Evaluating the effect of textile material and structure for printable and wearable e-textiles

During the fabrication of printed e-textile devices, it is often necessary to print a low-cost polymer interface layer to level the surface of the fabrics. The typical thickness of this interface layer is usually greater than the thickness of the fabric. This significantly affects the flexibility and wearability of the printed e-textile. This paper investigates the thickness reduction of the interface layer by studying the effect of the textile material and its thread count on the surface roughness and thickness of the printed interface. This is achieved by screen printing a polyurethane interface layer on fabrics of five different fabric materials and thread counts. The results show that the surface roughness of the fabrics and the printed interface layer thickness reduce at higher thread counts. More importantly, the thickness of the interface layer significantly reduces with the use of fabrics with high polyester content. A $50~\mu \text{m}$ thick polyurethane interface layer with a surface roughness, ${R}_{a}$ value of $1.7~\mu \text{m}$ is reported on a 100% plain weave polyester fabric. The PU thickness is 4 times less than the state of the art and shows more than 80 % reduction in the proportion of interface material to fabric thickness of the printed e-textile. This minimizes the impact of the printed film on the fabric.