Wearable ECG recorder with acceleration sensors for monitoring daily stress: office work simulation study.

A small and light-weight wearable electrocardiograph (ECG) equipment with a tri-axis accelerometer (x, y and z-axis) was developed for prolonged monitoring of everyday stress. It consists of an amplifier, a microcomputer with an AD converter, a triaxial accelerometer, and a memory card. Four parameters can be sampled at 1 kHz for more than 24 h and a maximum of 27 h with a default battery and a memory card of one giga byte (1 GB). Off-line data processing includes motion information along three axes and autonomic nervous system (ANS) activity bispectral analysis and the tone-entropy method (T-E method) from HRV data. The availability of the system was tested through simulated office work and three-day monitoring by replacing the battery and the memory card every 24 h. Both short-term and circadian rhythms of ANS activity were clearly observed. In addition, sympathetic nervous activities gradually increased from the second to the third day. The experimental data presented verifies the functionality of the proposed system.