Topological wave energy harvesting in bistable lattices

In this paper, we present an input-independent energy harvesting mechanism exploiting topological waves. Transition waves in discrete bistable lattices entail energy radiation in the form of trailing phonons. We observe numerically and experimentally that the most dominant frequencies of these phonons are invariant to the details of the input excitations as long as transition waves are generated. Most of the phonon energy at each unit cell is clustered around a single invariant frequency, enabling input-independent resonant energy transduction. An electromagnetic conversion mechanism is implemented to demonstrate that bistable lattices behave as generators of fixed-frequency electrical sources upon transition wave propagation. The presented mechanism fundamentally breaks the link between the unit cell size and the metamaterial’s operating frequencies, offering a broadband solution to energy harvesting, particularly robust for low-frequency input sources. We also investigate the effect of lattice discreteness on the energy harvesting potential, observing two performance gaps and a topological wave harvesting pass band where the potential for energy conversion increases almost monotonically. The observed frequency-invariant phonons are intrinsic to the discrete bistable lattices, enabling broadband energy harvesting to be an inherent metamaterial property.