High sensitivity balloon-like thermometric sensor based on bent single mode fiber

A simple and compact temperature sensor based on a Mach-Zehnder modal interferometer has been fabricated by bending a single-mode fiber into a balloon-like configuration. Three Different fiber sections: fiber without stripping, fiber with a stripped-off protective coating, and a fibre with a polyvinyl alcohol (PVA) coating have been utilized, each with a small bending diameter of 1 cm that mimics a balloon-like shape. The PVA-coated segment sensor structure showed the highest sensitivity of ~−1.492 nm/°C, a fast response time of ~2.78 ms and a good resolution of ~3 × 10−4°C, for the temperature range 30-55oC benefiting from the good thermo-optical properties of PVA. This sensor can potentially be used in various temperature monitoring processes such as food industries, chemical analysis, detections of molecular analysis, and label-free biomedicine.