TY - JOUR

T1 - Tilted fiber Bragg grating measurements during laser ablation of hepatic tissues: quasi-distributed temperature reconstruction and cladding mode resonances analysis

AU - Korganbayev, Sanzhar

AU - De Landro, Martina

AU - Wolf, Alexey

AU - Tosi, Daniele

AU - Saccomandi, Paola

N1 - Publisher Copyright: Author

PY - 2022/8/15

Y1 - 2022/8/15

N2 - In this work, we investigate the application of tilted fiber Bragg grating (TFBG) sensors during ex vivo laser ablation of porcine hepatic tissues. Initially, TFBG's ability to measure the surrounding refractive index (RI) for different sucrose concentrations and the possibility to measure the RI of the targeted tissue during laser ablation (LA) is analyzed. After, the temperature sensing modality of TFBG is investigated in detail. We have implemented an algorithm for quasi-distributed spatial temperature profile reconstruction along TFBG. The algorithm models the TFBG core mode spectrum as a chain of Bragg gratings (each Bragg grating is modeled via coupled mode theory), where each grating is sensitive to local temperature changes. After, the Gaussian-shape temperature profile along the TFBG is reconstructed using the iterative optimization technique. Temperature measurements have been compared with highly-dense FBG array measurements and with conventional TFBG point temperature measurements based on the core mode tracking techniques (maximum tracking, X-dB Bandwidth, centroid methods). Overall, the proposed reconstruction algorithm is able to provide a quasi-distributed temperature profile along TFBG, which is not possible to obtain using conventional point temperature measurements based on the TFBG's core mode tracking. The resulted root-mean-square error in comparison to FBG array reference measurements is 7.8±1.7 °C. In general, the results show that the main reliable sensing modality of TFBG during LA is temperature monitoring, which can be significantly improved by the proposed algorithm.

AB - In this work, we investigate the application of tilted fiber Bragg grating (TFBG) sensors during ex vivo laser ablation of porcine hepatic tissues. Initially, TFBG's ability to measure the surrounding refractive index (RI) for different sucrose concentrations and the possibility to measure the RI of the targeted tissue during laser ablation (LA) is analyzed. After, the temperature sensing modality of TFBG is investigated in detail. We have implemented an algorithm for quasi-distributed spatial temperature profile reconstruction along TFBG. The algorithm models the TFBG core mode spectrum as a chain of Bragg gratings (each Bragg grating is modeled via coupled mode theory), where each grating is sensitive to local temperature changes. After, the Gaussian-shape temperature profile along the TFBG is reconstructed using the iterative optimization technique. Temperature measurements have been compared with highly-dense FBG array measurements and with conventional TFBG point temperature measurements based on the core mode tracking techniques (maximum tracking, X-dB Bandwidth, centroid methods). Overall, the proposed reconstruction algorithm is able to provide a quasi-distributed temperature profile along TFBG, which is not possible to obtain using conventional point temperature measurements based on the TFBG's core mode tracking. The resulted root-mean-square error in comparison to FBG array reference measurements is 7.8±1.7 °C. In general, the results show that the main reliable sensing modality of TFBG during LA is temperature monitoring, which can be significantly improved by the proposed algorithm.

KW - Calibration

KW - Fiber gratings

KW - laser ablation

KW - Monitoring

KW - optical fiber sensors

KW - Optical fiber sensors

KW - refractive index sensing

KW - Sensors

KW - Temperature measurement

KW - temperature monitoring

KW - Temperature sensors

KW - thermal treatment

KW - tilted fiber Bragg grating

KW - Laser ablation

UR - http://www.scopus.com/inward/record.url?scp=85134289348&partnerID=8YFLogxK

U2 - 10.1109/JSEN.2022.3189153

DO - 10.1109/JSEN.2022.3189153

M3 - Article

AN - SCOPUS:85134289348

VL - 22

SP - 15999

EP - 16007

JO - IEEE Sensors Journal

JF - IEEE Sensors Journal

SN - 1530-437X

IS - 16

ER -