Precise Control of Magnetically Driven Microtools for Enucleation of Oocytes in a Microfluidic Chip

This paper presents two innovative driving methodologies using a magnetically driven microtool (MMT) for precise cell manipulations and automation systems. First, magnetic analysis has been conducted to show the current MMT problem and proved that static friction makes MMT control difficult. New driving methodologies that reduce the friction on the MMT effectively are introduced, and supported by finite element analysis and experimental results. The positioning accuracy improves 3-10 times and the response speeds become 10 times faster against the driving linear stage than in the conventional drive method. Stage feedback control by PI with a disturbance observer has been also investigated in order to obtain precise positioning accuracy and this was successfully improved by 16 times as compared to the conventional drive. Using this methodology, the enucleation of oocytes is demonstrated to show the effectiveness of the method. The required force to cut a swine oocyte is also estimated by the simplified model to prove that the MMT has sufficient force. Two MMT blades made of nickel were set on the microfluidic chip with a new drive methodology and successfully achieved the enucleation process with high throughput. (C) Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2011