A touch sensing catheter having a strain sensor assembly that may resolve the magnitude and direction of a force exerted on a distal extremity of the catheter, the strain sensor assembly being substantially insensitive to bulk temperature changes. A deformable structure having a plurality of optical fibers associated therewith that are strained by the imposition of a contact force transferred thereto. The optical fibers cooperate with the deformable structure to effect variable gap interferometers, such as Fabry-Perot resonators, that vary in operative length when a force is exerted on the deformable structure. The strain sensor assembly is rendered insensitive to bulk temperature changes by matching the coefficient of thermal expansion of the deformable body with that of the optical fibers. The strain sensor assembly may also be configured to mitigate the effects of thermal gradients using various thermal isolation techniques.
