Transcutaneous energy transfer with circuitry arranged to avoid overheating

Abstract

A device, system and method for transcutaneous energy transfer (TET). Implanted circuitry suitable for conditioning the power delivered transcutaneously may be constructed in planar fashion, may be located in or near an implanted coil, and may be oriented such that the plane of the circuitry is substantially tangent to the lines of magnetic flux. The orientation of the circuitry may reduce eddy currents and their potentially harmful effects.

What is claimed is:  
     
         1 . A device for use in transcutaneous energy transfer, comprising: 
 a coil for subcutaneous placement within a human, and circuitry that is electrically connected to the coil, and configured to conduct current induced in the coil,    wherein a major plane of the circuitry is oriented substantially perpendicular to a major plane of the coil, thereby reducing the generation of eddy currents within the circuitry while current is conducting in the coil.    
     
     
         2 . The device of  claim 1 , further comprising a casing composed of biocompatible material encapsulating the coil and the circuitry.  
     
     
         3 . The device of  claim 1 , wherein the circuitry is located within the aperture of the coil.  
     
     
         4 . The device of  claim 1 , further comprising leads permitting attachment to a subcutaneous electrical device.  
     
     
         5 . The device of  claim 1 , wherein the shape of the coil is substantially circular.  
     
     
         6 . The device of  claim 1 , wherein the circuitry is located near the axis of the coil.  
     
     
         7 . The device of  claim 1 , wherein the circuitry consists of substantially planar subcircuits, the planes of the subcircuits are substantially located perpendicular to the major plane of the coil.  
     
     
         8 . The device of  claim 1 , wherein the circuitry consists of planar subcircuits, the subcircuits being electrically coupled by leads, and the major planes of the subcircuits being substantially parallel to each other.  
     
     
         9 . The device of  claim 1 , wherein the coil is a secondary coil, and wherein the lines of magnetic flux are principally generated by a primary coil external to the skin.  
     
     
         10 . The device of  claim 9 , wherein the substantially planar circuitry is oriented substantially tangent to the lines of magnetic flux generated by the primary coil.  
     
     
         11 . The device of  claim 9 , wherein the substantially planar circuitry is curved such that the local plane of the circuitry is oriented substantially tangent to the lines of magnetic flux generated by the primary coil.  
     
     
         12 . The device of  claim 9 , wherein the primary coil and the secondary coil are arranged coaxially.  
     
     
         13 . A transcutaneous energy transfer system, comprising 
 a primary coil for placement external to the skin, the coil suitable for carrying a time-varying current,    a current source arranged in series with the primary coil, comprising a power supply and power circuitry capable of delivering an electric current to the primary coil to produce magnetic flux,    a secondary coil for subcutaneous placement, the coil suitable for carrying a current induced by the magnetic flux, and    substantially planar conditioning circuitry that is electrically coupled to the secondary coil and conducts current induced in the secondary coil,    wherein the plane of the conditioning circuitry is oriented substantially perpendicular to the a major plane of the secondary coil.    
     
     
         14 . The system of  claim 13 , wherein the conditioning circuitry performs at least one of the functions of rectification, filtering and regulation.  
     
     
         15 . The system of  claim 13 , further comprising: 
 a subcutaneous electrical device, and    leads permitting electrical coupling of the conditioning circuitry to the subcutaneous electrical device.    
     
     
         16 . The system of  claim 15 , wherein the subcutaneous electrical device comprises an implantable blood pump.  
     
     
         17 . The system of  claim 15 , wherein the subcutaneous electrical device comprises an electrical storage battery.  
     
     
         18 . The system of  claim 13 , wherein the conditioning circuitry is located within the aperture of the secondary coil.  
     
     
         19 . The system of  claim 13 , wherein the primary and secondary coils are arranged coaxially.  
     
     
         20 . The system of  claim 13 , wherein the shape of the primary coil is substantially circular and the shape of the secondary coil is substantially circular.  
     
     
         21 . The system of  claim 13 , wherein the plane of the conditioning circuitry is located substantially perpendicular to the major plane of the primary coil.  
     
     
         22 . The system of  claim 13 , wherein the conditioning circuitry is oriented to reduce eddy currents induced by the magnetic flux.  
     
     
         23 . The system of  claim 13 , wherein the conditioning circuitry comprises two or more electrically coupled substantially planar subcircuits, the plane of the subcircuits being oriented substantially perpendicular to the a major plane of the secondary coil.  
     
     
         24 . The system of  claim 13 , wherein the conditioning circuitry comprises two or more electrically coupled subcircuits, the subcircuits being oriented to reduce eddy currents induced by the magnetic flux.  
     
     
         25 . A method for delivering energy transcutaneously, the method comprising: 
 placing a primary coil external to the skin, the primary coil being electrically coupled to a power supply capable of delivering time-varying current to the primary coil,    determining the orientation of magnetic flux lines principally caused by time-varying current circulating in the primary coil,    constructing conditioning circuitry in substantially planar fashion, and    placing a secondary coil beneath the skin, the secondary coil being electrically connected to the conditioning circuitry and the conditioning circuitry oriented substantially tangent to the lines of magnetic flux.    
     
     
         26 . The method of  claim 25 , further comprising 
 dividing the conditioning circuitry into subcircuits, each subcircuit being substantially planar;    electrically coupling the subcircuits, and    orienting the planes of the subcircuits within the aperture of the secondary coil substantially parallel to the lines of magnetic flux.    
     
     
         27 . The method of  claim 26 , further comprising placing the planes of the subcircuits in a substantially parallel stacked configuration.  
     
     
         28 . The method of  25 , further comprising encapsulating the secondary coil and the conditioning circuitry within a casing composed of biocompatible material.