Liu Na, Saure Lena Marie, Sriramdas Rammohan, Schütt Fabian, Wang Kai, Nozariasbmarz Amin, Zhang Yu, Adelung Rainer, Baughman Ray H, Priya Shashank, Li Wenjie, Poudel Bed
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Functional Nanomaterials, Institute for Materials Science, Kiel University, Kaiserstrasse 2, 24143 Kiel, Germany.
ACS Nano. 2024 Mar 26;18(12):8988-8995. doi: 10.1021/acsnano.3c12726. Epub 2024 Mar 13.
Solid-state fabricated carbon nanotube (CNT) sheets have shown promise as thermoacoustic (TA) sound generators, emitting tunable sound waves across a broad frequency spectrum (1-10 Hz) due to their ultralow specific heat capacity. However, their applications as underwater TA sound generators are limited by the reduced mechanical strength of CNT sheets in aqueous environments. In this study, we present a mechanically robust underwater TA device constructed from a three-dimensional (3D) tetrapodal assembly of carbon nanotubes (t-CNTs). These structures feature a high porosity (>99.9%) and a double-hollowed network of well-interconnected CNTs. We systematically explore the impact of different dimensions of t-CNTs and various annealing procedures on sound generation performance. Furnace-annealed t-CNTs, in contrast to directly resistive Joule heating annealing, provide superior, continuous, and homogeneous hydrophobicity across the surface of bulk t-CNTs. As a result, the t-CNTs-based underwater TA device demonstrates stable, smooth, and broad-spectrum sound generation within the frequency range of 1 × 10 to 1 × 10 Hz, along with a weak resonance response. Furthermore, these devices exhibit enhanced and more stable sound generation performance at nonresonance frequencies compared to regular CNT-based devices. This study contributes to advancing the development of underwater TA devices with characteristics such as being nonresonant, high-performing, flexible, elastically compressible, and reliable, enabling operation across a broad frequency range.
固态制造的碳纳米管（CNT）片材已显示出作为热声（TA）声音发生器的潜力，由于其超低的比热容，可在宽频谱（1 - 10 Hz）内发射可调谐声波。然而，它们作为水下TA声音发生器的应用受到CNT片材在水环境中机械强度降低的限制。在本研究中，我们展示了一种由三维（3D）碳纳米管四足体组件（t-CNTs）构建的机械坚固的水下TA装置。这些结构具有高孔隙率（>99.9%）和相互连通良好的CNT双空心网络。我们系统地探索了不同尺寸的t-CNTs和各种退火程序对声音产生性能的影响。与直接电阻焦耳加热退火相比，炉内退火的t-CNTs在块状t-CNTs表面提供了优异、连续且均匀的疏水性。结果，基于t-CNTs的水下TA装置在1×10至1×10 Hz的频率范围内表现出稳定、平滑且广谱的声音产生，同时具有较弱的共振响应。此外，与常规基于CNT的装置相比，这些装置在非共振频率下表现出增强且更稳定的声音产生性能。本研究有助于推动具有非共振、高性能、灵活、可弹性压缩和可靠等特性的水下TA装置的发展，使其能够在宽频率范围内运行。
