Grating Coupled Self-referenced SPP Biosensor for Detection of Glucose Level in Urine in Optical Communication Band

The expeditious growth and development of different optical-based medical and biomedical instruments to detect various diseases nowadays put itself a potential research topic. In recent times, prevalence of diabetes mellitus among people has become alarming and often life-threatening. In this regard, efficient sensors with high sensitivity are extremely necessary for monitoring and quantification of glucose level in the urine samples. A self-referenced surface plasmon polariton sensor using trapezoidal TiO₂ grating on thin Au film has been proposed here to detect glucose level in urine samples for the first time. The proposed sensor has been optimized for better sensitivity and can be operated in the optical communication band which can help to achieve existing mature light sources and light detection instruments. The sensor has been designed with a thin dielectric grating on top of thin metal film resulting in generation of two surface plasmons at the two boundaries of the metal film. This technique is fascinating to improve the accuracy of sensitivity of the device and helps to eliminate cross-sensitivity problem. As a result, this type of self-referenced biosensor can be used for a wide range of applications in fields such as biochemistry, biophysics, and environmental monitoring. The proposed sensor shows a higher sensitivity compared to that of other plasmonic sensors reported in recent times due to incorporation of trapezoidal-shaped grating structure for the first time instead of rectangular shape. The spectral sensitivity of the proposed structure was obtained as 666.67 nm/RIU with optimized values of different structural parameters.