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A mechanical frequency up-conversion mechanism for vibration based energy harvesters

This paper presents a new mechanical frequency up-conversion (FUC) mechanism for harvesting energy from external low frequency vibrations. The structure consists of a magnet placed on a support, a polystyrene cantilever carrying a pick-up coil, and a mechanical barrier which converts low frequency vibrations to a higher frequency, hence increasing the efficiency of the system. The tested structure proved to give 20.3 mV and 68.7 ¿W RMS power output by up-converting 10 Hertz external vibration to 643 Hertz. The tests with different magnet configurations and cantilever lengths showed that horizontal cascading of the magnets improve the performance whereas an optimum cantilever length exits for the maximum generated power. An analytical model is also developed for the system, supporting the test results. The proposed structure is a good candidate to be realized by using microfabrication techniques in terms of generated voltage and power levels.