Implantable pump impeller thermal knockdown

Abstract

The present invention relates to kits and methods for calibrating a pump through performance of a thermal knockdown process including demagnetization of an impeller of the pump where the impeller is separate from the pump. By heat treating the impeller, a property of magnetic interaction of the pump is reduced in a repeatable manner. A kit includes a pump with impeller, a controller and an oven. The method generally involves an iterative process of testing the pump for a property related to magnetic interaction of the elements of the pump, removing the impeller from the pump, heating the impeller under controlled conditions, then placing the impeller back into the pump to repeat the test performed initially.

What is claimed is: 
     
         1 . A kit for calibrating a pump having a stator and an impeller having a permanent magnetization and a first voltage, comprising:
 a heater sized and configured to heat treat the impeller; and   a controller configured to measure back electromotive force related to a magnetic interaction between the impeller having permanent magnetization and the blood pump including the stator.   
     
     
         2 . The kit of  claim 1 , wherein the heater is configured to heat treat the impeller based on a comparison of the back electromotive force measured by the controller and a target back electromotive force value. 
     
     
         3 . The kit of  claim 1 , wherein the impeller is made of a platinum cobalt alloy. 
     
     
         4 . The kit of  claim 1 , wherein the heater is configured to heat treat the impeller between 60 to 95 degrees Celsius until the back electromotive force reaches a second voltage lower than the first voltage. 
     
     
         5 . The kit of  claim 4 , wherein the controller is further configured to determine if the second voltage of the back electromotive force related to magnetic interaction after the first heating cycle is greater than a predetermined target voltage of the back electromotive force. 
     
     
         6 . The kit of  claim 1 , wherein the heater is configured to heat treat the impeller separate and apart from the blood pump.