Micro-Patterning of Electret Charge Distribution by Selective Liquid-Solid Contact Electrification

Contact electrification (CE) at interfaces has been documented for over 2600 years, but its mechanism remains ambiguous and is not fully understood, especially for liquid-solid cases. For the first time, we proposed an electret micro-patterning charging method using flowing tap water. The selective oxygen plasma treatment restrained the involvement of the charge-transfer process in liquid-solid contact electrification and obtained an NPU-shaped 3D charge profile. The electret surface potential is up to -650V and able to maintain 82% of its initial potential after 45 days, demonstrating excellent charge stability. The water charging method can be further used for droplet-based electricity power generation and water-drop self-powered sensing applications. This work demonstrates the feasibility and effectiveness of the innovatively proposed electret water charging method and advances a novel application in the energy harvesting field.