Takao Yamanaka

Study of odor blender using solenoid valves controlled by delta–sigma modulation method for odor recorder

Abstract An odor recorder has the capability of not only recording odors electronically but also reproducing it anytime and anywhere. In this paper, we developed a new type of odor recorder, composed of the odor blenders that generate the mixture of components at any composition using solenoid valves controlled by the delta–sigma modulation method. We optimized the parameters of modulation and the characteristic of the low pass filter by simulation. Moreover, the recipes of apple flavor, jasmine scent, and spice flavor were successfully determined using the developed odor recorder by experiment. The new method is suitable for realizing an odor recorder for many components.

Fundamental study of odor recorder for multicomponent odor using recipe exploration method based on singular value decomposition

A new method for the odor recorder, electronically recording the recipe of odors or scents made up of many components, was proposed. Although apple flavors have been recorded with a mixture of five components using the odor recorder in previous work, the number of odor components should be increased to expand the applicable range of odors. Since the collinearity problem of the odor sensor array became apparent with the increase of components, a new method based on variable transformation using singular value decomposition was developed in this paper, to extract the effective subspace of the sensor outputs for recipe exploration. As a result, the sensor-array response pattern of the reproduced odor, with the eight-component recipe, almost agreed with that of the target apple flavor. Furthermore, human sensory tests revealed that the smell of the approximated odor was identical to that of the target flavor.

Study of recording apple flavor using odor recorder with five components

The odor recorder has been developed using the odor sensing system based on the active sensing method to electronically record odors and reproduce them anytime and anywhere. The recorder developed in this paper has capability of recording the target odor, the mixture of five odor components, using the odor sensor array composed of quartz crystal microbalance sensors. The difference between the sensor response patterns of the recipe and target odors was minimized so that the recipe of the five components for the target odor was determined. In this paper, the method of selecting the most appropriate sensors to record odors was investigated based on the condition number of the sensor array sensitivity matrix. Moreover, the method of determining the parameters of the odor-recording algorithm was studied. As a result, several apple flavors composed of the five components were successfully recorded. Furthermore, the typical apple flavor composed of nine components was approximated using the mixture of the five components. The approximation result by the sensing system was successfully verified by the human sensory test.

Study of real-time visualization of gas/odor flow image using gas sensor array

Abstract A new method to find a gas/odor source is proposed. A portable homogeneous gas sensor array is used to visualize the flow of a target gas. The direction of a gas source is estimated using a real-time image processing algorithm, and the source is located by following the estimated direction. The design of the sensor array has been performed using the simulation technique developed in the previous study. In the designing process, a virtual sensor array with an arbitrary time constant is placed in a dynamic gas distribution field visualized using a tracer such as smoke of joss sticks. The virtual sensor array behavior, which is much slower than the gas concentration change, is then calculated by inputting the optical data, captured by a video camera, to the sensor dynamics model. As a result, the designed system has been found effective through the simulation.

Analysis of gas sensor transient response by visualizing instantaneous gas concentration using smoke

Abstract A new method to analyze the transient response of a gas sensor is proposed. For the analysis of the sensor dynamics, the actual rapid gas concentration change during the measurement of sensor transient response should be obtained. Therefore, the distribution of the gas concentration around the sensor is visualized using the white smoke of joss sticks, and is measured as the brightness of the CCD camera image. The measured sensor response is found to be well described by a model with two phases, such as the response and recovery phases, and their transients in the two phases are expressed as second order linear systems. The results show the feasibility of estimating the sensor response from the visualized gas distribution image.

Odor recorder for multi-component odor using two-level quantization method

A new algorithm to electronically record an odor composed of the mixture of many components using the odor sensing system was proposed. Since the human impression on the odor mostly depends on the kinds of key components rather than the accurate mixture composition, the odor was approximated with the combination of several components. Moreover, the efficient method to explore the recipe for the odor approximation with the combination of many components was established. Then, the recipe of an apple flavor was recorded using the proposed method and was evaluated by the human sensory test. As a result, it was found that the odor approximated with up to eight components was close to the target apple flavor. Furthermore, it was confirmed that the response pattern of the QCM (quartz crystal microbalance) odor sensor array was a good indicator of the odors detected by human olfaction. The proposed method was useful to realize the odor recorder with many odor components.

Real-time reference method in odor recorder under environmental change

Abstract This paper presents the electronic record of dynamically changing odors under environmental disturbance using a new recording method for the odor recorder called ‘real-time reference method’. The target odor is recorded as the recipe of several odor components. Once the recipe to represent the target odor is determined, it can be reproduced anytime and anywhere. In the real-time reference method, the target and blended odors are alternately exposed to the sensor array every sampling interval to determine the recipe for reproducing the target odor. Since the two odors are measured in the almost same environmental condition, the influence of dynamically changing environmental disturbance (temperature and humidity disturbances) can be reduced. Moreover, the dynamically changing target odor can be recorded because of the real-time monitoring of the target odors. In this paper, the dynamically changing apple flavors composed of four components were successfully quantified under the temperature and humidity disturbances.

Concurrent Recording and Regeneration of Visual and Olfactory Information Using Odor Sensor

In this paper, a method of concurrent recording and regeneration of visual and olfactory information is presented using electronic nose technology. To accomplish this objective, the sensor response patterns of odors in the atmosphere were measured using QCM (quartz crystal microbalance) odor sensors with partially overlapping specificities. Then the odors were identified from the response patterns using LVQ (learning vector quantization), a pattern classification algorithm of neural networks with supervised learning. Visual information, presented as a movie, was captured using a digital video camera; concurrently, odors using odor sensor responses were paired to the video. The recorded visual and olfactory information was evaluated by sensory tests to investigate the effectiveness of the proposed system. As a result, it was found that the olfactory information recorded using the proposed method was appropriate for odor regeneration associated with the movie.

Improvement of odor-recorder capability for dynamical change of odor

The smell reproduction technique in addition to those for vision and hearing are useful in the fields of virtual environments, games and e-commerce in fragrances and foods. We have developed an odor recorder to record odors using quartz crystal microbalance sensors and to reproduce them based on the recorded data. In this paper, the results of recording dynamical changes in odors in the atmosphere are described. The dynamical changes in the odors were successfully recorded in spite of the rapid change of the odor concentration over a few seconds due to the airflow turbulence. First, the change in a binary mixture of apple-flavor components was successfully recorded using the odor recorder based on a feedback control. Next, the changes in four fruit flavors, apple, mandarin, pineapple, and banana flavors, were successfully recorded using the odor recorder based on a pattern classification method.

Olfactory display using solenoid valves controlled by delta-sigma modulation

A new type of olfactory display using solenoid valves controlled by delta-sigma modulation has been developed. It can be used to record and regenerate an odor with an arbitrary recipe in combination with an odor sensing system.