Biofouling of an All-Optical Sensor for Seafloor Monitoring of Marine Carbon Capture and Storage Sites

Abstract

Fiber-optic sensors for dissolved CO 2 are an emergent technology for monitoring marine geologic CO 2 sequestration sites. Fiberoptic sensing technology has been used successfully in the oil and gas sector and is advantageous because it is capable of costeffective, instantaneous, distributed sensing. This is an improvement over current practice, which normally requires samples to be pumped to the surface for analysis. Biofouling of fiber-based sensors is a concern for the marine environment, as the biofouling can cause signal drift and also adversely impact the sensor's ability to detect dissolved CO 2 . Single mode optical fibers with long period gratings etched onto the core of the fiber were used for this study. Pseudoalteromonas sp. NCIMB 2021 was cultured and grown on sensing elements using nutrient-dense synthetic seawater. Biofouling was shown to cause shifts in the baseline signal. Post-fouling sensitivity of the sensor was also reduced relative to pre-fouling levels. Mechanical cleaning of the sensors restored sensor sensitivity to that seen prior to bacterial colonization.

Nanocomposite thin film of Ag nanoparticles embedded in amorphous Al 2 O 3 on optical sensors windows: Synthesis, characterization and targeted application towards transparency and anti-biofouling

“…The degradation of the optical performance in short time period spanning from days to months has been a concern since more than twenty years [3,4], resulting in the development of antifouling measures to prevent the deterioration of the optical window transparency of the sensor. Such measures may involve incorporation of some type of brush or wiper, however it should be ensured that it will not scratch the optical surface.…”

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

“…Even a small amount of biofilm in the sensing area can produce undesired interferences in the readings of the sensor, which can no longer provide reliable information. These interferences can result from the clogging of sections, membranes, or filters in mechanical sensors (as also changes in the normal mechanical properties of MEMs sensors); contamination in chemical sensors (for example, macro-fouling in dissolved oxygen sensors); increasing resistance to heat exchange in thermal sensors; increasing of acoustic absorption and consequent decrease in receiving power in acoustic sensors; and increasing of optical absorption and consequent decrease in receiving power in optical sensors [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”

Optical Sensing of CO2 Geological Storage Using Distributed Fiber-Optic Sensor: From Laboratory to Field-Scale Demonstrations

“…Strain measurements using distributed fiber optical sensing (DFOS) technology have been promising for effectively monitoring various in situ geologic processes associated with CO 2 storage , and have been extensively applied in monitoring geohazard management. − Existing commercial fiber optical sensors mainly include single-point Fabry–Perot interferometer, quasi-distributed fiber Bragg grating (FBG) sensors, and DFOS, but the first two systems are generally used for local detections of embedded or bonded structures. , In comparison with other fiber sensors/cables, DFOS makes it possible to acquire measurands at thousands of points along one single-mode fiber (SMF) or cable and thus enable continuous imaging strain profiles under harsh deep/ultradeep subsurface conditions, such as high pressure and high temperature (HPHT). − …”