A new approach for an FE-model optimization of a MEMS piezoelectric accelerometer for implantable hearing devices

• Published in: The Journal of the Acoustical Society of America 2018-03, Vol.143 (3), p.1804-1804
• Main Authors: Neves Masson, Zargos, Gesing, Andre L., de Lorenzo, Matheus, Paul, Stephan, Cordioli, Julio A.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.5035908

Totally implantable hearing devices have been proposed as a solution to mitigate the constraints related to the presence of external elements in traditional hearing devices. This work reports on a novel approach for the development of a MEMS piezoelectric accelerometer as an implantable sensor for hearing devices. Traditionally these sensors are designed for maximum sensitivity; however, the primary bottleneck for this type of transducer is the internal noise level. Two differential evolution optimization routines were developed. The first used sensitivity maximization whereas the second seeks minimization of the equivalent input noise (EIN). Both methods were applied to different designs of Lead Zirconate Titanate (PZT) MEMS piezoelectric accelerometer in the frequency range of 250 Hz to 8 kHz with layer thickness varying from 0.1 μm to 1 μm. In the latter approach, the sensor's acceleration noise was estimated analytically, considering capacitance and charge response acquired through finite element modeling (FEM) previously validated. Acceleration noise was converted to EIN, in sound pressure level (SPL), through an FE-model of the middle ear considering the sensor coupled at the umbo. Preliminary results indicate that using EIN as optimization goal, opposed to sensitivity, leads to a higher performance over a broader bandwidth.