New E-nose can smell pesticides, nerve gas

Researchers have built a sensitive electronic nose that can detect pesticides and nerve gas in very low concentrations, an advance which may help screen someone's breath for lung cancer and multiple sclerosis (MS).
The best-known electronic nose is the breathalyser. As drivers breathe into the device, a chemical sensor measures the amount of alcohol in their breath, researchers said.
This chemical reaction is then converted into an electronic signal, allowing the police officer to read off the result, they said.
Alcohol is easy to detect, because the chemical reaction is specific and the concentration of the measured gas is fairly high.

But many other gases are complex mixtures of molecules in very low concentrations. Building electronic noses to detect them is thus quite a challenge.
Now, researchers from KU Leuven in Belgium have built a very sensitive electronic nose with metal-organic frameworks (MOFs).

"MOFs are like microscopic sponges. They can absorb quite a lot of gas into their minuscule pores," said Ivo Stassen from KU Leuven.
Researchers created a MOF that absorbs the phosphonates found in pesticides and nerve gases.
"This means you can use it to find traces of chemical weapons such as sarin or to identify the residue of pesticides on food. This MOF is the most sensitive gas sensor to date for these dangerous substances," said Stassen.

"The concentrations we are dealing with are extremely low: parts per billion - a drop of water in an Olympic swimming pool - and parts per trillion," he added.
The chemical sensor can easily be integrated into existing electronic devices, said Rob Ameloot from KU Leuven.
"You can apply the MOF as a thin film over the surface of, for instance, an electric circuit. Therefore, it is fairly easy to equip a smartphone with a gas sensor for pesticides and nerve gas," said Ameloot.
"MOFs can measure very low concentrations, so we could use them to screen someone's breath for diseases such as lung cancer and MS in an early stage. Or we could use the signature scent of a product to find out whether food has gone bad or to distinguish imitation wine from the original," he said.

The findings were published in the journal Chemical Science.