Zheng Qincheng, Cao Ke, Ma Xudong, Deng Ning, Chen Hao, Cheng Yulang, Lu Yao, Xie Huikai
School of Integrated Circuits and Electronics, Beijing Institute of Technology, Beijing, China.
Engineering Research Center of Integrated Acousto-opto-electronic Microsystems (Ministry of Education of China), Beijing Institute of Technology, Beijing, China.
Microsyst Nanoeng. 2025 Sep 4;11(1):167. doi: 10.1038/s41378-025-01031-0.
Piezoelectric MEMS loudspeakers based on cantilever diaphragms have demonstrated promising electroacoustic efficiency and low-frequency sound pressure level (SPL). However, their total harmonic distortion (THD) significantly increases near the first resonant frequency, and high-frequency SPL (above 10 kHz) rapidly decreases due to the resonance frequency and bandwidth limitations, severely affecting sound quality. This work presents a piezoelectric MEMS loudspeaker featuring a 2.7 µm-thick sputtered PZT film, comprising a cantilever diaphragm and four sets of Double-S actuators. The first resonance frequency of the cantilever diaphragm is 3.2 kHz, and the Double-S actuators introduce an additional resonance frequency at 21.3 kHz, addressing the issues of insufficient high-frequency SPL and poor THD performance. Testing on a 711-ear simulator reveals that, under 1-3 Vpp excitation, incorporating the Double-S actuators leads to an average SPL increase of 23 dB and an average THD reduction of 80% that remains below 0.6% across the 3.2-20 kHz range. Thus, both SPL and THD performance in the mid- to high-frequency range are improved. This work paves the way for the development of high-fidelity piezoelectric MEMS loudspeakers, offering new opportunities to improve sound quality and extend the frequency range for in-ear applications.
基于悬臂式振膜的压电微机电系统（MEMS）扬声器已展现出良好的电声效率和低频声压级（SPL）。然而，它们的总谐波失真（THD）在接近第一共振频率时会显著增加，并且由于共振频率和带宽限制，高频声压级（高于10 kHz）会迅速下降，严重影响音质。这项工作展示了一种压电MEMS扬声器，其具有2.7 µm厚的溅射锆钛酸铅（PZT）薄膜，包括一个悬臂式振膜和四组双S型致动器。悬臂式振膜的第一共振频率为3.2 kHz，双S型致动器引入了一个21.3 kHz的额外共振频率，解决了高频声压级不足和THD性能不佳的问题。在711耳模拟器上进行的测试表明，在1 - 3 Vpp激励下，加入双S型致动器会使平均声压级提高23 dB，平均THD降低80%，在3.2 - 20 kHz范围内保持低于0.6%。因此，中高频范围内的声压级和THD性能都得到了改善。这项工作为高保真压电MEMS扬声器的发展铺平了道路，为改善音质和扩展入耳式应用的频率范围提供了新机会。
