MIT researchers have developed a new way to power and communicate with medical devices implanted deep within the human body.
In use, the devices could deliver drugs, monitor conditions inside the body, or treat disease by stimulating the brain with electricity or light. The implants are powered by radio frequency waves and in animal tests the researchers showed that the waves can power devices located 10cm deep in tissue from a distance of 1m.
“This opens up entirely new types of medical applications,” said Fadel Adib, an assistant professor in MIT’s Media Lab and a senior author of a paper describing the research, which will be presented at the Association for Computing Machinery Special Interest Group on Data Communication (SIGCOMM) conference in August 2018.
In their study, the researchers tested a prototype about the size of a grain of rice, but they anticipate that it could be made smaller.
“Having the capacity to communicate with these systems without the need for a battery would be a significant advance. These devices could be compatible with sensing conditions as well as aiding in the delivery of a drug,” said Giovanni Traverso, an assistant professor at Brigham and Women’s Hospital (BWH), Harvard Medical School, a research affiliate at MIT’s Koch Institute for Integrative Cancer Research, and an author of the paper.
Medical devices that can be ingested or implanted in the body could offer doctors new ways to diagnose, monitor, and treat 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 GI tract.
In the brain, implantable electrodes that deliver an electrical current are used for deep brain stimulation, which is often used to treat Parkinson’s disease or epilepsy. These electrodes are now controlled by a pacemaker-like device implanted under the skin, which could be eliminated if wireless power is used. Wireless brain implants could also help deliver light to stimulate or inhibit neuron activity through optogenetics.
Implantable medical devices are currently equipped with batteries that occupy most of the space on the device and offer a limited lifespan. Adib has been exploring the possibility of wirelessly powering implantable devices with radio waves emitted by antennas outside the body.
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Until now, this has been difficult to achieve because radio waves tend to dissipate as they pass through the body. To overcome that, the researchers devised In Vivo Networking (IVN), a system that relies 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. This also means that they can power multiple devices simultaneously. At the same time that 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, the researchers said.
The MIT team worked with scientists from Brigham and Women’s Hospital on the project. Additional authors of the paper titled: ‘Enabling Deep-Tissue Networking for Miniature Medical Devices’ are Media Lab postdoc Yunfei Ma, Media Lab graduate student Zhihong Luo, Koch Institute and BWH affiliate postdoc Christoph Steiger.