Vibration-based electromagnetic type energy harvester for bridge monitoring sensor application

Fabrication and experimentation of vibration-based electromagnetic energy harvester is reported in this research paper. Energy harvester with both planar and wound coils have been developed and characterized under sinusoidal excitation. Energy harvester consists of two permanent magnets residing on a Latex membrane, two double sided PCB fabricated planar coils, Teflon spacers for providing gap between the permanent magnets and planar coils, and wound coils mounted on sides of Teflon spacers. When the harvester is subjected to vibration, due to the relative movement between the magnets and coils, the coils experience the change in magnetic flux density which causes an emf to generate at the coils terminals. Energy harvester has a dimension of 18 mm × 18 mm. Prototype has been characterized under sinusoidal excitation and are subjected to frequency sweep from 10 to 80 Hz at acceleration levels of 0.3 g, 0.5 g, 1 g, 2 g and 3 g. Single planar and wound coil of prototype generates an open circuit voltage of 15.7 mV and 11.05 mV respectively at 3 g and at resonant frequency 27 Hz. When excited at resonance and 3 g base acceleration a load power of 1.8 μW and 2.1 μW is obtained from single planar and wound coil respectively under matching impedance conditions for prototype.