Self-powering sensors have been desired for future platform sensor networks to minimize wiring and related problems. The selection of the proper area of piezoelectric patches at various operating conditions is an important challenge since the selection of a large patch area increases the complexity and weight. The small patch area could not provide enough energy to operate the electronics continuously. Many Finite Element Method (FEM) packages are capable of estimating the electricity after the stress or strain distribution is calculated. In this paper, the required energy for smart sensors is briefly discussed and the use of FEM is suggested for selection of the size and best location of the piezoelectric patch. The study indicated that the oscillation frequency affects the mode shape and the generated energy drastically. FEM is very useful to determine the mode shapes and the selection of patch locations with maximum dynamic strain.