The Institute of Laser for Postgraduate Studies / University of Baghdad discussed the Master’s thesis submitted by student Mohammed Hussein Weheeb, entitled:
“Improvement of Fiber Optic Sensor Sensitivity for Biomedical Measurement Based on SPR Principle” Under the supervision of Assistant Professor Dr. Zainab F. Mahdi
The study aimed to improve the sensitivity of fiber optic sensors by relying on the Surface Plasmon Resonance (SPR) phenomenon used in biomedical measurements. This was achieved by developing the sensor’s structural design and investigating the effect of several design variables on its performance and sensitivity in detecting minute changes in the concentrations of biomaterials. Glucose and sodium chloride were used as analytical models for biomaterials.
The study included the design and fabrication of fiber optic sensors coated with thin metallic layers and the investigation of their optical properties using different models and practical experiments, while evaluating sensor performance by measuring spectral response, sensitivity, and detection accuracy in biosensing applications.
The study also involved fabricating ten different sensor designs using multimode optical fibers coated with various metallic structures, including single, double, and triple layers. Gold nanoparticles with sizes of 3 and 20 nm were incorporated to enhance plasmonic interaction and improve sensing performance. Numerical simulations were also performed using COMSOL software to study electromagnetic behavior and interpret experimental results.
The results showed a remarkable improvement in the sensitivity of the developed sensors compared to conventional designs. The proposed modifications increased the sensor’s response to small changes in refractive index and slight variations in analyte concentrations, thereby enhancing its efficiency in diagnostic and biosensing applications. The results also demonstrated the potential of employing these sensors in biomedical applications that require high accuracy and fast response.
The study further showed that 3 nm nanoparticles provided a more uniform electric field and contributed to improving linearity, measurement accuracy, and detection limits. This made the sensor capable of operating over a very wide concentration range, which enhances its usability in biomedical diagnostics and the detection of trace concentrations of biomaterials.
These results represent an important step toward developing highly sensitive biosensing systems that can be utilized in the future for medical and diagnostic applications and for monitoring vital signs, thus contributing to enhancing the accuracy of biomedical measurements and supporting modern healthcare technologies.
The study also concluded that combining multilayer metallic coatings with gold nanoparticles represents an effective approach to increasing the sensitivity and performance of fiber optic sensors, making them a promising platform for future biomedical applications and advanced sensing systems.
The thesis was approved after fulfilling all requirements for obtaining the Master’s degree in Laser Applications.
