坏性切割工艺。此外，这些薄膜的独立性质增强了它们对MEMS加工的适应性，并且“毛细管桥”拓扑结构使PZT薄膜能够用于超声聚焦发射器，为医学成像提供了可能性。
