A hierarchical bio-mimetic surface engineering approach to prevent biofouling by microbial biofilms

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Biofouling, or the colonization of surfaces by unwanted organisms, has detrimental effects on several important industrially relevant structures, such as ship hulls, heat exchangers, sensors and pipelines. Biofouling is almost ubiquitous and controlling it remains an extremely challenging problem. Amongst the various biofouling relevant organisms are microbes. Microbes have attributes that allow them to 'explore' and colonize abiotic surfaces in the form of thin films called biofilms. These biofilms can result in several undesirable situations, such as surface degradation and energy losses amongst other issues. In fact, fouling of ship hulls by micro-organisms can easily generate energy penalties of the order of 10-15%. Currently, the need to deliver eco-friendly solutions to this problem is causing renewed interest in approaches such as use of surface topographies, which can prevent or delay biofouling. In this context, biologically inspired designs or biomimetic designs are expected to be very promising. The proposed research program addresses the challenge of designing novel bio-fouling resistant surfaces by using an innovative hierarchical (multi-scale) bio-mimetic surface topography. Biological materials can be highly organized, at various length scales, in a hierarchical manner with intricate structures that often give rise to multi-functional capabilities. In particular this research program will seek to employ two concurrent topographic scales: (i) nano-scale surface topographies that will interfere with molecular level processes and make the process of microbial adhesion energetically unfavorable and (ii) larger scale topographies (length scale ~ 100 µm), which under conditions of fluid flow will lead to formation of secondary flows near the surfaces. Secondary flows, which can even form under laminar flow conditions, can affect mass transfer near surfaces, and they would act against the transport of microbes to the surface thereby reducing microbial access to the abiotic surface. These surface features have been chosen from the topographies that are often present on aquatic creatures and are believed to be integral to their ability to prevent adhesion of disease causing microbes.