Adaptive energy harvesting from low-level ambient vibrations

Harvesting energy from ambient mechanical vibrations is an enabling technology with profound societal impacts. However, existing methods suffer from two major technical deficiencies: the weak coupling between the harvester and the vibrating source and the low energy transduction efficiency. Here we show an adaptive approach can overcome these challenges, leading to improvements by orders of magnitude. Using a piezoelectric device, we demonstrate that a conservative actuation force can block energy from flowing back to the vibrating source, thereby increasing the coupling strength and increasing the transduction efficiency significantly. Using low actuation forces, the adaptive approach can extract almost two orders of magnitude more power than the traditional approach from a multi-frequency vibration. The improvement can increase to three orders of magnitude when moderate actuation force is used. If materials that can withstand a high actuation voltage are available, the adaptive approach has the potential to surpass the theoretical performance ceiling of the traditional approach, improving the upper-bound performance by over 100 times and creating a significant opportunity for the technology to advance.