The breakthrough uses an electronic nose and nasal septum stimulation to create new sensory associations in people who have lost the ability to perceive fragrances. Details of a study published in Science Advances A recent scientific breakthrough offers new hope for those who have suffered loss of smell. A team of researchers, led by Halina B. Stanley and colleagues, has successfully tested a prototype device that allows people with anosmia — the total or partial loss of smell — to detect and distinguish odours again.
The discovery, published in the journal Science Advances, is based on a sensory substitution technique that teaches the brain to associate physical sensations in the nose with the presence of different odours. The importance of this development lies in the magnitude of the problem it addresses. Loss of smell affects about 20% of the world’s population and can be caused by infections, medications, or injuries. Until now, unlike hearing or vision, there were no devices or implants capable of restoring the sense of smell. The new device represents an important step towards a technological solution for millions of people living with this sensory impairment.
The study included 65 volunteers (13 with intact sense of smell and 52 with anosmia); all were able to perceive the presence of odours and most were able to distinguish between at least two different aromas, with no significant differences between those with normal sense of smell and those who had lost it. The prototype’s operation is based on a combination of technologies and neuroscientific principles. The system uses an electronic nose (e-nose) to capture odour molecules present in the environment. This chemical information is translated into a specific digital code, which is transmitted through a small electrical stimulator placed in the nasal septum.
This stimulator, in the form of a magnetic clip, activates the trigeminal nerve through electrical impulses. The trigeminal nerve, responsible for sensations such as temperature, touch and irritation in the nasal cavity, thus becomes the alternative channel for transmitting information about odours to the brain. The system uses an electronic nose to identify odour molecules and a magnetic clip that electrically stimulates the trigeminal nerve in the nasal cavity, allowing the brain to associate physical sensations with specific odours.
In practice, users of the device do not perceive odours in the conventional way. Instead, they experience unique physical sensations inside the nose, which the brain learns to associate with certain odours. In this way, the technology does not restore the original sense of smell, but teaches the brain to identify odours from new sensory signals. Test results show the device’s effectiveness across different user profiles. The study included 65 participants: 13 with normal sense of smell and 52 with smell loss. All were able to detect the presence of odour molecules, and most were able to distinguish between two different odours. In addition, the ability to detect and differentiate was similar in both healthy people and those with anosmia, confirming the reliability of the trigeminal nerve as an alternative route for the transmission of encoded olfactory signals.
The researchers plan to expand the range of odours recognisable by the device and miniaturise the system to make it practical and accessible, seeking to offer a functional alternative to millions of people affected by smell loss worldwide. The principle of sensory substitution that underpins this advance has already been applied in other fields, such as hearing and vision, through cochlear implants or visual prostheses. However, until now there has been no comparable solution for loss of smell.
The device takes advantage of the coexistence of two sensory systems in the nasal cavity: the olfactory system, responsible for detecting odours, and the trigeminal system, responsible for physical sensations. By using the trigeminal nerve to replace the function of the olfactory nerve, researchers are opening up a new path for sensory rehabilitation in people with anosmia.
The prototype is still in an experimental phase. The team’s next steps include expanding the range of odours and stimulation patterns that the device can encode, as well as miniaturising the system to make it easier to use on a daily basis. The goal is to transform the laboratory prototype into a portable and accessible device for those who need it. Although the technology does not allow for the recovery of the actual sense of smell, the researchers point out that it is the first genuine sensory replacement solution that may be available to patients in the future. This breakthrough opens up the possibility for millions of people with smell loss to once again distinguish and recognise odours, even if it is through new sensations learned by the brain.
Loss of smell may predict neurological disorders
Loss of smell can be associated with hundreds of diseases. A recent study identified 139 neurological, somatic, and congenital or hereditary conditions that may present this symptom. Several findings show that olfactory disorders usually appear in the early stages of diseases such as Parkinson’s and are also one of the first signs of Alzheimer’s, as the olfactory pathway is one of the first areas of the brain to be affected. In addition, it has been observed that changes in smell can precede episodes of depression, serious cardiac events, and multiple sclerosis, according to researchers.
Although there is strong evidence linking changes in smell to cognitive decline, it is still unclear whether one causes the other or whether both share mechanisms related to ageing or neurodegenerative processes. To investigate this relationship, scientists at Fudan University in China researched how olfactory dysfunction, cognitive decline in older adults, and the nasal microbiome are connected.
