Esmaeil-Hooman Banaei

Structured spheres generated by an in-fibre fluid instability

From drug delivery to chemical and biological catalysis and cosmetics, the need for efficient fabrication pathways for particles over a wide range of sizes, from a variety of materials, and in many different structures has been well established. Here we harness the inherent scalability of fibre production and an in-fibre Plateau–Rayleigh capillary instability for the fabrication of uniformly sized, structured spherical particles spanning an exceptionally wide range of sizes: from 2 mm down to 20 nm. Thermal processing of a multimaterial fibre controllably induces the instability, resulting in a well-ordered, oriented emulsion in three dimensions. The fibre core and cladding correspond to the dispersed and continuous phases, respectively, and are both frozen in situ on cooling, after which the particles are released when needed. By arranging a variety of structures and materials in a macroscopic scaled-up model of the fibre, we produce composite, structured, spherical particles, such as core–shell particles, two-compartment ‘Janus’ particles, and multi-sectioned ‘beach ball’ particles. Moreover, producing fibres with a high density of cores allows for an unprecedented level of parallelization. In principle, 108 50-nm cores may be embedded in metres-long, 1-mm-diameter fibre, which can be induced to break up simultaneously throughout its length, into uniformly sized, structured spheres.

Multimaterial preform coextrusion for robust chalcogenide optical fibers and tapers.

The development of robust infrared fibers is crucial for harnessing the capabilities of new mid-infrared lasers. We present a novel approach to the fabrication of chalcogenide glass fiber preforms: one-step multimaterial extrusion. The preform consists of a glass core and cladding surrounded by a built-in, thermally compatible, polymer jacket for mechanical support. Using this approach we extrude several preform structures and draw them into robust composite fibers. Furthermore, the polymer cladding allows us to produce robust tapers with submicrometer core diameter.

In-fiber production of polymeric particles for biosensing and encapsulation

Significance A scalable, chemistry-independent, fluid-instability–mediated in-fiber route for fabricating uniformly sized spherical polymeric particles over a wide span of diameters is developed targeting biomedical applications. Both surface functionalization of solid biocompatible polymer particles for protein–protein interactions and volume encapsulation of a biological material in spherical hollow polymer shells are confirmed, in addition to combining both surface and volumetric functionalities in the same polymeric particle. Polymeric micro- and nanoparticles are becoming a mainstay in biomedicine, medical diagnostics, and therapeutics, where they are used in implementing sensing mechanisms, as imaging contrast agents, and in drug delivery. Current approaches to the fabrication of such particles are typically finely tuned to specific monomer or polymer species, size ranges, and structures. We present a general scalable methodology for fabricating uniformly sized spherical polymeric particles from a wide range of polymers produced with complex internal architectures and continuously tunable diameters extending from the millimeter scale down to 50 nm. Controllable access to such a wide range of sizes enables broad applications in cancer treatment, immunology, and vaccines. Our approach harnesses thermally induced, predictable fluid instabilities in composite core/cladding polymer fibers drawn from a macroscopic scaled-up model called a “preform.” Through a stack-and-draw process, we produce fibers containing a multiplicity of identical cylindrical cores made of the polymers of choice embedded in a polymer cladding. The instability leads to the breakup of the initially intact cores, independent of the polymer chemistry, into necklaces of spherical particles held in isolation within the cladding matrix along the entire fiber length. We demonstrate here surface functionalization of the extracted particles for biodetection through specific protein–protein interactions, volumetric encapsulation of a biomaterial in spherical polymeric shells, and the combination of both surface and volumetric functionalities in the same particle. These particles used in distinct modalities may be produced from the desired biocompatible polymer by changing only the geometry of the macroscopic preform from which the fiber is drawn.

Fiber luminescent solar concentrator with 5.7% conversion efficiency

Luminescent Solar Concentrators (LSC’s) are a promising alternative for reducing the cost of solar power. Exploiting the advantages of optical fiber production, we present here a Fiber LSC (FLSC) in which the waveguide is a polymer optical fiber. We present modeling, fabrication and optical characterization of FLSC (conversion efficiency ~ 5.7%) with a hybrid fiber structure for two-stage concentration of incident light. Directional guiding in fiber allows for at least twofold geometrical gain improvement compared to conventional LSC. It also alleviates the size limitation of conventional LSC’s in one direction. Light-weight, flexible solar sheets assembled from such fibers can provide a means for mobile energy needs.

In-fiber fabrication of size-controllable structured particles

We present an approach for fabricating single-material and multi-material structured spherical particles in the size range 1 millimeter to 50 nanometers that makes use of the Plateau-Rayleigh capillary instability in a multi-material fiber.

Fiber luminescent solar concentrator fabrics

We present the design, fabrication, and characterization of all-polymer optical fiber luminescent solar concentrators. Large-area, lightweight, and flexible fabrics constructed of such fibers are a low-cost solar-energy harvesting alternative useful for mobile applications.

One-step multi-material preform extrusion for robust chalcogenide glass optical fibers and tapers

We demonstrate a novel process of one-step extrusion of multi-material fiber preforms containing chalcogenide glasses and polymers. The polymer lends mechanical robustness to the drawn chalcogenide infrared fibers and tapers.

Design and fabrication of polymer-fiber-based luminescent solar concentrator fabrics

We present the design and fabrication of all-polymer optical fiber luminescent solar concentrators. Large-area, lightweight, and flexible fabrics constructed of such fibers are a low-cost solar-energy alternative useful for mobile applications.