Wireless Electricity For Your Heart

by Jonah Shepp

Scientists gave a rabbit a tiny, wireless pacemaker:

A rabbit’s beating heart has been regulated using a tiny pacemaker that beams in energy from outside its body. It is the first time this kind of wireless energy transfer has been demonstrated in a living animal. If such wirelessly powered medical implants can work in people too, it would reduce the seriousness of the procedures required to get them fitted.

“Our device is small, so it will be much easier to deliver into the body,” says Ada Poon of Stanford University in California, who led the team that implanted the tiny pacemaker. Being fitted with a pacemaker currently requires surgery plus another operation when the battery eventually runs down. So Poon and her colleagues outfitted a rabbit with a pacemaker that has no battery and is just 3 millimetres long.

Olivia Solon explains how it works:

The system works on the principle that waves travel in different ways when they come into contact with different materials.

This is highlighted by the fact that you can hear the vibration of train wheels if you put your ear to the railway track much earlier than you would hear the train with your ears. It involves using a flat, credit card-sized power source positioned outside of the body over the device that can interact with the body’s tissue to induce propagating waves that converge on a micro-device implanted in the body.

The 2mm-long microdevice consists of a power harvesting coil, integrated circuits, electrodes and fixation structures. Such devices can be used as “electroceuticals” to strategically stimulate or silence nerves to treat a range of conditions including Parkinson’s, depression and chronic pain. The same devices could also be used to strategically deliver drugs or monitor vital functions deep inside the body. Power could either be delivered directly from outside of the body or the power could be sent to periodically recharge small, embedded batteries.

Cassandra Khaw looks at where this development could lead:

Poon believes that her work could lead to programmable microimplants like sensors that monitor vital functions, electrostimulators that alter neural signals in the brain, and drug delivery systems that apply medicine directly where needed. All without the bulk of batteries and recharging systems required today. Her endeavours could also help expedite the development of medical treatments that utilize electronics instead of drugs. Stanford Neurosciences Institute director William Newsome said that “the Poon lab has solved a significant piece of the puzzle for safely powering implantable microdevices.” So far, the wireless charging system has been tested in a pig and also used to power a pacemaker in a rabbit. The next step is human trials. Should those prove successful, it will likely take a few years before the system is authorized for commercial usage.