In-Fiber Breakup

In recent years, multifunctional multimaterial fibers based on the thermal drawing process have made considerable development, which enables various practical fiber devices with optoelectronics, photonics, acoustics, biomedicine, and energy harvesting functionalities. The future development of multifunctional fibers requests highly integrated ingenious in-fiber structures and excellent material properties. To meet these challenges, the technologies of using fluidic instabilities induced in-fiber breakup phenomena are presented, allowing us a way to modify the traditional axially invariant in-fiber structure and to achieve in-fiber material engineering. The post-drawing thermal treatment can soften the selective part of the functional fibers, induce perturbations on the interface between materials, and eventually break the continuous fiber inner structures to fabricate in-fiber functional structures. The in-fiber breakup process enables the fabrication of in-fiber structured particles by a variety of materials with a wide range of processing temperatures from 2400 to 400 K and material viscosity ratio of 10 orders. Moreover, the in-fiber breakup process provides a useful tool to form fiber-based functional devices. On the other hand, the fundamental understanding of the in-fiber breakup phenomena shall be contributing to optimizing the fiber thermal drawing process. By selecting suitable materials and suppressing the in-fiber breakup phenomena, the designed structure of the fiber preforms will be preserved in maximum. This chapter covers aspects of (1) the introduction and theory of thermal treatment induced in-fiber fluidic instabilities, (2) the in-fiber fabrications based on in-fiber breakup process, (3) potential applications of in-fiber breakup process, and (4) the future research directions.