Two-Channel Surface Plasmon Resonance Sensor for Simultaneous Measurement of Seawater Salinity and Temperature

Multichannel Fiber Optic SPR Sensors: Realization Methods, Application Status, and Future Prospects

“…The sensor was based on the inner and outer channels of HCF, where the outer channel was deposited with a gold film to measure the salinity of seawater, and the inner channel was coated with a silver layer and full of a temperature-sensitive polymer to sense temperature changes. [94] The results show that there are two well-separated resonance dips, which are sensitive to temperature and RI, realizing the simultaneous measurement of seawater temperature and salinity. By comparison with the cascade structure, the embedded structure realizes the physical separation of the internal and external channels and is more suitable for measuring two different parameters.…”

“…For example, silver mirror reaction can be employed to coat a silver film on the internal surface of the HCF. [94] The typical structures of MC-SPR sensors based on different metals are shown in Figure 11. The sensing configuration shown in Figure 11a adopts a cascade structure, and two regions of the fiber are coated with different metals to excite resonances of different wavelengths.…”

“…While the fiber optic seawater temperature and salinity sensing technology utilizing the SPR effect has received extensive attention from researchers due to the high sensitivity, corrosion resistance, anti-electromagnetic interference, and suitability for realtime monitoring. [36,67,94,142,170] In 2019, Wu et al proposed a fiber optic SPR sensor on the basis of MMF-SMF structure, in which a part of the sensing area was equipped with PDMS film to sense temperature changes, and the other part is a bare gold film to sense the salinity of seawater changes. The sensor structure is similar to Figure 12a, except that the PDMS is farther away from the fiber end face.…”

Liquid level sensor based on dynamic Fabry–Perot interferometers in processed capillary fiber

“…A LIF sensor is characterized by providing a wide functionality by integrating in relatively small dimensions a large number of sensor elements 1 – 4 . Typically, these are optical structures that allow small volumes (μL, nL) of biological fluids and liquids to be interrogated 1 , 3 , 5 . In an optical fiber, this type of optofluidic structures are favored by the presence of the fiber core as a waveguide that allows the different elements to be optimally interconnected.…”

“…Typically there are two options for sensing fluids located around the fiber: by guiding the light to the cladding 6 , 7 (or by modifying the geometry of the fiber 8 , 9 ), or by entering the fluid inside the fiber 1 , 3 , 10 , 11 . The latter notably improves sensitivity, and has been achieved through the manufacture of microchannels or microfluidic reservoirs 1 .…”