REAL-TIME DISTRIBUTED FIBER SENSING FOR BIOMEDICAL APPLICATION BY USING OPTICAL BACKSCATTER REFLECTOMETRY

Abstract

The recent fiber optic sensors (FOS) offer remarkable potentials allowing for precise measurements in space and time, achieving high spatial resolutions, thereby providing unprecedented advances for biomedical applications. Sensing possibilities of FOSs can be improved from acquiring only one sensing point to continuous number of sensing locations along the fiber. The ability to detect high-density sensing points distributed along the length of the fiber allows for the high-resolution measurement of physical parameters, which is a key feature of distributed fiber optic sensing (DFOS) systems. Advances in spatially resolved sensing techniques open up new opportunities for biomedical applications, particularly in highly accurate pressure sensing, which is critical for monitoring wound care, managing skin health, and preventing pressure ulcers. Additionally, this enhanced resolution facilitates precise bite force measurements, essential for dental diagnostics and treatment planning. By providing detailed, high-resolution pressure maps along the dental arch, FOSs enable the accurate assessment of occlusion and bite force distribution, which is vital for optimizing oral health care and designing personalized therapeutic interventions. The growing demand for accurate and reliable biomedical sensing solutions has highlighted the importance of DFOS. This thesis explores advancements in DFOS systems and their applications, focusing on the development and integration of advanced sensing technologies for biomedical fields. The study developed high-resolved pressure sensing carpet by sandwiching fiber into silicone material. Investigations were carried out on different methods of attaching the fiber to silicone, including configurations with and without cutting the silicone. The pressure calibration experiments were done by applying the different values of calibration weights. The pressure distribution along the surface was reconstructed by bending fiber lines into parallel lines with a distance 2 mm and was embedded into silicone material. Two silicone pressure-sensing carpets, made from Silcotin 20 and Sorta Clear 18, were investigated and validated. The results showed that the pressure-sensing carpets made of Sorta Clear 18 demonstrated superior sensitivity, stability, and exceptionally high resolution of 2 by 2 mm, highlighting their potential for biomedical applications such as skin health management and the prevention of pressure ulcers. The study proposes a novel application of DFOS for measuring occlusion and bite force, providing bilateral measurements. Silicone dental mouthguards were embedded with two different fiber topologies, enabling the measurement and reconstruction of wavelength shift responses along the dental structure. The two fiber topologies, spiral and parallel, were developed and validated. The spiral topology was achieved by folding fiber lines into four parallel lines, while the parallel topology was implemented using the scattering-level multiplexing (SLMux) approach with nanoparticle-doped fibers. Both fiber topologies were embedded into silicone materials. The parallel topology exhibited superior responsiveness to external stimuli compared to the spiral topology. This innovation enables precise bilateral bite force measurements, enhancing diagnostic and therapeutic practices in dentistry by providing detailed insights into bite force distribution, which is essential for treatment planning and oral health assessment. The research investigates real-time measurement capabilities of DFOS system using LabVIEW and MATLAB. The real-time system was improved by utilizing historical data obtained through optical backscattered reflectometry (OBR) from LUNA Inc. The LabVIEW software development kit (SDK) was employed to integrate real time response, enabling the dynamic monitoring of physical parameters. Real-time visualization of maximum values of physical parameters provided instant feedback during data acquisition, significantly enhancing the system's clinical utility. The findings presented in this thesis demonstrate the versatility and potential of DFOS systems for biomedical applications. By combining fiber attachment techniques, innovative fiber configurations, and integrated real-time software solutions, this research establishes a foundation for the development of highly efficient and precise measurement systems. The advancements in bite force measurements and pressure sensing applications highlight the system’s ability to deliver high-resolution, real-time insights critical for managing skin health, preventing pressure ulcers, and enhancing diagnostic and therapeutic outcomes in dentistry. These contributions underscore the transformative and wide-reaching potential of DFOS in modern biomedical applications, promising to significantly improve healthcare diagnostics and therapeutic strategies.