Multifield analysis of a piezoelectric valveless micropump: effects of actuation frequency and electric potential

Abstract

Coupled multifield analysis of a piezoelectrically actuated valveless micropump device is carried out for liquid (water) transport applications. The valveless micropump consists of two diffuser/nozzle elements; the pump chamber, a thin structural layer (silicon), and a piezoelectric layer, PZT-5A as the actuator. We consider two-way coupling of forces between solid and liquid domains in the systems where actuator deflection causes fluid flow and vice versa. Flow contraction and expansion (through the nozzle and the diffuser respectively) generate net fluid flow. Both structural and flow field analysis of the microfluidic device are considered. The effect of the driving power (voltage) and actuation frequency on silicon-PZT-5A bi-layer membrane deflection and flow rate is investigated. For the compressible flow formulation, an isothermal equation of state for the working fluid is employed. The governing equations for the flow fields and the silicon-PZT-5A bi-layer membrane motions are solved numerically. At frequencies below 5000 Hz, the predicted flow rate increases with actuation frequency. The fluid-solid system shows a resonance at 5000 Hz due to the combined effect of mechanical and fluidic capacitances, inductances, and damping. Time-averaged flow rate starts to drop with increase of actuation frequency above (5000 Hz). The velocity profile in the pump chamber becomes relatively flat or plug-like, if the frequency of pulsations is sufficiently large (high Womersley number). The pressure, velocity, and flow rate prediction models developed in the present study can be utilized to optimize the design of MEMS based micropumps.

Electrochemical membrane microactuator with a millisecond response time

“…A great number of principles and techniques is used to build microactuators [6][7][8] . They include piezoelectric 9,10 , electrostatic 11,12 , thermal [13][14][15] , electrokinetic 16,17 and many other actuation principles. Actuators using electrostatic forces are fast but they develop rather weak forces.…”

Electro-magneto-hydrodynamic peristaltic pumping of couple stress biofluids through a complex wavy micro-channel

“…Yang et al [27] considered AC electro-osmotic (ACEO) pumping on a symmetric gold electrode array. Many other studies have been communicated including Paul et al [28], Sayar and Farouk [29] (who simulated coupled multifield flow in a piezoelectrically actuated valveless micropump device for liquid transport). Tripathi et al [30] used a linearized analytical model to elucidate the effects of electro-osmotic velocity on peristaltic pumping of blood in capillaries.…”

Analytical modeling, simulations and experimental studies of a PZT actuated planar valveless PDMS micropump

“…Ullmann et al [27] presented a dynamic model in order to accurately simulate the pump performance parameters. Sayar et al [28] carried out a detailed study of a micropump using CFD studies. Ha et al [29] and Yao et al [30] carried out 3-D electro-fluidsolid analysis of valveless micropumps using CFD tools.…”

“…Also, many approximate analytical and simulation models have been reported [22][23][24][25][26][27][28][29][30][31][32][33]. However, in spite of considerable work in the area of valveless micropump, investigations of combined electro-fluid-structural interactions are limited due to the complicated physics involved.…”