Dispenser Printing with Electrically Conductive Microparticles

Abstract

Electrically conductive textiles for wearable smart devices are in increasing demand [1]. The advantages of flexible fabric structures are combined with electronic functions, such as sensing or actuating, energy harvesting or illuminating, for the design of a multitude of smart textiles. Those functions are often created by applying conductive layers or patterns onto the textile surface with two-phase systems based on conductive filler particles in polymeric binders. However, those systems alter the textile-typical properties regarding haptic, drape, flexibility or weight, depending on the type of conductive particle used, i.e., metal-or carbon-based ones. Generally, electrical conductivity increases with the increase of conductive filler concentration. The relation between the various factors determining the electrical behavior as well as the percolation threshold for some dispersions and in particular the size and shape of the filler particles were previously assessed for planar coatings [2]. In this research work electrically, conductive patterns were printed with dispenser printing technology using such two-phase dispersions based on polyurethane and polyacrylate binders and various metal microparticle flakes. With this application method linear resistance of approx. 25 to 100 Ohm per 100 cm depending on the textile structure could be realized, which was not even significantly reduced by household washing at 40°C or abrasion by Martindale.