Biofouling protection by electro-chlorination on optical windows for oceanographic sensors and imaging devices

Abstract

Oceans environmental monitoring and seafloor exploitation need in situ sensors and optical devices (cameras, lights) in various locations and on various carriers in order to initiate and to calibrate environmental models or to operate underwater industrial process supervision. For more than 10 years Ifremer deploys in situ monitoring systems for various seawater parameters and in situ observation systems based on lights and HD Cameras. To be economically operational, these systems must be equipped with a biofouling protection dedicated to the sensors and optical devices used in situ. Indeed, biofouling, in less than 15 days [1] will modify the transducing interfaces of the sensors and causes unacceptable bias on the measurements provided by the in situ monitoring system. In the same way biofouling will decrease the optical properties of windows and thus altering the lighting and the quality fot he images recorded by the camera.

Let’s Talk about Slime; or Why Biofouling Needs More Attention in Sensor Science

“…Instead, most research has focused on localized chlorination through the electrolysis of seawater. The effectiveness of this approach has been demonstrated through the application of optically transparent electrodes directly on a sensor’s optical windows. − Limitations of this approach include limited effectiveness against chlorine-resistant microorganisms and potential degradation of other sensor materials (e.g., rubber o-rings) exposed to chlorine. However, given its low cost, ease of integration, and relatively low power requirements, localized chlorination through electrolysis is considered one of the most promising antibiofouling methods.…”

Design and In Situ Validation of Low-Cost and Easy to Apply Anti-Biofouling Techniques for Oceanographic Continuous Monitoring with Optical Instruments

“…Primarily used in industrial applications, chlorine techniques have recently migrated to oceanographic instruments as is the case of Wet Labs/Sea-Bird WQM (the device uses a reservoir for the chlorine solution and a pump to inject it into the surface of the sensor) or electrolysis chlorination systems in monitoring stations [ 31 ]. Other techniques based on chlorine production that focused on protecting only the sensing area of the instrument, have been presented [ 32 ]. These techniques have less energetic needs and are more compliant with long-term monitoring power requirements.…”

Electric Potential Induced Prevention and Removal of an Algal Biofoulant from Planar SERS Substrates

“…1 As with all materials in marine environments, underwater sensors are vulnerable to biofouling, which can affect their operation, sensitivity, maintenance needs, and data quality. 2,3 There are various techniques used to prevent biofouling, including mechanical devices, antifouling paints (such as tributyltin or TBT), ultraviolet (UV) light irradiation, and rough topographies. 1,4−6 Many of these conventional techniques are not applicable to sensors that employ nanostructured architectures.…”

“…6,7 UV irradiation could be an effective tool for nanostructured sensors; however, it consumes a large amount of energy making it impractical for long-term underwater monitoring operations. 2 Surface-enhanced Raman spectroscopy (SERS)-based sensors can detect chemical contamination including pesticides, 8 perfluorinated compounds, 9 perchlorate, 10 organic and inorganic anions, 11−13 and other small toxic molecules 14 in aquatic environments. However, biofouling can permanently reduce the sensitivity and increase background noise of SERSactive substrates by blocking SERS "hotspots".…”

“…Many acoustic, electrical, optical, chemical, and biological sensors are available in submersible instruments for marine research and observation . As with all materials in marine environments, underwater sensors are vulnerable to biofouling, which can affect their operation, sensitivity, maintenance needs, and data quality. , There are various techniques used to prevent biofouling, including mechanical devices, antifouling paints (such as tributyltin or TBT), ultraviolet (UV) light irradiation, and rough topographies. ,− Many of these conventional techniques are not applicable to sensors that employ nanostructured architectures. For example, mechanical antifouling devices such as wipers and scrapers could damage sensor substrates and TBT paints would “cover” nanostructures and surface chemistries.…”