Since the circuit is cast in a plastic shell that keeps it from reacting chemically with the body, approval from the U.S. Food and Drug Administration was a breeze. John Glenn used the same pill sensor system in his latest space flight. Then pour some piping hot coffee into her and watch the graph go up. Then some ice cold beer. This cycling is much like what one observes in marathoners.
Body temperature goes up for the first few kilometers.
MIT student Maria Redin gave the technology a romantic twist. The rubies glow with every heartbeat. A transmitter carried in a clutch purse or built into an Armani eyeglass case sends the signal to the Net. Often it is worn near the heart. So it is well situated to monitor vital signs.