Recovering energy from ambient vibrating resources has been the subject of considerable research studies in the last decade. However, the vibrations found in the environment correspond to low frequencies, often below 200 Hz, and for small-scale applications and if the excitation is sinusoidal, the natural frequency of the micro-sensor must coincide with the excitation frequency in order to optimize the sensing performance. Lowering the resonant frequency for piezoelectric structures and generating greater electrical energy remain two of the challenges we will try to meet in this research study. This paper presents an innovative plate-form design of piezoelectric energy harvester based on topological optimization. Three plate structures are investigated and compared, as piezoelectric harvesters, using finite element calculation software. The simulation data analysis provides us a theory foundation for 2D structures' design and their performance as a piezoelectric energy harvester. For the same imposed congestion, new piezoelectric microstructures are being proposed. A numerical simulation was performed and under the same mechanical loading, the effect of the stiffness on the vibration sensing response was investigated. A generated power of 359.68μW/m3 was recorded at a resonance frequency of 111 Hz.