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Recording high quality biosignals by dry textile electrodes is a common challenge in medical health monitoring garments. The aim of this study was to improve skin-electrode interface and enhance the quality of recorded electrocardiography (ECG) signals by modification of textile electrodes embedded in WearItMed smart garment. The garment has been developed for long-term health monitoring in patients suffering from epilepsy and Parkinson's disease. A skin-friendly electro-conductive elastic paste was formulated to coat and modify the surface of the knitted textile electrodes. The modifications improved the surface characteristics of the electrodes by promoting a more effective contact area between skin and electrode owing to a more even surface, fewer pores, greater surface stability against touch, and introduction of humidity barrier properties. The modifications decreased the skin-electrode contact impedance, and consequently improved the recorded ECG signals obviously when low pressure was applied to the electrodes, therefore contributed to greater patient comfort. The created contact surface allowed the natural humidity of the skin/sweat to ease the signal transfer between the electrode and the body, while introducing a shorter settling time and retaining moisture over a longer time. Microscopic images, ECG signal measurements, electrode-skin contact impedance at different pressures and times, and water absorbency were measured and reported.

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A melt-processable polyaniline complex was blended with polypropylene under different mixing conditions and melt-spun into fiber filaments under different draw ratios. The conductivity, electrical resistance at different voltages, and morphological characteristics of the prepared fibers were investigated. The morphology of this two-phase blend was demonstrated to have a large effect on the conductivity level and the linearity of the resistance-voltage relationship of the blend fibers. Two factors had substantial effects on the morphology and electrical properties of the fibers. They were the size of the initial dispersed conductive phase, which depended on the melt blending conditions, and the stress applied to orient this phase to a fibril-like morphology, which was controlled by the draw ratio of the fiber. The two factors were shown to be associated with each other to maintain an appropriate balance of fibril formation and breakage and to create continuous conductive pathways.

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The impact of the composition of blends comprising low-density polyethylene (LDPE), isotactic polypropylene (PP) and a styrenic copolymer additive on the thermomechanical properties as well as the direct-current (DC) electrical and thermal conductivity is investigated. The presence of 5 weight percent (wt%) of the styrenic copolymer strongly reduces the amount of PP that is needed to enhance the storage modulus above the melting temperature of LDPE from 40 to 24 wt%. At the same time, the copolymer improves the consistency of the thermomechanical properties of the resulting ternary blends. While both the DC electrical and thermal conductivity strongly decrease with PP content, the addition of the styrenic copolymer appears to have little influence on either property. Evidently, PP in combination with small amounts of a styrenic copolymer not only allows to reinforce LDPE at elevated temperatures but also functions as an electrical conductivity-reducing additive, which makes such thermoplastic ternary formulations possible candidates for the insulation of high-voltage power cables.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Blends of polypropylene with multi-walled carbon nanotubes (CNT) have been prepared and melt spun to fibre filaments. The resulted filaments have been characterised regarding conductivity, thermal properties, and morphology. DSC suggests that carbon nanotubes act as nucleating sites in polypropylene and the TGA shows a high increase in thermal stability. Conductivity around 0.001 S/cm are achieved for both as-spun fibre and drawn fibre. A higher load of CNT up to 15 wt % increases the conductivity to 2.8 S/cm in as-spun fibre, but due to a high fibre diameter variation during spinning resulting in fibre breakage, melt spinning is very difficult. This is due to a non-uniform stress distribution during the drawing steps which can be a result of a non-homogeneous PP-CNT blend and the spinning machine process limitations. Differences in conductivities for extruded rods, as-spun fibre and drawn fibre which are made from the same blends, suggests that the crystallinity can affect the conductivity of the PP/CNT fibre.

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