Medical apparatus system having optical fiber load sensing capability
Apparatus is provided for diagnosing or treating an organ or vessel, wherein a device having at least two optical fiber sensors disposed in a distal extremity thereof is coupled to processing logic programmed to compute a multi-dimensional force vector responsive to detected changes in the optical characteristics of the optical fiber sensors arising from deflection of the distal extremity resulting from contact with the tissue of the wall of the organ or vessel. The force vector may be used to facilitate manipulation of the catheter either directly or automatically using a robotic system.
1. Apparatus for diagnosis or treatment of a vessel or organ, the apparatus comprising:
an elongated body having proximal and distal ends and a distal extremity, the distal extremity comprising a deformable material;
three optical fibers extending through the elongated body and affixed within the distal extremity so that the optical fibers are not co-planar;
each of the three optical fibers being coupled with at least one optical strain sensor disposed within the distal extremity; and
a storage device associated with the elongated body, the storage device containing a force-strain conversion matrix that enables computation of a three-dimensional force vector corresponding to a contact force between the distal extremity and a tissue wall of the organ or vessel.
2. The apparatus of claim 1 further comprising a console having a laser diode, a photodetector and processing logic, wherein the processing logic is programmed to receive an output from the optical strain sensor and to compute the three-dimensional force vector using the force-strain conversion matrix.
3. The apparatus of claim 2 , wherein the distal extremity further comprises an end effector to perform a diagnosis or treatment of the organ or vessel.
4. The apparatus of claim 3 , wherein the end effector comprises at least one electrode for ablating tissue by depositing radiofrequency energy.
5. The apparatus of claim 4 wherein the console is programmed to permit actuation of the electrode to ablate tissue only when the contact force falls within a determined range.
6. The apparatus of claim 4 , wherein the distal extremity further comprises an irrigation channel.
7. The apparatus of claim 6 , wherein the irrigation channel conducts radiofrequency energy to the at least one electrode.
8. The apparatus of claim 6 wherein the irrigation channel comprises a tube having proximal and distal portions, the distal portion disposed within the distal extremity and comprising a material having a coefficient of thermal expansion substantially less than the coefficient of thermal expansion of the deformable material, the at least two optical fiber sensors affixed to the distal portion.
9. The apparatus of claim 8 wherein the distal portion comprises titanium.
10. The apparatus of claim 8 further comprising a polymeric housing disposed in the distal extremity to at least partially surround the distal portion.
11. The apparatus of claim 1 wherein the optical fiber strain sensor is selected from the group consisting of: a Fiber Bragg Grating optical fiber strain sensor, a Long Period Grating optical fiber strain sensor, an Intrinsic Fabry-Perot Interferometer optical fiber strain sensor, an Extrinsic Fabry-Perot Interferometer optical fiber strain sensor, a Michelson interferometer optical fiber strain sensor and a Brillouin scattering optical fiber strain sensor.
12. The apparatus of claim 1 , wherein a distal part of one of the optical fibers extends distally beyond the other optical fibers and further comprises an additional optical fiber sensor for use in determining temperature.
13. The apparatus of claim 1 , wherein the three optical fibers comprise arms of a Michelson interferometer optical fiber strain sensor and an additional optical fiber extends through the elongate body and distally beyond the other optical fibers and includes an additional optical fiber sensor to measure temperature.
14. The apparatus of claim 1 , wherein the elongated body comprises a liquid crystal polymer.
15. The apparatus of claim 14 , wherein the liquid crystal polymer includes a moisture resistant coating.