The key challenge for successful deployment of Energy Harvester (EH) technology remains in the provision of adequate energy. This book aims to address this challenge by investigating on a Finite Element Analysis (FEA) EH device to enhance output power in µW levels of a fluid flow induced vibration based piezoelectric EH. Firstly, a simplified analytical model of a unimorph cantilever capable of transforming low-level vibrations into electricity has been developed based on Euler-Bernoulli method. Later, the cantilever utilized MATLAB based Genetic Algorithm (GA) optimization routine to find the optimum geometric parameters. Based on Reynolds number analysis of few bluff-body shapes, a D-shaped bluff body has been chosen to be integrated with the optimized micro cantilever. The whole structure is assembled inside a three-dimensional micro channel to develop the complete fluid flow based EH in COMSOL. The novelty of the design relies on integrating the optimized micro cantilever with the D-shaped bluff body that implies piezoelectric micro cantilever as a direct vortex shedding EH instead of using parasitic vibration. The EH can be utilized for low duty cycle sensors applications.