US Patent 7425210 Drug delivery system for implantable medical device

A drug delivery system and method in which an implantable medical device communicates with and controls an external drug delivery device with low energy potential signals. The implantable device generates potential signals modulated with digitally encoded command information by operating a current source to cause corresponding electrical potentials that can be sensed at the skin surface by the external drug delivery device. The drug delivery device then demodulates the sensed potentials and decodes the digital data to extract command information therefrom to deliver a drug accordingly.