Rainbow energy harvesting using a high-order topological meta-device

We present an innovative rainbow piezoelectric energy harvesting approach that harnesses the untapped potential of the topological meta-device for robust and efficient vibration energy trapping and conversion, from its theoretical rudiments, through design of the device to experimental validation. The rigorously designed meta-device features a series of second-order phononic topological insulators to host topologically protected corner states of different eigenfrequencies. By tailoring and tuning various corner sites, multi-frequency vibrations along a specially engineered channel that supports the edge states spanning these frequencies can be trapped into different corner sites. The vibrational energy is thus converted into electrical energy efficiently using strategically placed piezoelectric harvesters. Experimental results reveal the capability of the device in trapping targeted vibration, in which vibrational energy can be trapped into different corner sites in terms of its frequency, leading to an interesting rainbow energy conversion. This new approach not only implements high-efficiency energy harvesting but also offers enhanced design flexibilities for diverse applications by spatially separating vibrational frequencies.