A wearable system of micromachined piezoelectric cantilevers coupled to a rotational oscillating mass for on-body energy harvesting

In this paper, we present a compact, wearable piezoelectric on-body harvesting system that uses a small eccentric mass from a common watch movement to mechanically deflect a set of micromachined piezoelectric cantilevers when excited by the low frequency movements of the human body. The piezoelectric cantilevers are directly coupled to the rotating mass via a set of pins located near its rotational center. The energy produced by each pluck of a single cantilever is 545 nJ, corresponding to a maximum output power of 11 μW for continuous plucking; however, accounting for the periodic rest of typical human motion, the average output power over a full day cycle will be considerably less.