An experimental study of the interaction between a Mylar® polymer film and a multimode fiber-optic is presented for the simultaneous fiber-optic detection of low-pressure and liquid levels. The junction between the polymer and optical fiber produces an interference spectrum with maximal visibility and free spectral range around 9 dB and 31 nm, respectively. Water pressure, which is controlled by the liquid level, stresses the polymer. As a result, the spectrum wavelength shifts to the blue region, achieving high sensitivities around 2.49 nm/kPa and 24.5 nm/m. The polymeric membrane was analyzed using a finite element model; according to the results, the polymer shows linear stress response. Furthermore, the membrane material is operated below the yielding point. Moreover, the finite analysis provides information about the stress effect over the thickness and the birefringence changes. This sensor exhibits a quadratic polynomial fitting with an adjusted R-squared of 0.9539. The proposed sensing setup offers a cost-effective alternative for liquid level and low-pressure detection.
Keywords: Fabry–Perot interferometer; Fiber optic sensor; Liquid level measurement; Polymer; Pressure detection.
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2021.