Real-time monitoring and decoupling of multi parameters in vascular intervention using a cascaded LPFG-FBG sensor

During vascular interventional surgery, temperature, blood viscosity and vascular strain are very important for real-time monitoring in surgical navigation and intraoperative strategy. A highly integrated sensor for multiple index detection in real time is in great demand for robotic-assisted intraoperative surgery. In this study, we developed a cascaded long-period fiber grating-fiber Bragg grating (LPFG-FBG) sensor in which the temperature, blood concentration, and strain are decoupled and can be sensed independently in real-time. The experimental results show that when the temperature rises from 20°C to 70°C, the temperature sensitivity and linearity of the LPFG are significantly superior compared to those of the FBG; when the glycated hemoglobin concentration increases from 2% to 21%, the LPFG is more sensitive to glycated hemoglobin concentration variation, with a sensitivity of −0.053 nm/%; when the stress increases from 0 to 300 με, the FBG is solely sensitive to strain variation, with a sensitivity of 0.000291 nm/με. The two-parameter optical fiber sensor proposed in the study does not require special inscription techniques for fabrication, and it has a simple structure, good stability, and high sensitivity. With a single cascaded LPFG-FBG inserted into a blood vessel, temperature, concentration, and strain can be calculated in real time from the sensing coefficient matrices. Its different filtering characteristics are beneficial to multi-parameter coupled measurements and decoupling in vascular surgery intraoperative monitoring