A force sensor apparatus is provided including a tube portion having a plurality of radial ribs and at least one fiber optic strain gauge positioned over each rib of the plurality of radial ribs. A proximal end of the tube portion is operably couplable to a shaft of a surgical instrument that is operably couplable to a manipulator arm of a robotic surgical system, and a distal end of the tube portion is proximally couplable to a wrist joint coupled to an end effector. A thermal shunt shell is over an outer surface of the tube portion.
