Public Release: 

Putting batteries in a kidsafe coat of armor

Researchers develop simple coating to protect against injuries and deaths stemming from accidental ingestion

Brigham and Women's Hospital

A Brigham and Women's Hospital (BWH) led team has developed a simple "coat of armor" to encase small batteries, rendering them harmless if they are ever swallowed. Children, particularly infants and young toddlers, can ingest these batteries, leading to serious damage to their esophagus as well as other gut tissue, and sometimes, death. Such incidents are on the rise, yet up until now, no solutions have been directed at the battery itself. The new work, published online November 3, 2014 in the Proceedings of the National Academy of Sciences, offers a simple, cost-effective fix 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."

Each year, roughly 5 billion "button" batteries are produced across the world. 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 proliferation of such gadgets, and the demand for ever-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 age 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."

Karp and his colleagues became aware of this issue in 2010, and decided to apply their collective expertise toward developing a novel solution. "This seemed like a tractable problem that we could make significant headway on in a short period of time, just based on our expertise in materials and devices," says Karp.

Karp, together with first author Bryan Laulicht, PhD, a postdoctoral fellow in Karp's lab, noticed that when a battery sits within a device, there is gentle pressure applied to it, yet when it is outside the device, such force does not 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.

They used this material to coat one side of the batteries -- covering the "minus" ends or the 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 caused no damage while the uncoated batteries, as expected, caused significant damage.

In addition to reducing injuries, this innovation is also likely to be quite cost-effective. "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.

Now, Karp and his colleagues are working to determine the best route toward manufacturing and scaling up to a sufficiently large number of batteries, and then working with battery manufacturers to get the coated batteries into the hands of consumers.

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This work was funded in by NIH grant DE013023 and 787 EB000244, NIH grant GM086433 and NIH grant T32 DK 7191-38 S1.

Brigham and Women's Hospital (BWH) is a 793-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare. BWH has more than 3.5 million annual patient visits, is the largest birthing center in Massachusetts and employs nearly 15,000 people. The Brigham's medical preeminence dates back to 1832, and today that rich history in clinical care is coupled with its national leadership in patient care, quality improvement and patient safety initiatives, and its dedication to research, innovation, community engagement and educating and training the next generation of health care professionals. Through investigation and discovery conducted at its Brigham Research Institute (BRI), BWH is an international leader in basic, clinical and translational research on human diseases, more than 1,000 physician-investigators and renowned biomedical scientists and faculty supported by nearly $650 million in funding. For the last 25 years, BWH ranked second in research funding from the National Institutes of Health (NIH) among independent hospitals. BWH continually pushes the boundaries of medicine, including building on its legacy in transplantation by performing a partial face transplant in 2009 and the nation's first full face transplant in 2011. BWH is also home to major landmark epidemiologic population studies, including the Nurses' and Physicians' Health Studies and the Women's Health Initiative. For more information, resources and to follow us on social media, please visit BWH's online newsroom.

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