Room-Temperature Wide Measurement-Range Optical Fiber Fabry–Perot Tilt Sensor With Liquid Marble

We proposed a novel miniature liquid marble-based room-temperature optical fiber tilt sensor by using Fabry–Perot (F–P) interferometric detection, with the advantages of simple fabrication, wide range, good linearity, and low cost, aside from the immunity to electromagnetic interference. A mercury marble with a diameter of 1.3 mm and a length of 10 mm, acting as a light reflector, was dispensed into a capillary tube preprocessed by hydrophobic agent, therefore forming F–P interference with one end of a single-mode fiber. The developed sensor exhibited tilt-induced sensitivities of 6.62 $\mu \text{m}$ /ms⁻² and 4.28 $\mu \text{m}$ /ms⁻² with corresponding linearities of 3.44% and 4.28% within the ranges of 0°–90° and −90°–0°, respectively, due to asymmetric cavity lengths. The measured results were in agreement well with the governing model incorporating with contact angle hysteresis between mercury marble and capillary substrate.