A microelectromechanical system (MEMS) capacitive accelerometer-based microphone with enhanced sensitivity for fully implantable hearing aid: a novel analytical approach

The present work proposes a novel, compact, intuitively simple and efficient structure to improve the sensitivity of a microelectromechanical system (MEMS) capacitive accelerometer using an arrangement of microlever as a displacement amplifier. The accelerometer is proposed to serve as a microphone in the fully implantable cochlear prosthetic system which can be surgically implanted at the middle ear bone structure. Therefore, the design parameters such as size, weight and resonant frequency require deliberation. The paper presents a novel analytical model considering the impact of the mechanical amplification along with the width of the microlever and the capacitive fringe effects on the performance of the sensor. The design is simulated and verified using COMSOL MULTIPHYSICS 4.2. The accelerometer is designed within a sensing area of 1 mm2 and accomplishes a nominal capacitance of 4.85 pF and an excellent sensitivity of 5.91 fF/g.