Chaminda Ajith Kumara Ranathunga Ranathunga Mudiyanselage Ihala Gane Gedara


Presentation: 9:00-10:15 a.m., Kennedy Union Ballroom



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Bio-sensing plays an important role in the determination of bio-target molecules in medical applications. In this regard, Tapered Optical Fibers Sensor (TOFS) is emerging due to its higher sensitivity, real-time specimen, and practical measuring capabilities. The sensitivity of a typical TOFS is 0.0001 RIU (Refractive Index Units) meaning the device is capable of detecting a 0.0001 change in refractive indices. This allows TOFS to be sensitive in molecular-level interactions. A tapered region or the sensitive area of a TOFS is obtained by stretching single-mode fiber cables to desired dimensions. Typical dimensions of a tapered region are 20-25 mm. A wavelength-swept laser beam is launched at one end of the fiber, passes through the tapered region, and then is collected at the other end. The modes excited at the tapered region have evanescent components in the surrounding medium and are sensitive to the concentration of bimolecular antigen-antibody pairs. This evanescent electromagnetic (EM) field enables the detection of minute changes in the refractive index close to the surface of the fiber. For the detection of biomolecules, an aqueous solution that contains the target biomolecules is introduced where they can be captured by a functionalized fiber (carrying antibodies for the analyte).The developed TOFS system was experimentally tested for practical use and yielded repeatable results with high resolution. It had been tested using various liquids, such as PBS, water, and saliva. The system utilized for head and neck squamous cell carcinoma (HNSCC) through IL-8 virus in saliva and the Covid variant HCoV-OC43. Both experiments showed success with resolutions of 10 pg/ml for IL-8 and 50 viruses/ ml for HCoV-OC43 , exceeding practical requirements in real applications.

Publication Date


Project Designation

Graduate Research

Primary Advisor

Partha Banerjee, Cong Deng

Primary Advisor's Department

Electro-Optics and Photonics


Stander Symposium, School of Engineering

Institutional Learning Goals


Portable Optical Fiber Bio-Sensing Device for the Detection of Biomolecules in Bodily Fluids