Medical device with multi-core fiber for optical sensing

A catheter assembly comprising:

• a catheter tip assembly coupled to a distal end of a catheter body, the catheter tip assembly comprising:
• a flexing structure configured to bend in response to an external force;
• an electrode adjacent the flexing structure, the electrode comprising:
• a distal end wall;
• and
• a longitudinally extending inner wall intersecting with the distal end wall,
• wherein the distal end wall and the inner wall define a cavity;
• and
• a multi-core fiber comprising a plurality of cores and a distal end, wherein each of the plurality of cores extends from a proximal end to the distal end of the multi-core fiber, wherein at least one of the plurality of cores comprises a fiber Bragg grating and is configured to sense a shape of the flexing structure,
• wherein the distal end of the multi-core fiber is disposed within the cavity and is in contact with a surface of the distal end wall of the electrode, and
• wherein a distal end of the fiber Bragg grating is disposed within the cavity and is spaced apart from the distal end wall of the electrode.