Optimising optical port size on underwater marine instruments to maximise biofouling resistance

The limiting effects of biofouling have restrained the widespread deployment of optical marine sensors. This has necessitated the development of biofilm resistant coatings that are not detrimental to the quality of any measurement recorded. A comprehensive study has been carried out into the effect of changes in the diameter of optical ports. It was found that increasing the diameter of an optical port in the range 10–46 mm reduced the biofouling per unit area. Changes in the diameter did not affect the release of an antimicrobial agent from a hydrogel-based coating. The results show that the operational lifetime of optical ports is significantly improved for diameters over 30 mm and it is suggested that this should be considered a preferred design minimum for optical ports, regardless of the size of the underlying sensor.