Omnidirectional actuation of magnetically driven microtool for cutting of oocyte in a chip

In this paper, we developed and fabricated a magnetically driven microtool (MMT) and installed it on a microfluidic chip for use in the enucleation of oocytes. The fabricated tool is much smaller than a conventional mechanical micromanipulator used for cell manipulation. We succeeded in driving this MMT in two degrees of freedomin the X - and Y -directions. The MMT works on the principle of noncontact actuation by magnetic force; therefore, the microfluidic-chip part is fully disposable and inexpensive. The MMT consists of a polymer part with a controllable attitude and a rigid metal (Ni) part with good magnetic properties, which are useful for cutting oocytes. We analytically evaluated that the structure for easy attitude control of the polymer part is a four-leg-type configuration. Based on the novel and original design, the MMT and microfluidic chip were fabricated by photolithography. The MMT could generate a force of 3 mN, which is sufficient to cut an oocyte into half. We successfully demonstrated the cutting of an oocyte on a microfluidic chip by using the MMT.