Rapid and Multimaterial 4D Printing of Shape‐Morphing Micromachines for Narrow Micronetworks Traversing

Abstract

Micromachines with high environmental adaptability have the potential to deliver targeted drugs in complex biological networks, such as digestive, neural, and vascular networks. However, the low processing efficiency and single processing material of current 4D printing methods often limit the development and application of shape‐morphing micromachines (SMMs). Here, two 4D printing strategies are proposed to fabricate SMMs with pH‐responsive hydrogels for complex micro‐networks traversing. On the one hand, the 3D vortex light single exposure technique can rapidly fabricate a tubular SMM with controllable size and geometry within 0.1 s. On the other hand, the asymmetric multimaterial direct laser writing (DLW) method is used to fabricate SMMs with designable 3D structures composed of hydrogel and platinum nanoparticles (Pt NPs). Based on the presence of ferroferric oxide (Fe3O4) and Pt NPs in the SMMs, efficient magnetic, bubble, and hybrid propulsion modes are achieved. Finally, it is demonstrated that the spatial shape conversion capabilities of these SMMs can be used for narrow micronetworks traversing, which will find potential applications in targeted cargo delivery in microcapillaries.

Is Soft Carbon a More Suitable Match for SiOx in Li‐Ion Battery Anodes?

“…[27] As for the delithiation process, Gr presents an almost symmetric phase evolution from LiC 6 to LiC 12 , and finally to Gr phase through a series of intermediate GICs with different atomic ratios. [28] When it comes to the SC anode, things become even more interesting. The (0 0 2) Bragg reflection continuously shifts to lower/higher angles during the lithiation/delithiation of SC (Figure 3b).…”

Recent Advances on High‐Speed and Holographic Two‐Photon Direct Laser Writing

“…In this case, they demonstrated the fabrication of magnetically propelled hollow microtubes, used for targeted delivery of HeLa Cells and Doxorubicin drug particles for therapeutic applications. Very recently, [ 239 ] properties of pH‐sensitivity and magnetically driven handling have been combined with fabrication exploiting optical vortex beams of hollow trumpet‐shaped micromachines (TSMM), employing a pH‐sensitive resist, then incubated in a suspension of Fe 3 O 4 nanoparticles (Figure 11D). Through modification of their size controlled by pH and handling by magnetic field, these structures can shrink and pass through channels narrower than their original size and can be guided along microchannels of complex shapes, with bends, constrictions, and barriers, further increasing their adaptability to the environment.…”

“…(bottom) Timelapse sequence of magnetic TSMM passing through an hourglass-shaped microchannel. Adapted with permission [239]. Copyright 2022, Wiley-VCH GmbH.…”

Four-Dimensional Printing of a Fiber-Tip Multimaterial Microcantilever as a Magnetic Field Sensor

“…After being functionalized with magnetically responsive materials, the fiber-tip polymer microcantilever is expected as a highly sensitive magnetic sensor. However, traditional treatments such as electron beam sputtering and chemical coating cannot achieve precise functionalization of a local microstructure and require additional postprocessing, which limits its further application. − Four-dimensional (4D) printing is a process where 3D-printed objects autonomously change their configuration or function in response to environmental stimuli, such as exposure to heat, magnetic field, light, liquid, gas, and prestress. , …”

“…36−39 Four-dimensional (4D) printing is a process where 3D-printed objects autonomously change their configuration or function in response to environmental stimuli, such as exposure to heat, magnetic field, light, liquid, gas, and prestress. 40,41 Here, we report a successive multimaterial on-fiber TPP strategy for 4D microstructure fabrication and prepare a fibertip polymer magnetic sensing microcantilever in one step. First, the polymer cantilever beam and the supporting base are printed by Fs-laser-induced TPP on the end facet of a singlemode fiber (SMF).…”