The Optical Fiber Biosensor Enhancement Consisting of Nanocomposite by Using Graphene in Medical Application

Kidneys are one of the most important organs in the body. They cleanse the blood and convert waste and excess water into urine. If the kidneys are unable to perform their functions, dialysis is prescribed to assist the patient. Clean and healthy water, as well as accurate evaluation of dissolved substances in water, play a key role in the dialysis process to ensure the patient's safety and well-being. As the dissolved substances change the refractive index of pure water, a refractive index biosensor can be a useful system. In this research, a fiber optic sensor based on surface plasmon resonance with a coating of nanocomposite layers has been studied theoretically. In the numerical simulation, water is used as the sensing medium. The aim of this simulation is to test the sensors that detect impurities in water for dialysis. The simulation is conducted for nanocomposites of nickel-tellurium oxide, platinum-tellurium oxide, and cobalt-tellurium oxide with thicknesses of 50 nm, 70 nm, 90 nm, 110 nm, and 130 nm. The simulation also considers various volume filling factors, including 0.55, 0.65, 0.75, and 0.85. The comparison of the results showed that Ni-TeO2 (with a thickness of 110 nm and a volume filling factor of 0.85) has the highest quality and is considered the winning structure. The graphene layers are tested on the nanocomposites to enhance the quality of the final structure. The results of the simulations show that adding 50 layers of graphene can improve the sensor figure of merit from 80.603 (RIU-1) to 85.522 (RIU-1), while the refractive index of the aqueous media changes from 1.33 to 1.34.