FIBER OPTICS SENSOR TECHNOLOGY APPLIED TO BITE FORCE MEASUREMENT

Abstract

Fiber optic technology has recently been emerging in biomedical and biomechanical applications due to its number of useful capabilities. It can be exploited for human bite force measurement to improve their dental health and well-being. The approaches for this application have been limited to the use of multi-point sensing Fiber Bragg gratings (FBG). Therefore, we propose the bite force measurement system which allows to achieve distributed strain sensing at sub-mm spatial resolution. It employs Rayleigh scattering based on optical frequency domain reflectometry (OFDR) with single-mode fiber (SMF). The experimental setup is made to apply a range of weights onto the fiber sandwiched between two silicone layers. The first experiment with single fiber line is calibrated for preliminary testing among different measurement points. The second one is calibrated to obtain a response of strain in one point with the cut in the bottom layer for fiber insertion. Using the same measurement method, the main experiment involves bending the fiber into three lines in order to assess strain distribution among them. The measurements are conducted onto fiber lines and between them. Due to the manual cutting in the material, there is uneven depth in each fiber line. Calibration with single fiber line shows linear regression of applied weight to strain with coefficient of determination of 0.997. Following that, the 2D maps are reconstructed for more readable visual representation of strain distribution. Strain is observed to be elongated along the fiber lines for the entire length of silicone due to the stretching of fiber. Thus, Gaussian distribution is utilized for each peak of measurement points for different reading of the maps. This thesis also serves as the basis for optical fiber to be embedded in a biomedical device, similar to a mouth guard, which follows the shape of the bite.