In future, an 'electronic nose' will help to distinguish between certain plants. This could, for example, expose counterfeits of expensive tea varieties, said Christof Wöll from the Institute of Functional Interfaces at the Karlsruhe Institute of Technology (KIT). An attachment for smartphones is also conceivable, so that you have the right nose with you when searching for plants in nature. "The cell phone then serves as a data center." The researchers cite medical diagnostics and quality control in the pharmaceutical industry as other possible applications.

Possible area of application: quality assurance

Fragrances are to be deposited on the surface of twelve special sensors, each consisting of two electrodes with a quartz crystal. This changes their so-called resonance frequency; a kind of fingerprint of the respective fragrance is created from the data. The materials for the sensors were reportedly developed at the KIT, among others, and are highly porous so that they can absorb many molecules like a sponge. A combination of different materials forms a kind of neuronal network.

In comparison, the human nose has around 350 different receptor types, said Professor Wöll. This would theoretically allow us to distinguish between around 100,000 different odors. Dogs are able to do this with around one million odors, said the physicist. "Our goal is to beat humans and get to the dog."

Recognizing scents with machine learning

The scientists trained the 'electronic nose' using machine learning methods and six different types of mint, including classic peppermint, horse mint and catnip. The next step could perhaps be training with truffles, said Wöll.

According to him, the developers are currently thinking about founding a company to develop specific devices for the application. Engineers are also needed here. Ultimately, the planned additions for cell phones can be produced for just a few euros - and are therefore significantly cheaper and more portable than large systems for mass spectrometry, for example.

Electronic noses' have been built for decades and used in food production and industry, among other things. KIT has also been working for some time on making such odor sensors suitable for mass production and everyday use.