| Author: | Eccel Vellwock, Andre |
| Title: | Biomimetic surface engineering for biofouling control |
| Advisors: | Yao, Haimin (ME) |
| Degree: | Ph.D. |
| Year: | 2022 |
| Subject: | Fouling organisms -- Control -- Technological innovations Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Mechanical Engineering |
| Pages: | 112 pages : color illustrations |
| Language: | English |
| Abstract: | Aquatic organisms naturally attach to surfaces to replicate and colonize. This is known as biofouling. It is essential for the ecosystem, but when it proliferates uncontrollably on a surface that needs to be absent of encrustations, it is a big problem. The naval industry, such as in boat hulls, controls biofouling through biocidal paints, which have been demonstrated not to be an environmentally friendly solution. Biofouling control through greener methods is a human need, and few ways have been suggested in the last decades. This thesis focuses on understanding the factors contributing to biofouling and developing environmentally friendly methods such as surface engineering. Chapter 01 consists of an introduction to the field, such as current biofouling techniques, manufacturing methods for fabrication of biomimetic surfaces, methodologies to assess fouling, literature's proposed fouling theories, and so on. In Chapter 2, a meta-analysis was performed to understand the factors that affect the adhesion of organisms. Considering ten factors such as fouler species, water flow rate, and surface morphology, a data-driven approach was proposed and validated experimentally, showing a practical method for predicting the adhesion efficiency of fouling organisms. The outcome greatly facilitates the design of antifouling surfaces and materials. Many environmental-friendly solutions (i.e., surface topography alteration and coating) against fouling modify the base material's optical properties. In Chapter 3, a surface with nanowrinkles, inspired by the zebrafish (D. rerio) corneal surface, is fabricated. By varying the nanowrinkle's dimensions and through experimental and numerical analyses, the influence of wrinkles on the material's transparency is explored. Moreover, their antifouling performance is evaluated through bacterial assays and field tests, highlighting an optimal dimension of the nanowrinkles. This work provided a direct approach to reconciling antifouling performance and optical properties on wrinkled surfaces. The influence of the surface morphology and properties on the adhesion of foulers is a topic of constant debate. Research shows that a well-designed surface can reduce fouling drastically compared to a flat counterpart. To be effective, the surface features have to the sized similar to the fouling organisms such as marine bacteria, sized around one micrometer, and barnacles, sized around hundreds of micrometers. Antifouling is based on reducing the fouler contact force to the substrate. Fabrication methods to obtain large surfaces with micrometer-sized features are extremely costly, have complex processes, and are often made of fragile materials. Chapter 4 describes a facile fabrication method to obtain metallic-based, large-scaled surfaces covered by micrometer-sized controllable features. It is based on adding a metallic mesh onto a substrate and coating it with paint. The addition of natural antifoulant products to the paint composition is discussed. The best mesh dimension is proposed after field and laboratory biofouling analysis. Through this thesis, several topics related to biofouling were studied. These results are of significant value to designing and fabricating antifouling surfaces and understanding of factors influencing organisms' attachment. |
| Rights: | All rights reserved |
| Access: | open access |
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