Video: Stanford University in California
Researchers have demonstrated a method of transferring wireless energy to a medical device implanted inside a living animal.
The new system, which uses the same amount of power as a cell phone to transmit energy to implanted chips roughly the size of a grain of rice, is the culmination of years of work by Ada Poon, assistant professor of electrical engineering at Stanford University in California. The project focused on eliminating the bulky batteries and recharging systems that prevent implantable medical devices from being more widely used.
“We need to make these devices as small as possible to more easily implant them deep in the body and create new ways to treat illness and alleviate pain,” said Poon.
“Our device is small, so it will be much easier to deliver into the body.”
The key to the project’s success was the development of a new type of a wireless power transfer system that combines certain characteristics of both near-field and far field waves. Far-field waves, like those broadcast from radio towers, are able to travel over long distances but reflect off or are absorbed by biological tissue. Near-field waves can be used safely in wireless power systems, but can only transfer power over short distances, limiting their usefulness further inside the human body.
However, the researchers found that combining the safety of near-field waves and the reach of far-field waves yielded a versatile system able to alter its wave characteristics as needed. According to Poon, the power source initially generates a special type of near-field wave which, upon moving from air to skin, changes its properties to continue propagation inside the body.
Poon believes the new system, in addition to powering pacemakers and other modern implantable medical devices, could lead to the evolution of programmable micro-implants, such as sensors designed to monitor vital functions inside the body, electrostimulators that change neural signals in the brain and drug delivery systems capable of applying medicine directly to an affected area.
An independent laboratory that tests cell phones has already verified the new system to be below the maximum human exposure levels, says Poon.
The researchers have thus far tested the wireless charging system in a pig and used it to power a pacemaker inside a rabbit. Preparations for testing the system on humans are currently being made, after which is could take several years to satisfy safety and efficacy requirements for use of the system in commercial medical devices.