Fully coupled modeling and design of a piezoelectric actuation based valveless micropump for drug delivery application

The precise control over the drug delivery involved in several vital applications including healthcare is required for achieving a therapeutic effect. For such precise control/manipulation of the drugs, micropumps are used. These micropumps are basically of two types viz. check valve-based and valveless micropumps. The valveless micropumps are preferable due to the congestion-free operation of diffuser/nozzle valves. In this paper, design optimization of a valveless piezo-electric actuation based micropump is carried out using COMSOL Multiphysics 5.0 by coupling two Multiphysics interface modules namely fluid–structure interaction and piezoelectric physics modules. Using simulation studies, the influence of pump design parameters including diffuser angle, diffuser length, neck width, chamber depth, chamber diameter and diaphragm thickness on net flow rate is studied. An optimal set of design parameters for the proposed micropump is identified. Further, the influence of actuation frequency on the flow rate is analysed. It is found that the proposed micropump is capable to deliver a net flow rate of 20 µl/min and a maximum back pressure attainable is 200 Pa.

     

串联压电微泵特性研究

介绍了一种压电驱动的串联无阀微泵.基于收缩管/扩展管整流特性的分析,建立了微泵输出特性的表达公式.采用有限元仿真软件ANSYS对微泵内流体的流动过成进行了数值模拟,结果显示,在相同的驱动条件下,串联无阀微泵的工作性能优于单腔无阀微泵的工作性能.泵流量随着驱动电压的增加而增加.当固定的驱动电压下,存在最优的压电层厚度使得泵流量最大.研究结果为串联微泵的优化设计提供了依据.     

Development and application of a diaphragm micro-pump with piezoelectric device

In this study, a new type of thin, compact, and light weighed diaphragm micro-pump has been successfully developed to actuate liquid by the vibration of a diaphragm. The micro-diaphragm pump with two valves is fabricated in an aluminum case by using highly accurate CNC machine, and the cross-section dimension is 28 mm × 5 mm. Both valves and diaphragm are manufactured from PDMS. The amplitude of vibration by a piezoelectric device produces an oscillating flow and alters the chamber volume by the curvature change of a diaphragm. Several experimental set-ups for performance tests in a single micro-diaphragm pump, isothermal flow open system, and a closed liquid cooling system are designed and implemented. The performance of a one-side actuating micro-diaphragm pump is affected by the design of check valves, diaphragm, piezoelectric device, chamber volume, input voltage and frequency. The measured maximum flow rate of present design is 72 ml/min at zero total pump head in the range of operation frequency 70–180 Hz.     

一种低成本压电无阀微泵的研制

提出了一种低成本的由压电材料驱动的平面扩张/收缩管无阀微泵的制作工艺.通过数值模拟确定了扩张/收缩管扩张角的最优值,在此基础上,采用光刻和湿法刻蚀工艺,刻蚀了300μm深的泵腔基片和100 μm深的盖片;使用等离子体清洗技术将其与PDMS薄膜键合,完成了可以实现单向泵送的压电无阀微泵样机制作.研究了该压电无阀微泵样机的...     

Optimization design of multi-material micropump using finite element method

This paper presents a micropump fabricated from low cost materials with specific goal of cost reduction. The micropump does not require any valve flap and comprises one plastic pump polyether–ether–ketone (PEEK) body, one metal diaphragm, and three piezoelectric ceramics to form piezoelectrically actuated diaphragm valves. The valve actuation simplifies micropump structural designs and assembly processes to make the pump attractive for low cost bio-medical drug delivery applications. A detailed optimization design of geometric parameters of the piezoelectrically actuated diaphragm is undertaken by use of 3D finite element method (FEM) to maximize piezoelectric actuation capability and ensure actuation reliability. An optimized geometric dimensional design: the ratio of thicknesses between the piezoelectric ceramics and the metal diaphragm, and the lateral dimension of the piezoelectric ceramic, is obtained through simulations. Based on the optimized design, a good agreement has been reached between simulated and measured strokes of the micropumps. The tested results show that the micropump has a high pump flow rate for air, up to 39 ml/min, and for water, up to 1.8 ml/min, and is capable of ensuring diaphragm’s maximum stress and strain is within material strength for reliable work.     

