Kosuke Motoi

A fully automated health-care monitoring at home without attachment of any biological sensors and its clinical evaluation

Daily monitoring of health condition is important for an effective scheme for early diagnosis, treatment and prevention of lifestyle-related diseases such as adiposis, diabetes, cardiovascular diseases and other diseases. Commercially available devices for health care monitoring at home are cumbersome in terms of self-attachment of biological sensors and self-operation of the devices. From this viewpoint, we have been developing a non-conscious physiological monitor installed in a bath, a lavatory, and a bed for home health care and evaluated its measurement accuracy by simultaneous recordings of a biological sensors directly attached to the body surface. In order to investigate its applicability to health condition monitoring, we have further developed a new monitoring system which can automatically monitor and store the health condition data. In this study, by evaluation on 3 patients with cardiac infarct or sleep apnea syndrome, patients’ health condition such as body and excretion weight in the toilet and apnea and hypopnea during sleeping were successfully monitored, indicating that the system appears useful for monitoring the health condition during daily living.

Development of a fully automated network system for long-term health-care monitoring at home

Daily monitoring of health condition at home is very important not only as an effective scheme for early diagnosis and treatment of cardiovascular and other diseases, but also for prevention and control of such diseases. From this point of view, we have developed a prototype room for fully automated monitoring of various vital signs. From the results of preliminary experiments using this room, it was confirmed that (1) ECG and respiration during bathing, (2) excretion weight and blood pressure, and (3) respiration and cardiac beat during sleep could be monitored with reasonable accuracy by the sensor system installed in bathtub, toilet and bed, respectively.

Development of a Wearable Device Capable of Monitoring Human Activity for Use in Rehabilitation and Certification of Eligibility for Long-Term Care

The importance of human posture monitoring is well recognized in the field of rehabilitation, in order to evaluate quantitatively the effectiveness of rehabilitation by a physical therapist. The activity monitoring is also well recognized as being useful in the field of certification of eligibility for long-term care. Assessment of the actual physical condition of the applicant tends to be difficult when determining the level of need for long-term care. Taking these circumstances in consideration, we attempted to measure the activities of patients in rehabilitation using a wearable device for monitoring human activity. The results clearly demonstrated that detailed motion characteristics could be detected during standing up, walking and sitting up as angle changes between specific body segments and as trunk motion acceleration

Measurement of three-dimensional posture and trajectory of lower body during standing long jumping utilizing body-mounted sensors

The measurement method of three-dimensional posture and flying trajectory of lower body during jumping motion using body-mounted wireless inertial measurement units (WIMU) is introduced. The WIMU is composed of three-dimensional (3D) accelerometer and gyroscope of two kinds with different dynamic range and one 3D geomagnetic sensor to adapt to quick movement. Three WIMUs are mounted under the chest, right thigh and right shank. Thin film pressure sensors are connected to the shank WIMU and are installed under right heel and tiptoe to distinguish the state of the body motion between grounding and jumping. Initial and final postures of trunk, thigh and shank at standing-still are obtained using gravitational acceleration and geomagnetism. The posture of body is determined using the 3D direction of each segment updated by the numerical integration of angular velocity. Flying motion is detected from pressure sensors and 3D flying trajectory is derived by the double integration of trunk acceleration applying the 3D velocity of trunk at takeoff. Standing long jump experiments are performed and experimental results show that the joint angle and flying trajectory agree with the actual motion measured by the optical motion capture system.

Development of a New Vascular Endoscopic System for Observing Inner Wall of Aorta Using Intermittent Saline Jet

A prototype endoscopic system for observing inner wall of aorta was developed and tested in vivo using swine. The purpose of this system is to visualize the inner wall of aorta without stopping aortic flow for the use of an assistive technique for endovascular interventions such as stent-graft placement for aortic aneurysm. The technique newly introduced for this purpose was the use of intermittent high-pressure saline jet synchronized to heart beat (diastolic phase). For preliminary studies, a commercially available bronchoscope having an outer diameter of 5mm with a biopsy channel was used, and a discharging system for intermittent high-pressure saline jet was constructed using a high-speed solenoid valve and a pressurizing tank. From in vitro tests, it was confirmed that we could obtain sufficient amount of saline jet (about 1ml) within short period of time (about 100 ms) with the driving pressure of 0.1 MPa. Based on these results, we conducted in vivo tests using swine with the body weight of about 30 kg. The tip of the endoscope was introduced from the abdominal aorta and inserted proximally about 30 cm. At this point, the saline jet was discharged (period: 200 ms, driving pressure: 0.2 MPa), and then we could clearly observe the aortic bifurcations during the flushing period. This result strongly suggests an availability of the present method as an assistive technology for the endovascular interventions in aorta.

