Energy Harvesting from Drops Impacting onto Charged Surfaces

Hao Wu*, Niels Mendel, Dirk van den Ende, Guofu Zhou, Frieder Mugele

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

31 Citations (Scopus)
309 Downloads (Pure)


We use a combination of high-speed video imaging and electrical measurements to study the direct conversion of the impact energy of water drops falling onto an electrically precharged solid surface into electrical energy. Systematic experiments at variable impact conditions (initial height; impact location relative to electrodes) and electrical parameters (surface charge density; external circuit resistance; fluid conductivity) allow us to describe the electrical response quantitatively without any fit parameters based on the evolution of the drop-substrate interfacial area. We derive a scaling law for the energy harvested by such “nanogenerators” and find that optimum efficiency is achieved by matching the timescales of the external electrical energy harvesting circuit and the hydrodynamic spreading process.
Original languageEnglish
Article number078301
JournalPhysical review letters
Issue number7
Publication statusPublished - 12 Aug 2020


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