Knee-joint piezoelectric energy harvester Shown in the photos
above: (a) Knee-joint piezoelectric harvester. It is worn on the
external side of the knee and fixed by braces. Inside, a hub
carries a number of bimorphs, which are plucked by the ring-
mounted plectra as the joint rotates during walking. (b)
Geometrical details of the harvester showing side view (above)
and top view of the mounted bimorph. Click on image to enlarge A
team of UK researchers from Cranfield University, the University
of Liverpool and the University of Salford proposes a
piezoelectric energy harvester to be worn on the knee-joint that
relies on the plucking technique to achieve frequency up-
conversion. The energy harvester, which is designed to fit onto
the outside of the knee, is circular and consists of an outer
ring and central hub. The outer ring rotates as the knee joint
goes through a walking motion. The outer ring is fitted with 72
plectra which "pluck" four energy-generating arms attached to
the inner hub. By strapping the ene