Tiny, Injectable Pacemaker Runs on Light and then Dissolves
This temporary pacemaker, smaller than a grain of rice, could regulate the heart less invasively
A pacemaker uses electricity to regulate heartbeats.
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Temporary pacemakers can be used as a stopgap measure to regulate the heartbeat after surgery and in emergency situations. But the fact that they need to be surgically installed and removed also brings risk: moon walker Neil Armstrong famously developed fatal bleeding when surgeons removed his temporary pacemaker’s wires in 2012. Now researchers have developed a tiny temporary pacemaker that could eliminate some of that risk. Their device, just a few millimeters long, has no wires and needs minimally invasive placement. It can be injected into the body with a needle. And when its work is done, it simply dissolves.
A temporary pacemaker like this one, smaller than a grain of rice, could be injected into the body to regulate heartbeats.
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The mini pacemaker device does not have a separate battery. Instead its body functions as a simple type of battery called a galvanic cell—the two electrodes, made of different combinations of magnesium, zinc and molybdenum, react with the naturally occurring electrolytes in bodily fluids to produce an electric current.
When the pacemaker’s job is done, it simply dissolves into the body. The device has a finite operating time of between a few days and about three weeks, Rogers says, depending on the choice of metals for the electrodes.
The current study is an advance on an earlier dissolvable pacemaker by the same team. The previous iteration used a technology called near-field communication instead of a galvanic cell; it ran on power beamed to an antenna, which made it much bigger. The extreme miniaturization is one of the advances in the new model, Rogers says. “What follows from that is that we can use multiple of these millimeter-scale pacemakers simultaneously at different locations of the heart [with the devices] operating in different wavelengths.”
The researchers are also looking at the possibility of integrating the devices with medical implants, such as replacement heart valves, that currently don’t have any kind of cardiac control mechanisms.
Thanh Nho Do, a biomedical engineer at the University of New South Wales in Australia, who wasn’t involved with the study, calls this pacemaker a breakthrough in miniaturization. It gives reliable and sustained pacing without external energy inputs, he says, and could significantly reduce procedural risks and patient discomfort.
Virginia Tech researcher Xiaoting Jia, who was also not involved in the project, says it has great potential for practical use in humans. “The team has performed comprehensive tests in animal models and in ex vivo settings [experiments outside the body]. The next important step would be to thoroughly evaluate the safety for application in humans and obtain [Food and Drug Administration] approvals for clinical use.” The researchers are working toward this via a new start-up company.
One key challenge, Do adds, is selecting suitable materials to balance functionality and safe degradation without triggering excessive immune reactions such as inflammation.
Source: www.scientificamerican.com