Is It Hot in Here, or Is it Just My Cranial Nerve?

Virtual reality (VR) experiences are becoming ever more immersive. The visual and auditory signals can leave a VR user feeling almost as if they were in an alternate reality. Almost. One glaring shortcoming of most VR systems is the lack of practical means to simulate sensations outside of the visual and auditory realm.

In a recent advancement, a group of researchers at the University of Chicago have described a method to simulate sensations of temperature change with a small, low-power consumption device.

Existing methods to create hot or cold sensations use heat lamps, air conditioning units, or Peltier-elements. Air conditioning and heat lamps have high power requirements, and their size renders them stationary, which limits the ways in which they can be used. Peltier-elements are small, and therefore portable, however, they are limited in usefulness due to relatively high power consumption.

The new method described by Brooks et al. takes advantage of the fact that the nose’s trigeminal nerve responds to both temperature and chemical stimuli. Stimulating a subject’s trigeminal nerve with an appropriate molecule will give them the sensation of a temperature change. Several off-the-shelf chemicals were evaluated for effectiveness. It was important to choose chemicals without strong odors; smelling a distinctive odor each time the temperature changes could break the illusion. The authors chose capsaicin to give the illusion of heat, and eucalyptol to simulate coldness. Capsaicin is odorless, while eucalyptol has a light scent.

To deliver the chemicals, a standalone device was constructed that attaches to the front of a VR headset. Micropumps are used to push the scents onto a vibrating mesh atomizer that delivers the chemicals as a fine aerosol. Latency time from a VR software trigger to aerosol reaching the transgeminal nerve is about 200ms. At 0.25 watts, the device uses approximately twenty times less power than a Peltier-element.

The video above demonstrates a VR application for the device. With summer heat upon us, I wonder if there may be some application for trigeminal stimulation outside of the virtual realm.