Surface modification of polytetrafluoroethylene thin films by non-coherent UV light and water treatment for electrowetting applications
| Autor: | Manuel Dominguez-Pumar, Michelle Cedeño-Mata, Sandra Bermejo, Cristian Daniel López |
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| Přispěvatelé: | Universitat Politècnica de Catalunya. Doctorat en Enginyeria Electrònica, Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya. MNT - Grup de Recerca en Micro i Nanotecnologies |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Scanning electron microscope General Chemical Engineering Microfluidic devices Materials -- Aplicacions industrials 02 engineering and technology 010402 general chemistry Enginyeria dels materials [Àrees temàtiques de la UPC] 01 natural sciences Contact angle chemistry.chemical_compound Atomic layer deposition Materials Chemistry Polytef Thin film Polytetrafluoroethylene Spin coating EWOD Organic Chemistry electrowetting 021001 nanoscience & nanotechnology 0104 chemical sciences Surfaces Coatings and Films Chemical engineering chemistry Dispositius microfluidics Electrowetting Surface modification 0210 nano-technology Politetrafluoroetilè |
| Zdroj: | UPCommons. Portal del coneixement obert de la UPC Universitat Politècnica de Catalunya (UPC) |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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