They’re called button cells, coin cells or watch batteries. By any name, these tiny, round batteries pose a choking danger to small kids. And if a child succeeds in swallowing a button cell, the battery may short-circuit in the moist esophageal environment, burning the tissue. A few thousand kids wind up in emergency rooms each year after swallowing a button battery.
But a team of Harvard and M.I.T. researchers that includes prolific inventor Robert Langer thinks they have a partial solution: a protective coating.
The scientists covered batteries with a material—technically a quantum-tunneling composite—in which microparticles of conductive metal are suspended in an insulating layer. Under most circumstances, including inside of a child, the layer is nonconductive.
But when the material is subjected to high pressure, the microparticles are squeezed close enough together to carry a current. One such pressurized environment is the typical battery compartment in a small device—you often have to force the battery into place. So the same battery that remains inert when swallowed works just fine when it’s jammed into its slot in a hearing aid.
The waterproof design would also protect batteries from corrosion in high humidity. The research is in the Proceedings of the National Academy of Sciences USA. [Bryan Laulicht et al, Simple battery armor to protect against gastrointestinal injury from accidental ingestion]
Tests with pigs found the coated batteries to be gentle on the porcine esophagus. Next step: figure out a way to keep kids from putting the batteries in their mouths in the first place. Can a quantum tunneling composite be made to taste terrible?
[The above text is a transcript of this podcast.]