WHISPERS OF SMELL: THE ROSE PROJECT

Moustafa Bensafi, ROSE coordinator and director of research of the CNRS at the Centre for Research in Neuroscience, has long been curious, as both a psychologist and neuroscientist, about how odours shape our behaviour from the way we eat to how we interact socially. But he knew he could not answer these questions alone. 

“From the start, I always believed that complex problems need multiple perspectives. That is why my work has always been characterised by an interdisciplinary approach, involving collaborators from linguistics, philosophy, chemistry, computer science… it is really part of the DNA of all my projects.” 

The ROSE project emerged not only from this multidisciplinary foundation but also from the convergence of different research threads. Around ten years ago, a Franco-German research grant, secured alongside his German colleague Thomas Hummel, enabled them to explore the mental representation of odours —a project that combined the human sciences, neuroscience, and chemistry. At the same time, Moustafa began collaborating with Aryballe, a small company focused on developing artificial sensors to detect smells. 

These two parallel projects laid the foundation for what would become the ROSE project. As Moustafa recalls, they began to consider something that, at the time, felt almost unthinkable: an olfactory prosthesis. 

“At that time, the idea of combining these two paths, brain and cognition, and machine, was just a dream. Something wild. But slowly, it began to feel possible.” 

What truly pushed the idea forward did not come from scientific breakthroughs, but from the voices of people reaching out to him. Letters arrived, some handwritten, some emails, all from individuals who had lost their sense of smell and were desperate for help. With no clear diagnosis or solutions available to them, they were left adrift. Anosmia and hyposmia affect up to 20% of the world’s population, yet these individuals had nowhere to turn for answers or hope. 

“They were lost. They did not know where to go. Some had no diagnosis, no solutions. That is when it hit me: perhaps we could build something real. Something that could help.” 

That was the moment the ROSE project truly took root. 

Together with his collaborators, Moustafa began drafting a proposal. Their goal was not to create a market-ready product, but rather a proof of concept, a new kind of olfactory prosthesis. The idea was to combine a sensor that could detect odours with a stimulator that could transmit information directly into the nasal cavity or even to the brain, allowing people with smell loss to reconnect with their olfactory environment. 

To bring this ambitious vision to life, they formed a consortium across Europe, bringing together partners from France, including CEA LETI and Aryballe, Germany through the Dresden University of Technology, Italy via the Politecnico di Milano, the Aristotle University of Thessaloniki in Greece, and the Ecole Polytechnique Fédérale de Lausanne in Switzerland. Each team offered a crucial piece of the puzzle, from human sciences to nanotechnology, microengineering, mechanical design, clinical olfaction, and neurosurgery. It was a rare and powerful mix of disciplines. 

“At the beginning, we were speaking entirely different languages. A psychologist talking to a nanotechnologist… it just does not work. But we learnt. We adapted. We stepped out of our comfort zones.” 

The ROSE Project officially began in September 2021, with funding secured for four years. Now, as it enters its final months, the team has achieved what they set out to do: a functioning proof of concept. 

Today, the project has successfully created the proof of concept it was looking for: it’s a small piece of technology: a sensor that can detect odours by sending an affirmation to the nasal cavity inside the nose. So, it’s a very small, bioelectrical pulsation. This signal allows individuals to perceive the presence of a smell, even if they cannot have a real smell sensation and cannot yet identify exactly what it is.  

The team is currently exploring two pathways to deliver this sensory information. The first involves direct brain stimulation. Working with neurosurgeons in Germany and patients already implanted for other clinical purposes, they are testing how and where to stimulate the brain to evoke real olfactory perceptions. 

“This is very difficult. Scientifically, it is still at a low level of maturity, but we have seen some promising signs. It is not ready, but it is real.” 

The second approach relies on stimulating a lesser-known sense, known as trigeminal sensitivity. This system is responsible for physical sensations related to certain smells, such as the coolness of mint, the heat of chilli, or the tingling in the nose from fizzy drinks. Using a small stimulator placed inside the nose and glasses connected to an artificial nose, chemical signals are converted into digital data, and then into bioelectrical signals that activate the trigeminal system. While users do not experience a traditional smell, they can sense a physical reaction, allowing them not only to detect the presence of an odour, but also to distinguish between them based on specific patterns of stimulation. 

“It is not smell, exactly. But people can distinguish between different odours through patterns of trigeminal activation. It is something. It is the start of something.” 

The journey hasn’t all been smooth. The technology is still early. The sensor needs to become more specific, ideally able to identify specific smells like coffee or garlic. The stimulator must also be made more comfortable and adaptable for long-term use. The brain stimulation pathway, although promising, could take another ten to fifteen years to fully mature. 

There is also the emotional challenge of managing public expectations. 

“Because of the project’s title, people with smell loss reach out with hope. But this is just a first step. We always have to explain that it is a beginning, something really promising, but not yet a cure. That part is tough.” 

Still, the consortium remains energised. A patent has already been filed, several publications have emerged, and the team is writing a collective book. Each member of the consortium is contributing a chapter to tell the story from their unique perspective. The idea for the book was not in the original proposal, but it developed naturally as the project evolved. 

“I didn’t want to miss the opportunity. This is a story worth telling.” 

Reflecting on how the project has shaped his life both professionally and personally, Moustafa shares that it changed his focus. Although it took time away from his own scientific research, he found fulfilment in coordination, communication, and sharing ideas. 

“It made me more focused. It took time away from my own scientific work, yes, but I loved that! It also gave me something deeper and a sense of purpose in coordination, communication, and storytelling.” 

But ROSE is a project beyond the lab; Moustafa took it into schools and classrooms, sharing the project with children and young students. Armed with plastic brains, models of molecules, scent bottles, and simplified science, he’s teaching the next generation to see value in the senses they take for granted. 

“They look at me with so much fascination. And I tell them chemistry, literature, maths, they all matter. Because real innovation comes when disciplines meet.” 

What’s Next? 

With the project due to finish this year, the team is preparing a new proposal for EU funding. Their aim is to move from the laboratory to real-world testing and eventually bring the device into patients’ homes. The hope is that the next chapter of ROSE will take the technology closer to practical application. 

Despite the challenges, there’s no doubt in his voice when he reflects: 

“I have coordinated dozens of projects, nationally and internationally. But this… this is the one I am proudest of. Because we built something that did not exist. We brought people together who would never have met otherwise. And we showed that research, even the most complex kind, is always, at its heart, a human story.”

Photo by Julie Blake Edison on Unsplash