Hirooki Aoki

Study on respiration monitoring method using near-infrared multiple slit-lights projection

We describe the principle of the respiration monitoring by the multiple slit light irradiation and the configuration of the respiration monitoring system. In the developed system, the fiber grating vision sensor known as an active type high-speed three-dimensional sensor was applied to satisfy the non-contact and non-restraint respiration monitoring. The fiber grating vision sensor is composed of a multiple slit light projector and a CCD camera, and these are placed above the sleeping person oriented in a lengthwise direction of the bed. And the multiple slit light projector projects the slit light array on the body surface of sleeping person. In this paper, the algorithm for monitoring and analyzing of the respiration status of the sleeping person is proposed. And, the result of the preliminary experiment performed to verify the effectiveness of developed system is described. As results of preliminary experiment through the simultaneous measurements with the developed system and a spirometer, it is confirmed that respiratory waveforms obtained by this system reflect the changes of volume occurring with respiratory movement of the examinee.

Non-contact Respiration Monitoring Method for Screening Sleep Respiratory Disturbance Using Slit Light Pattern Projection

We proposed the respiration monitoring method with non-contact and unrestraint, applied the projection of the near-infrared multiple slit-light pattern. In the respiration monitoring method, the shift length of multiple-slit pattern light, projected on the thoracicoabdominal part of sleeping person, is calculated by motion-image analysis. By the simultaneous meas-urement with the spirometer, the validity of the non-contact respiration monitoring by our method was indicated. As a result of all night measurement, we found that our proposed method enable the disease presentation, which was typical of obstructive sleep apnea, to be detected.

Calculation of ventilation threshold using noncontact respirometry

We proposed the calculation method of the ventilation threshold using the noncontact respirometry under pedal stroke motion. By the simultaneous measurement with the expiration gas analyzer, we examined the effectiveness of the proposal method. There was high correlation over 0.8 between ventilation variations calculated by our proposed method and the expiration gas analyzer. On the other hand, the correlation between ventilation thresholds calculated by our proposed method and the expiration gas analyzer is 0.735. In this experiment, the sufficient examination seemed to be difficult on the correlation, since the difference between the systemic aerobic capacities of the examinees is small.

Non-contact Measurement Method of Respiratory Movement under Pedal Stroke Motion

We proposed the non-contact measurement method of the respiratory movement under pedal stroke motion, by the application of optical technique. By the simultaneous measurement with the expiration gas analyzer, we examined the effectiveness of the proposal method. As the results, we clarified that the calculated value obtained by our proposal method is highly correlated with the tidal volume expiration measured by the expiration gas analyzer.

Basic Study on Relationship between Respiratory Flow Volume and Volume Change of Thorax Surface

The pulmonary function test by spirometer is generally conducted. The test subject, especially child, woman and older person, feels uncomfortable as the mouthpiece and nasal plug must be attached to the face of them. We have studied the nonrestraint pulmonary function test using the dot matrix pattern projection in order to decrease the burden to the examinee. In our proposed system, the pattern light projector illuminates the thorax with the dot matrix pattern light. And the CCD camera takes a series of images of the dot matrix pattern. The three dimensional shape of the thorax surface can be calculated by the distribution of light dots. And the respiratory waveform is calculated by the time-series change of the three dimensional shape. The respiratory waveform of our system was similar to one of spirometer. Therefore, we clarified that our proposed system can equivalently measure the respiration with spirometer in previous research. In this paper, we compared the volume change of the three dimensional shape calculated by our system with the flow volume. And we examined the relationship between the flow volume and the volume change of the thorax surface.

Proposal on Nonrestraint Pulmonary Function Test Using Active 3D Measurement for Body Surface

We propose a new nonrestraint pulmonary function test using the dot matrix pattern projection. In the pulmonary function test, the function of respiratory gas exchange and air infiltration is examined. The pulmonary function test by spirometer is generally conducted. In this test, the respiratory compromise is diagnosed by FEV1.0% (Forced Expiratory Volume 1.0%) and %VC (% Vital Capacity). The test subject, especially child, woman and older person, senses the restraint sensation, because mouthpiece and nasal plug must be attached to the face of the test subject under the test. We have studied the nonrestraint pulmonary function test using the dot matrix pattern projection in order to decrease the burden to the examinee. In our proposed system, the pattern light projector illuminates the thorax with the dot matrix pattern light. And the CCD camera takes a series of images of the dot matrix pattern. The respiratory waveform is calculated by the shift quantity of dot matrix pattern between frames. The respiratory waveform of our proposed system was similar to one of spirometer. Therefore, we clarified that our proposed system can equivalently measure the respiration with spirometer in previous research. In this paper, we examined a further quantification of the respiratory movement. The three dimensional shape of the body surface is calculated by the distribution of dot lights. The volume variation by respiratory movement can be calculated by the time-series alteration of the three dimensional shape. As a result of comparing the waveform of the volume variation calculated by this system and the flow rate waveform measured by spirometer, there was the high correlation between this system and spirometer on measured value. In consequence, we thought that this system can be applied to the nonrestratint pulmonary function test.

