Table 3.

Summary of the main findings of the investigation

Parameter	Textile electrodes results	Textile electrodes vs Ag/AgCl electrodes
Contact impedance measurements	There are not significant differences between the different textile electrodes. The impedance is resistive-capacitive type reflected in the decrease in impedance with the increase in frequency	There are significant differences between textile electrodes and commercial electrodes. The contact impedance in the Ag/AgCl electrodes is lower
Polarization measurements	There are not significant differences between textile electrodes. The polarization signals are that they do not present variation in time, that is, the signals tend to be constant, which implies that they can be easily removed using analog instrumentation (AC coupling circuit) of by digital filtering (DC coupling). This is the most important finding in polarization measurements	There are significant differences between textile electrodes and commercial electrodes. The contact impedance at the electrodes of Ag/AgCl is lower. The average polarization obtained with the textile electrodes is 15.4 mV while the average polarization obtained with the commercial electrodes is less than 2 mV
Noise measurements	There are not significant differences between textile electrodes. In spite of the high measured polarization, textile electrodes correctly acquire cardiac signals with all their morphological components	The noise signals measured with textile electrodes are greater than with commercial electrodes; however, this noise is easily removable using digital filtering and the morphological components of the ECG signal can be identified successfully
Long-term performance measurements	After 36 h of adhering the electrodes to the test subject, the textile electrodes remain functional in the acquisition of cardiac signals with all their components. The only electrode that shows deterioration for the acquisition of the ECG signal are the nylon–silver electrodes	No tests were performed with commercial electrodes in long-term. In each measurement new Ag/AgCl electrodes are used to compare with the textile electrodes. The Ag/AgCl electrodes used are disposable. According to hospital standards, disposable electrodes should be replaced at least every 24 h and after a long time can generate irritation on the skin