A new color-changing syringe design could save millions of lives every year. In many cases, deaths or injuries resulting from the use of syringes are caused by poor sterilization.

In total, approximately 1.3 million people around the world die every year due to unsafe injections and the reuse of syringes. According to the World Health Organization, approximately two-fifths of all injections are administered with used needles that haven't been sterilized. This is estimated to cause 5% of HIV cases and 30% of hepatitis B/C cases.

At the University of Huddersfield, researchers developed a new type of "behavior-changing syringe" that could warn patients if a needle was unsafe.

"The difficulty for patients is that it is impossible to determine a visual difference between a used syringe that has been washed and a sterile syringe removed from its packaging," notes Dr. David Swann, a researcher who worked on the project. "Instigating a colour change would explicitly expose the risk and could indicate prior use without doubt."

To make the technology viable in developing nations, it was essential to keep the cost as low as possible. In part, researchers took inspiration from the food industry. By using inks that reacted in the presence of carbon dioxide, patients and physicians in developing countries can tell if a needle is used. Once a needle is removed from its nitrogen-filled packaging, the color of the syringe will change within one minute.

To reduce the risk of tampering, the piston of the syringe is designed to break if someone attempts to replace it. Researchers estimate that the syringe will cost only a little more than traditional disposable syringes.