Artificial intelligence (AI) is best known for its ability to see (as in driverless cars) and listen (as in Alexa and other home assistants). From now on, it may also smell. My colleagues and I are developing an AI system that can smell human breath and learn how to identify a range of illness-revealing substances that we might breathe out.
The sense of smell is used by animals and even plants to identify hundreds of different substances that float in the air. But compared to that of other animals, the human sense of smell is far less developed and certainly not used to carry out daily activities. For this reason, humans aren’t particularly aware of the richness of information that can be transmitted through the air, and can be perceived by a highly sensitive olfactory system. AI may be about to change that.
For a few decades, laboratories around the world have been able to use machines to detect very small amounts of substances in the air. Those machines, called gas-chromatography mass-spectrometers or GC-MS, can analyse the air to discover thousands of different molecules known as volatile organic compounds.
In the GC-MS machine, each compound in a sample of air is first separated and then smashed up into fragments, creating a distinctive fingerprint from which compounds can be recognised. The image below is a visualisation of a small part of the data from an analysis of a breath sample.
Each peak represents a fragment of a molecule. The particular patterns of such peaks reveal the presence of distinct substances. Often even the smallest peak can be crucial. Among the several hundred compounds present in the human breath, a few of them might reveal the presence of various cancers, even at early stages. Laboratories around the world are therefore experimenting with GC-MS as a non-invasive diagnostic tool to identify many illnesses, painlessly and in a timely manner.