Polarization and temperature insensitive surgical instrument force transducer

Abstract

A force sensor apparatus, operatively mounted in a surgical instrument includes the force transducer. The force transducer includes a transducer body having a coefficient of thermal expansion, and at least one optic fiber, fixedly attached to the transducer body, including a Bragg grating; and having a coefficient of thermal expansion matched to the coefficient of thermal expansion of the transducer body to mitigate polarization and calibration drift effects on the force transducer. The transducer body comprises a metal transducer body, and the metal transducer body is selected from a group of metal bodies including an aluminum alloy transducer body, a stainless steel alloy transducer body, a maraging steel alloy transducer body, and a titanium alloy transducer body. The at least one optic fiber comprises an optic fiber having a negative thermo-optic coefficient, such as a phosphate glass optic fiber reducing the thermal sensitivity of the transducer.

1 . A surgical instrument comprising:
 a force sensor apparatus operatively mounted in said surgical instrument, the force sensor apparatus comprising the force transducer, wherein said force transducer comprises:
 a transducer body having a coefficient of thermal expansion; and 
 at least one optic fiber fixedly attached to said transducer body, the at least one optic fiber including a Bragg grating, the at least one optic fiber having a coefficient of thermal expansion, the at least one optic fiber having a negative thermo-optic coefficient, and the coefficient of thermal expansion of the transducer body and the coefficient of thermal expansion of the at least one optic fiber being matched to mitigate polarization and calibration drift effects on said force transducer. 
   
     
     
         2 . The surgical instrument of  claim 1 , wherein said transducer body comprises an aluminum alloy. 
     
     
         3 . The surgical instrument of  claim 2 , wherein said aluminum alloy comprises 3.5% to 8.4% of zinc by weight. 
     
     
         4 . The surgical instrument of  claim 2 , wherein said aluminum alloy comprises 1.8% to 6.8% of copper by weight. 
     
     
         5 . The surgical instrument of  claim 2 , wherein said aluminum transducer alloy is a rapid solidification metglass based aluminum alloy comprising 5.0% to 11.5% of zinc by weight. 
     
     
         6 . The surgical instrument of  claim 2 , wherein said aluminum alloy comprises 0.6% to 1.3% of magnesium and 0.4% to 1.8% of silicon by weight. 
     
     
         7 . The surgical instrument of  claim 1 , wherein said transducer body comprises a stainless steel alloy. 
     
     
         8 . The surgical instrument of  claim 7 , wherein said stainless steel alloy comprises 10% to 18% of chromium by weight. 
     
     
         9 . The surgical instrument of  claim 7 , wherein said stainless steel alloy is a precipitation hardened stainless steel alloy comprising 10% to 18% of chromium and 3.0% to 11.5% of nickel by weight. 
     
     
         10 . The surgical instrument of  claim 1 , wherein said transducer body comprises a maraging steel alloy. 
     
     
         11 . The surgical instrument of  claim 10 , wherein said maraging steel alloy comprises 18% to 19% of nickel by weight. 
     
     
         12 . The surgical instrument of  claim 10 , wherein said maraging steel alloy comprises 11% to 12% of nickel by weight. 
     
     
         13 . The surgical instrument of  claim 1 , wherein said transducer body comprises a titanium alloy. 
     
     
         14 . The surgical instrument of  claim 13 , wherein said titanium alloy comprises 2.5% to 6.75% of aluminum by weight. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . The surgical instrument of  claim 1 , wherein said at least one optic fiber is fixedly attached to said transducer body by an adhesive. 
     
     
         20 . The surgical instrument of  claim 19 , wherein said adhesive has a coefficient of thermal expansion matched to said coefficient of thermal expansion of said at least one optic fiber and to said coefficient of thermal expansion of said transducer body. 
     
     
         21 . The surgical instrument of  claim 20 , wherein said adhesive has a glass transition temperature and when said at least one optic fiber is affixed to said transducer body by said adhesive, said adhesive is cured at a temperature less than said glass transition temperature and then post-cured above the glass transition temperature and above an autoclaving temperature. 
     
     
         22 . The surgical instrument of  claim 1 , wherein said transducer body includes a groove formed in an outer surface of said transducer body and said at least one optic fiber is fixedly attached in said groove of said transducer body. 
     
     
         23 . The surgical instrument of  claim 22 , wherein said groove is a straight groove substantially parallel to a longitudinal axis of said transducer body. 
     
     
         24 - 45 . (canceled)