Electrically Controlled Localized Charge Trapping at Amorphous Fluoropolymer–Electrolyte Interfaces

Hao Wu*, Ranabir Dey, Igor Siretanu, Dirk van den Ende, Lingling Shui, Guofu Zhou, Frieder Mugele

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

33 Citations (Scopus)
76 Downloads (Pure)


Charge trapping is a long-standing problem in electrowetting on dielectric, causing reliability reduction and restricting its practical applications. Although this phenomenon is investigated macroscopically, the microscopic investigations are still lacking. In this work, the trapped charges are proven to be localized at the three-phase contact line (TPCL) region by using three detecting methods—local contact angle measurements, electrowetting (EW) probe, and Kelvin probe force microscopy. Moreover, it is demonstrated that this EW-assisted charge injection (EWCI) process can be utilized as a simple and low-cost method to deposit charges on fluoropolymer surfaces. Charge densities near the TPCL up to 0.46 mC m−2 and line widths of the deposited charge ranging from 20 to 300 µm are achieved by the proposed EWCI method. Particularly, negative charge densities do not degrade even after a “harsh” testing with a water droplet on top of the sample surfaces for 12 h, as well as after being treated by water vapor for 3 h. These findings provide an approach for applications which desire stable and controllable surface charges.

Original languageEnglish
Article number1905726
Issue number2
Early online date11 Dec 2019
Publication statusPublished - 16 Jan 2020


  • UT-Hybrid-D
  • electrets
  • electrowetting
  • hydrophobic–water interfaces
  • surface charges
  • charge trapping
  • hydrophobic-water interfaces


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