Microfluidic Lithography of Bioinspired Helical Micromotors

Abstract

Considerable efforts have been devoted to developing artificial micro/nanomotors that can convert energy into movement. A flow lithography integrated microfluidic spinning and spiraling system is developed for the continuous generation of bioinspired helical micromotors. Because the generation processes could be precisely tuned by adjusting the flow rates and the illuminating frequency, the length, diameter, and pitch of the helical micromotors were highly controllable. Benefiting from the fast online gelation and polymerization, the resultant helical micromotors could be imparted with Janus, triplex, and core–shell cross‐sectional structures that have never been achieved by other methods. Owing to the spatially controlled encapsulation of functional nanoparticles in the microstructures, the helical micromotors can perform locomotion not only by magnetically actuated rotation or corkscrew motion but also through chemically powered catalytic reaction.

Requirement and Development of Hydrogel Micromotors towards Biomedical Applications

“…A nano/-micromotor part can be positioned inside or outside the hydrogel particles to fabricate hydrogel micromotors. Generally speaking, micromotors can be produced by a rich variety of fabrication methods including the Layer-by-Layer (LbL) assembly [34], the rolled-up nanomembranes [35], the emulsion solvent evaporation for generation of oil-in-water droplets [36], the glass capillary-based microfluidic lithography [37], the template-assisted electrodeposition [38], the replica molding of polydimethylsiloxane (PDMS) template [39], and the dynamic shadow growth method [40], to name a few examples.…”

“…Micromotors with different 3D configurations exhibit distinct motion behaviors and have been applied to different scenarios. Taking the micromotors controlled by magnetic field as examples, a magnetic helical microstructure powered by rotating magnetic fields can show rotation or corkscrew motion [37]. This kind of helical micromotor, when equipped with a hard shell, is particularly suitable to remove necrotic tissue because the corkscrew motion and the helical shape together could make the micromotor work as a microdrill.…”

Microfluidics for Microswimmers: Engineering Novel Swimmers and Constructing Swimming Lanes on the Microscale, a Tutorial Review

“…[43][44][45]47,[49][50][51] For instance, Zhou et al used a droplet microfluidic based fiber-confined approach to engineer microswimmers with spindle, drum, zigzag, and bi-layer shapes (Figure 2C), [44] while others have utilized a microfluidic lithography technique with spinning and spiraling systems to engineer bubble driven and magnetically actuated helical shaped swimmers. [52] Recently, inspired by theoretical predictions [53] we employed a stop flow lithography technique to fabricate enzyme driven "S" shaped rotors, "U" shaped propellers and "l" shaped pumps. [54] This fabrication strategy is known to engineer particles with tunable structures and thus provides an edge over other methods, particularly the freedom in selecting shapes and controlling the active regions in the fabricated structures.…”

“…Most of the reported work has used inorganic materials such as Pt [43][44][45][49][50][51][52] to drive bubble-propelled swimmers, with some exceptions striving to develop a biocompatible microswimmer using an enzymatic biocatalyst. [47] Keller et al fabricated catalase loaded poly(ethylene glycol) diacrylate (PEGDA) microswimmers using droplet microfluidics where the enzyme induced decomposition of H 2 O 2 fuel led to the hydrogel swimmers' propulsion.…”

Microfluidic Generation of Nanomaterials for Biomedical Applications

“…[44][45][46][47][48] For materials fabrication, microfluidics executes precise control over reaction procedures, and generates NMs with a defined size and morphology. [49][50][51][52][53][54][55][56][57] Owing to the homogeneous reaction environment, the production efficiency and monodispersity of generated materials from microfluidics are much higher than those from conventional methods. [58][59][60] In addition, through designing customized microchannels, introducing specific physicochemical processes and incorporating functional agents, the structures and functions of the NMs are extremely flexible.…”