Research Highlight

Bad breath detector

doi:10.1038/nindia.2009.351 Published online 15 December 2009

Researchers have designed an easy-to-use sensor to detect mouth malodour in humans1. The sensor will be beneficial in analysing causes of and effective treatments for mouth odour.

The mouth harbours a thriving colony of bacteria that breaks down proteins into amino acids. Amino acids are further broken down to form foul gases such as hydrogen sulphide. Volatile sulphur compounds have been linked to oral malodour levels.

The researchers invented the sensor consisting of a sensing solution, a gas sampling unit for collecting a known volume of mouth air and a photometric detector. The sensing solution was iodine and the depletion of iodine on reaction with hydrogen sulphide was detected using starch.

The detection limit of the sensor is 0.05 microgram per litre of hydrogen sulphide, which is fit for oral malodour detection in healthy subjects as well as halitosis patients (who have bad mouth odour).

The sensor can be easily fabricated in the laboratory and has potential to be used as a clinical evaluation tool, the researchers say.


  1. Alagirisamy, N. et al. Novel Colorimetric Sensor for Oral Malodour. Anal. Chim. Acta. doi: 10.1016/j.aca.2009.11.064 (2009)