What is an Electronic Nose?

Alexander Graham Bell once said- “Did you ever measure a smell? Can you tell whether one smell is just twice strong as another? Can you measure the difference between two kinds of smell and another? It is very obvious that we have very many different kinds of smells, all the way from the odour of violets and roses up to asafetida. But until you can measure their likeness and differences, you can have no science of odour. If you are ambitious to find a new science, measure a smell.” An electric nose is a device which has the capability of detecting, identifying and discriminating the presence of molecules in a sample of air. It was termed by Gardner and Barlett in 1994. The improvements over the past 20 years have led to the creation of the artificial olfaction technology.

Electronic noses are based on the mammalian olfactory model. The olfactory receptors that are responsible for detection of odorants in the human body are analogous to the array of electronic sensors in the electronic nose. Biomimetics is a field in which the principles of biology, chemistry and engineering are applied to develop an artificial system that is based on a natural phenomenon. Electronic nose is one example of it.

The electronic nose comprises of three components- a detecting system, computing system and sample delivery system. The delivery system collects the required sample, which is then sent to the detection system. The detection system is a group of sensors, which change their electrical characteristics on coming in contact with the volatile compounds. Scientists were successful in creating a global fingerprint for every unique smell and flavor. The computing system has an Artificial Neural Network. This ANN is trained with qualified samples taken from a reference database. The instrument then recognizes new samples by comparing them with the existing fingerprints from the database. With the help of this architecture, the electronic nose simulates the mammalian olfactory system.This has however proven to be inaccurate in some cases of odors, where it may be made up of multiple different molecules. The electronic nose interprets these different molecules as different compounds, thereby posing inaccurate results.
Current research aims to increase the accuracy, reliability and efficiency of the electric nose. With the emergence of this out-of-the-world technology, applications are endless. Detecting contamination, spoilage or adulteration of materials is a major use case. Electronic noses have been used for quality control applications in food, beverage, cosmetic and perfumery industries. They are used to identify volatile organic compounds in air,water and soil samples for conducting agricultural analysis. Currently, they are being developed for conducting medical diagnosis, where the patient’s breath is analysed to detect the presence of certain chemicals responsible for a disease. A person’s breath contains 2,500 chemical compounds. If a person is ill, his breath, when analysed can indicate the kind of disease he has. Tuberculosis is proven to be detected in this manner. Furthermore, research is being carried out to use this technique for detecting volatile organic compounds emitted by different types of cancerous cells. NASA has developed its own e-nose model that is able to sniff out cancerous Brain cells. Thus, electronic nose facilitates in detecting cancer in a non-invasive, rapid and reliable manner.

The scope of this technology has just scratched the surface. In a few years, this technology may even get embedded in smart phones. The Google Nose prank that the company played on us on April Fools’ day, might turn into reality. Who knows what technology has for us in the future; someday, people would be able to smell things just by searching them on Google!

Chaitanya Rahalkar
Graduate Student

Masters in Cybersecurity student at Georgia Tech.