We have developed a virtual olfactory environment using an olfactory display and computational fluid dynamics (CFD) simulation to provide odor concentration change according to user’s movement in real-time in a virtual space. Although CFD can calculate the odor distribution in the complicated geometry, its computational cost was expensive and did not work in real-time in the previous study. In this study, real-time CFD based on GPU calculation was introduced to generate olfactory VR environment. Using real-time CFD we investigated influence of the user’s body with its location and orientation changing irregularly. In the sensory test to find the odor direction, the correct answer rate was over 70% when the body influence was considered, while it was just a chance hit when the influence was not considered. The experimental result indicates the usefulness of considering the effect of the user’s body since we cannot avoid that influence.

It is important to include an olfactory cue to enhance the reality in the virtual environment. We have developed the virtual olfactory environment where a user searches for an odor source. The virtual olfactory environment was prepared using computational fluid dynamics calculation. It enables us to have the dynamic odor concentration distribution even if we have complicated obstacles in the virtual environment. Moreover, we developed the wearable olfactory display made up of multiple micro dispensers and SAW (Surface Acoustic Wave) device so that the rapid switching of the smells could be achieved. The wearable olfactory display was attached beneath a head mount display to present a smell quickly. We made the virtual environment of the two-story building where four rooms were located at each floor. A user searched for the source of smoke smell located at one room among four ones at the second floor since we simulated the fire at the early stage. A half of the users could reach the correct source locations in the experiment.

An olfactory display is a device which provides various scents to a user. One of the main problems in the conventional olfactory display is the residual smell in the ambient air. To suppress the unnecessary odor emission and let an user receive comfortable amount of odor, we have developed a newly structured olfactory display based on the combination of SAW atomizer with micro dispensing valves. The odor delivery process is designed so the odor can go into the nostril only when the user sniffs it. We also developed a VR game using the device combined with head mounted display(HMD). The user can experience the clear change of scent through the developed VR game in this research demonstration.

An olfactory display is a device which provides various scents to a user. Such devices are expected to be applied to VR since olfactory stimulus influences human emotion and enhances user experience. One of the main problems in the conventional olfactory display is that the odorants emitted from the device not only reach the nose but spread into the ambient air, so that the user experience may be changed by the remaining odor. To solve this problem, we have developed a newly structured olfactory display which utilizes human respiratory action. In the method, DC fan is driven to create an odor stream in front of the nostril. Thus, odor goes through the nostril only when the user sniffs it. The odor plume generation is based on the combination of SAW atomizer with micro dispensing valve. We have fabricated a prototype, and then evaluated the waste odor emitted into the air using a commercially available gas detector. It was demonstrated that the new structure makes it possible to reduce the waste odor emission into the air compared to the conventional method.

Olfaction is expected to provide reality and a sense of immersion in multimedia contents. Therefore, an olfactory display, a gadget to present scents to one or more user(s), has been developed. A wearable olfactory display has advantage from the viewpoint of reducing the odorant diffusion into the atmosphere and is suitable for virtual reality applications. In this study, we developed a portable olfactory display using surface acoustic wave (SAW) device and micropumps. In the experiment using quartz crystal microbalance (QCM) gas sensor, we confirmed that the olfactory display can present the odorant with intended intensity.

This paper shows our research effort towards the development of a visual-olfactory presentation system using a miniaturized olfactory display. The proposed system can present smell synchronously with the movie displayed on the screen. The olfactory display is composed of electroosmotic (EO) pumps and a surface acoustic wave (SAW) device to store liquid odorants and atomize them forcibly into smells. It is suitable for scents generation with movie because of the capability to generate smells rapidly even the scents of low-volatile substances which typically require long time to be released. A user can enjoy the video with scents by using this system without smell persistence. Lastly, a sensory test was conducted to evaluate the proposed system.

Recently, the research on olfactory display for incorporating the sense of smell into virtual reality has gradually expanded. To present odors with a vivid sense of smell, an ability to generate a variety of odors with efficient speed is indispensible. In this paper, we developed a new type of olfactory display, composed of a miniaturized electroosmotic pump and a surface acoustic wave device for presenting the low-volatile scents that are conventionally difficult to be generated with acceptable speed. We used an odor sensing system to evaluate the capability to present the low volatile scent and the ability to blend smells of our proposed new type olfactory display.

