Inspired by bacterial flagella in nature, magnetic helical microswimmer is an ideal model to perform complex task in a low Reynolds number environments. Shape Memory Polymers (SMPs) with desirable properties are considered as one of the most preferred options for the development of small-scale robots. However, fabricating and programming strategies are still challenging. Here, we report an approach to fabricate helical microswimmers based on thermoplastic SMP (polylactic acid). Melt-spun polylactic acid fibers containing magnetic particles were enwound to form helical microstructures. Their shape recovery behaviors were programmed by annealing and pre-deformation. Three forms of helical microswimmers (constant-helix-angle conical helix, constant-pitch conical helix, and straight helix) with controlled morphological parameters were tailored. The obtained microswimmers showed 3D locomotion capability under rotating magnetic fields. The maximum swimming velocity of microswimmers was nearly six body lengths per second, and the near-wall swimming of conical helixes along their sharp end exhibited a smaller drift. Moreover, we demonstrated programmed shape-switching processes (spring-like contraction and elongation, coiling and uncoiling) and self-repairing of the microswimmers. As demonstrations of potential applications, tasks of mobile microstent, cargo delivery, and minimally invasive injection were carried out. The multifunctional shape-memory microswimmers have immense potential in a variety of applications.

受自然界细菌鞭毛的启发，磁性螺旋微型游泳器是在低雷诺数环境中执行复杂任务的理想模型。具有理想特性的形状记忆聚合物 (SMP) 被认为是开发小型机器人的最佳选择之一。然而，制造和编程策略仍然具有挑战性。在这里，我们报告了一种基于热塑性 SMP（聚乳酸）制造螺旋微型游泳器的方法。含有磁性颗粒的熔纺聚乳酸纤维被缠绕形成螺旋状微结构。它们的形状恢复行为通过退火和预变形进行编程。定制了具有受控形态参数的三种形式的螺旋微型游泳器（恒定螺旋角锥形螺旋、恒定螺距锥形螺旋和直螺旋）。获得的微型游泳者在旋转磁场下显示出 3D 运动能力。微型游泳者的最大游泳速度接近每秒六倍体长，锥形螺旋沿其尖端的近壁游泳表现出较小的漂移。此外，我们还展示了微型游泳器的程序化形状转换过程（类似弹簧的收缩和伸长、卷曲和解卷）和自我修复。作为潜在应用的演示，进行了移动微型支架、货物输送和微创注射的任务。多功能形状记忆微型游泳者在各种应用中具有巨大的潜力。锥形螺旋沿其尖端的近壁游动表现出较小的漂移。此外，我们还展示了微型游泳器的程序化形状转换过程（类似弹簧的收缩和伸长、卷曲和解卷）和自我修复。作为潜在应用的演示，进行了移动微型支架、货物输送和微创注射的任务。多功能形状记忆微型游泳者在各种应用中具有巨大的潜力。锥形螺旋沿其尖端的近壁游动表现出较小的漂移。此外，我们还展示了微型游泳器的程序化形状转换过程（类似弹簧的收缩和伸长、卷曲和解卷）和自我修复。作为潜在应用的演示，进行了移动微型支架、货物输送和微创注射的任务。多功能形状记忆微型游泳者在各种应用中具有巨大的潜力。并进行了微创注射。多功能形状记忆微型游泳者在各种应用中具有巨大的潜力。并进行了微创注射。多功能形状记忆微型游泳者在各种应用中具有巨大的潜力。