Fundamental Research for Leg Band Type Wearable Electrocardiogram Monitor-Examination of Electrode Position and Construction of Basic System

With a view to future development of wearable leg-band device for daytime electrocardiogram (ECG) monitoring, we explored viable electrode configurations on the surface of the left thigh for three human subjects. A configuration composed of outer two segments in the top and the third stages for negative and positive electrodes, and of inner one segment in the second stage for indifferent electrode (we call this configuration as the site_c1c3f2) were compared with another configuration composed of outer two segments in the second and forth stages for negative and positive electrodes, and of inner one segment in the third stage for indifferent electrode (we call this as the site_c2c4f3) in terms of signal quality of measured ECG. By virtue of a self-produced bioamplifier with high common mode rejection (>90 dB), mean detection rate of sensitivity, accuracy and positive predictive value of ECG R wave during rest were 84.3%, 79.6% and 88.3%, respectively, for the site_c1c3f2. Whereas, those for the site_c2c4f3 were 5.2%, 2.1% and 4.1%, respectively. In the use of the site_c1c3f2 and a constructed interface circuit, left-thigh ECG were wirelessly transmitted and successfully displayed on a tablet computer.