A noninvasive electromagnetic conductivity sensor for biomedical applications

The authors present the theory and practice of using a simple coil sensor operated at high frequency (1-10 MHz) to measure changes in conductivity in a biological sample. Explicit results are obtained for symmetric configurations that are useful for calibrating the device and making order-of-magnitude estimates of the results of applying the technique to humans to monitor the onset and progress of brain edema. A simple model suggests that the technique may be able to successfully measure the onset of some medical complications using the technology described.