A frequency up-converted electromagnetic energy harvester using human hand-shaking
We present a frequency up-converted electromagnetic (EM) energy harvester that is capable of powering various portable devices and systems by hand-shaking. It consists of a freely movable ball to impact periodically (at low frequency) on the parabolic top surface of a mass of a cantilever beam allowing it to vibrate at higher (resonant) frequency. Relative motion between a magnet attached to the cantilever and a coil induces voltage. A prototype of the energy harvester has been fabricated and characterized by applying vibration from handshaking. The frequency and acceleration of the applied hand-shaking vibration has been experimentally found to be 4.6 Hz and 2g, respectively. With an optimum distance between magnet and coil, a maximum 672 mV peak-peak open circuit voltage of 370 Hz frequency and a maximum 413μW peak power delivered to an 85 matched load resistance have been obtained, respectively.