Wavelength-Phase Hybrid Coded Catheter Tip Three-Axis Force Optical Fiber Sensor With Uncertain Environment Self-Adaptivity

A wavelength-phase hybrid coded catheter tip three-axis force optical fiber sensor with uncertain environment self-adaptivity was developed to provide force feedback for surgeons during radiofrequency catheter ablation. The designed sensor includes a flexure consisting of multilayer continuous beams and a hollow cylinder, five fiber Bragg gratings (FBGs), Fabry–Perot (F-P) cavity. The theoretical models of the sensor under transverse and axial forces have been derived. The structural parameters of the sensor have been determined by sensitivity isotropy optimization to acquire the same sensitivity in each axis. Uncertain environment self-adaptivity strategies have been proposed including pressure and temperature compensation methods and fault-tolerant decoupling to resist environmental parameters interference and FBG fracture risk. Experimental sensitivities in
Fx
,
Fy
, and
Fz
are 495.2, 697.2, and 859.9 pm/N, respectively. Experimental results of uncertain environment self-adaptivity investigation including force-pressure coupling, force-temperature coupling, and force-pressure-temperature coupling indicate that the error compensation methods can effectively guarantee force measurement accuracy. The maximum full-scale relative errors of
Fx, Fy
, and
Fz
are less than 6% within a fault-tolerant decoupling when one FBG is fractured. Experimental results in the heart-vascular model prove the capabilities of the designed sensor for catheter-tissue contact force sensing and operating environment parameters detection.