News Feature | May 22, 2014

New Wireless Technique Safely Transmits Energy To Implants

By Joel Lindsey


A team of researchers at Stanford University has devised a way to wirelessly transmit energy to medical devices implanted deep inside a human body — a development that could make possible a host of new electrical treatments.

“With this method, we can safely transmit power to tiny implants in organs like the heart or brain, well beyond the range of current near-field systems,” John Ho, a member of the research team, said in a press release published recently on Stanford’s website.

This new method of energy transfer revolves around the use of what lead researcher Ada Poon, assistant professor of electrical engineering at Stanford, calls “mid-field wireless transfer.” This technique combines elements of far-field electromagnetic waves and near-field electromagnetic waves.

Far-field waves travel long distances but are either reflected off of or absorbed into human skin and tissue. Near-field waves are already used in various types of wireless power systems, but are limited in effectiveness since they can only travel very short distances.

According to Stanford’s press release, Poon’s technique “blend[s] the safety of near-field waves with the reach of far-field waves” by using a power source designed to generate a very specific type of electromagnetic wave — one that changes characteristics as it interacts with different substances. More specifically, Poon’s mid-field waves propagate when they interact with human tissue, allowing them to move effectively and deeply into the interior of a human body.

Many researchers, both those working in Poon’s lab and elsewhere, believe that this development could significantly impact the growing field of electronic microimplants and could potentially make possible new modes of electronic treatment, deemed “electroceuticals.”

“To make electroceuticals practical, devices must be miniaturized, and ways must be found to power them wirelessly, deep in the brain, many centimeters from the surface,” said William Newsome, director of the Stanford Neurosciences Institute. “The Poon lab has solved a significant piece of the puzzle for safely powering implantable microdevices, paving the way for new innovation in this field.”  

Increasingly, and as reported in a recent article from Med Device Online, researchers are exploring ways to use electrical signals, currents, and pulses for specific medical treatments. As they do, finding ways of powering these devices becomes a pressing demand.

“Such treatments could be more effective than drugs for some disorders because electroceutical approaches would use implantable devices to directly modulate activity in specific brain circuits,” Newsome said. “Drugs, by comparison, act globally throughout the brain.”

Poon’s findings were published recently in the Proceedings of the National Academy of Sciences. So far, she and the rest of her research team have used their power-generating device to run tiny pacemakers — smaller than a grain of rice — in a pig and a rabbit. They hope to move toward conducting human tests soon.

Image Credit: Austin Yee