A research team co-led by researchers from the City University of Hong Kong (CityU) recently invented a novel, wireless, skin-interfaced olfactory feedback system that can release various odors with miniaturized odor generators (OGs). The new technology integrates odors into virtual reality(VR)/augmented reality (AR) to provide a more immersive experience, with broad applications ranging from 4D movie watching and medical treatment to online teaching.

In view of this, Dr Yu and his collaborators from Beihang University developed a new-generation, wearable, olfaction feedback system with wireless, programmable capabilities based on arrays of flexible and miniaturized odor generators, reports CityU.

They created two designs to release odors on demand through the new olfaction feedback devices made of soft, miniaturized, lightweight substrates. The first one is a small, skin-integrated, patch-like device comprising two OGs, which can be directly mounted on the human upper lip. With an extremely short distance between the OGs and the user’s nose, it can provide an ultra-fast olfaction response. Another design is a flexible facemask design with nine OGs of different odor types, which can provide hundreds of odor combinations.

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The magic of odor generators is based on a subtle heating platform and a mechanical thermal actuator. By heating and melting odorous paraffin wax on OGs to cause phase change, different odors of adjustable concentration are released. To stop the odor, the odor generators can cool down the temperature of the wax by controlling the motion of the thermal actuator. By using different paraffin waxes, the research team was able to make about 30 different scents in total, from herbal rosemary and fruity pineapple to sweet baked pancakes. Even less-than-pleasant scents, like stinky durian, can be created. The 11 volunteers were able to recognize the scents generated by the OGs with an average success rate of 93 percent.

The new system supports long-term utilization without frequent replacement, or maintenance, and enables interaction with users for various applications. Most importantly, the olfactory interface can support wireless and programmable operation, and can interact with users in various applications. It can respond rapidly to burst or suppress odors and for accurate odor concentration control. And the odor sources are easily accessible and biocompatible.

In their experiments, demonstrations in 4D movie watching , medical treatment, human emotion control, and VR/AR experience in online teaching exhibited the great potential of the new olfaction interfaces in various applications.

For instance, the new wireless olfaction system can interact between the user and a virtual subject when the user is “walking” in a virtual garden by releasing various fruit fragrances. The new technology also showed potential for helping amnesic patients recall lost memories, as odor perception is modulated by experience, leading to the recall of emotional memories.

“The new olfaction systems provide a new alternative option for users to realize the olfaction display in a virtual environment. The fast response rate in releasing odors, the high odor generator integration density, and two wearable designs ensure the great potential for olfaction interfaces in various applications, ranging from entertainment and education to healthcare and human-machine interfaces,” said Dr Yu.

In the next step, he and his research team will focus on developing a next-generation olfaction system with a shorter response time, smaller size, and higher integration density for VR, AR and mixed reality (MR)applications.

The findings were published in the scientific journal NatureCommunications under the title “Soft, Miniaturized, Wireless OlfactoryInterface for Virtual Reality”.