High-Speed Magnetic Microrobot Actuation in a Microfluidic Chip by a Fine V-Groove Surface

Microrobots are promising tools for the treatment of biological cells because of their lack of skill dependence, high throughput, and high repeatability. Integration of a microfluidic chip and robotics based on microelectromechanical systems technology is a key challenge for biomedical innovations. In addition to the advantage of environmental control by a microfluidic chip, robots enable physical operations on the cell with high throughput. This paper presents high-speed microrobotic actuation driven by permanent magnets in a microfluidic chip. The developed microrobot has a milli-Newton-level output force from a permanent magnet, micrometer-level positioning accuracy, and drive speed of over 280 mm/s. The riblet surface, which is a regularly arrayed V-groove, reduces fluid friction and enables high-speed actuation. Ni and Si composite fabrication was employed to form the optimum riblet shape on the microrobot's surface by wet and dry etching. The evaluation experiments show that the microrobot can be actuated at a rate of up to 90 Hz, which is more than ten times higher than that of the microrobot without a riblet. Two distinguish applications of the developed microrobots were demonstrated in a microfluidic chip.