Efficient fabrication of micropillars for water repellency using photolightography
Faghihi, Parsa
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https://hdl.handle.net/2142/127341
Description
Title
Efficient fabrication of micropillars for water repellency using photolightography
Author(s)
Faghihi, Parsa
Issue Date
2024-11-07
Director of Research (if dissertation) or Advisor (if thesis)
Miljkovic, Nenad
Department of Study
Mechanical Sci & Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
Micro Pillars - Water Repellency - SU8 - Photolithography
Abstract
This study focuses on the fabrication and characterization of SU-8-based micropillars designed for water repellency and related applications. Using SU-8 photoresist, we created micropillars with various shapes and structures on silicon wafers to achieve enhanced water-repellent surfaces. Optimal baking and exposure parameters were thoroughly evaluated, revealing that efficient fabrication requires a higher exposure dose (~800 mJ/cm²) and extended baking time (~30 minutes) compared to standard recommendations. Both SU-8-2005 and SU-8-2015 were examined for their performance under these conditions. To enhance hydrophobicity and achieve superhydrophobic properties, two different hydrophobic coatings and boehmite nanostructures were applied.
Surface characterization was conducted using 3D confocal microscopy and a microgoniometer, with results demonstrating that the micropillars could increase water droplet contact angles by approximately 30° on hydrophobic surfaces, reaching a contact angle of ~149° with C4F8 coating. The application potential of these micropillars for water removal in condensation conditions was explored using Environmental Scanning Electron Microscopy (ESEM). The micropillars effectively support applications in water repellency, condensation, boiling, and particularly in droplet jumping phenomena on superhydrophobic surfaces. By optimizing the fabrication recipe, this study advances the fundamental understanding of micro- and nanoscale interactions for various applications, paving the way for future studies in water-repellent surface design and heat transfer efficiency improvements.
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