3D Moulded Flexible Vibration Energy Harvester With Hourglass Beams for Multimodal Response in Low-Frequency Range

This paper reports a 3D moulded flexible vibration energy harvester (MFVEH) with hourglass beams for multimodal response in low-frequency range. The flexible hourglass beams induce nonlinear exchanges between the eigenmodes, achieving left-shifting and widening bandwidth under increased excitation. Maximally, the device's effective bandwidth extends to 14.78-25.28 Hz at 0.7 g acceleration, and the maximal instantaneous voltage and power reach 12.65 V and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$14.55 \ \mu \mathrm{W} \ {@}10 \ \mathrm{M}\Omega$</tex>, respectively. The normalized power density reaches <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$34.88 \mu \mathrm{W}/\text{cm}^{3}/\mathrm{g}^{2}$</tex>. Such power performance is higher than most reported flexible vibration energy harvesters, which typically confront with low responsivity issue.