Antifouling modifications to ocean sensors
The ocean is not a hospitable place for monitoring equipment. Aside from salt and extreme temperatures and pressures, biofouling, the accumulation of microorganisms on sampling equipment, is also a problem. The longer the equipment is submerged, the greater the risk. Yet long-term (e.g. year-long) data series are increasingly in demand for use in climate change studies. With this in mind, Chelsea Instruments Ltd (CI) examined different antifouling techniques during the BRIMOM project. They focused on optical and membrane-based instrumentation whose accuracy can be severely limited by biofouling. Specifically, instruments used to measure the ocean's transmissivity, fluorescence, pH and dissolved oxygen levels were addressed. CI considered both modifications to existing instrument designs as well as the creation of brand new designs. Alterations included converting recessed windows to flush-mounted versions. Also, wipers and brushes were improved to help keep algal and other build-up at bay. Finally, chemical methods, such as special coatings, hydrogels and chlorination, were investigated. With respect to new designs, the British engineers from CI highlighted the importance of involving the end-users, i.e. the oceanographers, in the design phase. This helps ensure that the proper balance between antifouling features, instrument cost, maintainability, ease of use, etc. will be struck. Their involvement also increases the chances that development costs will be recovered as the products find a receptive market.