The 1939 movie Scent of Mystery was the first movie with the catchily named Smell-O-Vision system, that allowed viewers to experience scents that were released from behind their seats and timed with specific scenes. It utilized a manually operated machine called the Smell Brain, which was powered by compressed air. Unfortunately it was noisy and provided uneven scent dispersion in the cinema, resulting in mixed audience reviews.

Later devices for the gaming world have still tended to be relatively cumbersome and not easily integrated into wearable VR systems.

However, a team consisting of Prof. Takamichi Nakamoto from Institute of Science Tokyo, engineering doctoral student Zhe Zou from Science Tokyo, and Kelvin Cheng from Rakuten Institute of Technology has now come up with a smaller wearable device with improved compatibility with current setups.

"We created a small-sized scent generation system that can be worn together with a VR device, so a user can experience scents that match the virtual environments as they explore, and a single user can use it at the same time," explains Nakamoto.

The research team was able to reduce the driver circuit, the component that controls the device, and improve upon the methods for supplying and controlling the fragrances. The device has the ability to blend several scents to align in real time with the VR display. Up to eight different fragrance elements can be combined concurrently in varying ratios to reproduce a wide range of scents.

The team used a micro-dispenser that emits minute droplets of liquid fragrance, along with ultrasound waves to atomize those droplets into a fine mist. An electro-osmotic pump (a device that disperses liquids with electrical force) controls the fragrance delivery precisely, ensuring steady scent production with minimal timing gaps.

"We also created virtual travel content using these devices, so that users could visit various virtual locations and experience the scent at those places for a realistic travel experience," adds Nakamoto.

Test participants reported the added scents made the virtual environment feel more realistic and improved the feel of being present in a virtual reality environment.