Basic study on non-contact respiration measurement during exercise tolerance test by using kinect sensor

We propose a non-contact respiration measurement in the exercise tolerance test by using the Kinect sensor instead of the fiber grating sensor, and examine the validity of the proposed method by a comparison experiment with the expiration gas analyzer. As the result, it become clear that the tidal volume and the quasi-tidal volume increase with almost similar trend. However it is confirmed that the divergence between the tidal volume and the quasi-tidal volume increases over 100 watt ergo-metric load. Meanwhile, the quasi-tidal volume calculated from the region of respiration change with more similar trend than the quasi-tidal volume calculated from the entire region of interest.

Investigation of unifying transcutaneous transformer for transmission of energy and information

When patients are fitted with a totally implantable artificial heart (TAH), they need to be implanted with two additional devices: one for the transmission of energy and one for information. However, this is a cumbersome process that affects the quality of life of the recipient. Therefore, we investigated the use of electromagnetic coupling for the transmission of energy and information and the possibility of unifying two transcutaneous transformers for the simultaneous transmission of energy and information. While unifying the transformers, it is important to suppress the electromagnetic coupling between energy and information transmission. Therefore, we ensured that the electromagnetic fields generated from the transformer windings for the transmissions of information and energy intersected perpendicularly. If the fields are perpendicular, the electromagnetic coupling between the energy and information transmissions will be suppressed significantly. The characteristics of the simultaneous transmission of information and energy using the unified transcutaneous transformer, developed experimentally, were evaluated by changing the number of windings used for the transmission of information. The electromagnetic coupling between the energy and information transmissions was suppressed by determining the direction of the magnetic field. Moreover, the optimum number of transformer windings required for the simultaneous transmission of energy and information was determined. We concluded that the externally coupled transcutaneous transformer unified for the simultaneous transmission of energy and information performed with good transmission characteristics.

Fat Thickness Estimation Method Using Bio Electrical Property Examination by Gel Phantom Model Test

We examined the relationship between electrical bio-impedance and the ratio of muscle mass and fat mass using gel phantom model. Generally, somatic fat rate of the whole body is measured for the purpose of the health care. In the meantime, it is useful to know the partial ratio of muscle mass and fat mass for carrying out the health care, when exercise capacity and metabolic rate are known. We considered that the measurement of local electrical bio-impedance could calculate ratio of muscle mass and fat mass of each region in the body. Consequently, we examined the method for effectively carrying out measurement of local electrical bio-impedance and interpretation of measurement data. It is effective to conduct the verification experiment using the gel phantom model prior to in vivo experiment, because shape, size, and electrical properties of the gel phantom model can be easily set. In this study, we prepared the gel phantom model of two-layer structure composed of the muscle gel phantom and fat gel phantom. Using this gel phantom model, we examined how the thickness of fat layer on the muscle layer influenced the local electrical bio-impedance. As the result, the change of apparent resistivity calculated from measured value was confirmed by varying the fat thickness of the two-layer model. And, it seemed to be possible to know relative increase and decrease in amount of fat mass of each region by understanding apparent resistivity calculated from resistance value and electrode interval

Non-Contact Respiration Measurement during Exercise Tolerance Test by Using Kinect Sensor

This study aims to assess non-contact respiration measurement during the exercise stress test using an upright bicycle ergometer and to evaluate the ventilation threshold value. We propose the tracking of the chest and abdomen by applying the motion capture function of the Kinect V2 sensor to cope with an increase in physical exercise accompanied by an increase in exercise intensity. In the proposed method, the region enclosed by the four joints corresponding to the left and right shoulders and the right and left hip extracted using the Kinect sensor is set as the region of interest. The region is updated in response to changes in body movements. By extracting the signal of the pedaling frequency component from the time series data of the volume in the region, only the volume change due to respiration was extracted. The point at which the increased rate of the volume change elevates is estimated as the ventilation threshold. The assessment of the efficacy of the proposed method by comparative analysis using an expiration gas analyzer confirmed that non-contact respiration evaluation is possible with an exercise intensity of about 160 W. Furthermore, the ventilation threshold estimated by the proposed method is ±10 W of the estimated value by expiratory gas analyzer.