Daijiworld Media Network - Mumbai

Mumbai, Jan 16: Researchers have successfully tested a proof-of-concept device that allows people who have lost their sense of smell to detect certain odours by stimulating an alternative nerve pathway in the nose, offering a potential new aid for those suffering from long-term anosmia.

Instead of using the traditional olfactory pathway—where nasal cells transmit signals through olfactory nerves to the brain—the technology taps into the trigeminal nerve. This lesser-known nerve pathway is responsible for sensing sensations such as the sharpness of wasabi, the coolness of mint, and irritation in the nasal cavity.

The findings, published in Science Advances, have drawn cautious interest from experts. “This is not recovering a sense of smell, this is activating a different system,” said Zara Patel, a rhinologist at Stanford Medicine, who was not involved in the study. She noted that while the approach is innovative, its real-world benefit for people with smell loss remains to be seen.

Humans possess around 400 olfactory receptors that together allow the detection of billions of odours. However, head injuries, viral infections such as Covid-19, and other conditions can lead to partial or complete loss of smell. Researchers point out that long-term anosmia significantly affects quality of life and is linked to higher risks of mental health issues.

“The idea that losing the sense of smell is less serious than losing another sense is actually quite wrong,” said Halina Stanley, a research scientist at France’s CNRS and co-author of the study.

While earlier research has explored direct stimulation of the olfactory bulb—similar in concept to cochlear implants—such methods are invasive and far from clinical use. The current study instead focuses on a non-invasive alternative.

The research team designed a system using a chemical odour sensor that detects specific smells and converts them into unique electrical signal patterns, comparable to a “nasal Morse code.” These signals are then delivered through electrodes clipped inside the nose.

In early trials involving nine participants—five with normal smell and four with olfactory disorders—all reported feeling the electrical stimulation, though some described it as mildly unpleasant. Participants were also tested on their ability to distinguish between different odours encoded as varying electrical pulse patterns. While they could not identify the smells themselves, some were able to reliably differentiate between them, especially after the task was simplified.

Researchers believe that with training, users could learn to associate specific electrical patterns with real-world scents. Experts suggest that a miniaturised version of the device could one day help anosmic individuals detect critical hazard-related odours such as gas leaks.

However, scientists caution that the technology cannot replicate the full richness of human smell or evoke the emotional and memory-related responses linked to it. Significant challenges also remain in developing fast, accurate, and versatile odour sensors.

Despite these limitations, researchers say they are continuing work to improve digital smell encoding and make the stimulation more comfortable, viewing the technology as a potential assistive tool rather than a full replacement for the sense of smell.