Highly sensitive fiber-optic temperature sensor based on tapered no-core fiber for biomedical and biomechanical applications

A low-cost, easy to fabricate real-time temperature sensation device built on an In-Line Mach–Zehnder interferometer basis was manufactured by fusing a segment of no-core fiber amongst two fibers of single-mode. Two different structures, tapered no-core fiber, and untapered no-core fiber both retaining acrylate polymer coating were investigated. The 3 cm length tapered no-core fiber sensor showed the highest sensitivities of ∼ −1.943 nm ◦C−1 and ∼ −1.954 nm ◦C−1 for two different dips respectively. The sensor exhibited high linearity with a very good resolution of 0.0102 ◦C. making the most of the high coefficient of thermal expansion, thermo-optic properties of the acrylate polymer, and the tapering effect, the sensor could be utilized in many temperatures observing applications like biochemical labs, biomechanical studies, and bio-sensing analyses

Ultrasensitive Mach-Zehnder Interferometric Temperature Sensor Based on Liquid-Filled D-Shaped Fiber Cavity

A liquid-filled D-shaped fiber (DF) cavity serving as an in-fiber Mach–Zehnder interferometer (MZI) has been proposed and experimentally demonstrated for temperature sensing with ultrahigh sensitivity. The miniature MZI is constructed by splicing a segment of DF between two single-mode fibers (SMFs) to form a microcavity (MC) for filling and replacement of various refractive index (RI) liquids. By adjusting the effective RI difference between the DF and MC (the two interference arms), experimental and calculated results indicate that the interference spectra show different degrees of temperature dependence. As the effective RI of the liquid-filled MC approaches that of the DF, temperature sensitivity up to −84.72 nm/°C with a linear correlation coefficient of 0.9953 has been experimentally achieved for a device with the MC length of 456 μm, filled with liquid RI of 1.482. Apart from ultrahigh sensitivity, the proposed MCMZI device possesses additional advantages of its miniature size and simple configuration; these features make it promising and competitive in various temperature sensing applications, such as consumer electronics, biological treatments, and medical diagnosis