A cross-junction channel valveless-micropump with PZT actuation

A gas-jet micro pump with novel cross-junction channel has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and fluidic network. The design of the valveless pump focuses on a cross-junction formed by the neck of the pump chamber and one outlet and two opposite inlet channels. The structure of cross-junction allows differences in fluidic resistance and fluidic momentum inside the channels during each PZT diaphragm vibration cycle, which leads to the gas flow being rectified without valves. The flow channels were easily fabricated by using silicon etching process. To investigate the effects of the structure of the cross-junction on the gas flow rate, two types of pump with different cross-junction were studied. The design and simulation were done using ANSYS-Fluent software. The simulations and experimental data revealed that the step-nozzle structure is much more advantageous than the planar structure. A flow rate of 5.2 ml/min was obtained for the pump with step structure when the pump was driven at its resonant frequency of 7.9 kHz by a sinusoidal voltage of 50 V_p–p.     

Peristaltic micropump system with piezoelectric actuators

This work presents a driving system for a peristaltic micropump that is based on piezoelectric actuation. The effects of the actuation sequence on pump performance are also considered. A valveless peristaltic micropump based on piezoelectric actuation is designed and fabricated using microelectromechanical system technology. The pump has three parts––silicon, Pyrex glass and commercially available bulk PZT (lead zirconate titanate) chips. The peristaltic micropump actuated by PZT chips comprises three chambers that are in series. The driving system consists of an ATmega 8535 microprocessor, a high voltage power supply, three differential amplifiers, a phase controller, an A/D converter, a 555 oscillator and an LCD module. It is supplied via a 110 Vrms 60-Hz AC line and is programmable. The system can produce step-function signals with voltages of up to 100 V_pp and frequencies ranging from 10 Hz to 1 kHz, as the inputs for the pump. Fluid pumping with air is successfully demonstrated. Additionally, 3-, 4- and 6-phase actuation sequences for the pump are designed and used to study the effects on pump performance, as revealed by the flow rate and the displacement of a pump diaphragm. The experimental results show that the flow rate and the displacement of the diaphragm actuated by the 4-phase sequence exceed those actuated by the 3- and 6-phase sequences. A flow rate of 17.6 μl min⁻¹ and a displacement of 2.91 μm (peak-to-peak) in 4-phase peristaltic motion are achieved at 100 Hz and 100 V_pp. The results demonstrate that the pump actuated in the 4-phase sequence is the most efficient. Consequently, the actuation sequences can affect the pump performance.     

A study of PZT valveless micropump with asymmetric obstacles

The results of a study on a new type of PZT valveless micropump with asymmetric obstacles are presented in this paper. The valveless micropump was made through a MEMS fabrication process by using simply only one photo mask. Asymmetric obstacles are used for the flow directing device instead of the diffuser/nozzle elements used in previous studies. In this study, numerical simulations were also carried out to evaluate the design and the performance of the new micropump. The main feature of the present micropump is that it has a uniform cross-section area across the micro-channel, which gives many advantages. The differential pressure head and the pumping flow rate can be adjusted easily by using obstacles of different shapes and changing the PZT operating frequency without changing the dimensions of the micro-channel. In this experiment, the performance of the micropump was evaluated by measuring the pressure head difference and the flow rate as the input voltage ranged from 20 to 40 V, a range much lower than those in previous studies. The pumping pressure can reach a maximum of 1.2 kPa, and the maximum net volume flow rate is 156 μl/min. These test data indicate that this micropump fulfills the demands for most micro-fluidic systems. Moreover, the present device can be easily applied to complex systems with combinations of several pumps and microchannels in the future.     

Design and fabrication of a valveless micropump based on low temperature co-fired ceramic tape technology

Low temperature co-fired ceramic (LTCC) tape technology has been widely studied in microsystems and microfluidic devices. The current study presented the manufacturing process of a simple and inexpensive micropump which is made of LTCC. The components of micropump including fluidic channels, diaphragm, chamber, and planar diffuser valves were integrated in one LTCC module. Geometries of these components were designed based on numerical analysis. The finite element analysis was used to characterize the displacement of a piezoelectric actuator and the computational fluid dynamics was applied to design the diffuser. The performance of the micropump was optimized and performance of the designed micropump was carefully examined in the experiments. The data revealed that the performance of a micropump can be significantly increased by adding a pair of pockets. Overall, the study demonstrated that LTCC tape technology is a simple and reliable method to fabricate a valveless micropump.     

Valveless micropump with acoustically featured pumping chamber

This article presents a new design of a valveless micropump. The pump consists of a nozzle-shaped actuation chamber with acoustic resonator profile, which functions as both pumping chamber and flow rectification structure. The pump is fabricated by lamination of layers made of polymethyl-methacrylate (PMMA) and dry adhesives, and is driven by a piezoelectric disk. The performance of the pump has been studied by both experimental characterization and numerical simulations. Both the experimental and numerical results show that the pump works well at low frequencies of 20–100 Hz to produce relatively high backpressures and flowrates. Moreover, the numerical simulations show that in the pumping frequency range, the flow patterns inside the chamber are found to be asymmetric in one pumping cycle so as to create a net flowrate, while outside the pumping frequency range, the flow patterns become symmetric in the pumping cycle. The pumping frequency can be shifted by modifying the pump configuration and dimensions. The pump is suitable for microfluidic integrations.     

