Microfluidic manufacture of composite fibers for biomedical applications

Fibrous materials are essential structural elements widely distributed throughout natural systems. In order to replicate and harness the unique properties of natural fibers, microfluidic technologies have been employed and refined to allow for a precise control over the mechanical properties, diameter, alignment, and morphology of spun fibers. To further their versatility and adaptability, and to better mimic their natural counterparts, microfluidics technologies have also allowed for the integration of multiple materials and functional components at the microscale giving rise to composite fibers. These fibers, composed of a combination of different materials, offer a wide range of properties and functionalities that surpass those of their individual components and can be tailored to specific applications. This review discusses various microfluidic fabrication methods, highlighting their advantages and limitations. The review also compares natural and synthetic polymers employed in microfluidic fiber manufacture and examines the influence of process parameters on the properties of composite fibers, such as mechanical strength, porosity, and biocompatibility and discusses the incorporation of nanoparticles, biomolecules, and microstructures within the fibers to tailor their functionality for specific biomedical applications. Finally, the paper provides an outline of current trends as well as future directions for the field.