Fabien Sorin1

1, Ecole Polytechnique Federale de Lausanne, Switzerland, Lausanne, , Switzerland

The integration of complex functionalities within fibers and fabrics is at the heart of the technological turn the Textile industry has to take. Many strategies are being developed to functionalize fibers and textiles via a direct and selective coating of the already made fiber and fabric. An alternative strategy relies on thermally drawing a fiber from a preform that already contains the desired functional materials within a cladding. This approach enables to realize fiber-integrated devices with complex architectures and functionalities, at the scalability traditionally associated with optical fibers. Thus far however, the cladding materials have been made out of rigid thermoplastic or glasses that could not respond to mechanical external stimuli. In particular, they can only be deformed elastically by strains of a few percent, preventing any monitoring of deformation or pressure by multi-material fibers. More over, biodegradability of some polymers have not been exploited to make multi-material fiber responding to their surrounding by releasing substances in a controlled way.
In this presentation, we will show how we can provide fibers with novel structures and materials that can respond to any mechanical stimulations. We will first show how we can structure a fiber with rigid yet bendable domains to act as a distributed pressure sensor. We will then show how we can expand the map of materials compatible with the thermal drawing process, by looking at the required rheological and microstructural attributes at a deeper level. This analysis will point us towards some thermoplastic elastomers that can be thermally drawn with similar rheology as their thermoplastic counterparts, hence enabling the fabrication of stretchable multi-material fibers. We will show a variety of configurations where optical and electronic fibers can sense and differentiate pressure, strains or shear in a reliable and robust way. Finally, we will show how our analysis also enabled us to identify biodegradable polymers compatible with the thermal drawing process. We will demonstrate fibers with complex microstructures that can be tailored to deliver different substances at controlled times. These advances in fiber architectures and materials opens novel opportunities for fiber-based devices in the fields of stretchable optics and electronics, health care and drug release, and smart textiles.