Textile sensors, when embedded into clothing, can provide new ways of monitoring physiological signals, and improve the usability and comfort of such monitoring systems in the areas of medical, occupational health and sports. However, good electrical and mechanical contact between the electrode and the skin is very important, as it often determines the quality of the signal. This paper introduces a study where the properties of dry textile electrodes, textile electrodes moistened with water, and textile electrodes covered with hydrogel were studied with five different electrode sizes. The aim was to study how the electrode size and preparation of the electrode (dry electrode/wet electrode/electrode covered with hydrogel membrane) affect the measurement noise, and the skin-electrode impedance. The measurement noise and skin-electrode impedance were determined from surface biopotential measurements. These preliminary results indicate that noise level increases as the electrode size decreases. The noise level is high in dry textile electrodes, as expected. Yet, the noise level of wet textile electrodes is quite low and similar to that of textile electrodes covered with hydrogel. Hydrogel does not seem to improve noise properties, however it may have effects on movement artifacts. Thus, it is feasible to use textile embedded sensors in physiological monitoring applications when moistening or hydrogel is applied.

Textile sensors, when embedded into clothing, can provide new ways of monitoring physiological signals, and improve the usability and comfort of such monitoring systems in the areas of medical, occupational health and sports. However, good electrical and mechanical contact between the electrode and the skin is very important, as it often determines the quality of the signal. This paper introduces a study where the properties of dry textile electrodes, textile electrodes moistened with water, and textile electrodes covered with hydrogel were studied with five different electrode sizes. The aim was to study how the electrode size and preparation of the electrode (dry electrode / wet electrode / electrode covered with hydrogel membrane) affect the measurement noise, and the skin-electrode impedance. The measurement noise and skinelectrode impedance were determined from surface biopotential measurements. These preliminary results indicate that noise level increases as the electrode size decreases. The noise level is high in dry textile electrodes, as expected. Yet, the noise level of wet textile electrodes is quite low and similar to that of textile electrodes covered with hydrogel. Hydrogel does not seem to improve noise properties, however it may have effects on movement artifacts. Thus, it is feasible to use textile embedded sensors in physiological monitoring applications when moistening or hydrogel is applied.

New miniaturized portable electrocardiogram (ECG) measuring devices may require small interelectrode distance. However, finding a suitable location for a tiny measurement device may prove tedious, as reducing interelectrode distance reduces signal strength. The objective of the study was to define the optimal location for a very closely located (5 cm) bipolar electrode pair. A total of 120 bipolar leads were analyzed from a body surface potential map (BSPM) data with 236 subjects with a normal ECG. The average and standard deviation (SD) of the QRS-complex and the P-wave amplitudes in each electrode location and for each subject were determined. The results showed that deviation in signal amplitude between different subjects is significant. However, judging from average values, the best orientation for a closely located bipolar electrode pair is diagonally on the chest. The best locations for QRS-complex and P-wave detection are around the chest electrodes of the standard precordial leads V2, V3, and V4, and above the chest electrodes of leads V1 and V2, respectively.

A head cap made of fabric for measuring EOG and facial EMG signals is presented. Reusable and easy to use electrodes, embroidered of silver coated thread, are integrated into the cap. A two-way wireless data transmission link operating at license free 2.4 GHz frequency band is used for transferring the 16-bit measurement data, sampled with 1 kHz frequency from six channels at maximum, to the receiver device connected to a PC. Tailored PC software is used for displaying the signals and controlling the measurement parameters. The measurement system is intended for recording facial expressions during human emotion studies but it can also be utilized in computer user interface control. The paper shows preliminary results from EOG and facial EMG measurements.

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