Development of unconstrained heartbeat and respiration measurement system with pneumatic flow.

The management of health through daily monitoring of heartbeat and respiration signals is of major importance for early diagnosis to prevent diseases of the respiratory and circulatory system. However, such daily health monitoring is possible only if the monitoring system is physically and psychologically noninvasive. In this paper, an unconstrained method of measuring heartbeat and respiration signals, by using a thermistor to measure the air flows from the air mattress to an air tube accompanying the subject's heartbeat and respiration, is proposed.

Accelerometry-based gait analysis and its application to Parkinson's disease assessment- part 2: a new measure for quantifying walking behavior.

Gait analysis is a valuable tool for obtaining quantitative information on motor deficits in Parkinson's disease (PD). Since the characteristic gait patterns of PD patients may not be fully identified by brief examination in a clinic, long-term, and unobtrusive monitoring of their activities is essential, especially in a nonclinical setting. This paper describes a single accelerometer-based gait analysis system for the assessment of ambulatory gait properties.

Accelerometry-based gait analysis and its application to Parkinson's disease assessment--part 1: detection of stride event.

Gait analysis is widely recognized as a promising tool for obtaining objective information on the walking behavior of Parkinson's disease (PD) patients. It is especially useful in clinical practices if gait properties can be captured with minimal instrumentation that does not interfere with the subject's usual behavioral pattern under ambulatory conditions. In this study, we propose a new gait analysis system based on a trunk-mounted acceleration sensor and automatic gait detection algorithm.

Unconstrained estimation method of delta-wave percentage included in EEG of sleeping subjects.

This paper describes an unconstrained pneumatic method of estimating the δ-wave activity of the brain from the heartbeat signal. Based on experiments showing that transinformation of the heartbeat signal corrupted by body movement was correlated with the δ-wave activity, we developed a method of estimating the percentage of the δ-wave included in the EEG from the transinformation. The comb filtering technique was used to obtain accurate transinformation.

Sleep-states-transition model by body movement and estimation of sleep-stage-appearance probabilities by Kalman filter.

The judgment standards of R-K method include ambiguities and are thus compensated by subjective interpretations of sleep-stage scorers. This paper presents a novel method to compensate uncertainties in judgments by the subjective interpretations by the sleep-model estimation approach and by describing the judgments in probabilistic terms. Kalman filter based on the two sleep models with no body movement and with body movement was designed.

Construction of age model for the evaluation of swallowing function using photo sensors.

For the realization of better in-home nursing environment, understanding the swallowing function and its process are quite essential to realize appropriate rehabilitation policies and dietary menus to prevent aspirations. However, the swallowing function is currently examined using mainly large-scale and expensive methods such as video fluoroscopic examination of swallowing, mesophagia fiber, palatal pressure measurement, CT, and cine MRI, which are difficult to be used at patients' homes. This paper proposes an age model, which applies a self organization map (SOM) to evaluate the swallowing function.

Safe patient transfer system with monitoring of location and vital signs.

In recent years, ubiquitous computing technologies have been applied in the field of medicine. Especially radio frequency identification (RFID) and small sensor networks could provide information about medical practices and patient status in order to prevent malpractices and improve the quality of medical care. As an example of this application, we developed a new system, named "a smart stretcher," which continuously monitors the patient's vital signs and detects apnea during transfer within a hospital.

Noninvasive measurement of heartbeat, respiration, snoring and body movements of a subject in bed via a pneumatic method.

We have developed a noninvasive pneumatics-based system by which to measure heartbeat, respiration, snoring, and body movements of a subject in bed. A thin, air-sealed cushion is placed under the bed mattress of the subject and the small movements attributable to human automatic vital functions are measured as changes in pressure using a pressure sensor having an almost flat frequency response from 0.1 to 5 kHz and a sensitivity of 56 mV/Pa.

Noncontact method for sleep stage estimation.

This paper describes a novel method to estimate sleep stage through noninvasive and unrestrained means. The Rechtschaffen and Kales (R-K) method is a standard to estimate sleep stage. However, it involves restraining the examinee and, thus, induces psychological stress.