PZT MEMS Speaker Integrated with Silicon-Parylene Composite Corrugated Diaphragm

We have developed a true MEMS speaker with a Si-parylene composite diaphragm and a PZT actuator. The composite diaphragm is a closed form preventing air leakage and highly deformable by 10 µm thick parylene corrugation. The PZT actuator is composed of high quality 5 µm thick PZT with rated driving voltage higher than 50 V. The composite diaphragm and the PZT actuator were stacked and bonded. In the ear simulator environment, SPL (sound pressure level) higher than 120 dB was achieved at 4.2 kHz by applying 15 V
pp
. And a flat SPL of in the region of 85 dB was generated between 200 Hz and 2 kHz by applying 5 V
pp
. THD (total harmonic distortion) is almost smaller than 5% at a driving voltage of 5 V
p
p
.