Controllable Microfluidic Fabrication of Magnetic Hybrid Microswimmers with Hollow Helical Structures

Abstract

Controllable magnetic hybrid microswimmers with hollow helical structures are fabricated, by a facile strategy based on microfluidic template synthesis and biosilicification, to achieve enhanced rotation-based locomotion for cargo transport. The magnetic hybrid microswimmers are fabricated by first synthesizing Fe 3 O 4 -nanoparticles-containing helical Caalginate microfibers from microfluidics, followed with biosilicification and controllable dicing to engineer their rigid hollow helical structures. The microswimmers show hollow helical structures consisting of a rigid, biocompatible alginate/protamine/silica shell embedded with Fe 3 O 4 nanoparticles. Their helical structures can be engineered into open tubular structures or closed compartmental structures by using microfibers or diced microfibers as templates for biosilicification. Powered by a simple rotating magnet, the microswimmers can achieve enhanced rotation-based locomotion and provide good mechanical strength for supporting cargo for transportation. This work provides a simple and efficient strategy for fabricating controllable magnetic hybrid microswimmers with hollow helical structures to achieve enhanced rotationbased locomotion for cargo transport, encapsulation, and delivery.

Magnetically Driven Micro and Nanorobots

“…(F) Fabrication of helical microrobots with hollow structures with the assistance of coiled flow template. Reproduced with permission from ref ( 223 ). Copyright 2018 American Chemical Society.…”

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.…”

Bioinspired Polymeric Helical and Superhelical Microfibers via Microfluidic Spinning

“…As shown in Figure g–i, at constant Q in = 200 µL h −1 and Q out = 3.0 mL h −1 , both λ 1 and A 1 decreased with increasing viscosity of the outer phase, due to the increased shear force applied on the jet/fiber of the inner phase. It is worth noting that, as one of the most important parameters of helical structures, the amplitude of the reported microfluidic spinning helical fibers mainly depended on the inner dimension of the collection tube, and thus could not be adjusted once the device was made . To our knowledge, this is the first report showing highly online controllable amplitude of such helical microfibers.…”

“…These methods often exhibited less control over the composition, λ, d , A and length of the helical fibers. Recently, substantial elegant achievements have been made in microfluidic spinning helical microfibers via liquid rope coiling effect within the microchannels . However, these helical microfibers were mainly restricted to the Ca‐alginate system due to its unique and rapid gelation/solidification process.…”

“…So the application of these helical fibers is limited due to the restricted availability of materials . Additionally, the A of these helical fibers mainly depended on the inner dimension of the collection tube, and thus could not be adjusted once the device was made …”