Washing and abrasion resistance of conductive coatings for vital sensors

In the area of medical textiles, several applications necessitate conductive sensors, such as ECG or pulse measurements, breathing sensors, etc. Additionally, connections between electronic elements, data transfer units, and other parts of sensor networks need conductive paths. The resistance of conductive yarns or coatings against mechanical and chemical influences, however, is often low. Silver particles in coatings or on yarns, e.g., can oxidize during washing. Thin coatings can easily be abraded and offer only a low conductivity due to low layer height, while thicker coatings can be stiff and break during bending. In a recent project, we evaluate different coatings with respect to their resistance against mechanical stress due to abrasion against diverse materials, as a typical demand of sensory shirts or other medical textiles. Conductive silicone rubber, as well as graphite-polyurethane dispersions with different graphite concentrations, were coated on diverse textile fabrics in a defined height. Abrasion tests were performed on these samples using a linear abrasion tester. The electrical resistance of the conductive coatings was measured after each test cycle. Additionally, confocal laser scanning microscopy was used to detect micro-cracks or modifications of the coating surface. The article gives an overview of the results and depicts the advantages and challenges of the conductive coatings under examination.