Piezoelectrically actuated dome-shaped diaphragm micropump

This paper describes a piezoelectric micropump built on a dome-shaped diaphragm with one-way parylene valves. The micropump uses piezoelectric ZnO film (less than 10 /spl mu/m thick) to actuate a parylene dome diaphragm, which is fabricated with an innovative, IC-compatible process on a silicon substrate. Piezoelectric ZnO film is sputter-deposited on a parylene dome diaphragm with its C-axis oriented perpendicular to the dome surface. Two one-way check valves (made of parylene) are integrated with a piezoelectrically actuated dome diaphragm to form a multi-chip micropump. The fabricated micropump (10/spl times/10/spl times/1.6 mm/sup 3/) consumes extremely low power (i.e., 3 mW to pump 3.2 /spl mu/L/min) and shows negligible leak up to 700 Pa static differential pressure.     

一种基于MEMS技术的压电微泵的研究

介绍了一种基于MEMS技术的压电微泵。该微泵利用聚二甲基硅氧烷(PDMS)作为泵膜,使用了一个主动阀和一个被动阀,并利用压电双晶片作为驱动部件。压电双晶片和PDMS泵膜的组合可以产生较大的泵腔体积改变和压缩比,显著降低了加工成本,并提高了成品率。对压电微泵的输出流量进行了测试,结果显示:电压、频率以及背压对流量均有显著影响。在100 V,25Hz的方波驱动下,该压电微泵的最大输出流量为458μL/m in,最大输出压力为6 kPa。     

Study on a piezoelectric micropump for the controlled drug delivery system

We present the design of a new controlled drug delivery system potential for in vitro injection of diabetics. The system incorporates some integrated circuit units and microelectromechanical system devices, such as micropump, microneedle array and microsensor. Its goal is to achieve safer and more effective drug delivery. Moreover, a valveless micropump excited by the piezoelectric actuator is designed for the drug delivery system, and a simple fabrication process is proposed. A dynamic model is developed for the valveless micropump based upon the mass conservation. To characterize the micropump, a complete electro-solid-fluid coupling model, including the diffuser/nozzle element and the piezoelectric actuator, is built using the ANSYS software. The simulation results show that the performance of micropump is in direct proportion to the stroke volume of the pump membrane and there is an optimal thickness of the piezoelectric membrane under the 500 V/mm electric field. Based on this simulation model, the effects of several important parameters such as excitation voltage, excitation frequency, pump membrane dimension, piezoelectric membrane dimension and mechanical properties on the characteristics of valveless micropump have been investigated.     

磁力驱动微泵设计及优化

为提高收缩/扩散管无阀微泵的性能,设计了磁力驱动式无阀微泵,并利用ANSYS软件对微泵的整流部件收缩/扩散管和单腔微泵整体结构进行流体仿真,得到了微泵的结构优化参数.仿真和实验结果表明,流量随着管长、最小宽度、扩张角、泵腔半径的增大存在极大值.磁驱动微泵的流量在驱动电压12 V、驱动频率为25 Hz时达到最大值.     

Magnetic active-valve micropump actuated by a rotating magnetic assembly

We report on a high-efficiency and self-priming active-valve micropump consisting of a microfluidic chamber structure in glass that is assembled with a polydimethylsiloxane (PDMS) elastic sheet. The latter comprises two valving membranes and a central pumping chamber actuation membrane, having each an integrated permanent magnet that is magnetically actuated by arc-shaped NdFeB permanent magnets mounted on the rotation axis of a DC minimotor. The choice of this actuation principle allows very low-voltage (0.7 V) and low power (a few 10 mW) operation of the micropump. For the realisation, we use affordable powder blasting glass micropatterning and PDMS molding technologies. A flow rate of 2.4 mL/min and up to 70 mbar backpressure are obtained at the micropump resonance frequency of around 12 Hz, values that are much higher than reported so far for such type of micropump.     

Design,fabrication and characterization of a piezoelectrically actuated bidirectional polymer micropump

We present the design, fabrication and characterization of a new, piezoelectrically actuated fully polymeric three chamber peristaltic micropump. An optimized bimorph bending actuator has been designed to deform the polymer membranes in an optimal and most-efficient way. The piezoelectric actuators of the micropump are driven with actuation voltages of ±260 V. The pump has a total size of 46 × 18 × 4 mm, is produced by hot embossing and is assembled in a very simple way. The presented design is able to pump water with a flow rate of 4.8 ml/min and achieves a maximum back pressure of app. 200 mBar.     

