There are machines that can identify images and now there machines that can differentiate smells. Researchers from the University of Manchester and the University of Bari have managed to combine proteins and transistors, imparting machines with capabilities nearly comparable with the human ability to smell.

In a study published in the journal Nature Communication, researchers showed how they were able to give machines the ability to detect chiral molecules or smells that mirror each other, like carvone molecules that either smell like caraway or spearmint. Their work will now pave the way for the next generation of biosensors which may be used for various industrial applications.

Odorant binding proteins are located in the nose's mucus membrane and are responsible for stimulating olfactory receptors which give people their perception of smell. The researchers were able to come up with a way to manufacture not just enough odorant binding proteins such that they can be used in biosensors but proteins that are sensitive enough as well to pinpoint different kinds of chemicals.

With odorant binding proteins integrated into a transistor, researchers were able to measure specific current changes corresponding to how the proteins react to odors. These reactions were recorded, translating in effect to how a machine would detect an odor, sending a message that will be decoded to identify the smell.

"It has been challenging to get machines to be able to differentiate between smells that are mirror images of each other," said Professor Krishna Persaud from the University of Manchester, the lead author for the study.

This has been the real obstacle to making machines that have the ability to smell just as well or even better than a human being, she added.

Persaud explained that it is through collaborating with researchers from the University of Bari which allowed for the integration of field effect transistors with odorant binding proteins that a platform for a new chemical sensor was made possible. Now that the first step has been made, the researchers are confident that more and better sensors will be developed, which will ultimately expand the number of ways biosensors with the ability to smell can be used for.

With further tweaking to increase sensitivity, biosensors may be able to smell accurately when food has gone bad or detect just how much pollution is in the air.

The study received funding support from the Italian Ministry of Education, Universities and Research. Other authors include: Luisa Torsi, Mohammad Yusuf Mulla, Gerardo Palazzo, Elena Tuccori, Gianluca Lattanzi and Maria Magliulo.