基于MEMS的压电微泵建模与优化

以压电驱动的无阀微泵为研究对象,根据扩张管/收缩管的压力损失系数和连续方程,建立了无阀微泵的理论模型。利用有限元分析软件,建立了无阀微泵有限元模型,进行了耦合场仿真分析。模拟并分析了不同边界条件下驱动电压、电压频率、泵膜厚度、压电薄膜厚度和压电材料对无阀微泵输出特性的影响。仿真结果显示,无阀微泵具有很好的整流特性,并且驱动电压越大,输出特性越好。在局部固定边界条件下,当压电薄膜上施加电场强度为500 V/mm的驱动电压时,存在最优的压电薄膜厚度,使得微泵的输出流量最大。研究结果为无阀微泵的优化设计提供了依据。     

Piezoelectric diffuser/nozzle micropump with double pump chambers

To eliminate check valve fatigue and valve clogging, diffuser/nozzle elements are used for flow rectification in a valveless diffuser/nozzle micropump instead of valves. However, the application of this type of micropump is restricted because of its pulsating or periodic flow and low pump flux. In this paper, a diffuser/nozzle Si/Glass micropump with two pump chambers by IC and MEMS technology is designed. The fabrication process requires only one mask and one etch step, so that the fabrication has the advantages of low cost, short processing period, and facilitation of miniaturization. The pump is equipped with a glass cover board so as to conveniently observe the flow status. Pump-chambers and diffuser elements are fabricated by the anisotropic KOH-etch technique on the silicone substrate, and the convex corner is designed to compensate for an anisotropic etch. The driving force of the micropump is produced by the PZT piezoelectric actuator. The pump performance with both actuators actuated in anti-or same-phase mode is also researched. The result indicates that the micropump achieves great performance with the actuators working at anti-phase. This may be because the liquid flows steadily, pulse phenomenon is very weak, and the optimal working frequency, pump back pressure, and flow rate are both double that of the pump driven in same-phase.     

Piezoelectric diffuser/nozzle micropump with double pump chambers

To eliminate check valve fatigue and valve clogging, diffuser/nozzle elements are used for flow rectification in a valveless diffuser/nozzle micropump instead of valves. However, the application of this type of micropump is restricted because of its pulsating or periodic flow and low pump flux. In this paper, a diffuser/nozzle Si/Glass micropump with two pump chambers by IC and MEMS technology is designed. The fabrication process requires only one mask and one etch step, so that the fabrication has the advantages of low cost, short processing period, and facilitation of miniaturization. The pump is equipped with a glass cover board so as to conveniently observe the flow status. Pump-chambers and diffuser elements are fabricated by the anisotropic KOH-etch technique on the silicone substrate, and the convex corner is designed to compensate for an anisotropic etch. The driving force of the micropump is produced by the PZT piezoelectric actuator. The pump performance with both actuators actuated in anti- or same-phase mode is also researched. The result indicates that the micropump achieves great performance with the actuators working at anti-phase. This may be because the liquid flows steadily, pulse phenomenon is very weak, and the optimal working frequency, pump back pressure, and flow rate are both double that of the pump driven in same-phase.     

Design and analysis of a double superimposed chamber valveless MEMS micropump

The newly designed micropump model proposed consists of a valveless double chamber pump completely simulated and optimized for drug delivery conditions. First, the inertia force and viscous loss in relation to actuation, pressure, and frequency is considered, and then a model of the nozzle/diffuser elements is introduced. The value of the flowrate obtained from the first model is then used to determine the loss coefficients starting from geometrical properties and flow velocity. From the developed model IT analysis is performed to predict the micropump performance based on the actuation parameters and no energy loss. A single-chamber pump with geometrical dimensions equal to each of the chambers of the double-chamber pump was also developed, and the results from both models are then compared for equally applied actuation pressure and frequency. Results show that the proposed design gives a maximum flow working frequency that is about 30 per cent lower than the single chamber design, with a maximum flowrate that is 140 per cent greater than that of the single chamber. Finally, the influences of geometrical properties on flowrate, maximum flow frequency, loss coefficients, and membrane strain are examined. The results show that the nozzle/ diffuser initial width and chamber side length are the most critical dimensions of the design.     

