AsianScientist (Jul. 13, 2023)– Virtual reality scenarios have become increasingly realistic in recent years. In addition to hyperrealistic scenes and sounds that transport you to an alternate world, feedback from haptic gloves makes you feel you’re really interacting with it. These virtual reality worlds, however, have been odorless.

That is because creating smells requires odor generators, bulky gadgets that generally produce smells by heating up scented wax. These machines have a lot of messy wires and moving liquids, making them impractical for prolonged use. For smells to be built into commercial VR headsets, odor-generating electronics need to be shrunk in size and not come in the way of other components in these headsets.

In recent research published in Nature Communications, a team of scientists from multiple institutes in China report the development of two wireless olfactory wearables that can help you smell your virtual world easily. One of the wearables looks like an adhesive bandage and sits above the upper lip, whereas the other is worn like a face mask.

“The biggest challenge of this project was to miniaturize the overall size of odor generators for realizing a high channel [count] of odor generators in the olfaction interface system,” Yiming Liu, lead author of the paper, told Asian Scientist Magazine. Liu is a biomedical engineer at the City University of Hong Kong.

To design these interfaces, the team used flexible electronics, a class of lightweight and bendable circuits. The designs are marked by tiny channels and arrays of miniature odor generators with separate components for sensing and heating. To protect the wearers from the high temperatures required to heat scented wax, the wearables feature an air escape mechanism and a protective silicon barrier.

The bandage-style interface has two odor generators compared to the nine in the face mask-style interface. The greater number of odor generators in the mask wearable allows it to create a more complex range of fragrances by mixing different odors.

The different fragrances range from vanilla and green tea to durian, a fruit known for its particularly strong smell. Volunteers wearing both wearable designs were able to identify the smells correctly more than 9 in 10 times. But getting the scent right is only part of an immersive story.

If you’re in a VR simulation and there’s a lag between sight and smell or if the smell is too faint, that can ruin the whole experience. To prevent this, the researchers fabricated a mechanical actuator for modulating the temperature of the odor generators and rapidly cooling them down, providing better regulation of odor release.

This way, the scent production is quick and its intensity controllable, creating a seamless experience for a VR user. Wearing the bandage-style interface, a user wearing smelling a virtual rose could smell it more strongly (video here) as they moved it closer to their nose.

Since smell is a critical part of how we experience the world around us, olfactory interfaces like these add a new dimension to VR experiences. But the use cases of smell in VR go far beyond entertainment and gaming. For instance, adding smells could improve the quality of VR therapies by making patients more relaxed. It will also open up ways to help patients with partial or complete loss of smell.

While this study is a significant step in bringing smells to virtual worlds, there’s still some way to go before it can be used by  public. Researchers and startups are working to further miniaturize olfactory interfaces to existing VR headset designs. “We expect to commercialize the technology in three years,” Liu said.

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Source: City University of Hong Kong ; Image: Yipei Lieu/Asian Scientist Magazine