薄膜声学超材料高效低频声能收集机理及关键技术研究

Lightweight membrane-type acoustic metamaterial can control the low frequency sound waves effectively. Utilizing the acoustic energy concentration on the metamaterial property, this part of energy can be converted into electrical energy and to be harvested. The feasibility of harvesting low frequency acoustic energy using membrane-type acoustic metamaterial has been confirmed by recent research, but there are still many fundamental issues which are needed to be addressing and improving. Applicant has carried out relevant research on low-frequency acoustic energy harvesting, high-performance piezoelectric thin film fabrication and thin-wall structure low frequency noise control. Combined with the existing research basis, we propose solving the above problem from three aspects, which are material fabrication, structure design and highly efficient harvesting circuits. Firstly, high-performance piezoelectric thin film is fabricated and integrated within the membrane-type acoustic metamaterial, increasing its acoustical to electrical conversion ability. After that, multi-physical coupling model is set up to characterize the energy cell. Meanwhile, the physical parameters’ influence energy conversion mechanism and device optimization will be disclosed. Finally, the performance of energy harvesting network is analyzed to fulfill the energy conversion mechanism investigation. A new interface circuit is proposed to facilitate easy system integration. High efficient low frequency acoustic energy harvesting based on membrane-type acoustic metamaterial is achieved through experimental demonstration system, whose performance is evaluated quantitatively. This project establishes theoretical and technical bases to achieve efficient electro-acoustic conversion using membrane-type acoustic metamaterial, which provides a solid foundation for its engineering application.

轻质薄膜声学超材料可对低频声波实现有效控制。利用声能在超材料元胞上的聚集特性，还可将其转换为电能并加以回收。这种新策略的可行性已被最近的研究所证实，但仍存在诸多关键基础性问题需要进一步解决和完善。申请者前期已对低频声能收集、高性能压电薄膜制备、薄壁结构低频噪声控制开展了研究。结合已有研究基础，本课题从材料、器件结构和电路三方面开展薄膜声学超材料高效低频声能收集机理及关键技术研究。提出制备高性能压电薄膜并与薄膜超材料元胞进行集成，提高声电转换能力。建立系统多场耦合模型和优化方法，揭示各物理参数对能量转换的影响规律，实现器件的优化设计。分析能量回收网络的效能，完善能量转换机制，设计新型接口电路便于系统集成。结合实验演示系统，展示基于薄膜超材料的高效低频声能收集，并对其性能进行定量评价。通过此研究的开展，可为薄膜声学超材料实现高效声电转换奠定理论和技术基础，为最终工程化应用提供强力支撑。

低频声波可以作为一种能量源，通过适当的能量转换机制可以获得电能。由于声波激励较弱，通常采用特殊设计的结构来增强激励强度。本研究围绕基于声学超材料的低频声波能量收集开展理论研究与应用，主要研究内容包括多物理场耦合模型的建立及机制分析、亚波长超构低频声学能量收集单元的设计及优化、声场调控和声能量收集单元的阵列化等。参照人耳蜗结构，提出一种仿生螺旋结构，以较小的尺寸，实现对低频入射声的放大，分析了相关的声阻抗变化关系，以及结构参数对其的影响。提出一种紧凑式，管径成梯度变化的亚波长结构，该装置可对特定频率的低频入射声波实现有效放大，可对低频入射声波实现较好的能量俘获效果。提出了一种复合型隔声及能量收集装置，实现对150 Hz频率附近声能量的收集以及对400 Hz附近噪声的有效隔离。通过结构参数优化，在114分贝激励下，获得0.2 mW的电能输出。提出了一种亚波长声学谐振器，该装置可用于中低频管路降噪，且不影响空气流动，通过优化间距，使用一对亚波长谐振器，可实现84%的声压降低，如果是非最优的距离，声压降低仅为63%。提出了一种新型亚波长装置，对声能量采集装置从单个单元的设计，扩展到了阵列化的方案，并可以根据实际需求对声能量收集阵列进行扩展，以增大回收功率。该声能量收集系统实现了对计步器等小功率器件的驱动，并可实现噪声降低的功能，实现了功能的复用。本研究成果可为今后声能量采集的进一步发展及工业化应用、声学超构材料器件的开发，提供了有益探索和发展思路，为相关产品在物联网领域和噪声控制行业中的应用提供了坚实的基础。