Catheter with coaxial thermocouple
An improved thermocouple includes a drawn coaxial thermocouple wire pair having a more precise “hot” junction at which a first and second metallic material electrically connect with each other for measuring temperature. Adapted for use with an electrophysiologic catheter, the improved thermocouple comprising an elongated body having a proximal end and a distal end. The body includes a core of a first metallic material, a first coaxial layer of ceramic material, and a second coaxial layer of a second metallic material. The thermocouple further includes a solder cap on the distal end, the solder cap electrically connecting the core and the second layer at the distal end. A method of manufacturing includes drawing the body through a die, and applying solder on a distal end of the body to electrically connect the two metallic materials at the distal end.
1. A method of manufacturing a coaxial thermocouple wire pair member adapted for use with an electrophysiologic catheter, comprising:
providing a core of a first metallic material defining a longitudinal axis;
coaxially surrounding the core with a solid annular member formed from an insulating ceramic material;
coaxially surrounding the insulating material with a second metallic material different from the first metallic material;
repeatedly drawing the member through a die until the solid annual member is crushed to a powder; and
applying solder on a distal end of the member to electrically connect the core and the metallic layer at the distal end.
2. The method of claim 1 , further comprising:
forming an electrically non-conductive layer on the outside of the drawn thermocouple wire pair member by a film cast method.
3. The method of claim 1 , further comprising:
trimming the distal end to expose the core and the layer after drawing the member through a die and before applying solder on the distal end.
4. The method of claim 1 , where one of the first metallic material and the second metallic material is copper and the other of the first metallic material and the second metallic material is constantan.