Abstract
Electrowetting-on-dielectric (EWOD) technique has been used in the digital microfluidic system (DMF). Droplets can be generated, transported, separated, and merged by EWOD electrodes actuation. The actuation of the droplets by EWOD electrodes have the features of precise droplet actuation, less contamination risk, reducing reagents volume, better reagents mixing efficiency, less reaction time, flexibility for integration with other elements and its portability, and therefore EWOD based DMF has been widely applied in biomedical or chemical fields as a powerful sample preparation platform. In this study, the coplanar electrodes EWOD system was used for different kinds of biomedical applications. We also focused on the quality improvement of dielectric layer of the EWOD chip for increasing the breakdown voltage during biomedical sample manipulation. We proposed a new EWOD device fabrication process using low pressure chemical vapor deposited (LPCVD) Si3N4 as dielectric layer. LPCVD Si3N4 exhibits not only high permittivity but also purity and uniformity, which increase the breakdown voltage of dielectric layer and make EWOD system more stable when applied in biomedical researches. DNA ligation and single-nucleotide polymorphism (SNP) detection in specific DNA sequence were performed by the EWOD platform. With the combination of a micro-heater on the top cap of the EWOD, biomedical reaction requires specific temperature can be done in the chip. To use the DMF for assisted reproductive technology (ART) researches, we also present an in vitro culture of mouse embryo and in vitro of mouse gametes by using the EWOD system. These biomedical applications were all successfully demonstrated by our EWOD digital microfluidics, the results suggest that the EWOD chip is biocompatible and has the potential for sample processing of molecular biology and assisted reproductive technology researches.