In this blog post, we’ll explore the principles, current state of development, and various potential applications of the electronic nose—a biosensor that mimics the human sense of smell.
The Emergence of the Electronic Nose, Which Mimics the Human Sense of Smell
In today’s world, where cutting-edge control technologies are essential, the importance of sensors continues to grow across various fields, including industry, the environment, healthcare, and the home. Accordingly, research to develop more precise sensors is ongoing, and recently, alongside the miniaturization of sensors, the development of biosensors that mimic human sensory organs is actively underway. If machines could replicate human sensory functions, the potential applications would be vast.
The five senses, which allow us to interact with the world, are incredibly precious to humans. None of the five senses—sight, hearing, smell, taste, and touch—is unimportant, and the science and technology needed to replicate them have been steadily advancing. In particular, technologies that replicate sight, hearing, and touch are already commonplace around us. Cameras replicate sight, microphones and audio systems replicate hearing, and various touch sensors replicate touch—these are prime examples. In contrast, technologies that replicate smell and taste remain an area of active research.
Among these, the sense of smell—the ability to detect odors—has long been considered relatively less important. However, as the industrial value of the sense of smell has recently garnered significant attention, research on the “electronic nose”—a biosensor that mimics the olfactory process—is actively underway. What principles underlie the development of the electronic nose, a biosensor that detects odors?
How do humans distinguish between smells?
The electronic nose is a technology that mechanically replicates the human olfactory system. Therefore, to understand its principles, we must first examine how humans smell—that is, how the sense of smell works. The human olfactory system is broadly divided into two parts: the olfactory epithelium, located in the nasal cavity where odors are detected, and the olfactory bulb, which processes olfactory information in the brain.
The olfactory epithelium consists of supporting cells, basal cells, and olfactory neurons. When olfactory neurons recognize odor molecules—chemical substances—they are activated, generating electrical signals that are transmitted to the olfactory bulb. The olfactory epithelium contains a vast number of olfactory neurons, and various types of olfactory receptor proteins are distributed across the surface of each cell. Different olfactory receptors selectively respond to different chemical substances.
In other words, depending on which olfactory receptors are activated, we can distinguish between different odors and may even perceive certain odors more sensitively. Furthermore, the brain remembers the activation patterns of these receptors, so when the same odor is encountered again, it recalls the existing memory. Since the same odor produces the same activation patterns in the receptors and neurons, it is recognized as the same odor.
An electronic nose can be described as an electronic device that detects odors in place of humans. When an olfactory sensor detects a specific odor molecule, it converts that response into an electrical or chemical signal and analyzes it as a pattern to distinguish the odor. The patterned signal is processed by software that functions similarly to the human brain, enabling rapid analysis of the odor’s components and characteristics.
Electronic noses are expected to address the limitations of humans, who find it difficult to continuously distinguish various odors over long periods and have a limited range of detectable odors. In fact, research and practical applications of electronic noses are currently underway in various fields, including food quality control, environmental pollution monitoring, industrial process management, and medical diagnostics; they have moved beyond the stage of being merely “future technology” and are already in use in some sectors.
How are electronic noses being developed, and where are they being used?
To artificially replicate the human olfactory mechanism, a device capable of selectively capturing specific odor molecules is first required. To this end, research is underway to mass-produce olfactory receptor genes through cloning and express them as proteins to measure their responses to various odors. In addition, artificial olfactory receptors and highly sensitive signal transmission technologies are being developed to convert the measured responses into electrical signals and transmit them. Recently, the integration of signal analysis technologies utilizing nanomaterials and artificial intelligence (AI) has further improved the accuracy and usability of electronic noses, though research to perfectly replicate the human sense of smell is still ongoing.
As electronic noses capable of replacing human olfactory functions continue to advance, their range of applications is expected to expand significantly. Fundamentally, they can safely detect toxic gases, hazardous chemicals, and pollutants that are difficult for humans to smell directly, and they can also be used in quality control to verify food spoilage and freshness.
Furthermore, in industries where scent is crucial—such as perfumes, wine, and coffee—they can be used to analyze desired scents or maintain consistent quality. In the medical field, research is actively underway to diagnose diseases early by analyzing volatile organic compounds (VOCs) in patients’ breath, and their potential application as an auxiliary diagnostic tool for certain respiratory and metabolic diseases, as well as cancer, is being explored.
Beyond this, electronic nose technology can be utilized for detecting explosives and toxic substances, drug screening, industrial safety management, and environmental monitoring, as well as for developing assistive devices for people with olfactory impairments. If electronic noses—which can precisely distinguish odor molecules while remaining compact and portable—continue to advance, they will play a vital role in our daily lives and across all industries in the future.
