This work deals in specifying the design considerations while constructing a Micro Electro Mechanical Systems (MEMS) optical accelerometer working on capacitive sensing technique. Sensitivity is one of the most demanded characteristics of any sensor. The sensor considered is a MEMS capacitive accelerometer in which both displacement and capacitance are the primary sensing characteristics. This differential capacitive accelerometer causes change in displacement due to applied acceleration and further produces change in capacitance. So, the main focus in this work is to improve or select the suitable diaphragm dimensions of the differential capacitor in order to get optimal capacitive and displacement sensitivity. This is done for an Optical MEMS (MOEMS) based sensor where slight change has a large-scale impact. The electrical signal is converted to optical by adding an Optical Interferometer. Mach–Zehnder Interferometer (MZI) is used to carry out the intensity modulation which also gives protection in inflammable surroundings. This makes the system suitable for working in high temperature regions.