Design and Fabrication of Notched Beam Cantilever Design for Enhanced Energy Harvesting

This paper focuses on the geometric optimization of the cantilever beam to improve energy harvesting. The full-cosine arc-shaped notched beam is intended to distribute stress more uniformly, increasing the overall power output. The proof mass is attached to the end of the beam to harvest energy from the low acceleration vibrations (<200Hz) in the surrounding environment. In fabricating these devices, a flexible PVDF-TrFE piezoelectric layer with a thickness of 2 μm and a piezoelectric coefficient of 16 pm/V is utilized. TMAH-based anisotropic wet etching has been used in the bulk silicon with mask compensation. The voltage and corresponding power output values of the fabricated traditional and notched cantilever beams at low acceleration of 0.25 g are compared. The notched design’s maximum output power is 2.4 times (31.87 pW at 150 Hz) that of the traditional beam design (13.16 pW at 153.1 Hz) for the same proof mass.