CC BY
5Gold and graphene oxide coated tilted fiber Bragg grating biosensor design for clinical decisions
P.B. Prathap1, K. Saara2*
1- Department of Electronics and Communication Engineering, Malnad College of Engineering,
Hassan-573202
2- Department of Electronics and Communication Engineering, School of Engineering, Dayananda Sagar University, Bangalore-560114
* saara-ece@dsu. edu.in, [email protected]
Abstract: Fiber Bragg Grating (FBG) sensors excel in clinical decision-making due to their superior sensitivity and resolution. This study proposes a gold and graphene oxide-coated Tilted FBG (TFBG) biosensor with a grating angle of 9 degrees. The gold coating enhances reflectivity and sensitivity, while the graphene oxide (GO) coating improves plasmonic attraction and antibody/antigen absorption. The GO coating increases the refractive index, causing significant spectral shifts for biosensing. Simulated results demonstrate the sensor's potential for protein analysis and immunological assessments, supporting accurate therapeutic decisions.
I. INTRODUCTION
The growing worldwide population and pressure on healthcare infrastructures and human expertise have prompted business to automate and improve diagnosis and pharmaceutical solutions. Hardware advancements, especially sensor technology, have made diagnostics faster and more scalable. Rising health issues require more accurate and reliable sensors for early detection and diagnosis. This can minimize mortality and prevent complications if discovered and treated early. Highly sensitive sensors are needed for biomechanical, physiological, non-invasive surgery, and biosensing [1-3].
II. RESULTS AND DISCUSSION
Performance characterization is based on wavelength shift in response to changes in the surrounding refractive index to assess biosensor resilience. Increasing target molecule absorption on the coating surface raises the density and refractive index (n3), causing coupling wavelength shifts and amplitude reductions. The proposed biosensor design was evaluated for wavelength shift, transmission power vs. wavelength (^), and zero-crossing point shift.
Simulated spectral outputs for different surrounding indices (n3=1.50 and 1.56) show increased density and refractive index on the coating surface. Results indicate that an exceedingly high refractive index saturates the transmission spectra (dB), with spectral output at n=150 resembling that at n=16. High saturation or density due to excessive molecular absorption at the cladding mode or coating surface can result in zero internal reflection, making the fiber core act as a normal dielectric hollow cylinder. Additional simulations for surrounding indices (n3=1.45, n3=150, n3=156, n3=160, and n3=165) are shown in Fig. 1 (a-c).
Fig. 1. (a-c) Transmission spectrum with different refractive indices.
[1] A.G. Leal-Junior, C.A.R. Diaz, L.M. Avellar, M.J. Pontes, C. Marques, A. Frizera, Polymer optical Fiber sensors in healthcare applications: A comprehensive review, Sensors, 19(14), 3156, (2019).
[2] S. Korganbayev, M. De Landro, A. Wolf, D. Tosi, P. Saccomandi, Tilted Fiber Bragg Grating Measurements during Laser Ablation of Hepatic Tissues: Quasi-Distributed Temperature Reconstruction and Cladding Mode Resonances Analysis, in IEEE Sensors Journal, 22(16), 15999-16007, (2022).
[3] D. Lo Presti, et al, Fiber Bragg Gratings for Medical Applications and Future Challenges: A Review, in IEEE Access, 8, 156863-156888, (2020).
