Thermal Profile Detection Through High-Sensitivity Fiber Optic Chirped Bragg Grating on Microstructured PMMA Fiber

Abstract

In this work, a linearly chirped fiber Bragg grating (CFBG) inscribed in a microstructured polymer optical fiber (mPOF) has been demonstrated for detecting temperature profiles during thermal treatments. A CFBG of 10 mm length and 0.98 nm bandwidth has been inscribed in a mPOF fiber by means of a KrF laser and uniform phase mask. The CFBG has a high temperature sensitivity of -191.4 pm/ • C. The CFBG has been used as a semi-distributed temperature sensor, capable of detecting the temperature profile along the grating length, for scenarios that account minimally invasive biomedical treatments. Two experiments have been designed to validate the CFBG temperature reconstruction, using a linear gradient, and a researchgrade radiofrequency ablation (RFA) setup to apply Gaussianshaped temperature spatial profiles. The result is that the higher sensitivity of the CFBG supports the detection of spatially nonuniform temperature fields by means of spectral reconstruction.

Latest Achievements in Polymer Optical Fiber Gratings: Fabrication and Applications

“…An essential feature of these systems is the possibility of detecting temperature spatial distributions, also known as thermal maps [117]. A linearly chirped POFBG has been demonstrated as a semi-distributed temperature sensor capable of monitoring the temperature profile along the grating length for minimally invasive scenarios [118]. As shown in Figure 12, the chirped POFBG has been placed close to a radiofrequency applicator, with a tip inserted in situ of the target-the applicator connected to the Radio Frequency generator.…”

“…(a) Schematic of thermal ablation and (b) measurement of a Gaussian temperature gradient by using a chirped POFBG; image adapted from[118].…”

Measurement of Mechanical and Thermal Strains by Optical FBG Sensors Embedded in CFRP Rod

“…Rearranging equation (4) in terms of the mechanical strain gives equation (6). Figure 3 plots the wavelength and strain measured in each specimen.…”

“…FBG (fibre Bragg grating) sensors are widely used in telecommunication and measurement [1]. It is basically used as a strain sensor and for expanding the application area, and it can be used for the measurement of acceleration [2] and liquid level [3], temperature field detection using a linearly chirped FBG [4], and biodetection using an SPR (surface plasmon resonance) sensor [5]. There is also a smart rod [6] that has been developed to easily install FBG sensors on concrete structures.…”

Multifunctional Textile Platform for Fiber Optic Wearable Temperature-Monitoring Application

“…Until the 2000s, FBG sensors were maturely fabricated into standard optical sensors by using various techniques, including phase mask, pico-, and femtosecond laser inscription, and interferometric setting [15][16][17]. Recently, Bragg grating fabrication based on various materials or special fiber structure design is emerging rapidly [18][19][20][21], for instance, a chirped Bragg grating on microstructured polymethyl methacrylate fiber proposed by Korganbayev et al (2018) [22] that demonstrated excellent sensitivity for thermal profile detection; and some multicore fibers (MCFs) have been used as fiber optic three-dimensional shape sensors such as the helical MCF with continuous grating developed by Lally et al (2012) [23] for real-time shape sensing using the optical frequency domain reflectometry technique. Such sensors have been widely applied in civil engineering [24], healthcare medical devices [25,26], structural engineering [27,28], aerospace [29], oil and fuels [30], and harsh environments [31], among others.…”