Study of fluid damping effects on resonant frequency of an electromagnetically actuated valveless micropump

As fluid flow effects on the actuation and dynamic response of a vibrating membrane are crucial to micropump design in drug delivery, this paper presents both a mathematical and finite-element analysis (FEA) validation of a solution to fluid damping of a valveless micropump model. To further understand the behavior of the micropump, effects of geometrical dimensions and properties of fluid on the resonant frequency are analyzed to optimize the design of the proposed micropump. The analytical and numerical solutions show that the resonant frequency decreases with the slenderness ratio of the diffuser and increases with the opening angle, high aspect ratio, and thickness ratio between the membrane and the fluid chamber depth. A specific valveless micropump model with a 6-mm diameter and 65-μm thickness polydimethylsiloxane (PDMS) composite elastic membrane was studied and analyzed when subjected to different fluids conditions. The resonant frequency of a clamped circular membrane is found to be 138.11 Hz, neglecting the fluid. For a gas fluid load, the frequency is attenuated by slightly shifting to 104.76 Hz and it is significantly reduced to 5.53 Hz when the liquid fluid is loaded. Resonant frequency remarkably shifts the flow rate of the pump; hence, frequency-dependent characteristics of both single-chamber and dual-chamber configuration micropumps were investigated. It was observed that, although the fluid capacity is doubled for the latter, the maximum flow rate was found to be around 27.73 μl/min under 0.4-A input current with an excitation frequency of 3 Hz. This is less than twice the flow rate of a single chamber of 19.61 μl/min tested under the same current but with an excitation frequency of 4.36 Hz. The proposed double-chamber model analytical solution combined with the optimization of the nozzle/diffuser design and assuming the effects of damping proved to be an effective tool in predicting micropump performance and flow rate delivery.     

Performance of a serial-connection multi-chamber piezoelectric micropump

1Introduction Micropumpsaretheessentialcomponentsin micro fluidicsystemwhichhasemergedasa popularareaofresearchwiththedevelopmentof micro electro mechanicalsystem(MEMS).Sinceoneoftheearlypiezoelectricmicropumps forinsulindeliverywasfabricatedin1978,more andmoreeffortshavebeenmadeintheresearch ofmicropumps[1].Duetotheirpreciselycon trolledflowrate,micropumpspresentpromising applicationsinanalyticalchemistry,medical treatment,pharmacy,bioengineering,fuel drop generatorforautomobileheater,etc.A…     

压电驱动微泵泵膜振动有限元分析

以压电驱动微泵泵膜为研究对象,分析了压电复合泵膜膜片的弹性曲面微分方程,建立了泵膜膜片有限元数值模拟的模型,对泵模膜态进行了计算和分析,模拟并分析了驱动电压、泵膜压电层半径与泵膜单晶硅层半径之比、单晶硅层厚度、压电层厚度对泵膜位移的影响。所作研究为压电驱动微泵的优化设计提供了理论依据。     

Optimisation Design of a Piezoelectric Micropump

A new aluminium based valveless fluid micropump is manufactured by the micromachining method. The pump consists of two fluid-diffuser/nozzle elements on each side of a chamber with an oscillating diaphragm which is actuated with a piezoelectric disk. The two simultaneous vibrating diaphragms produce a large oscillating chamber volume. To obtain the optimal structural parameters at the design stage of the pump, the ANSYS simulation method is used. The pump prototype with two aluminium diaphragms of ○ (with a slash) 10 mm 3 0.1 mm has been simulated. The chamber oscillating volume can be as large as 800 ml for water pumping.     

泵用压电振子动态特性的研究

为了提高压电泵的效率、优化压电泵的结构,对泵用压电振子的动态特性进行了研究。介绍了一种新型压电泵——Y形流管无阀压电泵的结构和工作原理;对Y形流管无阀压电泵压电振子的振动状态进行了理论分析,得到了压电振子的固有频率及最大振幅的理论计算公式,并证明了理论分析结果的正确性;根据理论分析结果,对压电振子几何参数和基底层材料对其振动特性的影响进行了分析讨论。分析结果表明：压电振子的PZT层与基底层的直径比应在0.75左右,厚度比应小于1;基底层材料对频率影响较大,但对最大振幅影响较小。     

