New batteries are safe for children to swallow

Scientists have developed a special coating for small batteries which can prevent against injuries and deaths stemming from accidental ingestion, especially by children.
A Brigham and Women's Hospital (BWH) led team has developed a simple "coat of armour" 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 oesophagus as well as other gut tissue, and sometimes, death, researchers said.
Such incidents are on the rise, yet up until now, no solutions have been directed at the battery itself.
The new work offers a simple, cost-effective fix that if implemented, could dramatically reduce if not eliminate, this problem.

"To date, there has been no innovation to address this issue with small batteries," said Jeff Karp, 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," said Karp.
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.
With the proliferation of such gadgets, and the demand for ever-powerful batteries to power them, the problem of accidental ingestion is increasing, researchers said.

"Ingested disc batteries require emergent removal from the oesophagus," said co-first study author Giovanni Traverso, a gastroenterologist at Massachusetts General Hospital and a researcher at Massachusetts Institute of Technology (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," said Traverso.
"We set out to create a specialised 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 tunnelling 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 research was published in the journal PNAS.