Design and fabrication of a MEMS filter bank for hearing aids applications

A novel MEMS filter bank was developed for hearing aids application. It directly processes the sound signals by separating the sound into specific frequency bands. Therefore, the filter bank can replace some function of the microphone and the processor within the modern hearing aids. Such a MEMS filter bank works as a passive component, and it has the advantages of lower energy consumption and without computation time. Combining with its excellent aging and thermal stability characteristics, the novel MEMS filter bank will be a potential device for effective sound signal processing in modern hearing aids. The paper shows the fabrication process of the novel MEMS filter bank. Our preliminary results show that the device dimensions of the filter bank are about millimeter level for the low operating frequency requirement, 100 Hz to 10000 Hz. The devices are then apparent bending by residual stress with low stress silicon nitride film.