Medical device having capacitive coupling communication and energy harvesting

A wearable medical device in contact with a user's body for administering drug therapy to the user, the medical device comprising:

• a microcontroller electrically coupled to a pump mechanism, a transceiver and a power supply system, wherein:
• the microcontroller commands the pump mechanism to administer a drug to the user;
• the transceiver comprises a first electrode capacitively coupled to an outer surface of the user's skin and a second electrode coupled to a reference potential, wherein the impedance between the second electrode and the reference potential is higher than the impedance between the first electrode and the outer surface of the user's skin, and wherein the first electrode provides an oscillating potential to cause a displacement current in the user's body, and communicates with a host device on or near the user's body via a personal area network that transmits data across the user's body by modulating the displacement current, wherein said host device monitors or controls the medical device;
• and
• the power supply system selectively provides power to the microcontroller, pump mechanism and transceiver supplied from an energy harvesting component that harvests energy from the user's body.