Motion Energy Harvesting Using Catch-and-Release Mechanism

Small-scale motion energy harvesting has garnered significant interest in recent years, especially given advances in piezoelectric materials, but with limited commercial application. Most harvesting methods to date, including those employing magnetic induction, have focused on coupled resonance. Such harvesters are tuned to resonate with their excitation source and have shown promise in capturing moderately high-frequency (>10Hz), low-displacement motion that is steady. However, coupled harvesters lose efficiency significantly when a source deviates slightly in frequency. They also require large masses and/or buoyant volumes to efficiently capture low frequency (<10Hz) motion. We have been developing a novel technology that combines electromagnetic induction with a proprietary catch-and-release mechanism that absorbs an input motion and then releases it at a much higher frequency to improve conversion efficiency. The energy harvester is simple, compact, and insensitive to excitation frequency. Initial prototypes have demonstrated power densities and specific powers many multiples greater than the best-performing, commercial vibration harvester. We have also developed a validated computer model of the system that indicates that performance could be improved 2–4 times over initial prototypes.