Characterization of surface wettability

• Main Author: Quek, Jordan Wei Jie
• Other Authors: Zhang Yi
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/141406
• Institution: Nanyang Technological University

Since the 1980s, research and development of digital microfluidics have been significant due to strong demands in the biotechnological field. Digital microfluidics, where droplets are maneuvered on an open-surface platform, plays a significant role in droplet-based microfluidics as it allows individual droplets to be manipulated and used as a medium for reactions. Therefore, digital microfluidics facilitates the complex handling of sensitive and hazardous samples in their liquid states. In addition, conducting tests in such miniature scales allows for increased automation, creating more opportunities for systematic testing. In magnetic digital microfluidics, a permanent magnet or electromagnet is used to control the movement of the droplet. This is possible because magnetic particles are mixed with the droplet, allowing it to be dragged along the hydrophobic glass substrate by the permanent magnet underneath. Furthermore, magnetic particles serve as a platform for molecule absorption. Magnetic digital microfluidics uses hydrophobic substrates with a low coefficient of friction such as glass. However, glass itself is not hydrophobic and requires coating with a hydrophobic material such as Teflon. At the moment, the most commonly used hydrophobic coating method is applying Teflon on the surface using spin-coating. However, Teflon spin coating is only favorable to flat and smooth surfaces like glass. Teflon itself is also expensive and requires a certain temperature and time to fabricate. Thus, this project aims to identify alternative coating materials that can be used in magnetic digital microfluidic fabrications by characterizing the surface wettability of surfaces coated with various chemicals by measuring their contact angles.