Department of Physics, Naval Postgraduate School, Monterey, CA, 93943, USA.
Sci Rep. 2020 Jul 29;10(1):12714. doi: 10.1038/s41598-020-69563-1.
MEMS acoustic sensors have been developed to mimic the highly-accurate sound-locating system of the Ormia ochracea fly, which detects sound wavelengths much larger than its hearing organ. A typical ormia-based MEMS directional sound sensor possesses two coupled wings that vibrate in response to sound according to a superposition of its two main resonant modes, rocking and bending. Vibrations are transduced into electronic signals by interdigitated comb finger capacitors at each wing's end along with a capacitance measuring circuitry. A sensor designed to exhibit resonant modes closely placed in frequency, enhancing their coupling, was operated with a closed cavity behind the wings. Simultaneous and independent measurements of electronic signals generated at each of the single sensor wings were used to determine incident sound direction of arrival (DOA). DOA was found proportional to the phase shift between them and to the difference over the sum of their amplitudes as well. Single sensor phase shift DOA measurement presented a resolution better than 3° for sound pressure levels of 25 mPa or greater. These results indicate that a single sensor operating in closed-cavity configuration can provide hemispherical unambiguous direction of arrival of sound waves which wavelength is much larger than the sensor size.
MEMS 声学传感器已经被开发出来，以模拟 Ormia ochracea 苍蝇高度精确的声音定位系统，该系统可以检测到比其听觉器官大得多的声音波长。一个典型的基于 Ormia 的 MEMS 指向性声音传感器具有两个耦合的翅膀，根据其两个主要共振模式（ rocking 和 bending ）的叠加，响应声音而振动。振动通过每个翅膀末端的叉指梳状电容和电容测量电路转换为电子信号。为了展示紧密放置的共振模式，以增强它们的耦合，设计了一个带有翅膀后面封闭腔的传感器。通过同时独立测量每个单传感器翼产生的电子信号，确定了到达（DOA）的入射声波方向。发现 DOA 与它们之间的相位差成正比，与它们的幅度之和的差值也成正比。对于声压水平为 25 mPa 或更高的情况，单传感器相位差 DOA 测量的分辨率优于 3°。这些结果表明，在封闭腔配置中工作的单个传感器可以提供比传感器尺寸大得多的波长的声波的半球形无歧义的到达方向。
