Bashirullah says one big advantage of the smart pill is that it doesn't require an onboard battery. Instead, the pill's antenna picks up the transmitter's low frequency energy. The team has so far tested the smart pill in models that simulate the electrical properties of a human body. They were able to find a low frequency signal that elicited a response from the pill's antenna within a few milliseconds.

Maysam Ghovanloo, assistant professor of electrical and computer engineering at Georgia Institute of Technology, has designed a similar smart pill that contains a tiny magnet. A magnetic necklace worn by a patient creates a magnetic field only when it detects the magnetized pill in the digestive tract. And a company called Proteus Biomedical has designed a smart pill tagged with a chemical that reacts with stomach acid to produce an electrical signal that can be transmitted to an external receiver.

Ghovanloo says both these competing designs employ relatively passive external receivers. "The burden is on the pill to announce and identify itself," says Ghovanloo. In contrast, the University of Florida's design relies more on the external transmitter to send signals, searching for the presence of a pill.

"The question is, how much energy can you store in that wristwatch to be sufficient," says Ghovanloo. "If they resolve that issue, the advantage would be the simplicity and small size of the pill."

As a power solution, Bashirullah says the system could be paired with other technologies, such as automated reminders from cellphones that could momentarily turn on the external transmitter to search for the presence of a pill.

"It has to be integrated with other technologies," says Bashirullah. "There's certainly going to be power constraints, and that's something we're looking at now."