Piezoelectric MEMS speakers with non-closed diaphragms are promising to generate high sound pressure levels (SPLs), but a serious diaphragm breakage issue exists. In this work, a novel piezoelectric MEMS loudspeaker with a quasi-closed diaphragm is proposed. The quasi-closed diaphragm consists of a diagonally-cut but center-linked diaphragm, that is coated with a thin layer of Parylene-C. Under the combined action of the stress dispersion structure, the application of the Parylene-C film prevents the diaphragm from breakage and significantly reduces the air loss. The MEMS loudspeaker with a small size of 2.5 × 2.5 mm² has been successfully fabricated and the acoustic performance has been characterized in an 711 ear simulator. The measured SPL reaches its maximum value of 124 dB at 11.8 kHz under a drive voltage of 4 V_pp. The SPL is further increased to 88 dB in the low-frequency range (20–500 Hz) under a voltage of 35 V_pp.

具有非闭合振膜的压电 MEMS 扬声器有望产生高声压级 (SPL)，但存在严重的振膜破损问题。在这项工作中，提出了一种具有准封闭振膜的新型压电 MEMS 扬声器。准封闭隔膜由对角线切割但中心连接的隔膜组成，并涂有一层薄薄的聚对二甲苯-C。在应力分散结构的共同作用下，Parylene-C薄膜的应用防止了膜片破裂，显着降低了空气损失。^{2.5 × 2.5 mm 2}的小尺寸 MEMS 扬声器已成功制造，声学性能已在 711 耳模拟器中表征。_{在 4 V pp}的驱动电压下，测得的 SPL 在 11.8 kHz 时达到其最大值 124 dB 。_{在 35 V pp}的电压下，低频范围 (20–500 Hz) 的 SPL 进一步增加到 88 dB 。