Study Of Novel Digital Microfluidic Chips Based On EWOD

As the development of MEMS technology and the interinfiltration between different subjects, the Lab-on-a-chip (LOC), which realizes the full auto-process and auto-analysis on a single chip, has demonstrated an exciting future. Among all the microfluidic technology, the digital microfluidic based on EWOD (Electrowetting-on-dielectrics) is the most competitive and promising one to achieve the LOC. However, there still exist some obstacles for the commercialization of EWOD based LOC. Aiming at solving the existing problem and meeting the demand of commercial applications, the thesis focuses on innovative study on novel dielectric material, new manipulation function and advanced integrated technology of EWOD digital microfluidic devices.1. Study on novel dielectric materialA polymer dielectric material Cyanoethyl Pullulan (CEP) is introduced as the insulator of the EWOD device. Through novel fabrication process, the CEP film formed by spin-coating and low-temperature annealing (100℃ in atmosphere) reaches great dielectric properties (with a high dielectric constant of 18) as well as excellent electrowetting performance. The polarity related, frequency related and long term electrowetting experiments demonstrate that the CEP insulator behaves with outstdanding reversibility and stability on electrowetting. The application of CEP can not only lower the driving voltage of EWOD chip, but also improve its performance for commercial LOC use.2. Study on novel manipulation of EWOD deviceWe firstly propose a novel electrode configuration and control method to improve the precision of droplet dispensing on EWOD chip. The novel design can increase the precision 10 more times than that of traditional EWOD chip, which is the most efficient and simple way up to now.An innovative EWOD chip based on interdigitated electrodes are proposed to automatically actuate size-variable droplets in a very large range.These two novel structure proposals enhance the manipulation ability of EWOD chip for its complex and diversified applications in the future.3. Study on integration of electrochemical detection on EWOD chipWe proposed and realized the fully monolithic Lab-on-a-Chip with electrochemical detection for the first time. Through optimized design and fabrication process, the micro electrochemical electrodes are embedded in the EWOD chip efficiently. This novel chip can simultaneously realize multifunctional manipulation and online powerful electrochemical detection for reagent droplets, showing a great promise for commercial LOC with wonderful applications.