Superior performance of multilayered fluoropolymer films in low voltage electrowetting

• Published in: Journal of colloid and interface science Vol. 368; no. 1; pp. 592 - 598
• Main Authors: Papageorgiou, Dimitrios P., Tserepi, Angeliki, Boudouvis, Andreas G., Papathanasiou, Athanasios G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15.02.2012; Elsevier
• Subjects: Chemical vapor deposition; Chemistry; coatings; Composite coatings; contact angle; Contact angle saturation; Devices; Dielectric breakdown; Electric potential; electric power; electrolysis; Electrowetting on dielectric; Exact sciences and technology; Failure; Fluoropolymers; General and physical chemistry; hydrophobicity; perfluorocarbons; Plasma-deposited fluorocarbon; Solid-liquid interface; Surface physical chemistry; vapors; Voltage; Plasma-deposited fluorocarbon; Contact angle saturation; Electrowetting on dielectric; Plasma; Coating material; Multilayer; Film; Spin; Device; Saturation; Contact angle; Fluorocarbon; Hydrophobicity; Chemical vapor deposition; Thin film; Degradation; Resistance; Lifetime; Halogenated hydrocarbon; Electrolysis; Composite coating
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2011.10.035

[Display omitted] ► Multilayered hydrophobic dielectric featuring plasma-deposited fluorocarbon interlayer. ► Increased lifetime of the proposed multilayered (composite) top coating. ► High resistance to dielectric breakdown (visible as electrolysis). ► Improvement of electrowetting performance in long term application of AC and DC voltage. ► Persistence of dielectric properties checked by sensitive leakage current measurements. The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma-enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon® amorphous fluoropolymer. The resulting multilayered hydrophobic top coating improves the electrowetting performance of the stack, by showing high resistance to dielectric breakdown at high applied voltages and for continuous long term application of DC and AC voltage. Leakage current measurements during electrowetting experiments with the proposed composite coating showed that current remains fairly constant at consecutive electrowetting tests in contrast to plain Teflon® coating in which material degradation is evident by a progressive increase in the leakage current after multiple electrowetting tests. Since the proposed composite coating demonstrates increased resistance to material failure and to dielectric breakdown even at thin configurations, its integration in electrowetting devices may impact their reliability, robustness, and lifetime.