Heilongjiang Provincial Key Laboratory of Complex Intelligent System and Integration, Harbin University of Science and Technology, Harbin, 150080, China.
State Key Laboratory of Robotics and Systems, Harbin Institute of Technology, Harbin, 150001, China.
Soft Matter. 2023 Apr 26;19(16):2883-2890. doi: 10.1039/d2sm01436j.
Magnetic microrobots have tremendous potential applications due to their wireless actuation and fast response in confined spaces. Herein, inspired by fish, a magnetic microrobot working at liquid surfaces was proposed in order to transport microparts effectively. Different from other fish-like robots propelled by flexible caudal fins, the microrobot is designed as a simple sheet structure with a streamlined shape. It is fabricated monolithically utilizing polydimethylsiloxane doped with magnetic particles. The unequal thicknesses of different parts of the fish shape enable the microrobot to move faster a liquid level difference around the body under an oscillating magnetic field. The propulsion mechanism is investigated through theoretical analysis and simulations. The motion performance characteristics are further characterized through experiments. It is interesting to find that the microrobot moves in a head-forward mode when the vertical magnetic field component is upward, whereas it moves in a tail-forward mode when the component is downward. Relying on the modulation of capillary forces, the microrobot is able to capture and deliver microballs along a given path. The maximum transporting speed can reach 1.2 mm s, which is about three times the microball diameter per second. It is also found that the transporting speed with the microball is much higher than that of the microrobot alone. The reason for this is that when the micropart and microrobot combine, the increased asymmetry of the liquid surfaces caused by the forward movement of the gravity center can increase the forward driving force. The proposed microrobot and the transporting method are expected to have more applications in micromanipulation fields.
磁性微机器人由于其在受限空间内的无线驱动和快速响应，具有巨大的潜在应用。在此，受鱼类启发，提出了一种在液体表面工作的磁性微机器人，以便有效地运输微部件。与其他通过柔性尾鳍推进的类鱼机器人不同，该微机器人设计为具有流线型形状的简单片状结构。它是利用掺杂有磁性颗粒的聚二甲基硅氧烷整体制造的。鱼形不同部位的不等厚度使微机器人能够在振荡磁场下更快地移动到身体周围的液位差。通过理论分析和模拟研究了推进机制。通过实验进一步表征了运动性能特性。有趣的是，当垂直磁场分量向上时，微机器人以头部向前的模式移动，而当分量向下时，它以尾部向前的模式移动。依靠毛细作用力的调制，微机器人能够沿着给定路径捕获和输送微球。最大输送速度可达 1.2mm/s，约为微球直径的三倍每秒。还发现，带有微球的输送速度远高于微机器人单独的速度。原因是当微球和微机器人结合时，由于重心的向前运动引起的液体表面不对称性增加，可以增加向前驱动力。所提出的微机器人和输送方法有望在微操作领域得到更多应用。
