A Characteristic Evaluation of an Undershirt for Measurement of Bioelectricity Using Conductive Ink Wires

Abstract

Measurements of biological signals, such as those emanating from electrocardiography (ECG) and electromyography, are required in such fields as medical science, sports science, and robotics. There have been many studies that biological signals are measured using conductive cloth or textiles. Although the conductive materials were contact with the body, there have been few studies that considered the deterioration caused by deformation and moisture. We describe here an “undershirt" that we developed for measuring ECG signals. Its electrodes and wires are composed of conductive ink. We expected that even if the subject moved and perspired, measurement performance would not decrease. In our first experiment, we investigated characteristics of electrical resistance when the samples were deformed or became wet. The results indicated that the conductive ink wire was not broken by a 30% stretch or by bending it at a 1-mm curvature radius. The wire also maintained sufficient insulation resistance in the presence of 0.5 wt% NaCl aqueous solution. In the second experiment, ECG signals were measured via the undershirt with the ink wiring. The results showed that deformation of the ink wire on the undershirt is difficult to affect the ECG data.