Multi-scent olfactory display with visual and sound interaction

• The authors have developed a multi-scent olfactory display that integrates visual, sound, and smell interactions for an immersive experience. • The display uses off-the-shelf spray bottles and a custom mechanical system to achieve scent generation and switching. • The device demonstrates the ability to align scents with visual and audio events to create an engaging multi-sensory experience. • A user study was undertaken with 28 participants to test the system. • Most participants correctly identified the scents and rated the experience as comfortable and immersive. Historically, research into olfaction and its related technologies has developed at a slower pace than work into other human senses. Recently, the impact of COVID-19 has resulted in temporary smell loss for many people and has brought the importance of olfaction to the public's attention. This has prompted ideas on how we might utilise olfaction and its related technologies better in our daily lives. However, the limited research in this area means the public has been restricted to devices as simple as air fresheners and scented candles. Here, we report on the development and use of a multi-scent olfactory display designed to be integrated with vision and sound. Our device is designed for applications including promotion and film/video events. The system used off-the-shelf spray bottles for scent generation, with a control and actuation system constructed around them. The spray bottle is actuated using a solenoid valve combined with a fan to help deliver the aroma to the user. Scent switching is achieved by sliding the spray bottles on a fixed rail. The final unit can release up to four different aromas, with a fifth slot used for water. A user study was conducted with 28 participants to test the functionality and user experience of the device. During the user study, a video accompanied by a soundtrack was used in parallel with the olfactory display. We show that the unit can be controlled for scent delivery aligned with visual/sound cues. Participants' feedback indicated that they had a positive and immersive experience when using our system.