Electromagnetic coil configurations for power transmission through tissue

Abstract

Several embodiments of relatively compact transmitter coils and receiver coils having an improved transcutaneous power transfer efficiency. The transmitter coils are preferably applied to the outer surface of a cutaneous layer on a patient's body and held in place using adhesive tape or other appropriate supporting material. Implanted within the patient's body is a receiver coil. To improve the power transfer efficiency of one embodiment, a transmitter coil and receiver coil include cores having pole faces with a substantially larger area than the cross section of the core at other locations. In addition, the core of the receiver coil is substantially shorter than that of the transmitter coil so that the lines of flux produced by the transmitter coil tend to pass through the pole faces of the receiver coil in greater density than they would if the pole faces of the transmitter and receiver cores were spaced identically. Relatively compact configurations for the transmitter core include an angled portion adjacent each of the pole faces so that the main portion of the transmitter core is disposed generally parallel and closely spaced to the surface of the cutaneous layer against which the transmitter core is placed. Further, two separate transmitter windings are provided on the transmitter core with an intermediate section joining the portions of the core on which these windings are disposed. This configuration provides enhanced power transfer capability compared to using a single winding around the intermediate section of the core.