Highly conductive and stretchable filament for flexible electronics

Abstract

Conductive and stretchable filaments are crucial for advancing additive manufacturing, particularly in flexible electronics. However, existing conductive filaments suffer from limitations in conductivity and stretchability. To overcome these challenges, this study presents a highly conductive and stretchable filament for material extrusion type 3D printing. The developed filament achieves an initial electrical conductivity of 558 S/cm and maintains low resistance up to 60 % strain with 10 vol% silver loading. This significantly surpasses the performance of commercial filaments and previous literature reports. The addition of polyethylene glycol (PEG) as a plasticizer for the silver filled thermoplastic polyurethane (Ag-TPU) composite enhances extrusion and improves filament surface quality. The printability of the filament in material extrusion 3D printing was evaluated, and the electrical conductivity of the printed objects was assessed. Two demonstrator structures, an electrical interconnection and a capacitive strain sensor, were successfully prototyped, showcasing the potential applications of this filament in stretchable electronics. The developed filament paves the way for creating intricate and stretchable electronic devices using material extrusion printing techniques. These advancements contribute to the field of additive manufacturing and enable the fabrication of flexible electronic components with enhanced conductivity and stretchability.