Graphene based chalcogenide fiber-optic evanescent wave sensor for detection of hemoglobin in human blood

Fiber optic evanescent wave sensor with graphene as an absorption-enhancing layer to measure hemoglobin concentration in human blood is proposed. Previous modal functions and experimental results describing the variation of optical constants of human blood with different hemoglobin concentrations in the near-infrared spectral region are considered for sensor design simulation. The sensor's performance is closely analyzed in terms of its absorption coefficient, sensitivity, and detection limit. It is found that the proposed sensor should be operated at longer light wavelength to get more enhanced sensitivity and smaller detection limit. At 1000 nm wavelength, a detection limit of 18 μg/dL and sensitivity of 6.71 × 10−4 per g/dL is achievable with the proposed sensor. The sensitivity is found to be better for larger hemoglobin concentrations. The results are correlated with the evanescent wave penetration depth.