Robotic Pick-And-Place of Multiple Embryos for Vitrification

Abstract

Embryo vitrification is an essential cryopreservation technique in IVF (in vitro fertilization) clinics. Vitrification involves pick-and-place of an embryo in multiple types of cryoprotectant solutions for processing before placing the embryo on a vitrification straw for cryopreservation in liquid nitrogen. Manual operation and existing robotic vitrification are only capable of aspirating one embryo at a time for processing; thus, other embryos are kept in the culture dish on a microscope stage for tens of minutes, which is detrimental to the development potential of the embryos. In order to minimize the total vitrification time, we have recently developed a robotic system for the pick-and-place of multiple embryos and process every three embryos as a group. Visual detection algorithms were developed for locating multiple embryos in three dimensions. Dynamics of embryo motion was modeled and a linear quadratic regulator (LQR) controller was developed to aspirate each embryo with a minimum volume of excess medium. The robotic system then placed the embryos onto vitrification straws by depositing a thin layer of medium that contains the embryos, and finally, aspirated away the medium surrounding the embryo for fast cooling. Experimental results demonstrate that robotic multiembryo processing has a throughput three times that of manual operation and achieved a high success rate of 95.2%, embryo survival rate of 90.0%, and development rate of 88.8%.