A Wearable Single-Arm Electrocardiograph System: Design and Experimental Evaluation

Electrocardiographic (ECG) signals play a key role in many healthcare applications, especially in out-ofhospital monitoring of vital signs. Wearable technologies are used for this purpose, but they often produce low-quality ECG signals or interfere with the user’s daily activities and do not provide automatic acquisition since they require human intervention. Implantable loop recorders (ILRs) or Holter devices record high-quality signals but have disadvantages related to expensive surgical procedures and risks of infection. On the other hand, smartwatches or smartphone-based ECG recorders interfere with users’ daily routines as they require touching specific metal pads on the measurement device and, for this reason, are only suitable for intermittent monitoring. In this article, we design and implement an ECG acquisition device to be worn on the arm for long-term acquisition. The device respects the characteristics of comfort and autonomy, and could also be useful in the future for automatic recognition of cardiac arrhythmias. In addition, our study analyzes the intensity and attenuation of the ECG signal at different positions along the arm, in order to investigate how its amplitude varies as the distance from the heart increases. The amplitude of the trace in the upper arm, measured in µ V, decreases with increasing distance from the heart but remains sufficient for clear identification up to the elbow. R-peaks show mean values in the order of 10-5 in the upper arm, decreasing to 10-6 in the elbow area, with standard deviations in the order of 10-6