Flexible Magnetic Micropartners for Micromanipulation at Interfaces

Microrobots working at liquid surfaces
have immense potential for
micromanipulation in tight and enclosed spaces, whereas constructing
agile and functional microrobots with simple structures at liquid
surfaces is a great challenge. Herein, a pair of magnetic circular
microdisks working as partners at ethylene glycol (EG) surfaces are
proposed in order to accomplish flexible locomotion and in situ micromanipulation
tasks. The microdisks can be controlled to connect and separate by
modulating the orientation of the applied magnetic field. After the
two disks connect as an entity, they are transformed into micropartners
under an oscillating magnetic field in 3D space. By changing the vertical
component of the oscillating field, the micropartners can obtain controllable
propulsion through paddling and wriggling modes, and the locomotion
speed can reach approximately two body lengths per second. They can
also climb a meniscus, and even crawl on a solid surface in a liquid.
Finally, this pair of micropartners is demonstrated as a flexible
microgripper to implement manipulations at the liquid surfaces, including
cargo capture, delivery along prescribed paths, and release.

在液面上工作的微型机器人，在狭窄密闭空间的微操作任务中具备巨大应用潜力，但在液面上制备结构简洁、运行灵活且功能完备的微型机器人仍是一项重大挑战。为此，本文提出了一对可在乙二醇（ethylene glycol, EG）液面协同作业的磁性圆形微盘，以实现灵活的运动控制与原位微操作任务。通过调控外加磁场的方向，可精准控制这对微盘的连接与分离动作。当两个微盘结合为一体后，在三维空间的振荡磁场作用下，二者将转变为协同工作的微伙伴系统。通过调整振荡磁场的垂直分量，该微伙伴系统可通过划动与蠕动两种模式实现可控推进，运动速度可达约2倍体长每秒。该系统还可攀爬液弯液面，甚至可在液体中的固体表面爬行。最后，本文验证了该微伙伴系统可作为柔性微夹持器，在液面上完成各类微操作任务，包括货物捕获、沿预设路径输送以及释放作业。