In the brain, implantable electrodes that deliver an electrical current are used for a technique known as 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, which so far has not been adapted for use in humans but could be useful for treating many neurological disorders.
Currently, implantable medical devices such as pacemakers carry their own batteries, which occupy most of the space on the device and offer a limited lifespan. The possibility of wirelessly powering implantable devices with radio waves emitted by antennas outside the body has been explored but until now, this has been difficult to achieve because radio waves tend to dissipate as they pass through the body, so they end up being too weak to supply enough power.
To overcome that, In Vivo Networking (IVN) was developed 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.
The new way to power and communicate with devices implanted deep within the human body could be used to deliver drugs, monitor conditions inside the body, or treat disease by stimulating the brain with electricity or light. The implants can power devices located 10 centimeters deep in tissue, from a distance of 1 meter.
Because they do not require a battery, the devices can be tiny. In this study, a prototype about the size of a grain of rice was tested but it could be made even smaller. Medical devices that can be ingested or implanted in the body could offer doctors new ways to diagnose, monitor, and treat many diseases.
With the new system, the exact location of the sensors in the body does not need to be known, as the power is transmitted over a large area. This also means that multiple devices may be powered at once.
At the same time the sensors receive a burst of power, they also receive a signal telling them to relay information back to the antenna. This signal could be used to stimulate release of a drug, a burst of electricity, or a pulse of light.
The researchers are now working on making the power delivery more efficient and transferring it over greater distances. This technology also has the potential to improve RFID applications in other areas such as inventory control, retail analytics, and “smart” environments, allowing for longer-distance object tracking and communication.