Considerations for testing anti-fouling coatings designed for implementation into Earth-based and spacecraft water systems

Biofilms are common in water systems and can lead to mechanical failure or illness of water system users. Methods for evaluating anti-fouling coatings have largely been informed by the medical industry and have not been tailored to industrial or spacecraft water systems. The goal of the paper is to help guide researchers in designing experiments to evaluate coatings that accurately represent the system under investigation. This review identified eight experimental design considerations when evaluating coatings in water systems: biofilm reactor operation, microorganism selection, reinoculation, coating surface area, liquid medium, experiment duration, coating performance evaluation, and the use of microgravity. The impact of each decision made within each of these considerations is presented. Further, the methods featured in eight studies investigating coatings for Earth-based or spacecraft water systems are discussed. This review serves to guide researchers toward improved experimental design to enable successful technology transfer from the lab bench to Earth and beyond.