Wearable ECG Recorder with Acceleration Sensors for Measuring 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.