Automated robotic vitrification of embryos

Abstract

This paper reports the first robotic system for vitrification of mammalian embryos. Vitrification is a technique for preserving oocytes and embryos in clinical IVF (in vitro fertilization). The procedure involves multiple steps of stringently timed pick-and-place operation for processing an oocyte/embryo in vitrification media. In IVF clinics, vitrification is conducted manually by highly skilled embryologists. Processing one oocyte/embryo occupies the embryologist 15-20 minutes, depending on protocols chosen to implement. Due to poor reproducibility and inconsistency across operators, success rates and survival rates also vary significantly. Through collaboration with IVF clinics, we are in process to realize robotic vitrification and aim ultimately to standardize clinical vitrification from manual operation to fully automated robotic operation. Our robotic system is embedded with two contact detection methods to determine the relative Z positions of the vitrification micropipette, embryo, and vitrification straw. A 3D tracking algorithm is developed for visually servoed embryo transfer and real-time monitoring of embryo volume changes during vitrification. Excess medium is automatically removed from around the vitrified embryo on the vitrification straw to achieve a high cooling rate. Tests on mouse embryos demonstrate that the system is capable of performing vitrification with a throughput at least three times that of manual operation and achieved a high survival rate (88.9%) and development rate (93.8%).