Stretchable Optical and Electronic Fibers via Thermal Drawing

Stretchable optical and electronic fibers constitute increasingly important building blocks for a myriad of emerging applications, such as smart textile, robotics, or medical implants. Yet, it remains challenging to fabricate efficient and advanced soft fiber-base devices in a simple and scalable way. Conventional fiber manufacturing methods, such as wet and dry spinning, or extrusion, are not well adapted to fabricate multi-material functional fibers. The preform-to-fiber thermal drawing technique on the other hand is an emerging powerful platform to fabricate multi-material fibers with complex architectures and functionalities. Thus far however, this fabrication approach has been restricted to rigid thermoplastic or glass fibers. In this contribution we will show how we could revisit the selection criteria for cladding materials compatible with the thermal drawing process. In particular, thanks to a deeper rheological characterization, we could identify thermoplastic elastomers that could be drawn from a solid preform at high viscosity. Subsequently, we will demonstrate that thermoplastics, metals, and conductive polymer composites could be co-drawn with prescribed architectures within thermoplastic elastomer cladding. This allowed us to successfully fabricate stretchable optical and electronic fibers that are used as precise and robust pressure and strain sensors, as well as soft and stretchable waveguides as we will show via concrete examples, the ability to thermally draw soft multi-material fibers open new opportunities not only for exploring new academic research directions, but also in industrializing fiber-based flexible and stretchable devices for applications in sensing, health care, robotics and smart textiles.