Taka-aki Suzuki

Wearable ECG Recorder with Acceleration Sensors for Monitoring Daily Stress

A small and light-weight wearable electrocardiograph (ECG) equipment with three accelerometers (x, y and zaxis) was developed for prolonged monitoring of autonomic nervous system in daily life. It consists of an amplifier, a bandpass filter, a microcomputer with an AD converter, a triaxial accelerometer, and a memory card. Four parameters can be sampled at 1 kHz (10 bits) for more than 24 hours, maximum 27 hours, with a default battery and a memory card (1 GB). The availability of the system was tested for three subjects for three days by replacing the battery and the memory card every 24 hours under each environment. Both short-term and circadian rhythms of the autonomic nervous system were clearly observed. The change of the autonomic nervous system from body movement (i.e. walking or turning over) was observed by check acceleration data. The feasibility of the application in clinical practice is also discussed.

Development of a Wearable ECG Recorder for Measuring Daily Stress

The purpose of the study is to show the feasibility of a light-weight wearable electrocardiograph with three accelero-meters for monitoring stress in everyday life. It consists of an amplifier, a band pass filter, a microcomputer with an AD converter, a triaxial accelerometer, and a memory card. An ECG and three accelerations are sampled at 1 kHz for more than 24 hours, maximum 27 hours with a default battery and a memory card. The heart rate variability analysis program detects R waves and determines R-R intervals for 24 hours by a data acquisition algorithm. An algorithm was also developed. It was designed to reduce motion artifacts induced by body movements on ECG. Autonomic nervous activity levels are calculated based on the heart rate variability spectrum analysis. The availability of the system was tested for three subjects for three days by replacing the battery and memory card every 24 hours under each environment. Both short time rhythms and a circadian rhythm of autonomic nervous system were clearly observed. The feasibility of the system for monitoring the long-term stress level is discussed.