Abstract Hypothesis The electrowetting on dielectric or EWOD phenomenon is used in a wide range of applications, such as Liquid Lenses, Lab-on-Chip devices, or EWOD displays, among others. Its chemical resistance, electrical stability, ease of application, and low cost make polytetrafluoroethylene (PTFE) the preferred hydrophobic dielectric layer for such applications. However, the hydrophobic behaviour represents a challenge for spin coating other layers over its surface. As a consequence, several techniques are implemented to modify the surface of PTFE. These methods are complex, time-consuming, and produce morphology changes over the surface that are difficult and sometimes impossible to recover. In this work, we propose a new surface modification method that is based on a non-coherent UV light exposition method and a specific water treatment, that lead to a change from hydrophobic to hydrophilic, and a perfect recovery from hydrophilic to hydrophobic behaviour. Experiments In this work, the fabrication of the hydrophobic layer treatment starts with the creation of a thin layer of alumina ( A l 2 O 3 ) over a glass substrate using an atomic layer deposition technique (ALD). A mixture of 10:1 FC40 solvent and Teflon Dupont AF1600 was coated over the alumina layer. The Teflon film was exposed to UV light produced by a low-pressure mercury (Hg) lamp for a period that ranges from 3−6 min. The results were analysed by scanning electron microscopy, x-ray spectroscopy, and static deionized water contact angle measurements. Findings Contact angles dependent on UV light exposure time were observed. From the scanning electron microscopy analysis, it was confirmed that the UV treatment does not produce morphology changes over the surface. Nevertheless, the x-ray spectroscopy revealed that the UV exposed samples react when they are brought into contact with deionized water, improving the adhesion of the surface. The original hydrophobic behaviour of the surface is recovered (up to 98 %) after 3 h of thermal treatment. Furthermore, the thermal recovery analysis reveals a correlation between the recovery percentage and the applied temperature.

中文翻译：

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通过非相干紫外光和水处理对聚四氟乙烯薄膜进行表面改性，用于电润湿应用

摘要假设电介质上的电润湿或 EWOD 现象被用于广泛的应用，例如液体透镜、芯片实验室设备或 EWOD 显示器等。其耐化学性、电气稳定性、易于应用和低成本使聚四氟乙烯 (PTFE) 成为此类应用的首选疏水介电层。然而，疏水行为代表了在其表面旋涂其他层的挑战。因此，实施了多种技术来改性 PTFE 的表面。这些方法复杂、耗时，并且会在表面上产生难以甚至有时无法恢复的形态变化。在这项工作中，我们提出了一种基于非相干紫外光暴露方法和特定水处理的新表面改性方法，这导致从疏水性变为亲水性，以及从亲水性到疏水性行为的完美恢复。实验 在这项工作中，疏水层处理的制造开始于使用原子层沉积技术 (ALD) 在玻璃基板上创建氧化铝 (Al 2 O 3 ) 薄层。将 10:1 FC40 溶剂和 Teflon Dupont AF1600 的混合物涂覆在氧化铝层上。特氟龙薄膜暴露于低压汞 (Hg) 灯产生的紫外线下 3-6 分钟。结果通过扫描电子显微镜、X 射线光谱和静态去离子水接触角测量进行分析。结果 观察到依赖于紫外光暴露时间的接触角。从扫描电镜分析，经证实，UV 处理不会在表面上产生形态变化。然而，X 射线光谱显示，暴露在紫外线下的样品在与去离子水接触时会发生反应，从而提高表面的附着力。热处理 3 小时后，表面的原始疏水行为恢复（高达 98%）。此外，热恢复分析揭示了恢复百分比与应用温度之间的相关性。