New Hydrogen Sulfide Sensor to Detect Bad Breath

Most people wish they could do a quick “breath check” prior to a crucial meeting or date. Scientists have now developed a sensor capable of detecting tiny quantities of hydrogen sulfide gas, the compound behind bad breath, in human exhalations. Details of the research have been published in ACS’ journal Analytical Chemistry.

According to the American Dental Association, 50% of all adults have suffered from bad breath, or halitosis, at one time or the other in their lives. Although in a majority of cases bad breath is just an annoyance, it can occasionally be a symptom of more serious medical and dental problems. However, many people are not conscious that their breath is foul unless somebody informs them, and doctors do not possess a simple, objective test for detecting halitosis. The currently available hydrogen sulfide sensors require precise calibration or a power source, or they show a slow response or low sensitivity. Il-Doo Kim and coworkers were keen on developing a sensitive, portable detector for halitosis that doctors could use to rapidly and economically diagnose the condition.

To build their sensor, the team utilized lead(II) acetate—a chemical that changes to brown when exposed to hydrogen sulfide gas. By itself, the chemical is not adequately sensitive to detect trace quantities (2 ppm or less) of hydrogen sulfide in human breath. So the scientists fastened lead acetate to a 3D nanofiber web, providing many sites for lead acetate and hydrogen sulfide gas to react. By observing a color change from white to brown on the sensor surface, the scientists could observe as little as 400 ppb hydrogen sulfide with the naked eye in just one minute. Furthermore, the color-changing sensor was able to detect traces of hydrogen sulfide added to breath samples from ten healthy volunteers.

The researchers received funding from the National Research Foundation of Korea.