AI 中文总结
研究共振声悬浮器声场状态，利用安装在换能器上的MEMS麦克风作外部传感器，通过线性麦克风配置在特定共振模式下扫描换能器-反射器距离，比较相关数据，证明其可用于场状态评估及换能器侧反馈，原理或可用于其他架构。
AI 中文摘要
共振声悬浮器的可靠运行需要了解声场状态，因为最佳换能器-反射器距离和共振运行条件会随波长、温度、物体插入和机械对准而变化。现有调整方法有限。本文研究了安装在换能器上的微机电系统（MEMS）麦克风作为离轴外部传感器，在不将传感器置于悬浮腔内的情况下获取相对声学信号。通过线性麦克风配置，在共振模式n = 5-8下进行换能器-反射器距离扫描，并将麦克风振幅与精密天平测量的声辐射力以及换能器峰峰值电流进行比较。结果表明麦克风振幅能更精确地定位力最大值，在频率偏移实验中，麦克风相位为校正方向估计提供了原理证明，包络调制捕获了物体振荡期间通道分辨的场变化。环形测量显示了随换能器-反射器倾斜变化的通道相关响应。这些结果表明外部MEMS麦克风作为共振相关场状态评估的相对声学观测手段的潜力，为紧凑的换能器侧反馈提供了基础，该原理也可能适用于换能器-换能器和基于阵列的架构。
英文摘要
Reliable operation of resonant acoustic levitators requires knowledge of the acoustic field state because the optimum transducer-reflector distance and resonant operating condition shift with wavelength, temperature, object insertion, and mechanical alignment. Existing adjustment methods are limited, especially for compact closed-loop operation and architectures without a passive reflector. Here, we investigate transducer-mounted microelectromechanical system (MEMS) microphones as off-axis external sensors that acquire relative acoustic signals without placing sensors inside the levitation cavity. Using a linear microphone configuration, we performed transducer-reflector distance sweeps over resonance modes n = 5-8 and compared microphone amplitude with acoustic radiation force measured by a precision balance and with peak-to-peak transducer current. The channel-mean microphone-voltage maxima occurred within two sampled distance increments, or at most 30 micrometers, of the force maxima. At the microphone-derived peak positions, at least 98.3% of the corresponding maximum force was retained. Microphone amplitude localized the force maximum more sharply than peak-to-peak transducer current. In one frequency-shift experiment, microphone phase provided a proof of principle for correction-direction estimation, while envelope modulation captured channel-resolved field changes during object oscillation. Ring measurements showed channel-dependent responses as transducer-reflector tilt was varied, but did not provide a calibrated or unique tilt estimate. These results show the potential of external MEMS microphones as relative acoustic observables for resonance-related field-state assessment and provide a basis for compact transducer-side feedback. The principle may also be transferable to transducer-transducer and array-based architectures.
Comments36 pages, 8 figures, 1 table. Jan H. Dörsam and Maximilian L. Amberg contributed equally to this work
