An energy harvesting system includes a composite structure that has a first spring, a piezoelectric structure, and a proof mass. The cutter cassette further includes a holding mechanism for holding the cutter case in a completely inserted state and an extending mechanism for protruding the cutter case from the case holder. Either or both of the superior and inferior components are made of a hard material such as chrome cobalt, titanium, or a ceramic including alumina, zirconia, or calcium phosphate. An annular flat plate portion which seals one axial end portion of the annular space between the inner race and the outer race is integrally formed in one of the two annular members constituting the cage. The system can include an actuator for relative displacement of the storage layer with respect to the micro-tips. , cellulose fibers, and a bicomponent andor a biconstituent elastic.