Modeling and experimental verification of the flow characteristics of an active controlled microfluidic valve with annular boundary

The principle and structural configuration of an active controlled microfluidic valve with annular boundary driven by a circular piezoelectric unimorph actuator is presented in this article. Its active controlled flowrate is modeled using the classical laminated plate theory and the extended Bernoulli equation in fluid mechanics. According to the established mathematical model, we simulate and analyze the influence of the voltage applied to the circular piezoelectric unimorph actuator and the structural parameters on the flow characteristics. The prototypes of the active controlled microfluidic valves with annular boundaries of three different combinations of the inner and outer radii are fabricated and tested. The experimental results show that the active controlled microfluidic valves with annular boundaries possess the on/off switching capability and the continuous control capability of the fluid with simple structure and easy fabrication processing; the maximum flowrate of the active controlled microfluidic valve with the annular boundary with the inner and outer radii of 1.5 and 3.5 mm, respectively, is 0.14 mL/s when the differential pressure of the inlet and outlet of the active controlled microfluidic valve is 1000 Pa and the voltage applied to circular piezoelectric unimorph actuator is 100 V; and the established flowrate model can accurately predict the controlled flowrate of the active controlled microfluidic valves with the maximum relative error of 6.7%.