Title : Highly sensitive early detection of breast cancer using surface plasmon resonance based fiber optic biosensor by shining gaussian beam: A wave theory based approach
With the experimental validation, a new approach towards the wave theory based fiber optic biosensor using Gaussian beam for early detection of breast cancer is explored, in a multilayered fiber structure. This structure comprises an unclad multimode fiber with a core diameter of 15 μm, followed by the layers of gold of 15 nm thin, a layer of APTES, Glutaraldehyde, HER2 antibody and HER2 antigen, respectively. Here, HER2 antigen is used as a sensing layer with varying concentrations from 2 ng/mL to 100 ng/mL. It is well known that, for a healthy person, the HER2 concentration is between 2 ng/mL and 15 ng/mL and after 15 ng/mL breast cancer patients will be detected. Here, the wave theory based technique is used to achieve more similarities between analytical and experimental solutions and for accurate analysis of different modes within the fiber.
Thus, as compared to the ray theory, this strategy is more apparent and successful. Here, the proposed technique is shined by a Gaussian beam and the output beam is observed with the help of power-meter head. With the help of graphical representations, the amplitude distribution of the electric field and its propagation inside the MMF for the suggested fiber sensor has also been observed. It can be deduced from the graphical representation that the radial mode number 2 has the highest coupling efficiency among all the modes inside the MMF. The transmission loss within the MMF varies in response to the change in concentration of HER2 biomarker in Phosphate Buffered Saline (PBS). The proposed sensor has a sensitivity of 6734.93 dB/RIU and 0.26 nm/ng/mL and a resolution of 1.48×10-6, which is 3 times better than the reported ray theory-based articles till date. Here, owing to the more spectral shifts from 2 ng/mL to 15 ng/mL, an enhanced sensitivity and resolution is observed at lower concentration, through which the proposed idea of early detection of breast cancer is materialized. The proposed biosensor intends to improve in the existing fiber optic based sensors in terms of sensitivity and resolution for early detection of breast cancer using HER2 biomarker. It is also observed that resonance wavelength of the proposed sensor shifts towards right with an increase in the concentration of the HER2 biomarker. The proposed idea will result in a better sensing platform for identifying breast cancer by optically assessing the earlier stage of the cancer.