Electrically heated surgical blade and methods of making

A blade for a hemostatic surgical instrument comprising:

• a first region including a portion defining a cutting edge, the first region of a laminate comprising a core of a high strength hardenable material having lateral faces, and first and second outer layers of a high thermal conductivity material, each one of the first and second outer layers joined to one of the material faces of the core;
• a second region of a low thermal conductivity material welded to the first region at a longitudinal joint, the longitudinal joint mechanically finished to provide a smooth surface, the blade being heat treated while in blank form by passing it through a reducing atmosphere at an elevated temperature and then being cooled to obtain a high hardness level in the core of the first region;
• a first layer of a high expansion dielectric material coated on the first and second regions, the first layer having a thermal expansion coefficient in the range of the thermal expansion coefficient of one of the pair of outer layers of the first region and the low thermal conductivity material of the second region;
• a resistive conductor material deposited in a first pattern of the first layer of dielectric material so that the first pattern is superimposed over the first region, the resistive conductor material having a specific sheet resistance in the range of from about 10 to about 50 milliohms per square mm at 20.degree. C.;
• a conductor material deposited in a second pattern on the first dielectric layer superimposed over the second region, the second pattern overlapping the first pattern of first dielectric material so that the resistive conductor material and the conductor material are in electrical contact;
• and
• a second layer of dielectric material deposited over all of the first pattern and the second pattern except for a portion adapted for completing an electrical contact between the conductor material and the hemostatic surgical instrument.