This article describes the experiments on an interactive application of an olfactory display system into which computational fluid dynamics (CFD) simulation is incorporated. In the proposed system, the olfactory display is used to add special effects to movies and virtual reality systems by releasing odors relevant to the scenes shown on the computer screen. To provide high-presence olfactory stimuli to the users, a model of the environment shown in the scene is provided to a CFD solver. The airflow field in the environment and the dispersal of odor molecules from their source are then calculated. An odor blender is used to generate the odor with the concentration determined based on the calculated odor distribution. In the experiments, a virtual room was presented on a PC monitor, and the panel were asked to stroll in the room to find an odor source. The results showed the effectiveness of the CFD simulation in reproducing the spatial distribution of the odor in the virtual space.

The results of our current multidisciplinary research efforts on the development of an olfactory display system are demonstrated. To present odors with a vivid sense of reality, we propose to use computational fluid dynamics (CFD) simulation in conjunction with the olfactory display system. In this demonstration, an odor is released with a movie clip using the olfactory display. A CFD solver is employed to calculate the turbulent airflow field in the given environment and diffusion/advection of odor molecules from their source. The olfactory display system generates an odor with the concentration determined by the calculated odor distribution. The user is assumed to be a small animal slowly walking through a virtual room, and experiences the spread of the odor in the room.

This article shows our research efforts toward the development of an olfactory display system for presenting odors with a vivid sense of reality. A multi-component olfactory display is developed, which enables generation of a variety of odors by blending multiple odor vapors with arbitrary ratios. In this research demo, the two contents using the olfactory display will be demonstrated. The first one is the experiment on odor approximation using odor components extracted from a mass spectrum database. The second one is the reproduction of video with smell. The temporal changes of odor kind and its concentration can be recorded and can be presented together with movie obtained from a Web camera. People can enjoy the recorded video with scents.

A variety of smells can be realized by blending multiple odor components using an olfactory display. Since a set of odor components to cover the entire range of smells has not yet been known, we studied a method of selecting odor components using a large-scale mass spectrum database. Basis vectors corresponding to odor components were extracted by the NMF (nonnegative matrix factorization) method. Then, the recipe of the target odor was obtained using the nonnegative least-squares method. The basis vectors were successfully obtained from 10,000 compounds within a tolerable error. Moreover, the mass spectra of 104 odors composed of 322 compounds could be approximated using 32-50 basis vectors.

The research on olfactory sense in virtual reality has gradually expanded even though the technology is still premature. We have developed an olfactory display composed of multiple solenoid valves. In the present study, an extended olfactory display, where 32 component odors can be blended in any recipe, is described; the previous version has only 8 odor components. The size was unchanged even though the number of odor components was four times larger than that in the previous display. The complexity of blending was greatly reduced because of algorithm improvement. The blending method and the fundamental experiment using a QCM (quartz crystal microbalance) sensor are described here

We developed the olfactory display to blend 8 component odors at any composition. The solenoid valVes controled by the algorithm of of the delta sigma modulation showed the sufficient capability. Then,we developed the system for presenting a movie together with scents. We actually made the content of the movie with scents and evaluated it using questionnaire survey. It was found that the scene with smell attracted the people's attention and, moreover, the contrast of the pleasant smell with the offensive one emphasized their attention. Furthermore, we established several guidelines to make the contents of the movies with scents.

A new architecture of a digital neural network circuit using 1-bit data stream circuit was proposed. It enables the reduction of the number of wires and components in the digital circuit. It was applied to the pattern recognition problem in odor sensing system and successfully classified closely similar patterns of the sensor responses.

A three-dimensional odor compass is proposed to develop a navigation tool used in searching for an odor source. The compass, which continuously points to the source, is equipped with four semiconductor gas sensors and a small fan to draw air to the sensors. The direction of the source is obtained by rotating the compass head to obtain the direction where the responses of the sensors along the horizontal and vertical directions are balanced. The following algorithmic improvements have been made to reduce the measurement time after the previous report on the two-dimensional compass. First, the transient sensor response model is introduced to compensate the response delay of the gas sensors. Secondly, the head of the compass is made to rotate continuously and three-dimensionally during the directional estimation to gather plenty of data over a short time period. As a result, the measurement time at a practical level (20 s) has been achieved. The experimental results demonstrate the effectiveness of the compass in practical environments where the wind blows three-dimensionally and/or where the odor distribution is modified by an obstacle.