Innovative UV Biofouling Mitigation Technique for In-water Optical Sensors

A new technology for reducing biofouling (accumulation of biological matter on submerged surfaces) on radiometers measuring light in the water column will be developed. This technology will improve the long-term accuracy of sensors monitoring the health of the oceans and their data products (e.g., con-centration of chlorophyll and dissolved organics). Inhibition of biofouling will be achieved using germi-cidal UV-C radiation. Irradiating instruments with external UV-C sources has been shown to prevent bio-fouling, but this method cannot be applied to radiometers requiring unobstructed field-of-views. As op-tical components (windows) of radiometers considered here are made of materials that are transparent to UV-C radiation (PTFE, quartz glass), we will use UV-C LEDs installed inside the instruments. The main objectives in Phase I are to find the best LED type, duty cycle, power system, and geometry without in-terfering with the radiometric measurements. One challenge will be to irradiate surfaces surrounding the entrance window because organisms accumulating in this area may grow into the window. The de-sign will be aided by the optical modeling capabilities of our subcontractor. Fixtures with various optical configurations will be designed and tested. In Phase II, we will build and test prototype radiometers with this new technology.