Special Coating to Make Batteries Child-Safe
Engineers from Boston in the US have managed to find a way of making batteries safe if they are accidentally swallowed – potentially saving the lives of thousands of children around the world.
The batteries in question are those small, round button-like ones that you might find in a watch, hearing aid, toy, or other small electronic device. They can easily be swallowed and thus result in injury, which can be fatal. In fact, in the US alone, there are more than 3,000 cases of these kinds of batteries being swallowed every year.
The injuries happen when the battery gets wet and an electrical current is released. The current breaks down the water, producing hydrogen ions which are corrosive to organic tissue.
But researchers from Brigham and Women’s Hospital, Massachusetts General Hospital (Harvard’s largest teaching hospital) and MIT have developed a special coating for button batteries. The team has described the process in PNAS.
To do this, they have made use of a property called quantum tunnelling, which is also used in touchpads and touchscreens. The team covered the negative terminal of a button battery with a layer of a material called QTC (quantum-tunnelling composite), which is mostly silicone laced with tiny particles of metal.
When the QTC is tightly squeezed – as it would be when the battery is safely tucked into its spring-loaded compartment – the metal particles are brought closer together. This allows electrons to “tunnel” between them (hence the name), and conduct electricity.
Ultimately, this means that the battery itself is only conducting electricity itself when it is under pressure along with the QTC. For the rest of the time, the battery is being insulated by the QTC coating, making it inactive. If the battery were to be swallowed, then no current would be conducted and no nasty side effects would occur.
To test out their method, the scientists stuck some QTC on the negative terminal of a button battery, with the edges of the battery covered in a sealant to make the whole thing waterproof.
When an untreated battery was placed in simulated stomach fluid for 24 hours, it short-circuited and leaked badly. But when the new battery was put to the same test, it remained completely intact. This means that if a battery coated with QTC was in the stomach of a person, it wouldn’t break down and would, therefore, be unable to cause any damage.
Brigham and Women’s Hospital’s Dr Jeff Karp is senior author of the paper. He said that the team wants to get their design out in the world as soon as possible and so have already filed a patent for it.
“We think this is a relatively simple solution. It should be easy to scale, won’t add significant cost, and can address one of the biggest problems associated with ingestion of these batteries,” Dr Karp explained. “We hope to work with battery manufacturers in the near future, to help prevent these injuries from happening.”