COMSOL Simulation of MEMS Piezoelectrically Actuated Micropump

In this poster, the design and COMSOL simulation of a piezoelectric micropump [1] with dome-shaped diaphragms and diffuser-nozzle fluid rectifiers is reported. The micropump uses piezoelectric ZnO film (less than 10µm thick) to actuate the vibration of a parylene dome diaphragm, so that microfluid can be pumped in and out of the chamber. The device is to be fabricated on silicon substrate with an IC-compatible process. Piezoelectric ZnO film is sputter-deposited on a parylene dome diaphragm with its C-axis oriented perpendicular to the dome surface. The micropump utilizes two symmetric dome diaphragms for improved pumping rate. Diffuser-nozzle elements are integrated with piezoelectrically actuated dome diaphragms to form a multi-chip micropump. Due to the MEMS (Microelectromechanical Systems) technology used, the proposed micropump has very small size (10×10×1.6mm 3 ) and consumes extremely low power. It also shows negligible leakage up to 700 Pa static differential pressure. The function of the proposed micropump is verified with COMSOL simulation. Micropumps are miniature fluid delivery devices which are capable of generating microfluid flow at finite pressure loads. Micropumps base on MEMS (Microelectromechanical Systems) technology have functional dimensions in the range of microns (1µm=10 -6 m). Due to their small size, low cost, low energy consumption and high efficiency, MEMS micropumps have been widely used in many applications, such as Micro Total Analysis System (µTAS), Lab-on-a-chip, and micro drug delivery systems. MEMS micropumps can be divided into two categories: passive and active micropumps. Passive micropumps requires no external energy supply, while active micropumps need energy supply to operate. Micropumps based on different actuation techniques have been reported, such as magnetic micropumps, electrostatic micropumps, piezoelectric micropumps, thermodynamic micropumps, shape-memoryalloy micropumps, etc. Among them, piezoelectric micropumps are able to produce significantly large force with low power consumption. In this poster, a piezoelectric micropump with dome-shaped valveless membrane structure is designed and simulated. Valveless diffuser-nozzles are used for inlet and outlet ports. The pumping chamber is sealed by top and bottom dome-shaped parylene diaphragms. Piezoelectric ZnO actuators are deposited on the surface of each diaphragm. When AC driving voltage is applied, piezoelectric actuator expands and shrinks periodically, causing the diaphragm to bend up and down. Hence the microfluid is sucked into the chamber and pumped out periodically.