悬臂式微型压电泵的试验研究

利用压电晶片致动式压电泵的工作原理,提出一种整机采用迭片式结构,单向阀采用悬臂式薄片阀的新结构微型压电泵,设计、制作了试验样机,并对该泵的工作性能进行了较为系统的试验测试和研究。通过试验测试：该泵工作性能稳定,整机具有较高的体积功能比。该泵设计方法及制作工艺对研发适于大量生产的实用微型泵是一个有益的尝试。     

Simulation of the fluidic features for diffuser/nozzle involved in a PZT-based valveless micropump

PZT-based valveless micropump is a microactuator that can be used for controlling and delivering tiny amounts of fluids, and diffuser/nozzle plays an important role when this type of micropump drives the fluid flowing along a specific direction. In this paper, a numerical model of micropump has been proposed, and the fluidic properties of diffuser/nozzle have been simulated with ANSYS. With the method of finite-element analysis, the increased pressure drop between inlet and outlet of diffuser/nozzle induces the increment of flow rate in both diffuser and nozzle simultaneously, but the increasing rate of diffuser is faster than that of nozzle. The L/R, ratio of L（length of cone pipe） and R （radius of minimal cross section of cone pipe） plays an important role in fluidic performance of diffuser and nozzle as well, and the mean flow rate will decrease with increment of L/R. The mean flow rate reaches its peak value when L/R with the value of 10 regardless the divergence angle of diffuser or nozzle. The simulation results in-dicate that the fluidic properties of diffuser/nozzle can be defined by its geometric structure, and accordingly determine the efficiency of micropump.     

Flow behavior of liquid-solid coupled system of piezoelectric micropump

This paper employs a shallow water model and the finite element method to approximate periodical flows of a micropump to a two-dimensional thickness-averaged flow. A liquid-solid coupled system equation of the micropump is presented. Through the mode analysis of the liquid-solid coupled system, the first-order natural frequency, diaphragm vibration shape and amplitude-frequency relationship are obtained. The vibration response of the diaphragm is calculated when an external electric field is applied. Based on the thickness-averaged flow equation, the periodical flow of the micropump is studied using the finite volume method to investigate the flow behavior and flow rate-frequency characteristics. Numerical results indicate that an optimal working frequency can be obtained, at which the flow rate of the micropump achieves the maximum when the external electric voltage is fixed. __________ Translated from Journal of Hydrodynamics, 2006, 21(4): 512–518 [译自: 水动力学研究与进展]     

“Y”形流管无阀压电泵驱动器的动态研究

为满足输血或输液工作需求而特别设计了一种新型"Y"形流管无阀压电泵,研究了它的驱动器--压电驱动器的工作特性.理论分析了驱动器的动态特性,并推导出其固有频率和最大振幅的计算公式.然后,验证了理论分析的正确性.最后,基于理论模型,对驱动器的几何参数和材料特性对其动态性能的影响进行分析讨论.分析结果表明,压电陶瓷层与基底层的半径比应为0.75左右,厚度比应<1.0.本研究亦为其他类型压电泵的优化设计和制作提供了实用性的参考.     

面向压电泵脉动消除的流体滤波器设计与实验

设计了一种被动式流体滤波器,它由薄膜及微通道组成,旨在消除由压电泵引起的流体脉动。对流体滤波器进行了理论分析,利用Comsol软件建立滤波器的有限元模型,分别对薄膜变形以及微通道流阻进行数值计算,并分析了影响滤波效果的参数。仿真结果表明,当微通道内的流体阻力较大时,泵的驱动频率越高,薄膜半径越大,滤波效果更佳。通过实验验证,表明所设计的流体滤波器可以有效减小脉动,压电泵能够提供稳定的流量。     

新型压电无阀微泵效率分析及试验研究

提出了一种用于无阀压电微泵的新型效率模型,根据传统扩张/收缩管型结构设计出侧面带有环形面积新型锯齿型带锥度和无锥度两种微流道.用CFD软件对传统扩张/收缩型微流道及新型锯齿型微流道进行了三维流动模拟,绘制出几种微流道特性曲线,并用新型效率模型计算了三种微流道在两种限制条件(最大流量零压力头和最大压力头零流量)下的稳态效率,并进行了分析比较,结果表明由于结构改变,锯齿型微流道最大流量和压力损失实现了预期的变化,并且带锥度锯齿型微流道微泵稳态效率均大于标准扩张/收缩型微流道及无锥度锯齿型微流道微泵.最后制作出含有标准扩张/收缩及带锥度锯齿型微流道结构微泵,并对其进行试验,结果证明由于环形面积和锥度存在,带锥度锯齿形微流道微泵性能明显优于传统扩张/收缩型微泵.     

