MIT scientists, working with researchers from Brigham and Women’s Hospital, have developed a new system to power and communicate with devices implanted deep within the human body. Systems like this could be used for drug delivery, monitor conditions inside the body, or treat diseases by stimulating the brain with electricity or light.
One of the problems with electronic implantable devices is that they need to be powered by a battery or pass wires through the skin. None of these approaches is safe: wires limit where a device can move or be implanted, whereas batteries limit the size of the device and come with a limited lifespan.
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MIT researchers decided to address this issue by developing a way to wirelessly power an implantable device, using radiofrequency waves. This hasn’t been easy to achieve, because the waves tend to disappear during their travel through the body. However, by using an assortment of antennas that discharge radio waves at different frequencies, the scientists were able to make them combine and overlap so that they produce enough energy to power a device.
The implants, powered by radio frequency waves, can safely pass through human tissues. In tests in lab animals, the researchers showed that the waves can power devices located 10 centimeters deep in tissue, from a distance of 1 meter.
“Even though these tiny implantable devices have no batteries, we can now communicate with them from a distance outside the body. This opens up entirely new types of medical applications,” says senior author Fadel Adib, an assistant professor in MIT’s Media Lab.
Because they don’t require a battery, the devices can be very small. In the study, the scientists tested a prototype about the size of a grain of rice, but they expect that it could be made even tinier.
The system has numerous possibilities. This wireless power system could be very helpful for powering ingestible devices, such as smart drug delivery capsules and gastrointestinal sensors, to brain implants for deep brain stimulation or optogenetics.
“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,” says study author Giovanni Traverso, an assistant professor at Brigham and Women’s Hospital (BWH).
The team is currently working to expand the range of the system. So far, they have achieved wireless power up to 10 cm deep in the body from antennas up to 1 meter away, but if they can place the sensor just under the skin, the range will increase to 38 meters. “There’s currently a tradeoff between how deep you can go and how far you can go outside the body,” said Adib.
Other authors of the paper are Media Lab postdoc Yunfei Ma, Media Lab graduate student Zhihong Luo, and Koch Institute and BWH affiliate postdoc Christoph Steiger.
The findings will be presented at the Association for Computing Machinery Special Interest Group on Data Communication (SIGCOMM) conference in August.
