Counterintuitive VR Device Produces Scents to Make You Feel Temperature

The entire purpose of virtual reality is to immerse you in a digital world, but, as the technology stands today, you can really only immerse two of your senses: sight and hearing. A lot of work is being done on haptic feedback devices that let you physically feel virtual objects, but none of them provide a truly comprehensive experience. More importantly, they almost all rely entirely on producing pressure. They aren’t capable of letting you feel heat or cold in the digital world. This new virtual reality device is able to make you feel a wide range of temperatures by, counterintuitively, producing specific scents.

At first, it seems like it would be easy to integrate temperature into a virtual reality device. Just add heating elements or thermoelectric coolers, right? Unfortunately, those take several seconds (at least) to reach the requested temperature. That delay would completely ruin the experience in a virtual reality game. Imagine you’re playing a VR game and you’re traversing a snowy landscape, when suddenly an enemy hits you with a fireball spell. You want to feel the heat from that fireball immediately, not ten seconds later when the heating elements finally catch up. This device is able to make you feel a temperature change almost immediately, and it does that by producing a scent that creates the illusion of actual heat or cold.

This device contains three reservoirs of scented liquid that can be aerosolized either independently or together and then sprayed in front of your nose. Capsaicin (which makes peppers spicy) provides a hot sensation, eucalyptol (the stuff that makes your mouthwash minty) provides a cold sensation, and the third channel can be used for something to reinforce those. A burning wood smell, for example, can make the heat of capsaicin feel more real. Part of the temperature illusion comes from our associations with capsaicin and eucalyptol, but the effect is enhanced because these excite the trigeminal nerve that is responsible for a great deal of the sensation in your face. In a limited study, most of the participants reported that these scents increased their level of immersion in a VR experience designed specifically to test them.

The prototype device built for this, which was given the catchy “Trigeminal-Based Temperature Interface” name, was constructed from off-the-shelf hardware. It’s controlled by an Adafruit Feather nRF52 Bluetooth LE board and power comes from a LiPo battery through an Adafruit PowerBoost 1000. The liquids are atomized by a vibrating mesh transducer. The most expensive components are the piezoelectric diaphragm micropumps and their controllers. Those are made by Bartels Mikrotechnik, and cost a total of $303 for the three pumps and controllers. It could, however, be possible to use much cheaper pumps. If the costs can be reduced and the device can be made more comfortable to wear, this could provide a deeper level of immersion when in virtual reality.