This study is about investigation of design considerations of a MEMS switch that is considered to pull in under electrostatic force generated by a piezoelectric based voltage generator inside the MEMS. Here the energy source to drive the piezoelectric device is vibrations the whole system undergoes. In this study, a new approach is brought to calculate the pull-in voltage easily and effectively under certain assumptions. There are a number of conditions the switch has to meet such as its robustness against environmental vibrations. Some are discussed in brief. Following the design considerations a series of MEMS switches are fabricated and the pull-in voltages are measured in order to compare the true data with calculations and simulations. Numerical results prove the validity of the new approach to calculate the pull-in voltage, and experimental results coincide greatly with the calculations. Several materials are investigated to be used in the design of the cantilever beam and finally a beam structure is proposed that fits best for overall specifications.