Micropumps are used in microfluidics systems to accurately deliver small volumes of fluid. For gas pumping applications, actuation is commonly accomplished by piezoelectrically- or electrostatically-driven membranes, which is often limited in their membrane displacement volume and requirement of high drive voltages. Recently, curved electrodes have been proposed to achieve larger deflection with lower voltage, but the fabrication of such electrodes remains a challenge.
Researchers at the University of Michigan have designed and fabricated a microvacuum pump assembly that can achieve increased volume displacement with low operating voltage. The assembly consists of pumping cavities with electrostatically-actuated membranes interconnected by electrostatically-actuated microvalves. The actuator can produce a large deflection, with curved fixed-drive electrode and a flat, movable polymer electrode, which is a parylene membrane placed on the curved electrode using a wafer-level transfer and parylene bonding process. The curved electrodes are fabricated by buckling the electrode, and enable the movable electrode to travel over larger distances than is possible using a flat electrode.
Applications and Advantages
- Microgas chromatography
- Microfluidics systems
- Generates a large force via so-called-nl-zipping effect from electrode edges
- Can operate in air and be easily-nl-integrated into MEMS-fabricated-nl-microfluidic systems