According to the World Health Organization, more than half of patients don’t take their prescriptions correctly. The centerpiece of the Proteus system is a pill that doubles as a radio, creating a feedback loop that will help doctors track compliance. When the pill hits the stomach, a one-millimeter chip sends a binary signal to an adhesive abdominal patch. The patch relays that signal to a smartphone. The FDA approved a placebo-based version of the system this summer, and pharmaceutical companies could start using it in about two years.