Issue 26, 2024

Surface charge density and induced currents by self-charging sliding drops

Abstract

Spontaneous charge separation in drops sliding over a hydrophobized insulator surface is a well-known phenomenon and lots of efforts have been made to utilize this effect for energy harvesting. For maximizing the efficiency of such devices, a comprehensive understanding of the dewetted surface charge would be required to quantitatively predict the electric current signals, in particular for drop sequences. Here, we use a method based on mirror charge detection to locally measure the surface charge density after drops move over a hydrophobic surface. For this purpose, we position a metal electrode beneath the hydrophobic substrate to measure the capacitive current induced by the moving drop. Furthermore, we investigate drop-induced charging on different dielectric surfaces together with the surface neutralization processes. The surface neutralizes over a characteristic time, which is influenced by the substrate and the surrounding environment. We present an analytical model that describes the slide electrification using measurable parameters such as the surface charge density and its neutralization time. Understanding the model parameters and refining them will enable a targeted optimization of the efficiency in solid–liquid charge separation.

Graphical abstract: Surface charge density and induced currents by self-charging sliding drops

Supplementary files

Article information

Article type
Paper
Submitted
12 Feb 2024
Accepted
08 Apr 2024
First published
10 Apr 2024
This article is Open Access
Creative Commons BY license

Soft Matter, 2024,20, 5045-5052

Surface charge density and induced currents by self-charging sliding drops

P. Bista, A. D. Ratschow, A. Z. Stetten, H. Butt and S. A.L. Weber, Soft Matter, 2024, 20, 5045 DOI: 10.1039/D4SM00205A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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