Compact force sensor for catheters

A force sensor for use at a distal tip of a catheter, comprising:

• a structural member;
• a plurality of reflecting members, each affixed to and extending from the structural member;
• and
• a plurality of fiber optics, each paired with a corresponding one of the plurality of reflecting members, each paired fiber optic and reflecting member defining a corresponding gap therebetween,
• wherein the plurality of reflecting members each comprises a material having a coefficient of thermal expansion differing from that of the plurality of fiber optics, the coefficient of thermal expansion of the reflecting member being selected for passive compensation of changes in the corresponding gaps between each paired fiber optic and reflecting member that are caused by temperature change,
• wherein the structural member is configured to produce a change in a dimension of at least one of the corresponding gaps in response to a force exerted on the distal tip of the catheter,
• wherein a rotational displacement of each of the plurality of fiber optics and the corresponding reflecting members relative to a plane of y-y inertial axes is between about 60° and about 90°, and
• wherein a sensitivity of each of the corresponding gaps is optimized with respect to lateral force components.

A force sensor for use at a distal tip of a catheter, comprising:

• a structural member that defines a longitudinal axis and includes
• a first segment and a second segment that are adjacent each other along the longitudinal axis, the first and second segments defining a first slot therebetween, the first slot being bridged by a first flexure, and
• a third segment adjacent the second segment along the longitudinal axis, the second and third segments defining a second slot therebetween, the second slot being bridged by a second flexure;
• a plurality of reflecting members, each affixed to and extending from the third segment of the structural member and each including a reflective surface;
• and
• a plurality of fiber optics, each paired with a corresponding one of the plurality of reflecting members and each oriented and adapted to irradiate the reflective surface of the corresponding one of the plurality of reflecting members and to collect at least a portion of a light reflected from a proximal end of a corresponding reflecting member, each paired fiber optic and reflecting member defining a corresponding gap having a dimension there between, each of the corresponding gaps being disposed proximate the second slot,
• wherein the force sensor is configured to compensate for thermally induced changes to each of the dimensions of the corresponding gaps,
• wherein a rotational displacement of each of the plurality of fiber optics and the corresponding reflecting members relative to a plane of y-y inertial axes is between about 60° and about 90°, and
• wherein a sensitivity of each of the respective gaps is optimized with respect to lateral force components.