Design and analysis of graphene surface plasmon biosensors

Abstract

Absorption of incident light is the most critical property of surface plasmon resonance (SPR) biosensors. Besides, damping of electron oscillations in metal is another significant issue. Hence, the reflected light intensity-profile is widened. Instead, SPR-based Kretschmann biosensors show poor magnetic response and their magnetic properties have never been applied for biosensing. We have proposed the use of magnetic resonance of a Kretschmann based SPR biosensor which is promising in biosensing. Moreover, a SPR-based glucose sensor is proposed where monolayer graphene optical property is controlled by applying a suitable gate voltage (Vg). We find that the sensor performance parameters such as figure-of-merit and sensitivity are improved by 49.57\% and 21.48\%, respectively when Vg = 20 V applied to the graphene monolayer. We use a linear regression model to calculate the detection accuracy of the blood sugar level. We observe the detection error in 4.75% on an average and within 7.40% of the worst-case situation when temperature changes by ±10o C from a reference 25o C. Precise detection of ultra-low-level severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is censoriously important, recently. We have proposed a SPR sensor with multi-layer graphene to detect the SARS-CoV-2. The proposed sensor has detected as small as ~1 fM SARS-CoV-2, S-protein concentration. However, using multi-layer graphene in SPR biosensors show low detection accuracy. Then, a graphene photonic crystals-based Tamm plasmon and surface plasmon hybrid mode for hemoglobin detection is proposed. We use double-dips method which shows polarization-dependent behavior where the maximum sensitivity is 314.5 degree/RIU when hemoglobin level is 189 g/L. From terahertz to mid infrared wavelength range, graphene shows a metallic response that supports high light confinement. We have shown that transverse magnetic mode is created in the visible spectrum by applying a suitable Vg and appropriate ZnO thickness. We have proposed graphene nanostrips-based dual-channel refractive index sensor, an optimistic alternative to the traditional Kretschmann arrangement where no need of noble metal in the structure. The propose sensor gives a maximum 2530 degree/RIU sensitivity when both the sensing channels have the same refractive index.