Using Chaos for Facile High-throughput Fabrication of Ordered Multilayer Micro- and Nanostructures

Abstract

This paper introduces the concept of continuous chaotic printing, i.e., the use of chaotic flows for deterministic and continuous fabrication of fibers with internal multilayered micro-or nanostructures. Two free-flowing materials are coextruded through a printhead containing a miniaturized Kenics static mixer (KSM) composed of multiple helicoidal elements. This produces a fiber with a well-defined internal multilayer microarchitecture at high speeds (>1.0 m min-1). The number of mixing elements and the printhead diameter determine the number and thickness of the internal lamellae, which are generated according to successive bifurcations that yield a vast amount of inter-material surface area (~102 cm2 cm-3) and high resolution features (~10 µm). In an exciting further development, we demonstrate a scale-down of the microstructure by 3 orders of magnitude, to the nanoscale level (~10 nm), by feeding the output of a continuous chaotic 3D printhead into an electrospinner. Comparison of experimental and computational results demonstrates the robust and predictable output and performance of continuous chaotic 3D printing. The simplicity and high resolution of continuous chaotic printing strongly supports its potential use in novel applications, including-but not limited to-bioprinting of multi-scale tissue-like structures, modeling of bacterial communities, and fabrication of smart multi-material and multilayered constructs.

Fabrication of Multilayered Composite Nanofibers Using Continuous Chaotic Printing and Electrospinning: Chaotic Electrospinning

“…ChE combines CCP technology [31,32] and far field electrospinning into a versatile and scalable nanofabrication technique for synthesizing nanofibers with internal multilayered structures. Initially, alternated micro-layers of two flowing materials are formed inside a chaotic static mixer and are then extruded through the spinneret, where the electrospinning jetting stretches the chaotic structure into the nano domain (Figure 1).…”

“…For CCP, the combination of polymer solutions should be compatible in terms of interfacial tension and polarity. [31,32] Additionally, both flowing materials should behave as Newtonian liquids within the window of shear rates that they experience when extruded along the mixer. This compatibility and Newtonian behavior will allow the polymer solutions to flow stably side-to-side (without mixing), creating defined layers during CCP.…”

“…This compatibility and Newtonian behavior will allow the polymer solutions to flow stably side-to-side (without mixing), creating defined layers during CCP. [31,32] For the electrospinning stage, the blend must exhibit adequate ionic conductivity and viscoelastic profile to establish and sustain the electrospinning jet and produce coherent nanofibers steadily. [5,22] Moreover, ChE involves additional challenges.…”

Simultaneous Regeneration of Bone and Nerves Through Materials and Architectural Design: Are We There Yet?

“…[ 331 ] Recently developed technologies, such as continuous chaotic printing, can fabricate multiscale layered tissue structures as well as multimaterial and multilayered constructs such as organoids. [ 334 ] These studies demonstrate the immense potential of heterogeneous scaffolds fabricated through 3D printing for simultaneous regeneration of bone and nerves ( Figure ). Simultaneous bone regeneration and angiogenesis within a bone defect has been made possible with the advent of 3D printing.…”

Recent progress in extrusion 3D bioprinting of hydrogel biomaterials for tissue regeneration: a comprehensive review with focus on advanced fabrication techniques

“…the number of layers and the average spacing between them) within a single 3D printed fiber. The principal part of this technological platform is the use of an on-line static mixer in the printhead for presenting a partial mixing of various materials as they are coextruded through the nozzle [333].…”