A Brigham and Women’s Hospital (BWH) led team has developed a simple “coat of armor” to encase small batteries, making them harmless if they are swallowed. Children, mainly infants and young toddlers, can ingest small batteries, leading to serious damage to their esophagus as well as other stomach tissue, sometimes even leading to death.
These incidents are on the rise. However, up until now, there haven’t been any solutions that were directed to the batteries themselves. The new work, published online November 3, 2014 in the Proceedings of the National Academy of Sciences, offers a simple, cost-effective solution, that, if implemented, could dramatically reduce if not eliminate, this unfortunate problem.
“To date, there has been no innovation to address this issue with small batteries,” says Jeff Karp, PhD, BWH Division of Biomedical Engineering in the Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute. “To address this challenge we sought to develop something that would render the battery inert, specifically when it was outside of a device.”
Roughly 5 billion “button” batteries are produced, each year, worldwide. These small, disc shaped batteries, power everything from children’s toys, hearing aids and laser pointers to remote controls and musical greeting cards.
While recent legislation requires battery compartments in children’s toys to be secured with screws, many items commonly used by adults contain these batteries in easily accessible formats and their packaging provides no protection.
With the increase of these devices, and the constant demand for more powerful batteries to power them, the problem of accidental ingestion is increasing. In 2013, there were more than 3,000 reported cases of accidental battery ingestion, the majority in children under the age of 6.
“Ingested disc batteries require emergent removal from the esophagus,” says co-first study author Giovanni Traverso, MB, BCh, PhD, a gastroenterologist at Massachusetts General Hospital and a researcher at MIT. “The swallowing of these batteries is a gastrointestinal emergency given that tissue damage starts as soon as the battery is in contact with the tissue, generating an electric current and leading to a chemical burn.”
Together with first author Bryan Laulicht, PhD, a postdoctoral fellow in Karp’s lab, Karp noticed that when a battery sits within a device, there is gentle pressure applied to it. However, when it is outside the device, this force doesn’t exist.
“We set out to create a specialized coating that could switch from an insulator to a conductor when subjected to pressure,” said Co-author Robert Langer, Institute Professor from the Harvard-MIT Division of Health Sciences and Technology.
The scientists discovered this unique substance in an unlikely place, touch screens. Using an off-the-shelf material known as a quantum tunneling composite, they identified a nanoparticle-based coating that, when subjected to pressure, allows an electrical current to pass through. In contrast, it allows no current to run in the absence of such pressure.
The scientists used this material to coat one side of the batteries, covering the negative ends (anodes). To determine the coating’s effectiveness, they teamed up with Traverso, exposing coated and uncoated batteries to gut tissue both in a laboratory dish and in living animals. In all cases, the coated batteries didn’t cause any damage.
In addition to reducing injuries, the coating is likely to be inexpensive. “The ultimate cost will depend on the exact composition of the material that is used, but for our current formulation, we’re talking cents, not dollars,” says Laulicht, first author of the paper.