Autonomous cryoprotectant loading of the oocyte using microfluidic transistors.

Abstract

Oocyte cryopreservation is a critical step of <i>in vitro</i> fertilization (IVF). The handling and loading of cryoprotectant currently rely on manual pipetting methods, which leads to outcome variations, high cost and limited accessibility. Here we developed a low-cost and user-friendly microfluidic device to automate the complex multistep process of oocyte CPA loading, delivering cryopreservation-ready oocytes. We utilized microfluidic transistors to create fluidic timers and logic gates, which generated time-dependent pressure signals to control the embedded valves, thereby regulating the flow conditions over the oocyte. Using constant pressure supplies, we demonstrated autonomous mouse oocyte trapping, linear loading of equilibrium solution, dehydration with vitrification solution and oocyte extraction from the device. Our work represents an important step towards autonomous IVF-on-a-chip to enhance the accessibility and affordability of IVF.