Anyone who immerses themselves in a virtual world with data glasses does not have to be content with looking at the objects of the computer-generated environment. Equipped with headphones and special gloves, you can also hear and feel what is happening around you. Cameras even make it possible to interact with the artificial world and become a part of it as an avatar. While virtual vision and hearing are now well advanced, an important sense has been missing in the virtual world: smell. Chinese scientists have now closed this gap with a wireless interface. Now, during their excursions into the virtual worlds, users could smell the sweet scent of flowers, the intense smell of freshly mown grass or damp earth themselves.

Manfred Lindinger

Editor in the "Nature and Science" department.

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There are already fragrance dispensers that make life in the virtual world more sensual. These are usually rigid and poorly dosed perfume bottles or atomizers. These are connected by wires to the computer, which combines the virtual audiovisual with the olfactory impressions. However, because the systems react sluggishly, their ability to spread scents in the computer world is rather limited. This is not the case with the odor generators that the researchers led by Xinge Yu from the City University of Hong Kong present in "Nature Communications". These can be integrated into a face mask or stuck directly under the nose.

The new fragrance dispensers consist of thin layers of wax enriched with various aromatic substances. An externally controllable thermocouple heats the wax, causing the substance to evaporate and release its fragrance within 1.5 seconds. The dosage is controlled by the temperature of the thermocouple. To prevent the scent from rising permanently into the nose, the fragrance wax can be cooled down quickly.

With the nine odor generators in the face mask, just as many individual scents can be created. However, it is also possible to generate numerous mixtures. Currently, about 30 flavors are possible, such as mint, jasmine, orange, rosemary or strawberry. Which fragrance is activated and with what intensity can be controlled wirelessly via an interface. This receives information via a controller about which virtual object a user is currently targeting and how long its "distance" is. If, for example, the wearer of the olfactory VR glasses approaches a bouquet of flowers, the scent emanating from it becomes more intense. If it moves away again, the scent becomes correspondingly weaker.

The user can grab individual flowers, bring them to his nose and smell them, as the researchers demonstrate in a video. To do this, however, he must wear a VR glove connected to a sensor that registers the movement of the arm. The data is transmitted wirelessly to the odor generators. With the distance to the nose, the temperature of the respective fragrance wax rises and thus the. Concentration of the fragrance in the air.

According to the researchers, thanks to the portable odor dispensers, the virtual worlds can now be experienced even more intensively, as smells and scents evoke special emotions. The scent generators could help to alleviate depressive moods or train olfactory skills. This could benefit, for example, patients who have only a limited sense of smell due to age or as a result of a disease such as Covid-19. Now Yu and her colleagues want to downsize their system. Because it is still comparatively bulky and heavy and annoying if you stick it directly under your nose.