A bioelectronic nose mimicking that of a human could be used to detect bacteria in water even in the tiniest concentrations, South Korean researchers have found.
The smelling device, based on a tiny sensor mimicking a human smell receptor, is very sensitive and capable to detect concentrations of just 10ng of bacteria per litre of water, which are effectively otherwise undetectable with existing techniques.
“Water that smells bad isn’t necessarily toxic,” said Professor Tai Hyun Park from Seoul National University, the lead author of the study. “Imagine you don’t do your laundry; it’s not that toxic but you don’t want to wear it because the smell is bad. With drinking water, if there’s off flavour, even if the water isn’t toxic, you don’t want to drink it.”
Conventional contamination-detection techniques rely on culturing methods when a sample of water is taken and bacteria cultivated in the laboratory. Alternatively, smell-based detection systems already exist, including bulky chromatographs or mass spectroscopes, which are not suitable for work in the field.
The human nose-inspired device, on the other hand, is compact and portable. It could be used to assess the quality of water in outdoor reservoirs, providing early detection of problems and control of disease spread.
The current version of the system focuses on detection of two specific molecules - geosmin and 2- methylisoborneol - which provide the typical earthy and musty odours caused by bacterial contamination.
Eventually, the researchers would like to make the artificial nose much more complex.
“Our eventual goal is to develop a real human nose-like bioelectronic nose,” said Professor Park. “In the human nose, there are about 400 different olfactory receptors. If we could develop our technology to include all of these, we would have a device that could smell anything we can, at lower concentrations.”
The technology could also be used in medicine to diagnose certain diseases, which are related to a particular smell, such as lung cancer. Furthermore, the researchers envision, it could be used for sampling perfume, cosmetics and wine, or for detection of drugs at airports.
Eventually, the team believes, the technology could give rise to a smell classification system.
“We don’t have a system for the classification of smell yet; it all still depends on our human sensory system,” Professor Park said. “With our bioelectronic device, we can systematically detect and label smells, perhaps coming up with a universal smell code we can use to communicate in the future.”