Micro-electro-mechanical system multi-resonant accelerometer for auditory prosthetics

Abstract

Low usage of auditory prosthetics such as hearing aids can be attributed to several factors including appearance, stigma, acoustic feedback, and poor performance in noisy environments. Cochlear implants suffer from similar stigma; furthermore, external components of the system must be removed for sleeping, bathing, and physical exercise. Designing a completely implantable system that includes a sensor placed in the middle ear can mitigate these issues. Our approach is to use a miniature piezoelectric accelerometer to sense the vibration of the middle ear ossicles rather than employing an external or subcutaneous microphone to sense incoming sound. Results of our previous work showed the potential of this approach using a traditional single-resonance sensor. We seek to improve the low-frequency input referred noise (IRN) of the system by using a new architecture consisting of an array of piezoelectric MEMS beams with different resonant frequencies. The beams are connected electrically in a manner that increases the system sensitivity over the bandwidth of interest, thereby decreasing the IRN. Preliminary analytic studies have illustrated that 10 parallel-connected beams can improve the IRN by approximately 45 dB at 100 Hz. This method could further miniaturize sensors capable of detecting ossicular vibration from 100 Hz to 8 kHz.Low usage of auditory prosthetics such as hearing aids can be attributed to several factors including appearance, stigma, acoustic feedback, and poor performance in noisy environments. Cochlear implants suffer from similar stigma; furthermore, external components of the system must be removed for sleeping, bathing, and physical exercise. Designing a completely implantable system that includes a sensor placed in the middle ear can mitigate these issues. Our approach is to use a miniature piezoelectric accelerometer to sense the vibration of the middle ear ossicles rather than employing an external or subcutaneous microphone to sense incoming sound. Results of our previous work showed the potential of this approach using a traditional single-resonance sensor. We seek to improve the low-frequency input referred noise (IRN) of the system by using a new architecture consisting of an array of piezoelectric MEMS beams with different resonant frequencies. The beams are connected electrically in a manner that incr...