Patent ID: 8157789

Claim:
A catheter for use in a medical procedure comprising: a flexible elongate body defining a central axis and adapted to be introduced into a patient during said medical procedure and including a strain sensing assembly proximate a deformable portion of said elongate body, said strain sensing assembly including: a proximal portion and a distal portion separated by at least one standoff member to define a separation between said proximal portion and said distal portion, a plurality of transmitting elements affixed to and extending from said proximal portion of said strain sensing assembly and partially spanning said separation, each of said plurality of transmitting elements including a free end to define a plurality of free ends located between said proximal portion and said distal portion, and at least one reflecting surface carried by said distal portion of said strain sensing assembly and operatively coupled with at least one of said plurality of free ends to define a plurality of gaps for interferometery, one of said plurality of gaps being presented between each of said plurality of free ends and said at least one reflecting surface, each of said plurality of gaps having an operative length between the respective free end and the at least one reflecting surface, said operative length being variable and responsive to deformation of said deformable portion of said elongate body, said at least one standoff portion and said transmitting element having substantially similar coefficients of thermal expansion in a direction substantially parallel to said operative lengths of said plurality of gaps so that each of said operative lengths remains within a predetermined range when said deformable portion of said elongate body is subject to a predetermined range of bulk temperature change; one or more sources of electromagnetic radiation operatively coupled to each of said plurality of transmitting elements and transmitting electromagnetic radiation to each of said plurality of gaps to form a plurality of interferometers, each of said interferometers outputting modulated waveforms characteristic of the corresponding of said operative lengths; one or more receivers operatively coupled to said plurality of transmitting elements to detect said modulated waveforms; and a microprocessor configured to analyze said modulated waveforms to infer a plurality of strains on said deformable portion of said elongate body and to repeatedly resolve a force vector that contacts said catheter distal to said standoff member from said plurality of strains, said force vector including a computed magnitude and an axial component and a transverse component relative to said central axis.