Locomoting microscale robots—microswimmers—have the potential to impact numerous applications due to their ability to selectively interact with their environment with microscale control. Previous microswimmer designs lack either submicron-level precision over their construction or instantaneous control over their shape. Thus, existing microswimmer designs limit the control afforded over microswimmer interactions with their environment. This work presents a magnetically actuated microswimmer constructed from DNA and microspheres in a hybrid top-down and bottom-up assembly technique that allows for submicron-level precision over microswimmer body construction. Microscale features were fabricated via two-photon polymerization, from which polydimethylsiloxane templates were molded. Templated assembly by selective removal was used to deposit microspheres of select size and composition into the templates. This technique was confirmed to be size-selective within a population of microspheres. To construct the microswimmer, a ferromagnetic microsphere and a nonmagnetic microsphere were deposited into a template, connected with DNA nanotubes in their arrangement, magnetized, and pulled from the template. We demonstrate instantaneous control over shape changes via expansion and contraction of a microswimmer’s body in an external magnetic field. In a rotating magnetic field of constant magnitude, the microswimmer expanded as the two microspheres separated a distance of 4.1± 0.5 micrometers, approximately the distance between microspheres deposited in the template. In an oscillating magnetic field, the same microswimmer contracted and locomoted 58.8± 0.7 micrometers over 126 seconds. [2020-0183]

中文翻译：

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可定制的基于 DNA 和微球的磁驱动微型游泳器

移动微型机器人——微型游泳者——具有影响众多应用的潜力，因为它们能够通过微型控制选择性地与环境交互。以前的微型游泳器设计既缺乏亚微米级的结构精度，也缺乏对其形状的即时控制。因此，现有的微型游泳者设计限制了对微型游泳者与其环境交互的控制。这项工作展示了一种由 DNA 和微球体构成的磁驱动微型游泳器，采用自上而下和自下而上的混合组装技术，可在微型游泳器主体结构上实现亚微米级精度。通过双光子聚合制造微尺度特征，从中模制聚二甲基硅氧烷模板。通过选择性去除的模板组装用于将选定尺寸和组成的微球体沉积到模板中。该技术被证实在微球群体中具有尺寸选择性。为了构建微型游泳器，将铁磁性微球和非磁性微球沉积到模板中，与排列中的 DNA 纳米管连接，磁化并从模板中拉出。我们展示了通过微型游泳者身体在外部磁场中的膨胀和收缩对形状变化的瞬时控制。在恒定大小的旋转磁场中，当两个微球分开 4.1±0.5 微米的距离时，微型游泳器膨胀，大约是沉积在模板中的微球之间的距离。在振荡磁场中，同一个微型游泳者在 126 秒内收缩并移动了 58.8±0.7 微米。[2020-0183]