If we could predict what harmonics each tissue needed at a given time, we could design devices that would provide more consistent results in pain management, healing and regulating biological processes. The body accepts frequencies and pulse repetition rates in a non-linear, differential manner. For example, low frequencies penetrate greater depths of tissue than high frequencies. This eddy current produces a back electromotive force and blocks the penetration. The higher the frequency, the greater the rejection and shallower the penetration.
Complex frequencies interact in the body causing a non-linear spread of current.
A prime example of a non-linear electrical device is a diode. A diode conducts current of one polarity far greater than the opposite polarity. Most living tissue exhibits non-linear characteristics, functioning somewhat like diodes. Our present knowledge of electromedicine is not sufficient to determine the optimum frequency for a specific tissue response so the use of sine waves is not recommended. The length of time the pulse lasts is called the width.