Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA.
Research Triangle Materials Research Science and Engineering Center, Durham, NC 27708, USA.
Sci Adv. 2017 Aug 4;3(8):e1701108. doi: 10.1126/sciadv.1701108. eCollection 2017 Aug.
Colloidal-scale assemblies that reconfigure on demand may serve as the next generation of soft "microbots," artificial muscles, and other biomimetic devices. This requires the precise arrangement of particles into structures that are preprogrammed to reversibly change shape when actuated by external fields. The design and making of colloidal-scale assemblies with encoded directional particle-particle interactions remain a major challenge. We show how assemblies of metallodielectric patchy microcubes can be engineered to store energy through magnetic polarization and release it on demand by microscale reconfiguration. The dynamic pattern of folding and reconfiguration of the chain-like assemblies can be encoded in the sequence of the cube orientation. The residual polarization of the metallic facets on the microcubes leads to local interactions between the neighboring particles, which is directed by the conformational restrictions of their shape after harvesting energy from external magnetic fields. These structures can also be directionally moved, steered, and maneuvered by global forces from external magnetic fields. We illustrate these capabilities by examples of assemblies of specific sequences that can be actuated, reoriented, and spatially maneuvered to perform microscale operations such as capturing and transporting live cells, acting as prototypes of microbots, micromixers, and other active microstructures.
胶体尺度的组装体可以按需重新配置，它们可能成为下一代软“微机器人”、人造肌肉和其他仿生设备。这需要将粒子精确地排列成结构，这些结构预先设计成在外部场激励下可以可逆地改变形状。具有编码定向粒子-粒子相互作用的胶体尺度组装体的设计和制造仍然是一个主要挑战。我们展示了如何设计金属-介电镶嵌微立方体形貌的组装体，通过磁极化储存能量，并通过微尺度重新配置按需释放能量。链状组装体的折叠和重新配置的动态模式可以通过立方体形貌的顺序来编码。微立方体形貌的金属表面的剩余极化导致相邻粒子之间的局部相互作用，这种相互作用由它们从外部磁场中获取能量后形状的构象限制所决定。这些结构也可以通过外部磁场的全局力来定向移动、转向和操纵。我们通过特定序列的组装体的例子来说明这些能力，这些组装体可以被激活、重新定向和空间操纵，以执行微尺度操作，例如捕获和运输活细胞，作为微机器人、微混合器和其他主动微结构的原型。
