In tests in animals, MIT researchers, working with scientists from Brigham and Women's Hospital, showed that the waves could power devices located 10 centimeters deep in tissue, from a distance of 1 meter, according to the study to be presented at the Association for Computing Machinery Special Interest Group on Data Communication conference in August.
The implants are powered by radio frequency waves, which can safely pass through human tissues. In this study, the researchers tested a prototype about the size of a grain of rice, but they anticipate that it could be made even smaller, because they do not require a battery.Medical devices that can be ingested or implanted in the body could offer doctors new ways to diagnose, monitor, and treat many diseases.
Traverso's lab is now working on a variety of ingestible systems that can be used to deliver drugs, monitor vital signs, and detect movement of the gastrointestinal tract. Implantable medical devices usually carry their own batteries, which occupy most of the space on the device and offer a limited lifespan.
Efforts to explore the wirelessly powering implantable devices with radio waves emitted by antennas outside the body have been difficult because radio waves tend to dissipate as they pass through the body.
The researchers devised a system that they call "In Vivo Networking," relying on an array of antennas that emit radio waves of slightly different frequencies.
As the radio waves travel, they overlap and combine in different ways. At certain points, where the high points of the waves overlap, they can provide enough energy to power an implanted sensor.
With the new system, the researchers don't need to know the exact location of the sensors in the body, as the power is transmitted over a large area. It also means that they can power multiple devices at once.
When the sensors receive a burst of power, they also receive a signal telling them to relay information back to the antenna. This signal could also be used to stimulate release of a drug, a burst of electricity, or a pulse of light, according to the researchers.
In tests in pigs, the researchers showed they could send power from up to a meter outside the body, to a sensor that was 10 centimeters deep in the body. If the sensors are located very close to the skin's surface, they can be powered from up to 38 meters away.
This technology also has the potential to improve radio frequency identification devices applications in other areas such as inventory control, retail analytics, and "smart" environments, allowing for longer-distance object tracking and communication, according to the researchers.