Potential of high-sensitivity tactile sensing using polymer optical fiber gratings

We characterize fiber gratings inscribed line-by-line in perfluorinated graded-index polymer optical fibers (PFGI-POFs) for tactile sensing. First, we measure the dependence of the wideband transmitted light spectrum on the distance between the fiber grating and an object composed of metal or rubber, clarifying that the spectral power is significantly dependent on the object position in a wide wavelength range. Subsequently, we experimentally show that this behavior is caused by the light scattering at the fiber grating, indicating that PFGI-POF gratings are potentially applicable to simple low-cost tactile sensors or high-sensitivity short-range displacement sensors with no need for additional supportive tools.