Imagine being able to instruct a machine to perform a simple button-press to “smell” something for you. E-noses, sometimes known as electronic noses, are used for this. To replicate the sense of smell, these devices incorporate chemical gas sensors, signal processing, and machine learning algorithms. E-noses can be employed for a variety of tasks, including inspecting the quality of food, keeping track of air pollution, diagnosing illnesses, and spotting explosives. How do they function? What opportunities and difficulties exist in this field?In a thorough examination of the techniques and algorithms created for e-noses, a team led by Jingdong Chen of Northwestern Polytechnical University in Xi’an, China, and Weiwei Wu of Xidian University in Xi’an, China, recently investigated these issues.