Multidimensional evaluation of highly durable scalable and seamlessly integrated fiber-based electrodes for wearable applications

The emergence of “green” electronics is a response to the pressing global situation where conventional electronics contribute to resource depletion and a global build-up of waste. For wearable applications, green electronic textile (e-textile) materials present an opportunity to unobtrusively incorporate sensing, energy harvesting, and other functionality into the clothes we wear. However, the robustness and functional longevity of the majority of e-textiles made of green electronic materials are not sufficient. Here, we demonstrate knittable, washable, durable, electroactive fibers produced through a scalable roll-to-roll coating process using a biocompatible polymer:polyelectrolyte complex poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) ink. In order to analyze the fiber`s wetting behavior prior to coating, surface energy of synthetic fiber materials was evaluated. For the first time, the Owens, Wendt, Rabel and Kaelble (OWRK) approach along with the Washburn method were used to determine apparent surface energies of fiber materials and calculate the work of adhesion and interfacial tension between the conductive ink and fiber substates. The coated fibers developed in this study were successfully knitted into 3D textile electrodes using an industrial-scale knitting machine and machine washed for 60 times without any deterioration in performance to collect electrocardiogram signals. The wash durability of the coated fibers in combination with the scalable coating process make these fibers suitable to be integrated into smart textiles and wearable products for various application.