Detection Of Marine Temperature,Salinity And Oil Spill Using Optical Fiber Surface Plasmon Resonance Sensors

In this work,we mainly focused on the application of terminal reflective optical fiber surface plasmon resonance(FOSPR)sensors in the ocean.On the one hand,the optical fiber temperature sensor and the optical fiber salinity sensor were constructed to measure the sensitivity of temperature and salinity respectively.On the other hand,we independently built a fiber optic SPR sensor system for offshore oil spill detection and we studied the relationship between the oil film and the reflected light intensity under the water-oil interface and the air-oil interface by quantifying the amount of oil spilled.The main conclusions were drawn as follows:(1)Optical fiber temperature and salinity sensor analysis based on FOSPR sensor:The terminal reflection optical fiber temperature sensor and the optical fiber salinity sensor were prepared by using the method of polydopamine accelerated wet chemical coating of gold nanoparticles.The sensitivity of the FOSPR sensor tested in different refractive index solutions was 2566 nm/RIU,the FWHM of reflection spectrum was167.84 nm.And the quality factor was 15,indicating that the sensor had a high comprehensive performance.The optic fiber temperature sensor measured temperature sensitivity as high as-0.3262 nm/°C,the resonance wavelength decreased with the increase of temperature.The optical fiber salinity sensor measured the salinity sensitivity of 0.4099 nm/‰,and the resonance wavelength became longer with the increase of salinity.Within a certain range,there were good linear relationships between temperature and reflected light intensity,salinity and reflected light intensity.(2)Real-time thickness measurement of marine oil spill by fiber optic surface plasmon resonance sensors: As surface plasmon resonance(SPR)sensors are sensitive to slight changes in refractive index,they can monitor offshore oil spills arising from significant differences in the refractive index between oil and water.This study presents a gold-film fiber optic surface plasmon resonance(FOSPR)sensor prepared by polydopamine accelerated wet chemical plating for rapid and real-time measurement of oil slick thickness.We examined oil thickness detection at two interfaces: water–oil and air–oil.Detection sensitivity of-1.373 %/mm is obtained at the water–oil interface in the thickness range of 0-5 mm;Detection sensitivity of-2.742 %/mm is obtained at the air–oil interface in the thickness range of 0–10 mm.Temperature and salinity present negligible effects on the oil slick thickness measurement.The fabricated FOSPR sensor has the ability to detect the presence of oil as well as quantify the oil thickness with favorable repeatability and reusability.