A Piezoelectric Microvalve for Compact High-Frequency, High-Differential Pressure Hydraulic Micropumping Systems

A piezoelectrically driven hydraulic amplification microvalve for use in compact high-performance hydraulic pumping systems was designed, fabricated, and experimentally characterized. High-frequency, high-force actuation capabilities were enabled through the incorporation of bulk piezoelectric material elements beneath a micromachined annular tethered-piston structure. Large valve stroke at the microscale was achieved with an hydraulic amplification mechanism that amplified (40 50 ) the limited stroke of the piezoelectric material into a significantly larger motion of a micromachined valve membrane with attached valve cap. These design features enabled the valve to meet simultaneously a set of high frequency ( 1 kHz), high pressure( 300 kPa), and large stroke (20–30 m) requirements not previously satisfied by other hydraulic flow regulation microvalves. This paper details the design, modeling, fabrication, assembly, and experimental characterization of this valve device. Fabrication challenges, such as deep-reactive ion etching of the piston and valve membrane structures, wafer-level silicon-to-silicon fusion bonding, wafer-level and die-level silicon-to-glass anodic bonding, preparation and integration of piezoelectric material elements within the micromachined tethered piston structure, and filling of degassed fluid within the hydraulic amplification chamber are detailed. [829]