State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150080, China.
ACS Appl Mater Interfaces. 2023 May 31;15(21):25942-25951. doi: 10.1021/acsami.3c02986. Epub 2023 May 19.
Faced with complex and diverse tasks, researchers seek to introduce stimuli-responsive materials into the field of microrobots. Magnetic helical microrobots based on shape-memory polymers demonstrate excellent locomotion capability and programmable shape transformations. However, the stimulation method of shape changes is still dependent on the rising of ambient temperature and lacks the ability to address individuals among multiple microrobots. In this paper, magnetic helical microrobots were prepared based on polylactic acid and FeO nanoparticles, which demonstrated controlled locomotion under rotating magnetic fields and programmable shape changes in their length, diameter, and chirality. The transition temperature of shape recoveries was adjusted to a range above 37 °C. At 46 °C, helical microrobots had a fast shape change with a recovery ratio of 72% in a minute. The photothermal effect of FeO nanoparticles under near-infrared laser can actuate the shape recovery rapidly, with a recovery ratio of 77% in 15 s and 90% in a minute. The stimulation strategy also allows addressing among multiple microrobots, or even within a single microrobot, selectively stimulating one or a part to change its shape. Combined with the magnetic field, laser-addressed shape changes were used for precise deployment and individual control of microrobots. Multiple microrobots can be enriched at the targeted point, heating the ambient temperature over 46 °C. The shape changes of internal parts of microrobots help them to grasp and assemble objects. Such microrobots have great potential in biomedicine and micromanipulation.
面对复杂多样的任务，研究人员试图将刺激响应材料引入微机器人领域。基于形状记忆聚合物的磁性螺旋微机器人表现出了优异的运动能力和可编程的形状变换能力。然而，其形状变化的刺激方法仍然依赖于环境温度的升高，并且缺乏在多个微机器人中对个体进行寻址的能力。在本文中，我们基于聚乳酸和 FeO 纳米粒子制备了磁性螺旋微机器人，它们在旋转磁场下能够进行受控运动，并能够在长度、直径和手性方面进行可编程的形状变化。形状恢复的转变温度被调整到高于 37°C 的范围。在 46°C 下，螺旋微机器人具有快速的形状变化，在一分钟内恢复率达到 72%。FeO 纳米粒子的近红外激光光热效应可以快速驱动形状恢复，在 15 秒内恢复率达到 77%，在一分钟内达到 90%。这种刺激策略还允许对多个微机器人进行寻址，甚至在单个微机器人内进行寻址，可以选择性地刺激一个或一部分来改变其形状。结合磁场，激光寻址的形状变化可用于微机器人的精确部署和个体控制。多个微机器人可以在目标点富集，将环境温度升高到 46°C 以上。微机器人内部部件的形状变化有助于它们抓取和组装物体。这种微机器人在生物医学和微操作中有很大的应用潜力。
