School of Chemical Engineering, National Technical University of Athens, GR-15780 Athens, Greece.
J Colloid Interface Sci. 2012 Feb 15;368(1):592-8. doi: 10.1016/j.jcis.2011.10.035. Epub 2011 Oct 25.
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.
在使用薄膜介电质满足低工作电压要求的电润湿器件中，通常会出现严重的材料失效问题。介电击穿（可见为电解）通常在接触角饱和开始后不久就明显出现。在这里，等离子体增强化学气相沉积（PECVD）用于在旋涂聚四氟乙烯（Teflon®）无定形氟聚合物之前沉积氟碳薄膜。所得的多层疏水性顶涂层通过在高施加电压和连续施加直流和交流电压时显示出对介电击穿的高电阻，从而改善了堆叠的电润湿性能。在使用所提出的复合涂层进行的电润湿实验中进行漏电流测量时，与在多次电润湿测试后漏电流明显增加的普通 Teflon®涂层相比，电流在连续的电润湿测试中保持相当稳定。由于即使在薄膜配置中，所提出的复合涂层也表现出对材料失效和介电击穿的更高抵抗力，因此将其集成到电润湿器件中可能会影响它们的可靠性、鲁棒性和寿命。
