Temperature-Insensitive Contact Force Sensing in Bi-Directional Catheter Using Fiber Bragg Grating Pair

Bi-directional catheters are commonly used in electrophysiology mapping and ablation procedures. We have designed and demonstrated a temperature-insensitive contact force sensor for bi-directional catheters with variable curve diameter during deflection. The compact force sensor is based on a fiber Bragg grating (FBG) pair, where both FBGs have the same center wavelength and are fixed at two opposite deflection arcs of the bi-directional catheter. When the catheter is deflected or when contact force is applied to the catheter, bifurcation of the FBG pair spectrum is observed. The amount of spectral bifurcation and the applied contact force has a linear relationship. Contact force measurement, therefore, is accomplished by measuring the change in the spectral bifurcation of the FBG pair, i.e., the change in the Bragg wavelength difference between the two FBGs. Since the approach relies solely on the amount of spectral bifurcation of the FBG pair instead of the Bragg wavelength shift of one single FBG, the proposed contact force sensor is temperature insensitive.