The generation of smells in virtual reality (VR) is an irritating problem. It has so far prevented VR devices from offering a full sensory experience in most situations. “People can touch in VR,” says Xinge Yu, a professor at the City University of Hong Kong from Beihang University in Beijing and lead author of the new work, published in the journal Nature Communications in early May. “And of course you can see and hear in VR. But what about smell and taste?”
Previous attempts to create scents in VR have involved lots of cables, filthy liquids, and bulky devices that aren’t suitable for home use. As a solution, Yu and his co-author Yuhang Li, both experienced in flexible electronics design, developed two wearable interfaces. One can be taped to the skin between the nose and mouth like a bandage, and the other straps under a headset like a face mask.
Scent for VR works like a scented candle
Both types of interfaces use miniaturized scent generators, a grid of tiny containers filled with scented paraffin wax. When a heat source underneath the wax is activated, the wax heats up and essentially becomes a scented candle, which Yu and Li say can reproduce multiple smells within 1.44 seconds. When the experience is over, a copper coil prods a magnet, which depresses and cools the wax, ending the fragrance.
The higher the temperature, the stronger the smell and the easier it is to spot, Yu says. However, this means that the interfaces can become dangerously hot for human skin at up to 60 degrees. According to Yu, however, the interface is safe because it is designed so that the hot air can escape. A piece of silicone forms a barrier between the skin and the actual device.
In a test involving 11 volunteers, the interface between the nose and mouth was considered safe as long as it was at least 1.5 millimeters from the nose and the temperature at the skin’s surface was 32.2 degrees. That’s less than our body temperature. However, Yu is aware that a scalding hot interface on the face is not safe enough to use. Together with Li, he wants to test alternatives, such as running the interface at lower temperatures or cooling it down more efficiently.
Headset with flavors
Yu and Li aren’t the only ones trying to create seamless olfactory experiences in VR. At this year’s CES consumer electronics trade show, OVR Technology announced it would be launching a headset containing a cartridge of eight “primary” flavors that could be mixed and matched.
“This is an exciting development,” says Jas Brooks, a graduate student at the University of Chicago’s Human-Computer Integration Lab who has been studying chemical interfaces and odors. “It’s about a core problem of smells in VR: How can we miniaturize the whole thing without getting dirty and without using liquid?”
Artists have long attempted to bring scents into entertainment. Back in 1960, “Smell-O-Vision” made its first and only appearance with the film “Scent of Mystery,” in which smells were released via air conditioning during key plot points. But the attempt failed. The odors were either released with a delay or perceived too weakly.
Scents and smells are powerful factors
The new interfaces are a remarkable development and could change the way we experience VR. Perceiving scents and smells is a powerful sense and a prerequisite for our mouths to be able to perceive a taste. Possibilities range from the obvious – sniffing a virtual flower meadow or inhaling VR food – to some less obvious uses. For example, perfumeries could test fragrances virtually.
From a medical point of view, scented VR could be therapeutic for patients with memory problems and even improve mood. Yu told me he found that using green tea scent in his tests made him feel happier. He realized the smell was nostalgic: “When I was little, I used to eat green tea-flavored chocolate,” he recalls. “I still remember peeling off the packaging and loving the smell.”
Scents for a more intense VR experience
The special thing about these new interfaces is that they are light, small and wireless. While the device has not been directly tested with any VR game, platform or specific device. But the fact that it can be used without bulky cables should mean less footprint and a more immersive experience.
A disadvantage is that the interfaces remain limited in scope. Yu used 30 different fragrances, chosen for their distinctive, recognizable smell, such as rosemary and durian fruit. However, many real-life scents are less memorable and may not be as easy to spot. In addition, the miniaturized scent generators still have to be programmed in such a way that they work smoothly with existing VR headsets. “It’s hard to say how this would work in a commercial interface,” says Brooks.
According to Yu, the next steps include testing mechanisms to release scents at the right moment. He also wants to use his knowledge of smells to figure out how to introduce taste into VR. Maybe one day he can recreate the experience of biting into a green tea-flavored candy.
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