A pizzicato sounds like it might be a type of tiny flute or mini pizza; in reality it is a ring the size of a roll of masking tape that may eliminate the need for batteries to run heart-rate monitors, pedometers and accelerometers. The pizzicato knee-joint energy harvester, developed by a U.K. research team from Cranfield University, University of Liverpool and University of Salford, makes use of two simple scientific facts: the human knee changes its angle during routine walking, and movement creates mechanical energy.
The device consists of an outer ring (strapped to the lower thigh) fitted with 72 plectra and an inner hub with four arms called bimorphs (strapped to the upper calf). As the person walks, bimorphs “pluck”
the plectra, setting up vibration—a type of mechanical energy that can be converted into electrical energy. Prototypes can harvest two milliwatts of power now, but could exceed 30 milliwatts after a few improvements. “I’d put a cost tag of less than £10 [approximately $16] for each harvester on a large scale production,” says Dr. Michele Pozzi, lead author of the research team.