An Active Controlled Microfluidic Valve With An Annular Boundary

With the rapid development of micromechanical electronic science in recent years, mirofluidic valve, which is one of the key components in the microfluid control systems, has been widely used in many fields of bioengineering such as chemical analysis, drug release, integrated circuit chip, and Lab-on-Chip. Due to the complex structure, large volume, slow response, and low reliability of the conventional valves, it is important how to simplify the structure, heighten the reliability, and improve the response speed of the microfluid valves. Keep this in mind, the principle and structure of a novel active controlled microfluidic valve with an annular boundary is proposed in this dissertation and a novel active controlled microfluidic valve based on piezoelectric actuator is realized and analyzed subsequently.The major research works and achievements completed in this dissertation include:1.The principle of a novel active controlled microfluidic valve with an annular boundary is proposed. And the on/off states of the proposed valve are realized through changing the fluid flow gap between the membrane component and the annular boundary, which can be changed by the deformation of the membrane component.Based on the proposed principle, the structure of the microfluidic valve utilizing actuator is designed as well as the fluid flow control model is established. Moreover, the influence of the internal and external radii of the annular boundary on the performance of the active controlled micro-fluidic valve and the fluid flow control characteristics of the actuation and the pressure difference between the inlet and outlet of the active controlled micro-fluidic valve are simulated. The research results indicate that the fluid flow of the valve increases with the increase of the internal radius of the annular boundary when the external radius keeps unchanged. On the other hand, the fluid flow of the valve reduces with the increase of the external radius of the annular boundary when the internal radius keeps unchanged.2.The influence of the composing materials, boundary condition, and vibration mode on the performance of the composite piezoelectric oscillator is also simulated and analyzed. The simulation results indicate that simply boundary condition is beneficial to deformation of the composite piezoelectric oscillator. The ratio of thickness of the piezoelectric ceramics to substrate 0.35 and the ratio of radius of the piezoelectric ceramics to substrate 0.8 are beneficial to the deformation of the composite piezoelectric oscillator.3.The principle and structure of the valve based on piezoelectric driving is realized. The influence of the internal and external radii of the annular boundary on the leakage flow of the valve and the fluid flow control characteristics of the control command voltage on the composite disc-shaped piezoelectric oscillator and the pressure difference between the inlet and outlet of the valve are simulated. The research results indicate that the fluid flow of the valve increases with the increase of the internal radius of the annular boundary when the external radius keeps unchanged while the check flow characteristics will be reduced. On the other hand, the fluid flow of the valve reduces with the increase of the external radius of the annular boundary when the internal radius keeps unchanged while the check flow characteristics of the valve will reduces. In addition, the influence of increasing the fluid flow of the valve through decreasing the external radius of the annular boundary on the check flow characteristics of the valve is relatively small. The research results also show that the fluid flow of the valve can be continuously controlled through the control command voltage applied on the composite piezoelectric oscillator and the fluid flow of the valve can also be controlled through changing the pressure difference between the inlet and outlet to some extent.4,A test setup for the composite piezoelectric oscillator and the valve based on piezoelectric driving is established to validate the proposed principle and the novel valves. The initial testing results indicate that the novel valve is feasible.