Although there already are devices that allow you to objectively check if you've got bad breath (aka halitosis), they typically require a power source and an involved calibration process, plus they often aren't very sensitive or quick to respond. A newly-developed sensor, however, could change that.

Developed by scientists from KAIST (Korea Advanced Institute of Science and Technology) and MIT, the sensor incorporates a chemical known as lead(II) acetate. It turns brown when exposed to hydrogen sulfide gas, which is the key ingredient in bad breath.

Because lead(II) acetate isn't sensitive enough on its own for use in the sensor, the researchers "anchored" fine droplets of the chemical to a three-dimensional nanofiber web composed of polyacrylonitrile polymer. This setup greatly increased the number of sites available for the chemical to interact with the gas. As a result, the sensor was able to detect trace amounts hydrogen sulfide gas in exhaled breath, reacting to concentrations as low as 400 parts per billion (one part per million is considered the minimum for a useful reading).

It indicated the presence of the gas by turning from white to brown, in a process that took only a minute and was visible to the naked eye.

The detection of bad breath is important not only from a social aspect, but also because it can indicate underlying health problems. It is hoped that once developed commercially, the sensor could allow doctors to quickly and definitively diagnose halitosis, using an inexpensive portable device.

A paper on the research, which was led by KAIST's Il-Doo Kim, was recently published in the journal Analytical Chemistry.