MEMS microphones, since their first introduction in 1983 have achieved a high commercial success due to their compatibility with MEMS and IC integration, small footprint and immunity to vibrational effects. There are around one billion microphones in production every year. However most microphones require an on-board battery for functioning, which is not desirable in many situations such as communication with microphones in auto and biomedical applications. In this master thesis, design of passive MEMS Microphone with no on-board power or energy-harvesting source is presented. Analysis of feasible transduction mechanisms were conducted. The final design is based on the concept of frequency modulation with the detection of shift in resonance frequency of a Contour Mode Resonator due to the deflection of a suspended metallic membrane from an external acoustic pressure source. Optimization of the suspended membrane was performed using thermo-acoustic simulations with which the displacement output was analyzed between 20Hz to 20,000Hz. Optimization of the Contour Mode Resonator was carried out to maximize the frequency shift for a given displacement of the membrane. Finally, a combined response behavior of the device confirms the feasibility of acoustic pressure detection for human audible range. Results of the process steps for the first generation of devices that have been fabricated up to the time of submission of the thesis report are presented.