Human bodies occasionally require a boost. Pacemakers are tiny devices that control the electrical impulses in the heart to maintain a regular heartbeat for millions of Americans. However, researchers hope to make these gadgets even more compact and unobtrusive to minimize difficulties.
University of Chicago materials researcher Pengju Li with a prototype device that can deliver a thin pacemaker membrane via minimally invasive surgery. Image Credit: Jean Lachat
A group of scientists from the University of Chicago have created a wireless, light-powered gadget that may be inserted into the body to control neurological or cardiovascular activity. With no moving parts and the ability to be placed with minimally invasive surgery, the featherlight membranes are thinner than human hair.
The research was published in the journal Nature. The findings may help lower the risks associated with cardiac surgery and open up new possibilities for medical technology.
The early experiments have been very successful, and we are really hopeful about the future for this translational technology.
Pengju Li, Study First Author and Graduate Student, Pritzker School of Molecular Engineering, University of Chicago
A New Frontier
For years, Professor Bozhi Tian's lab has been working on creating gadgets that excite the body using solar-cell-like technology. For this reason, photovoltaics are appealing since they lack moving parts and cables that could malfunction or become obtrusive, which is especially advantageous in sensitive tissues like the heart. To supply electricity, researchers merely implant a tiny optic wire next to it in place of a battery.
However, to achieve optimal outcomes, the scientists had to modify the system to function for biological reasons instead of following the conventional design of solar cells.
In a solar cell, you want to collect as much sunlight as possible and move that energy along the cell no matter what part of the panel is struck, but for this application, you want to be able to shine a light at a very localized area and activate only that one area.
Pengju Li, Study First Author and Graduate Student, Pritzker School of Molecular Engineering, University of Chicago
For instance, cardiac resynchronization treatment is a popular heart therapy in which the heart's many components are synchronized again by precisely timed electrical charges. Wires, which can have their own set of problems, are used in contemporary therapy to do that.
Li and the group set out to develop a photovoltaic substance that would only turn on in the precise spot where the light was shining on it.
In the end, they decided on a design with two layers of P-type silicon, which generates electrical charge in response to light. The top layer is recognized for its nanoporosity, which is a large number of microscopic pores that improve electrical performance by concentrating electricity while preventing it from spreading.
The end product is a thin, flexible membrane that may be surgically implanted into the body with a tiny tube and an optic fiber in a minimally invasive procedure. The membrane detects and converts the precise pattern of light from the optic fiber into electrical impulses.
The membrane is a few mm square and only a single µm thin, roughly 100 times thinner than the tiniest human hair. It is substantially lighter than the most recent generation of pacemakers, which weigh at least five grams, weighing less than one-fiftieth of a gram.
Li said, “The more lightweight a device is, the more comfortable it typically is for patients.”
The device is designed to be used temporarily in this specific version. Rather than requiring another intrusive surgical procedure, the pacemaker gradually dissolves into silicic acid, a non-toxic substance.
Nevertheless, based on how long cardiac stimulation is wanted, the devices might be designed to have varying desirable lifespans, according to the researchers.
This advancement is a game-changer in cardiac resynchronization therapy, and we are at the cusp of a new frontier where bioelectronics can seamlessly integrate with the body's natural functions.
Narutoshi Hibino, Study Co-Corresponding Author and Professor, Department of Surgery, University of Chicago Medicine
Light Use
Despite the fact that the initial experiments were carried out on cardiac tissue, the researchers stated that the method might also be applied to neuromodulation that is, activating nerves to cure chronic pain or other illnesses or to treat movement disorders like Parkinson's. Li gave the field its name, "photoelectroceuticals."
According to Tian, he still clearly remembers the day they used the pacemaker for the first time in testing using pig hearts, which are extremely similar to human hearts.
Tian said, “I remember that day because it worked in the very first trial, and it is both a miraculous achievement and a reward for our extensive efforts.”
Tian mentioned that a screening technique created by Li to map the photoelectrochemical output of several silicon-based materials can potentially be useful in other areas, like photovoltaic cells, catalysts, or new battery technologies.
To commercialize the gadget, the research team is presently collaborating with the University of Chicago Polsky Center for Entrepreneurship and Innovation.
Other authors from UChicago contributed to the paper are Jing Zhang, Hidenori Hayashi, Jiping Yue, Wen Li, Chuanwang Yang, Changxu Sun, Jiuyun Shi, and Judah Huberman-Shlaes.
The research was conducted in the Pritzker Nanofabrication Facility at the UChicago Pritzker School of Molecular Engineering and the Electron Microscopy Service of the University of Illinois Chicago Research Resources Center.
The research was funded by the National Institutes of Health, the US Air Force Office of Scientific Research, the National Science Foundation, US Army Research Office.
Journal Reference
Li, P. et al. (2024) Monolithic silicon for high spatiotemporal translational photostimulation. Nature. doi.org/10.1038/s41586-024-07016-9.