On-chip high speed microrobot made of Ni-Si composite structure with three-dimensionally patterned surface

This paper presents the high speed microrobot actuation driven by permanent magnet in a microfluidic chip. The comprehensive analysis of fluid force, the optimum design and its fabrication was conducted to reduce the fluid force on the magnetically driven microrobot by attaching riblet shape on the microrobot. The Ni and Si composite fabrication was employed to form the optimum riblet shape on the Ni based microrobot by anisotropic Si wet etching and deep reactive ion etching. The evaluation experiments show the microrobot can actuate up to 100 Hz, which is 10 times higher than the original microrobot. In addition, since the microrobot was covered by Si, which is bio-compatible, it can be applied to cell manipulation without harm.