Smelling out bacteria

British doctors are investigating the possibility of diagnosing certain illnesses by "smelling" the patient's breath using an electronic "nose". The ScanMaster is extremely sensitive and can detect the presence of the ulcer-forming bacteria Helicobacter pylori in the stomach.

The ScanMaster relies on vibrating quartz crystals coated with a thin film of fluorescent material. When this layer absorbs volatile compounds from the patient's breath, the vibration frequency changes, sniffing out even nanogram quantities. The input from each crystal is fed into the computer and combined to create a profile "smell".

Says John Slater of Birbeck College, University of London, who is also collaborating with the Middlesex Hospital to test ScanMaster, "This non-invasive technique will be very useful for screening patients with H pylori and diagnosing medical conditions such as kidney problems or diabetes.