In this blog post, we explore the potential for e-nose technology to replace the human sense of smell and the revolutionary changes it could bring to healthcare, the environment, and food safety.
Technology that mimics the human senses is constantly evolving, but compared to other senses, the sense of smell has yet to be conquered. Recently, however, scientists are challenging the mysteries of the sense of smell by inventing a machine called the “electronic nose”.
In the 1980s, researchers discovered that when a gas molecule hits a sensor with an electric current, it changes the electrical resistance of the sensor, and that if this change in resistance is analyzed with the right software and converted to a point in coordinates, it can be used to obtain information about the gas molecule from its own database. This process is similar to what happens in the human nose, which led to the creation of the “e-nose” device.
But the human sense of smell is much more sophisticated than this. The olfactory epithelium in the lining of the nostrils is responsible for detecting odor molecules that flow in through the nostrils, and there are about 1,000 different odorant receptor proteins on the surface of olfactory epithelial cells that detect odor molecules. These receptors allow humans to distinguish between 10,000 different odors, but there are still only a dozen odorant receptor sensors in e-noses.
The first commercial e-nose was introduced in 1993, and it used a series of metal oxides as odor sensors. The electrical signals from six to 12 different sensors were processed into data and converted into a point in coordinates. Later, plastics were used as the material for the sensors, but the downside is that not many plastics conduct electricity, which limits the number of chemicals that can be detected. Recently, a team of researchers developed a new type of electronic nose. By mixing carbon particles with ordinary plastics as the sensing material, they were able to conduct electricity, which means that a variety of plastics can be used to create a sensor that can detect multiple chemicals.
Advancements in e-nose technology have led to a wide range of potential applications across a variety of fields, including healthcare, the environment, and food safety. For example, in the medical field, researchers are exploring how e-noses can be used to diagnose diseases in their early stages by analyzing volatile organic compounds in a patient’s breath. This has the advantage of being non-invasive and faster than traditional diagnostic methods. In the environmental field, e-noses can be used to detect harmful substances in the air and monitor pollution levels in real time. This technology could help prevent health effects from air pollution and contribute to more accurate environmental policy.
If e-noses were to become a reality, they would have many different uses. The human nose is very good, but it’s not always consistent, and it can’t quantitatively track how much an odor changes over time because it can’t quantify its intensity. However, there are many challenges that need to be addressed before e-noses can become a true “artificial nose” that can replace the human nose. Current e-noses often react to substances that humans can’t smell, while odors that are strong enough for humans to notice often go unnoticed. Furthermore, the sensitivity of the sensors is typically around 1 ppm (parts per million), which is far behind the human sense of smell. And only a few dozen of the sensors developed so far have practical applications. This is because to be a sensor, the binding to the volatile molecule must be transient, the sensor molecule must not deform, and the same molecule must give the same signal no matter when it is measured.
Ultimately, for e-nose technology to fully replace the sophistication of the human sense of smell, it is essential to develop more advanced sensor technology and sophisticated software algorithms, as well as to ensure stability in different environmental conditions and reliability in repeated measurements. If these challenges are met, e-noses will go beyond the human sense of smell and become a tool for detecting and analyzing environments and substances in a more precise and consistent manner. This has the potential to grow beyond the ability to simply smell and become a transformative technology that aids or extends human capabilities across industries.
