Electromagnetic generators for power harvesting

The design of electromagnetic generators that can be integrated within shoe soles is described. In this way, parasitic energy expended by a person when walking can be tapped and used to power portable electronic equipment. Designs are based on discrete permanent magnets and copper wire coils, and it is intended to improve performance by applying micro-fabrication technologies. Detailed descriptions of design and measurements of initial prototype structures are presented, with which RMS voltage levels of over 500 mV have been achieved. Predicted power levels are comparable to those achieved with integrated piezoelectric generators. The design of a second generator structure is introduced. A comparison of the two types of electromagnetic generator structures is presented.