Abstract
Understanding the critical condition and mechanism of the droplet wetting transition between Cassie-Baxter state and Wenzel state triggered by an external electric field is of considerable importance because of its numerous applications in industry and engineering. However, such a wetting transition on a patterned surface is still not fully understood, e.g., the effects of electrowetting (EW) number, geometry of the patterned surfaces and droplet volume on the transition have not been systematically investigated. In this paper, we propose a theoretical model for the Cassie-Baxter-Wenzel wetting transition triggered by an external voltage applied to a droplet placed on a mirco-pillared surface or a porous substrate. It is found that the external field applied lowers the energy barrier for the droplet to cross over and complete the wetting transition. Our calculations also indicate that for a fixed droplet volume, the critical EW number (voltage) will increase (decrease) along with the surface roughness for a micropillar-patterned (porous) surface, and if the surface roughness is fixed, a small droplet tends to ease the critical EW condition for the transition. Besides, three-dimensional phase diagrams in terms of EW number, surface roughness, and droplet volume are constructed to illustrate the wetting transition. Our theoretical model can be used to explain the previous experimental results about the Cassie-Baxter-Wenzel wetting transition reported in the literature.
- Received 27 January 2021
- Accepted 12 August 2021
DOI:https://doi.org/10.1103/PhysRevResearch.3.033277
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society