Inducing a cold sensation without changing skin temperature — Non-contact VR technology developed by the University of Tsukuba

Professor Yoshihiro Kuroda from the Institute of Systems and Information Engineering/Center for Cybernetics Research, and his colleagues reported the development of a technology that provides a non-contact virtual cooling sensation without substantially changing skin temperature. The technology uses a cold air source for cold stimulus and a light source for warm stimulus and takes advantage of the characteristics that help people easily perceive quick temperature changes. The system instantly switches between a quick cold stimulus and a gentle warm stimulus to induce a cooling sensation. It is expected to facilitate the realization of an experience with continuous temperature sensation as well as instantaneous temperature sensation in the VR world. The results were published in IEEE Transactions on Haptics on October 16.

In the field of VR, thermal sensations are attracting attention as an important element in the perception of the surrounding environment. The research group has built a non-contact cooling proposal technology that uses novel vortex effects. In this phenomenon, compressed air injected into a tube becomes a rapidly rotating air stream that eventually splits into cold and warm air, this cold air is used in cooling systems. In this development, the researchers worked on a new non-contact-type cooling proposals based on this phenomenon.

People recognize temperature sensations from the changes in the body conditions they feel on their skin. However, if they continue to receive the same stimuli, they become accustomed to them and are less likely to perceive new stimuli. The developed system is characterized by a feature to perceive quick temperature changes. Based on this feature, repeated switching between a quick cold stimulus and gradual warm stimulus causes a cold sensation without causing any change in the skin temperature.

In the experiment, the participants (14 males and 1 female in their 20s and 30s) were presented with combinations of cold and warm stimuli of different intensities, and the temperature sensations felt by the participants were recorded. The results revealed that it was possible to create a continuous coolness in a non-contact situation without a substantial change in the skin temperature.

When the speed of cold stimulation was increased by 1.5 times (temperature change at 0.24℃ per second). even though the skin temperature was not substantially changed, the intensity of the cold sensation was found to be the same level of that of the conventional technology (temperature change at 0.16℃ per second), which the skin temperature is continuously lowered over time.

In the VR world, the experience of instantaneous temperature sensations, such as rapid combustion or sudden cold wind, and continuous temperature sensations over an extended period is realized. It is expected that this technology will enable visitors to experience the climate of places that are difficult to visit in person.

According to Kuroda and Xu Jiayi (a graduate student at the time of the research)"At the beginning of the research, we alternated between cold airflow and warm light sources, which caused the pressure sensation caused by the wind in the airflow to stand out. By increasing the output of the light source and repeatedly turning it on and off while continuing to emit the cold air flow without changing its volume, we were able to successfully create alternating cold and warm states with the synthesized thermal stimulus. In the future, we would like to downsize the device and seek cooperation from companies to commercialize it."

Journal Information
Publication: IEEE Transactions on Haptics
Title: Integration of Independent Heat Transfer Mechanisms for Non-Contact Cold Sensation Presentation With Low Residual Heat
DOI: 10.1109/TOH.2023.3324754