The proposed research is focused on developing MEMS-based fully implantable hearing aid device. Hearing impairment is affecting more than 360 million people all over the world. In India alone, 63 million people suffer from significant auditory loss. Considerable interest in middle ear implants has emerged over the years to facilitate patients who do not receive benefits with conventional hearing aids. Moreover, the social stigma of wearing external hearing aids discourages some users from even considering conventional devices. The totally implantable devices provide freedom from the social and practical difficulties of using conventional hearing aids. So research is going on in the development of a fully implantable microphone for cochlear prosthesis and middle ear implants. The primary beneficiary of such microphones is intended to be the patients suffering from severe hearing impairment (damage to the hair cells in the cochlea). The objective of fully implantable microphones isto have minimum sound level detection. The sensitivity of the microphone is its measure of minimum sound level detection. The research involves proposing microphones with improved sensitivity.