Fabrication of a high frequency piezoelectric microvalve

A normally-closed piezoelectric micro-valve with flexible stopper

“…More important, all of the hydraulically amplified piezoelectric micro-valves in Ref. 14,15, and 18 are normally opened valve and driven by PZT stack, which have expensive cost and are not suitable for the occasion of the flow channel need to be cut-off when powering off. In some controlled drug system, the micro-valve should be closed for several months or even a few years, 19 so normally opened valve will consume much energy when it is not delivering drugs.…”

“…In 2003 and 2004, D.C. Roberts et al 14 and H.Q. Li et al 15 reported a piezoelectric driven hydraulic amplification micro-valve which took PZT stack as the driving source, multilayer silicon and glass structure was selected, it turned out that the working frequency was higher than 1 kHz, but it required a complex fabrication process including 22 photolithography steps and particle tolerance is low as it utilize rigid plate as valve stopper. 16,17 In 2011, in order to simplify the fabrication progress and circumvent the sealing problem, X.S.…”

Fundamentals of Microfluidics Devices

“…This limitation has been addressed by a number of groups using the hydraulic amplification principle. 51,52 Actuation mechanisms that depend on transfer of thermal energy include thermopneumatic, bimetallic strip actuated valves (thermomechanic) and valves that use shape memory alloy. In the case of thermopneumatic actuation, energy derived from a change in volume of sealed liquid, solid, or gas due to thermal loading is used to drive a membrane or diaphragm that controls fluid flow.…”

Indirectly heated micro-electrothermal actuator with a monolithically integrated displacement sensor

“…Commonly used actuation methods include electrostatic (Lee and Cho 2001;Shimoyana et al 1997;Brand et al 1999;Cho and Ahn 2002), piezoelectric (Li et al 2004), and electrothermal-based (Que et al 2001;Stevenson et al 2007;Enikov et al 2005;Butler et al 1999;Chow and Lai 2009) actuators. Electrothermal-based actuators utilize constrained thermal expansion to generate output motion and force.…”