Improved transcutaneous signal coils for detecting two-dimensional dislocation

Transcutaneous power transmission coils continuously transmit electric power into implanted devices, such as FES (Functional Electrical Stimulation), implanted artificial hearts and so on. For a transcutaneous power-transmission system, a transcutaneous signal-transmission coil is required to monitor and control the implanted devises. However, in the event that transcutaneous power-transmission coils are dislocated, power-transmission decreases. It is therefore necessary to determine how they are dislocated for monitoring the state of power transmission. In this paper, the authors study a system to determine the dislocation of coils by measuring the current value of the signal coil outside the body. The dislocations and the shift direction of the coils can be evaluated within about /spl plusmn/15 [mm]. The authors can determine each dislocations of an X and Y direction independently by using a figure of coil.