There are times when our bodies need… mechanical assistance to function properly. So millions of people around the world live “in company” with a pacemaker – a small device that regulates the heartbeat so that it “works around the clock”, while more and more patients with neurological and other diseases rely on a brain pacemaker to have a (as far as possible) normal everyday life.
“Light” mode
Although these types of devices offer a lot, researchers are looking for ways to make them smaller and less “intrusive” to reduce the risk of complications. And that’s exactly what researchers at the University of Chicago have done, according to their publication in the scientific journal “Nature” – they’ve created a wireless device that works with light and can be placed inside the body to regulate heart or nerve function.
Reducing complications for heart patients
The device’s lightweight membranes, much thinner than a human hair, can be inserted into the body in a minimally invasive procedure and have no moving parts. According to the scientists who created the new pacemaker… light, it can help reduce the complications that occur in heart patients and not only. “Our first experiments have been very successful, and we are really optimistic about the future of this technology,” said Pengju Li, a graduate student at the University of Chicago and first author of the study.
University of Chicago materials science researcher Pengju Li holds the prototype of the… luminous pacemaker which consists of a specially designed membrane and an optical fiber. The new pacemaker weighs just one fiftieth of a gram and is much smaller and lighter than current pacemakers. Credit: Jean Lachat
Technology similar to solar cells
Professor Bozi Tian’s lab where Mr. Li works has been developing devices that use technology similar to solar cells for use in the human body for years.
Photovoltaic systems are a highly attractive solution because they have no moving parts or wires that could break or even cause tissue damage – and so are particularly attractive for sensitive tissues such as the heart. At the same time, instead of being powered by a battery, the photovoltaic pacemakers are placed together with a tiny optical fiber that provides energy.
Targeted application
“In a solar cell the goal is to collect as much sunlight as possible and transfer all that energy across the cell regardless of which panel the sun is hitting. But to apply this philosophy to the body, the light must fall on a very specific area and activate only that area.”
That’s exactly what Lee and the rest of the team from the University of Chicago set out to achieve. They created a photovoltaic material that is activated only where the light hits it. This material consists of two layers of a type of silicon known as P-type, which responds to light by creating an electrical charge.
The invasive procedure is minimal
The top layer has many small holes which concentrate the electrical energy in one place and do not allow it to dissipate. The end result is a flexible, delicate membrane that can be inserted into the body through a cannula along with an optical fiber – a minimally invasive procedure.
The optical fiber is activated in a specific pattern which the membrane recognizes and converts into electrical pulses. The membrane is only one micrometer thick (that is, it is about 100 times thinner than… the thinnest human hair). It weighs less than a fiftieth of a gram – much less than the most advanced pacemakers which weigh at least five grams. “The lighter the device, the more convenient it is for patients,” Li noted.
No removal required
This version of the device is intended for temporary use. In fact, it is not necessary to remove the pacemaker after it stops working, but the device gradually dissolves and forms a non-toxic compound known as silicic acid.
However, the researchers said that such devices could be adjusted to have a longer lifespan, depending on the heart’s pacing needs.
Integration into the human body
“This development changes the field of cardiac resynchronization therapy,” said Dr Naruto Hibinoprofessor of surgery at the University of Chicago and lead author of the study, and added that “we are close to crossing a new frontier in which bioelectronic devices can be integrated into the body’s natural functions.”
Against Parkinson’s and chronic pain
Although the first experiments were carried out in heart tissue, the research team noted that this particular approach could also be applied to neuromodulation – in diseases such as Parkinson’s, but also for the treatment of chronic pain and other disorders. Lee even “christened” this new field “photoelectroceuticals”.
Lots of apps
Professor Tian stressed that he will never forget the day he tested the new pacemaker…light on experiments with pig hearts which have many similar characteristics to human hearts. “I remember that day because the device worked correctly from the first moment.” The professor concluded by saying that the new philosophy followed by his team could also be applied in other fields such as batteries, catalysts and photovoltaic systems.
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