A new miniaturized traveling-wave electro-osmotic micro-pump by low velocity of fluid for lab-on-a-chip application

Low Reynolds number of fluids is one of the main challenges by lab-on-a-chip and “micro total analyzers”. Any miniaturization of fluid channels and used microfluidics components in such systems intensified the phenomena. This paper presents a modified fabrication process to produce an “electrokinetic micropumps” with minimized channel geometry. Application of this type of micropumps is suitable by very low Reynolds number. The proposed device is a 4-phase travelling wave AC-electroosmotic micropump, which is fabricated by surface micromachining technique. Due to fabrication process, a thin silicon nitride layer covers the electrodes. The pumping performance is investigated by presence of this thin insulator layer. The result of this study reveals that the pump operates, if the electric conductivity of fluid buffer is low. Additional advantage of the insulator layer over electrodes is the preventing of high electric field on electrode edges and consequently undesired electrolyses of fluid. The fabrication process flow and results of finite element analysis is presented. The maximum flow rate of 2.39 mm/s is achieved at the frequency of 10KHz.