Controllable Microfluidic Fabrication of Microstructured Materials from Nonspherical Particles to Helices

Abstract

delivery, [1] drug release, [8] assembling, [9,10] packing, [11,12] and magnetic-driven motion. [13,14] For example, cylindrical microstructured materials self-assembled from copolymers can persist in the blood circulation of rodents ten times longer than their spherical counterparts. [2] Helical microstructured materials can convert rotational motion into translational motion in liquid media, such as water and blood, under remote control of a rotated magnetic field, showing great potential for many applications. [13,15] With such unique motion behaviors, helical microstructured materials can be utilized for uses such as picking and placing of microcargo, [14] mixing and pumping of fluid, [16] remote sensing of pH, [17] drilling of bovine tissues, [18] and cancer hyperthermia. [19] Thus, creation of uniform microstructured materials with versatile nonspherical and helical shapes is crucial for achieving advanced functions.Generally, microstructured materials with nonspherical and helical shapes can be produced by methods such as film-based extension of spherical microparticles, [20][21][22] mold-based template synthesis, [23,24] microfluidic-based template synthesis, [8,[25][26][27] and polymerization induced by 3D direct laser writing. [14] For example, incorporation of polystyrene-based microparticles in polymeric film, followed with 1D or 2D film extension, can produce various nonspherical microparticles. [20][21][22] By confining precursor solutions in differently shaped microwells of molds, nonspherical microparticles with flexible shapes can also be produced. [23,24] With excellent manipulation of microflows, [28][29][30] microfluidic technique provides a powerful platform for fabricating nonspherical microparticles with versatile structures and compositions. [26,31,32] Mask-assisted selective polymerization of photo-curable solution in microchannel can fabricate nonspherical microparticles with flexible shapes depending on their mask, [25,33] and the flow configuration. [34,35] Alternatively, monodisperse emulsion droplets from microfluidics, with versatile shapes, provide excellent templates for engineering uniform nonspherical microparticles. Deformed droplets confined by microchannel with different dimensions, [26,27] Janus droplets with one curable hemisphere, [31,36] and evolved acorn-shaped droplets from double emulsions, [32] can be generated from microfluidics for fabricating nonspherical microparticles with different shapes. However, for the above-mentioned methods, it is difficult to produce microstructured materials with complex Microstructured MaterialsThis work reports on a facile and flexible strategy based on the deformation of encapsulated droplets in fiber-like polymeric matrices for template synthesis of controllable microstructured materials from nonspherical microparticles to complex 3D helices. Monodisperse droplets generated from microfluidics are encapsulated into crosslinked polymeric networks via an interfacial crosslinking reaction in microchannel to in situ produce the droplet-...

Designable 3D Microshapes Fabricated at the Intersection of Structured Flow and Optical Fields

“…Microfluidic approaches to nonequilibrium particle and fiber synthesis also have a limited library of possible 3D geometries. Droplet‐based approaches to nonspherical particle fabrication are restricted to creating particles with equilibrium surface features because the factors that determine the shape of the interface between immiscible fluids are surface tension dominated . While flow‐lithography based particle fabrication, in which photocurable polymers are flowed through a microfluidic chip and polymerized by UV light passing through a photomask, has shown to have excellent control of particle shape along a single 2D extrusion axis, a similar level of shape control in the direction of flow is yet to be achieved .…”

Preparation of ethyl cellulose particles with different morphologies through microfluidics

“…Recently, microfluidics 14,15 has attracted wide attention in the synthesis of micro/nano particle materials due to its unique advantages such as the micro-volume, high efficiency, high throughput, miniaturization, integration and automation. 16,17 The microfluidic technique could control the droplet size precisely, and thus, these monodisperse droplets could be used as the template to generate particles of uniform size.…”

“…Hwangbo et al 22 successfully generated uniform golf-ball-like particles with an internal porous structure by forming organic droplet containing polymers and inert organic volatile materials. By using microfluidics, Wang et al 16 produced monodisperse droplets which are in situ encapsulated into crosslinked polymeric networks via the interface crosslinking reaction. By stretching and twining the dried fiber-like matrices, the encapsulated droplets can be engineered into versatile shapes from tablets to helixes.…”

Microfluidic synthesis of ultrasmall Co nanoparticles over reduced graphene oxide and their catalytic properties

“…A variety of nano/micromaterials have been continuously synthesized in a microreactor. The as‐prepared materials can be simply classified into inorganic single‐component micro/nanoparticles (e.g., Ag, Au, Pd, CdS, layered double hydroxides, ZIF‐8, In(OH) 3 ), inorganic micro/nanocomposites (e.g., Ag@Cu 2 O, MOF@SiO 2 ), and polymeric‐based materials . In the case of single‐component micro/nanoparticles, considerable efforts have been devoted to achieve how to manipulate the particle size and morphology of micro/nanoparticles.…”