This chapter discusses the selection of piezoelectric materials and circuit design in vibrational energy harvesting. The performance of unimorph devices using PZT-based and BT-based ceramics to capture 60 Hz frequencies is evaluated. Output voltages and power depend on amplitude, frequency, and load resistance, with PZT-based ceramics generally superior. Key material parameters, such as the piezoelectric voltage coefficient ($g_{31}$), are discussed to predict maximum voltages, while $d_{31}g_{31}/\tan \delta$, $k_{1}^{2}Q_{m}$, and $d_{31}g_{31}$ are closer to maximum power behavior. The combination of unimorphs and power management circuits produced constant voltage output, suitable for power sources. The study highlights the importance of material selection and circuit design in implementing piezoelectric generators for various applications.This chapter discusses the selection of piezoelectric materials and circuit design in vibrational energy harvesting. The performance of unimorph devices using PZT-based and BT-based ceramics to capture 60 Hz frequencies is evaluated. Output voltages and power depend on amplitude, frequency, and load resistance, with PZT-based ceramics generally superior. Key material parameters, such as the piezoelectric voltage coefficient ($g_{31}$), are discussed to predict maximum voltages, while $d_{31}g_{31}/\tan \delta$, $k_{1}^{2}Q_{m}$, and $d_{31}g_{31}$ are closer to maximum power behavior. The combination of unimorphs and power management circuits produced constant voltage output, suitable for power sources. The study highlights the importance of material selection and circuit design in implementing piezoelectric generators for various applications.