“Y”形流管无阀压电泵模拟与试验研究

为了对“Y”形流管无阀压电泵的工作特性有更深入的了解,使其更好地满足输血、输液等工作的需要,对“Y”形流管无阀压电泵内部流场及泵流量特性进行了模拟及试验研究。采用CFX软件对“Y”形流管无阀压电泵泵腔内的流场特性进行了模拟分析。结果表明：“Y”形流管无阀压电泵工作时泵腔内的压强变化很小,涡旋对流体传输活体细胞及长链大分子基本无影响。实际制作了“Y”形流管无阀压电泵,并通过改变“Y”形流管的几何尺寸,研究了压电泵进出口端压差的变化规律。试验结果表明压差随支管夹角增大而减小,并且当两支管宽的和接近主管宽时,压差值达到最小,当支管夹角为5°,宽为1.2mm时,压差达到最大的74mm水柱。     

静电微泵的3D流固耦合动态特性分析

采用任意拉格朗日—欧拉(ALE)描述建立了无阀微泵的静电-结构-流体全耦合三维模型,数值仿真表明:泵内流体的动态特性与泵膜的运动存在着密切的关系;扩散/收缩口单元两端的压力差必须达到一定值后才有"整流"泵送效用;泵腔内流体压力的分布几乎一致;流体流动的最大雷诺数远小于宏观条件下认定的临界雷诺数;流体黏滞损失的非线性不容忽视。     

FLOW DIRECTION OF PIEZOELECTRIC PUMP WITH NOZZLE／DIFFUSERELEMENTS

The piezoelectric pump with nozzle/diffuser-elements, which oscillating form differing from regular volumetric reciprocating or rotating pumps because there are nozzle/diffuser-elements substituted for regular valves, is a new type pump whose actuator is a piezoelectric ceramal part with verse piezoelectric effect. In recent year, piezoelectric pump is paid increasing attention to because it is an ideal candidate in application in such area as medical health, mechanical tools and micro-mechanism. The fundamental research on it, however, is still not made through. Focuses on the phenomenon of different directions of flow among Germany pump, Chinese pump and Swiss pump, which are all fitted with nozzle/diffuser-elements, and analyzes the cone angle of nozzle/diffuser-elements based on the flow equation of valve-less piezoelectric pump with nozzle/diffuser-elements. As a result, the concepts of diffuser loss coefficient and loss coefficient are introduced to explain these phenomena, from which a discussion     

基于悬臂梁阀的微型压电泵的实验研究

利用压电晶片致动式压电泵的工作原理,提出一种整机采用迭片式结构,单向阀采用悬臂梁式薄片阀的新结构微型压电泵,设计、制作了实验样机,并对该泵的工作性能进行了较为系统的实验测试和研究,并提出了利用多腔体串联结构提高压电泵性能的优化设计方案。通过实验测试:该泵工作性能稳定,整机具有较高的体积功能比(样机尺寸:15 mm×1.8 mm;50 V正弦信号输入,80 Hz条件下,最大输出压力22 kPa,流量达到3.6 m l/m in)。该泵的设计方法及所用制作工艺对研发适于大量生产的实用微型泵是一个有益的尝试。     

A bidirectional valveless piezoelectric micropump with three chambers applying synthetic jet

A new type of valveless piezoelectric micropump is presented. Synthetic jet and Coanda effect are utilized to achieve larger and bidirectional flow rate. The numerical simulation applying the velocity and pressure boundary conditions as well as the SST turbulence model were utilized to research the performance and internal flow state of the micropump. The simulation method was tested by the previous experimental data and the results matched well. The results suggest that the flow rate of the micropump is related to the Reynolds number and frequency. The entrainment flow rate of synthetic jet accounts for over 80% of the total outflow rate. The outflow rate is much larger than the volume change of the micropump chambers. There is an optimal frequency to obtain the maximum flow rate regarding the volume change of the chambers as a constant. The fluctuation of the flow rate decreases with the increase of frequency. When the frequency is higher than 25 Hz, the outflow can be continuous. Working at the Reynolds number of 1000 and optimal frequency of 50 Hz, the flow rate is 6.8 ml/min.