At the otolaryngology department at the Ohio State University, Kai Zhao is on a quest to solve smell loss. While cochlear implants or hearing aids can be used to treat auditory impairments and lenses or surgery can tackle vision loss, there is no equivalent go-to treatment for a weakened sense of smell.
Among all the senses, smell is perhaps the least well understood. Scientists are only just beginning to get to grips with how smell is organized in the brain and body. And exactly why and how some people lose their sense of smell is unclear at best.
“Smell loss is a really underrecognized problem and medical condition, and currently there [is] no treatment at all,” Zhao says. Some researchers have experimented with bionic noses and implants that pulse electrical signals into the olfactory system to try and restore smell. But Zhao is trying a different method: wearable devices that help redirect airflow in the nose to the olfactory region.
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Only a fraction of the air we breathe in through our noses reaches the olfactory cleft—that’s the place inside our noses where the olfactory bulb, a structure in the forebrain that processes smell signals, resides. Zhao theorized that perhaps it would be possible to increase the airflow to the olfactory system. He likens the idea to hearing aids, which amplify sound signals in the ears. “You’re amplifying the smell signal instead of the sound,” he says.
In March 2025 Zhao and his colleagues published the results of their first prototypes in BMC Medicine. They developed a nasal foam plug and a clip similar to those used by synchronized swimmers. Both work to enhance the odor delivery to the olfactory region. The plug helps open the odor flow to the nose. Meanwhile, according to Zhao, the clip is a bit more counterintuitive: it pinches the nasal valve to enhance narrowing, which can improve function.
A person testing the nasal smell aids.
Wexner Medical Center Media Relations
Since then the team has been working on the prototypes, using 3D printing to enhance the aids to further restore patients’ sense of smell. The researchers presented their latest results in April2026. Jeremy Klein, a 51-year-old pastor in Ohio who lost his sense of smell from COVID in May 2025, participated in one of Zhao’s trials. Klein describes the experience as “amazing.”
“I could smell just about everything,” he says. “I had not been able to smell chocolate or coffee for a whole year, and I could smell it with those things in my nose.”
Importantly, the plug-and-clip device may not work for everyone, Zhao says.
“My guess is that you need some residual smell function for it to work,” he says. “Just as with hearing loss, if you have complete hearing loss, then no hearing aids can help you; but if you have some residual hearing left, then hearing aids will be great for the first line of treatment.”
Thomas Hummel, head of the Smell and Taste center in the department of Otorhinolaryngology at the Dresden University of Technology, who has developed olfactory implants, says Zhao’s work is commendable. But there are limitations, he adds.
“These experiments are a good first step into this area,” Hummel says.
For one, Zhao’s research has looked at whether patients using the device can identify a presented odor rather than the odor threshold, which measures the lowest concentration at which an aroma can be detected. For his part, Zhao acknowledges that the work is currently confined to the lab and involves testing for a limited selection of smells.
“We have not collected long-term data yet, asking patients to wear it during their daily life,” Zhao says. “Some odors might be more enhanced or better enhanced than others, depending on the chemical or physical properties.
Hummel also questions whether people would be willing to wear the device. “It’s in the nasal cavity, and people are usually very sensitive about it,” he says, hough some of his patients are open to wearing similar devices on an ad hoc basis.
Klein, the pastor, says that his biggest criticisms of the device are that it is black and that the nasal plugs stick out. “As a guinea pig, it would be weird for me to go out public,” he says. According to patient surveys, more than half of respondents said they may be willing to use Zhao’s device regularly, however, so long as it works.
Klein, at least, is happy to wear it in private. As the cook of his household, Klein likes to smell what he’s preparing. The researchers allowed him to take his prototype home—sometimes he’ll put it in his nose and take a whiff.
“My wife laughs at me, but it doesn’t hurt anybody,” he says. “And if they can figure out a way to design this that is sleek, they’re onto something.”
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