Micromachined silicon Generator for Harvesting Power from Vibrations

This paper describes the design, simulation and fabrication of an electromagnetic device for generating electrical energy from vibrations. A range of dimensions has been simulated using ANSYS in order to determine natural frequencies and material stresses. A 300µm wide paddle beam gives a natural frequency of 6.4 kHz for the mode of operation and induced stresses at maximum amplitudes are well within material limits. Ansoft's Maxwell 2D has been used to predict the voltages generated and an integrated electroplated coil of 71 turns produces 0.38V with no load. Devices are currently being fabricated and the process is described.