A superhydrophobic magnetoelectric generator for high-performance conversion from raindrops to electricity

Abstract Traditional utilization of hydraulic power not only requires heavy and bulky electromagnetic generators but also is restricted by geographical condition and the scale of water sources. The development of new protocols which are miniature, flexible and able to generate electricity from disperse hydropower, such as raindrops, is highly required. In this study, we demonstrate the fabrication of a superhydrophobic magnetoelectric generator (SMEG) which is able to generate electricity from rainfall. The SMEG comprises three parts: a polymeric top containing a coil, tiny springs and a magnet/Ecoflex bottom. The tiny springs in the middle could deform/recover when the raindrops impact/leave the SMEG, allowing for the electrical generation of a charge density as high as 51.5 mC/m2, which is beyond the performances of currently reported surface-charge approaches. Related mechanism has been analyzed by the Maxwell numerical simulation, which guides further improvement of the SMEG by tailoring diverse parameters. Furthermore, by serving as the roof cornice at traditional Chinese buildings, the SMEG could convert flow-guiding rainfall impact to electricity, lightening a light-emitting diode or charging a capacitor to 0.78 V within 700 s. We believe that such a SMEG can extend the energy harvesting of disperse hydraulic energy.