Research On The Piezoelectrics-Stress-Fluid Coupling Numerical Simulation Of The Valveless Micropump

Piezoelectric valveless micropump (PVMP) is a novel fluid transporter, in which the fluid is driven by the deflection of the piezoelectric vibrator. With many merits such as simple structure, easy processing and micromation, high performance under low applied voltage etc, the PVMP is mostly used as one of the most important components in laboratory experiments for the precise, continuous and tiny volume dispensing of fluids in the micro-total-analysis systems (μ.-TAS).In the present study, multiphysics coupling software CFD-ACE+ was used to do the 3D dynamic numerical simulation of the PVMP. The output characteristics and the application as the injection source to the microfluidic chip were detailed and deeply studied through the structure optimization, piezoelectrics-structure-fluid coupling numerical simulationof the PVMP, and the systematic simulation of the microfluidic chip integrating with PVMP. Driven by the sinusoidal voltage, the piezoelectric vibrator transfers its deformation to the fluid, and the fluid reacts at the same time. The piezoelectrics-structure-fluid coupling numerical simulation to this interation is very important to the exact output characteristics of PVMP and the micromation of the μ-TAS.Structural grids were used to discretize the geometrical model of the PVMP. Electric module, fluid dynamics module, and structural mechanics & dynamics module from CFD-ACE+ were employed to do the piezoelectrics-stress-fluid coupling numerical simulation of the PVMP. Time step, time accuracy and iteration times were adjusted repeatedly to insure all the variable residual numbers are below 1E-05. Besides, the secondary development method of the CFD-ACE+ was carried out to get the transient flux output with Fortan90 language.The numerical simulation result of the diffuser Reynolds number agrees well with the experimental results from German researcher Torsten Gerlach. Systematic simulations to the PVMP were done to get an optimization structure which is suitable to be machined and operated in the laboratory. The optimized diffusion angle is 9°, the diffusion ratio is 15, the chamber depth is 80 μm and the diffuser neck cross-section is 80×80μm. The resonant frequency of the square piezoelectric vibrator composed of Si (12000×l2000×50μm) and PZT bulk (10000×l0000×200μm) is 7.114 kHz. The flux of PVMP increases as the voltage amplitude increasing and the characteristic curve changed complicatedly as the frequencyincreasing. The maximum displacement tendency of the vibrator is different from the flux changed current, which proved it is not accurate to equate the PVMP flux and the volume enclosed by the deformation of the vibrator. At low actuating frequencies, the peak value of the frequency corresponding to the vibrator deflection is not sure to be the resonant frequency of the vibrator, which is possible much higher. Meanwhile, it also explained the importance of the multiphysics coupling numerical simulation of the PVMP. The pump could work normaly and the fluid in the sample injection channel shows stable flow characteristics from the systematic simulation to the microfludic chip interating with PVMP, which demonstrated the micromation PVMP could be used in μ-TAS.