Button batteries of all kinds often appear in our life. They bring convenience to life, but also bring hidden dangers to children's safety. Curious infants who find button batteries are likely to swallow them up. Compared with other foreign bodies, button batteries are more likely to cause serious esophageal (or other gastrointestinal mucosa) burns, and may even endanger life. Such accidents are not uncommon, and so far, there are no better preventive measures than to hide button batteries. Recently, a team of researchers from Bryant Women's Hospital offered a new solution to this problem. Their research results were published in the Proceedings of the National Academy of Sciences (PNAS) on November 3.

At present, about 5 billion button batteries are produced every year in the world. Although some children's toys are screwed to reinforce the back cover, a large number of button batteries in electrical appliances can be easily removed by children. According to CDC data, in 2010, 4,800 children went to the hospital emergency room for treatment because they swallowed button batteries by mistake, and the number of such accidents increased year by year [1].

"Batteries must be removed from the esophagus as soon as possible after the mistake occurs," said study co-author and gastroenterologist Giovanni Traverso. "Devoting batteries can cause acute damage to the digestive tract. When batteries contact tissues, they generate electric currents, and chemical burns occur very quickly." When swallowed incorrectly, button batteries can produce certain electrolysis effect on body fluids. Hydrogen and oxygen ions gather near the negative electrode of the batteries, and local pH rises. This is an important reason for mucosal damage caused by the batteries [2]. To solve this problem, the team put a layer of "safety armor" on button batteries, enabling them to automatically switch between "power supply" and "inert" states.

Kapp and his colleagues began to focus on the safety of button batteries in 2010 and began to seek solutions. "It doesn't seem difficult, as long as we use our expertise in materials and devices, we can make remarkable progress in a relatively short period of time." Karp said.

Researchers realized that when batteries are installed in equipment, they all have to bear a certain degree of pressure, and when they are removed, the pressure will disappear. Therefore, they use varistors to wrap the negative electrodes of batteries as "safety switches" of batteries. They use quantum tunneling composites, which are also used to make touch screens. When the pressure sensitive layer is added, the battery will only supply power when it is under pressure, and if the pressure disappears, it will automatically change to an insulating state to avoid the harm of electrolysis to the mucosa. In order to verify the effect of the safety coating, the researchers also used isolated gastrointestinal mucosa tissues and experimental animals to conduct comparative experiments. The results showed that untreated batteries caused significant damage to the mucosa, while those treated with pressure sensitive coatings reduced the damage to the tissues.

This coating technology can not only avoid accidental damage, but also is quite economical. "The final cost depends on the material, but according to our current formula, the cost will only increase by a few cents." That's what Bryan Laulicht, the first author of the paper, said.

Now, Kapp and his colleagues are continuing their research to determine the best way to mass-produce this safe button battery. They will also work with battery manufacturers to make this improved product eventually reach consumers'homes.