Development of a Wearable Sensor System for Monitoring Static and Dynamic Posture together with Walking Speed for Use in Rehabilitation

We have developed a wearable system for monitoring static and dynamic posture in sagittal plane together with walking speed, and reported its usefulness in the rehabilitation field. However, in the previous system, there still remain several drawbacks for practical use such as accuracy in angle measurement, cumbersome cable arrangements, and so on. In order to improve these practical drawbacks, a new sensor system was designed, and its availability was evaluated. Using 11 healthy subjects (21 to 75 yrs) and 14 patients with hemiplegia (61 to 87 yrs) under their informed consent, the measuring accuracy of the improved system was evaluated by simultaneous recordings of a digital video. The results demostrated that the accuracy of this system (angle change; r=0.997, walking speed; r=0.992) showed superior to that of the previous system (angle change; r=0.986, walking speed; r=0.960). It is clearly shown through the practical monitoring that this system appears to be a useful and significant means for quantitative assessment of the human motion during rehabilitation programs.

Development of an ambulatory device for monitoring posture change and walking speed for use in rehabilitation.

Monitoring of posture change in sagittal plane and walking speed is important for evaluate the effectiveness of rehabilitation program or brace. We have developed a wearable device for monitoring human activity. However, in the previous system, there still remain several drawbacks for practical use such as accuracy in angle measurement, cumbersome cable arrangements, and so on. In order to improve these practical drawbacks, a new sensor system was designed, and its availability was evaluated. The results demonstrated that the accuracy of this system showed superior to that of the previous, and this system appears to be a significant means for quantitative assessment of the patients motion

Development of a ubiquitous healthcare monitoring system combined with non-conscious and ambulatory physiological measurements and its application to medical care

The demand for ubiquitous healthcare monitoring has been increasingly raised for prevention of lifestyle-related diseases, acute life support or chronic therapies for inpatients and/or outpatients having chronic disorder and home medical care. From these view points, we developed a non-conscious healthcare monitoring system without any attachment of biological sensors and operations of devices, and an ambulatory postural changes and activities monitoring system. Furthermore in this study, in order to investigate those applicability to the ubiquitous healthcare monitoring, we have developed a new healthcare monitoring system combined with the non-conscious and the ambulatory measurements developed by us. In patients with chronic cardiovascular disease or stroke, the daily health conditions such as pulse, respiration, activities and so on, could be continuously measured in the hospital, the rehabilitation room and subjects own home, using the present system. The results demonstrated that the system appears useful for the ubiquitous healthcare monitoring not only at medical facility, but also during daily living at home.

Feasibility study of a urine glucose level monitor for home healthcare using near infrared spectroscopy.

Urine glucose level monitoring technique using near infrared spectroscopy in conjunction with the chemometric method was newly developed aiming for the use of home health care. The calibration models were obtained by the partial least square method and their validity were assessed using albumin added glucose solution and urine samples. From the results obtained, it was clearly demonstrated that the present method had a capability of predicting urine glucose level with reasonable accuracy (standard error of prediction; 22.3 mg/dl, correlation coefficient; 0.99) and appeared to be a useful means for long-term home health care

A new calibration method with support vector machines for pulse oximetry

A novel calibration method using support vector machines regression (SVMsR) of pulse oximetry was proposed and attempted. Conventional calibration method of pulse oximetry that based on an optical density ratio of transmitted visible red light and infrared radiation whereas a proposed method here was not based on the optical density ratio directly. In theory, conventional calibrations using the ratio can be considered as a technique for nonlinear problem: nonlinear relation between two optical densities (red and IR) and oxygen saturation could be linearized by the ratio calculation. We thought, that nonlinear problem could be solved by using nonlinear analyses. Among them, the support vector machines regression method that has been studied well in this decade was attempted to be applied for pulse oximetry calibration. As an experiment, two photo plethysmograms (PPGs) by red and IR were measured on a subject. Simultaneously, oxygen saturation (SpO2) level was measured by a commercial pulse oxymeter. SpO2 level was controlled by breathing 10% oxygen gas obtaining 98–76% SpO2 level. Sequentially, feature points of two PPGs were extracted in beat by beat. AC and DC components were separated then convex peaks and concave valleys on AC waveform and DC levels of PPGs were selected as feature points. Then, nonlinear regression using SVMs were attempted to obtain relationship between SpO2 by meter (regressand) and feature points of PPG (regressor). Parameters of SVMsR were obtained by trial-and-error method. In result, a regression model by training data derived from 1408 cardiac beats was obtained and evaluated by validation data of 202 beats. The root mean squared error for the validation data is 1.309 [%] and 197 of 202 validation data fell within ± 2 % of SpO2 level by the meter. In conclusion, SVMsR might be applicable on calibration for pulse oximetry.