Cantilever-based ferroelectret energy harvesting

We present a vibrational energy harvester with fluorinated ethylene propylene (FEP)-ferroelectrets working in d₃₁ mode. The ferroelectret film consists of two FEP films, fused together to form a parallel tunnel structure with well-defined air gaps. Its dynamic piezoelectric g₃₁ coefficient is 0.7V mN⁻¹. The energy-harvesting device is an air-spaced cantilever arrangement that was produced by the additive manufacturing technique. The device was tested by exposing it to sinusoidal vibrations with an acceleration a, generated by a shaker. The measurement shows a resonance at about 35 Hz and a normalized output power of 320 μW for a seismic mass of 4.5 g at an acceleration of 0.1 g (g is the gravity of the earth). This demonstrates a significant improvement of air-spaced vibrational energy harvesting with ferroelectrets and greatly exceeds previous performance data for polymer cantilever devices.