An Electrowetting Valve with Air Channel

Abstract

In recent years, microfluidic systems are used in various fields. In important component is the valve. In a variety of valve principles, the electrowetting valve promises high reliability, good controllability, low voltage operation and high transmission speed characteristics. The micro-fabrication method to create a chip-level electrowetting valve will have lots of applications.

In this thesis, two designs of an electrowetting valve are presented that can be used to precisely control the flow of liquids. The hydrophobic air valves are used in the designs to allow liquid to flow forward when the valve is activated and to stop when it is deactivated. The design has different widths for the air channel to study its effect on the valve performance. Also, the after the design is completed, the design is translated into a mask set which is used to fabricate the chip in a cleanroom. Before fabrication, different types of materials with different thickness are simulated in Comsol Multiphysics to see what the respected expected saturation voltage are. Fabrication of the devices in the cleanroom involved silicon etching, TEOS deposition, metal deposition, insulating layer deposition and hydrophobic layer deposition and patterning. The depths of the channels were chosen as 20μm and 10 μm respectively. Subsequently measurement were performed to test the performance of the different designs and materials. Finally the conclusions and suggestions for the future work have been drawn.