Advancement in glucose concentration measurement in human blood: a surface plasmon resonance-based optical sensing approach

Diabetes is a chronic metabolic disorder defined by persistently increased blood glucose levels. This research aims to evaluate the effectiveness of a surface plasmon resonance (SPR)-based sensor for near-continuous diabetes monitoring. The proposed SPR sensor aims for frequent, near-continuous glucose monitoring through periodic blood sampling. Future advancements in miniaturization and integration of microfluidics could enable continuous, real-time monitoring. The proposed surface plasmon resonance sensor follows the bimetallic plasmonic metals copper (Cu)/ silver (Ag), and platinum (Pt) coated over the BK7 prism to detect surface plasmon phenomena. This unique combination significantly enhances the sensor's sensitivity and stability compared to traditional SPR sensors, which typically use single metal layers. The Cu/Pt or Ag/Pt bimetallic layers improve the sensor's plasmonic response, resulting in higher sensitivity to glucose molecules. The addition of Platinum enhances the chemical stability and biocompatibility of the sensor, making it more reliable for near-continuous glucose monitoring. The graphene nanosheet improves the sensitivity of detecting water-containing glucose in human blood samples. This work numerically examined the effect of the bimetals Cu/Ag-Pt and graphene on the performance of a Kretschmann-configured SPR biosensor with a visible wavelength of 632.8 nm. Two distinct sensor structures-structure I and structure II-have been meticulously designed in this research, incorporating specific layers to enhance sensitivity. The highest sensitivities for structures I and II, 351.06 deg/RIU and 276.59 deg/RIU respectively, are achieved with different combinations of the sensing layers. The angular interrogation technique optimises the thickness of metals and 2D materials to reduce reflection. The highest sensitivity of 351.06 deg/RIU is attained for detecting glucose. The proposed study demonstrates higher sensitivity than previously reported SPR biosensors for blood glucose monitoring, indicating its potential utility in the medical industry.