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

Abstract

Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different techniques for biofouling protection based on different housing materials, biocides, and transparent coatings. Six optical turbidity probes were built using polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), PLA with copper filament, ABS coated with PDMS, ABS coated with epoxy and ABS assembled with a system for in situ chlorine production. The probes were deployed in the sea for 48 days and their anti-biofouling efficiency was evaluated using the results of the field experiment, visual inspections, and calibration signal loss after the tests. The PLA and ABS were used as samplers without fouling protection. The probe with chlorine production outperformed the other techniques, providing reliable data during the in situ experiment. The copper probe had lower performance but still retarded the biological growth. The techniques based on transparent coatings, epoxy, and PDMS did not prevent biofilm formation and suffered mostly from micro-biofouling.

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.…”