writer：Jinlong Sun, Boling Lan, Shenglong Wang, Hongguang Li, Tianpei Xu, Longchao Huang, Peiwen Li, Wei Zhao, Yong Ao, Long Jin, Wei Zhu, Weiqing Yang, Weili Deng
keywords：Phase matching，PVDF，Ultrasonic transducer，Energy harvesting，Wireless power transfer
source：期刊
Issue time：2026年

Securing a continuous and biocompatible power supply remains a primary challenge for implantable devices. Ultrasonic wireless power transfer based on poly(vinylidene fluoride) (PVDF) transducers exhibits excellent acoustic impedance matching with soft tissues. However, insufficient acoustic-to-electric conversion efficiency restricts their practical applications. Here, we propose a vertically stacked ultrasonic energy harvester inte grating dual PVDF functional layers. Guided by theoretical acoustic wavelength calculations and multiphysics simulations, the interlayer spacing is rationally engineered to achieve identical phase responses across both functional layers during ultrasonic propagation. This phase-matched architecture enables synchronized acoustic excitation and constructive superposition of piezoelectric potentials across the stacked PVDF layers, thereby maximizing acoustic energy conversion. Evaluated under a weak ultrasonic field, the device delivers an output power of 156.56 μW and a power density of 423.14 μW/cm3, demonstrating an 89.12% improvement over conventional single-layer devices without compromising intrinsic structural flexibility. Meanwhile, compared with conventional piezoelectric ceramic transducers, the proposed PVDF-based device retains the distinctive advantages of low acoustic impedance, full flexibility, and improved tissue conformability, which are highly desirable for efficient ultrasonic coupling and energy transfer in implantable applications. This phase-matching strategy provides a scalable approach to improve the efficiency of polymer-based piezoelectric harvesters, advancing the development of sustainable power sources for implantable bioelectronics