Analysis of electrical and comfort properties of conductive knitted fabrics based on blending ratio of silver-coated yarns for smart clothing

In this study, the relationship between the functionality and comfort of conductive fabrics for smart clothing is investigated by examining changes in the mechanical, electrical, and comfort properties of knitted fabrics based on the blending ratio of conductive yarns. Hence, flat knitted fabrics of the same structure are manufactured using polyester and silver-coated polyamide yarns. Subsequently, their weight, thickness, tensile strength, tensile strain, bending rigidity, breathability, surface properties are measured, and their cool touch feeling, surface resistance, and electrical heating performance are evaluated. Because the strength and specific gravity of a silver-coated conductive yarn are high, with an increase in its blending ratio, its weight, tensile strength, and bending rigidity increase, whereas its strain decreases. In terms of the comfort properties, the air permeability increases as the blending ratio of the conductive yarn increases, because the pores on the surface of the knitted fabric are increased structurally owing to the conductive yarns. However, the water vapor transmission rate remains unchanged. Meanwhile, the surface roughness does not change significantly in the wale direction; however, it increases in the course direction as the blending ratio of the conductive yarn increases. The recoverability from compression decreases, and the work of compression increases as the blending ratio of the conductive yarn increases. This implies that the conductive fabric can be compressed easily but is less likely to recover from compression. Changes in the surface roughness and compression property show that the hand value of the knitted fabric is altered by the insertion of the conductive yarn. The electrical properties improved by increasing the blending ratio of the conductive yarns. In particular, even with only 33% insertion of conductive yarns, extremely good electrical properties are obtained, that is, low resistance, sensitive resistance change due to stretching, and heating of 48°C. Therefore, blending conventional and conductive yarns instead of using only conductive yarns improve comfort and wearability when applying conductive knitted fabrics to smart clothing.