Body-Motion Driven MEMS Generator for Implantable Biomedical Devices

A MEMS-based axial flux power generator has been developed for use in implantable biomedical devices, such as cardiac pacemakers, hearing aid instruments, etc. The microgenerator can provide a greater energy supply per unit volume at a much smaller size and weight compared to conventional batteries. The device operates on the principle of electromagnetic induction of a voltage across a microfabricated planar copper coil exposed to a changing magnetic flux due to a bio-mechanically driven microfabricated magnetic (NdFeB) planar semi-circular pendulum. A thin air gap separates the magnetic pendulum from the underlying planar coil. The generated voltage peaks can be rectified, filtered, stepped up, and stored in super capacitors to provide a stable voltage supply. With a footprint area of 1.0 mm² and thickness of 500 mum, the device can generate 390 muW_RMS power at an open-circuit voltage of 1.1 V_RMS. A number of microgenerators could be stacked or a scaled up version can be used if greater amount of power is necessary.