Normally-closed peristaltic micropump with re-usable actuator and disposable fluidic chip

We present a new peristaltic micropump offering three key features: (i) a disposable pump body and a re-useable actuator unit, (ii) an intrinsic normally-closed mechanism blocking unintended liquid flows up to a pressure of 100 kPa and (iii) a backpressure independent pump performance up to 40 kPa. The modular concept basing on a re-usable actuator unit and a low-cost disposable microfluidic chip enables an easy and cost-efficient exchange of all contaminated parts after use, which addresses especially the needs in the health care sector. The intrinsic normally-closed feature blocks liquid flow in both directions up to a pressure difference of 100 kPa when the electric power is off. The micropump is actuated in a peristaltic manner by three piezostack actuators. Up to a frequency of 15 Hz the pump rate increases linearly with operation frequency leading to a pump rate of 120 μL/min. This was proved for an operation voltage of 140 V by pumping water. In addition the pump rate is independent on backpressure up to 40 kPa and shows a linear decrease for higher pressure differences. The maximum achievable backpressure at zero flow rate was extrapolated to be 180 kPa. As for all peristaltic micropumps, the pump is bidirectional, e.g. the pump direction can be changed forward to reverse mode.     

Design and modeling of electromagnetic actuator in mems-based valveless impedance pump

This study models and optimizes the electromagnetic actuator in an MEMS-based valveless impedance pump. The actuator comprises an electroplated permanent magnet mounted on a flexible PDMS diaphragm and electroplated Cu coils located on a glass substrate. In optimizing the design of the actuator, the objective is to maximize the output flow rate of the micropump while maintaining the mechanical integrity of its constituent parts. The study commences by developing optimized theoretical models for each of the components within the actuator, namely the diaphragm, the magnet, and the micro-coils. The theoretical models are then verified numerically using FEA software. The magnitude of the magnetic force acting on the flexible diaphragm is calculated using Ansoft/Maxwell3D FEA software. The simulation results obtained by ANSYS FEA software for the diaphragm deflection are found to be in good agreement with the theoretical predictions. In general, the results show that the desired diaphragm deflection of 15 μm can be obtained by passing a current of 0.6–0.7 A through the micro-coil to produce a compression force of 11 μN. The valveless micro impedance pump proposed in this study is easily fabricated and is readily integrated with existing biomedical chips due to its plane structure. The results of this study provide a valuable contribution to the ongoing development of Lab-on-a Chip systems.     

A PMMA valveless micropump using electromagnetic actuation

We have fabricated and characterized a polymethylmethacrylate (PMMA) valveless micropump. The pump consists of two diffuser elements and a polydimethylsiloxane (PDMS) membrane with an integrated composite magnet made of NdFeB magnetic powder. A large-stroke membrane deflection (~200 m) is obtained using external actuation by an electromagnet. We present a detailed analysis of the magnetic actuation force and the flow rate of the micropump. Water is pumped at flow rates of up to 400 µl/min and backpressures of up to 12 mbar. We study the frequency-dependent flow rate and determine a resonance frequency of 12 and 200 Hz for pumping of water and air, respectively. Our experiments show that the models for valveless micropumps of A. Olsson et al. (J Micromech Microeng 9:34, 1999) and L.S. Pan et al. (J Micromech Microeng 13:390, 2003) correctly predict the resonance frequency, although additional modeling of losses is necessary.     

Microfabricated centrifugal pump driven by an integrated synchronous micromotor

This paper presents the development of a new design of the microfabricated centrifugal force pump. The pumping concept is based on running an impeller (a rotor including permanent magnets carrying straight and backward blades) within an integrated synchronous motor, which can be operated at different rotational speeds to pump water. The impeller is 5.5 mm in diameter, and is 1.5 mm in height. This micropump with 7-straight-blade impeller can operate smoothly up to a rotational speed of 9000 rpm. It can deliver a non-pulsating maximum flow rate of up to 12 ml/min and allows water to be pumped up to a 24 cm water head. Additionally, the micropump with the backward-blade-impeller pump delivered a flow rate of up to 14.3 ml/min. at a rotational speed of 11,400 rpm with no back pressure. The micropump was patterned using a series of microfabrication processes including sputtering, photolithography and electroplating within a clean room. Such a pump can be integrated into a system of a compact size and can provide a wide range of flow rates. It could also be a promising device for use within biological and micro biomedical fields. To our knowledge, this is the smallest centrifugal pump in the world with an integrated electromagnetic synchronous motor that offers such high flow rates.