Abstract
Additive manufacturing (AM) provides a near-infinite design space to create unique and custom components. Recent advances have enabled the development of novel self-sensing materials for fused filament fabrication (FFF) AM, which have potential applications in areas such as soft robotics, smart textiles, embedded structural sensing, and, among others, biomedicine. Sensing in these fields is often done using traditional strain sensors that have limited capability for large deformations and little-to-no customizability. Through the use of piezoresistive filaments, AM has the potential to create highly customizable, application-specific sensors. However, the widespread adoption of self-sensing filament has been constrained due to developmental challenges, such as low conductivity and inconsistent or highly variable electrical properties. To address these issues, in this work, we manufacture a modified thermoplastic polyurethane (TPU) filament with 10 wt.% carbon nanofiber (CNF) inclusions using a novel wet-mixing technique previously developed within our research group. This CNF/TPU filament is flexible and has consistent electrical properties. Building on the extensive use of self-sensing composites in soft robotic applications, the CNF/TPU filament was embedded into a soft silicone skin to demonstrate sensing and localization of pressure points applied to the skin via simple electrical measurements taken from the printed and embedded CNF/TPU sensors. These preliminary results highlight the incredible potential and far-reaching design space of AM-produced sensors.
