Abstract
This study mainly makes use of the electrowetting on dielectric (EWOD) chip to apply in the dynamic culture of mouse embryos and screen printing technologies. The advantage of EWOD chip is simple fabrication, low cost, and easily to operate microfluidic generating, transporting, separating, merging. In our study, the application of EWOD in reproductive medicine is making use of EWOD chip as a dynamic culture platform for fertilized embryos. We manipulated the HTF droplets with electro-wetting force in an oil bath environment to imitate the dynamic movement of the embryos inside the mother. The experiments contained three groups: the traditional droplet culture method is taken as the experimental control group, the second one is the static culture group on chip without any movement, and the third one is dynamic culture group driven by electric wetting force on the chip. In the static culture group, the fertilized embryos were injected into equilibrated culture medium and placed them in the oil on the EWOD chip. In the dynamic culture group, the fertilized embryos were injected into equilibrated culture medium droplet, and the culture medium droplet was moved every 5 minutes for two hours to imitate the dynamic process of the fertilized embryos moving from the fallopian tube to the uterus. After 3 day cell culture, about 77.8% (N=54) of the embryos eventually developed to the morula and blastocyst stage cultured in the dish(control group); the rate of static group is 62.5% (N=56), and the rate of dynamic group is similar with the control group, 75.0% (N=56) of the embryos developed to the morula and blastocyst stage. The development rate of embryos of dynamic culture was 12.5% higher than the static group at embryo age E4.5. In fact, early blastocysts can be observed in each group at embryo age E3.5. The early blastocyst proportion of dynamic group (23.2%) is 9.0% higher than the static group (14.2%), and similar with the control group (26.0%). The result suggests that the electro-wetting force may not affect the embryos which proves that the biocompatibility of EWOD and the potential of EWOD chip for delivering biological cells and cells culture. The motivation of patterning of microfluidic is hoped that the digital microfluidic system can be used in printing technologies. Because current printing technologies easily cause the mother's mold damage and short life, and molds of small line width are expensive and time-consuming, this paper used EWOD chip to realize microfluidic patterning of propylene carbonate fliud. The experiment generated, transported, separated and merged droplets by using the parallel plate EWOD system at 120Vpp / 20kHz. The experiment found that when the volume of the droplet is larger, the voltage required to pattern the droplet is higher. When the gap of the top plate and bottom plate is fixed to 100μm, the 0.563μL droplet cab be covered with 5 electrodes (one electrode size:1.5mm × 0.75mm) by applying 200 Vpp / 20 kHz, and the 1.113μL droplet can be covered with 10 electrodes by applying 260 Vpp / 20 kHz.