Over the past several years, we've heard about a number of swallowable electronic devices that perform functions such as transmitting video and measuring gases as they pass through the gastrointestinal tract. In the case of implants that are designed to stay in the tract for longer periods of time, however, battery life is a potential issue. Scientists at Brigham & Women's Hospital, MIT and The Charles Stark Draper Laboratory may have the solution, in the form of a system that allows power to be wirelessly transmitted to those devices, from outside the body.

There are already medical gadgets such as cochlear implants, which are wirelessly powered by an external source. These utilize a technique known as near-field coupling, which only works if the transmitter and receiver are quite close to one another. It's fine for implants which are located just under the skin, but not for small electronics that are deep within the digestive tract.

Instead, the scientists turned to a new technique called mid-field coupling. It operates at higher frequencies than near-field coupling, delivering power two to three times more efficiently.

In lab tests, an antenna located outside of a pig's body was used to transmit power to three other antennas located inside the animal's esophagus, stomach and colon – this was done using mid-field coupling. All three of the implanted antennas received enough power to run "a range of medical devices."

"Electronic devices that can be placed in the gastrointestinal tract for prolonged periods of time have the potential to transform how we evaluate and treat patients," says Dr. Carlo "Gio" Traverso, co-corresponding author of a paper on the research. "This work describes the first example of remote, wireless transfer of power to a system in the stomach in a large preclinical animal model – a critical step toward bringing these devices into the clinic."

The paper was recently published in the journal Scientific Reports.