Sometimes our bodies need a boost. Millions of Americans rely on pacemakers — small devices that regulate the heart’s electrical impulses to keep it beating smoothly. But to reduce complications, researchers would like to make these devices even smaller and less intrusive.

A team of researchers at the University of Chicago has developed a light-powered wireless device that can be implanted in the body to regulate cardiovascular or neurological activity. Thin feather membranes made from human hair can be inserted with minimally invasive surgery and have no moving parts.

Published on February 21. nature, The findings may help reduce complications in heart surgery and offer new horizons for future devices.

“The initial experiments have been very successful, and we are really optimistic about the future of this translation technology,” said Pengju Li, a graduate student at the University of Chicago and first author of the paper.

‘A New Frontier’

Professor Buzi Tian’s lab has been developing devices for years that can use technologies like solar cells to stimulate the body. Photovoltaics are attractive for this purpose because they have no moving parts or wires that can break or interfere — especially useful in delicate tissues like the heart. And instead of a battery, the researchers attached a tiny optic fiber to provide the power.

But for the best results, the scientists had to adapt the system to work for biological purposes, rather than how solar cells are typically designed.

“In a solar cell, you want to collect as much sunlight as possible and transfer that energy along the cell, no matter which part of the panel is hit,” Lee explained. of “But for this application, you want to illuminate a very localized area and activate only one area.”

For example, a common heart therapy is known as cardiac resynchronization therapy, where different parts of the heart are brought back into sync with the charges at the right time. In current treatments, this is achieved with wires, which can have its own complications.

Li and team set out to create a photovoltaic material that would only activate where light hits it.

The final design they settled on has two layers of silicon material known as P-type, which respond to light by creating an electrical charge. The top layer has many tiny holes — a condition known as nanoporosity — which increases electrical efficiency and concentrates electricity without allowing it to diffuse.

The result is a small, flexible membrane, which can be inserted into the body through a small tube with an optic fiber — a minimally invasive surgery. The optic fiber is illuminated in a precise pattern, which is picked up by the membrane and converted into electrical impulses.

The membrane is only one micrometer thin — about 100 times smaller than the finest human hair — and a few centimeters square. It weighs less than one-fiftieth of a gram. Significantly less than current state-of-the-art pacemakers, which weigh at least five grams. “The lighter a device is, generally the more comfortable it is for patients,” Lee said.

This particular version of the device is for temporary use. Instead of another invasive surgery to remove the pacemaker, it dissolves over time into a non-toxic compound called silicic acid. However, the researchers said the devices could be engineered to last for different desired ages, depending on how long the heart’s stimulation is desired.

“This development is a game changer in cardiac resynchronization therapy,” said Narutoshi Hibino, a professor of surgery at the University of Chicago Medicine and co-author of the study. “We are on the edge of a new frontier where bioelectronics can seamlessly integrate with the body’s natural functions.”

Light use

Although the first trials were done with heart tissue, the team said the approach could also be used for neuromodulation — for example, stimulating nerves in movement disorders like Parkinson’s, or treating chronic pain or other disorders. of the. Lee coined the term ‘photoelectrotherapeutics’ for the field.

Tian said the day he first tried the pacemaker with pig hearts, which are very similar to human hearts, is vivid in his memory. “I remember that day because he had already worked on the case,” he said. “This is a miraculous achievement and a reward for our extensive efforts.”

Tian pointed out that the screening method developed by Li is also used elsewhere to map the photoelectrochemical output of various silicon-based materials, such as in areas such as new battery technologies, catalysts, or photovoltaic cells. May be.