Automated Noncontact Micromanipulation Using Magnetic Swimming Microrobots

This letter reports an approach to automated microfluidic trapping and manipulation using a peanut-like magnetic-drive swimming microrobot of about 0.8-<inline-formula><tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula>m diameter and 3 <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>m in length. A hybrid electromagnetic actuator was developed to drive the microrobot in two motion modes: rolling and kayaking. The rolling mode can generate strong vortex flows for two-dimensional trapping and manipulation of a microparticle several hundred times the volume of the microrobot by pushing, pulling, and steering. Because of its weaker trapping force, kayaking mode is more effective for the release operation. A vision- and behavior-based controller is proposed to iteratively correct emerging manipulation behaviors for improved performance in complicated trajectory tracking and transportation of microparticles in complex environments. The experimental results demonstrate the capability and flexibility of the microrobot in trapping and transporting microparticles of up to 15- <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>m diameter along trajectories defined by scattered points, even steering microparticle out of a micromaze along the automatically generated trajectory point by point.