Design Of Micropump Research Articles

Design and simulation of a magnetohydrodynamic micro-pump to provide time varying tensile force for vibration suppression in viscoelastic micro-beams

In this paper, a new strategy for providing tensile force to suppress the transverse vibration of a micro-beam is introduced. This axial tensile force is supplied by a specific fluid flow called “magnetohydrodynamics” (MHD), which flows in a micro-pump, and then the fluid enters the micro-beam. The micro-beam is vibrated by an oscillating external force acting at its base. Therefore, a fluid structure interaction problem arises. The pressure of the fluid is increased due to the Lorentz force appears in the micro pump, and is directed by the channel towards the micro-beam and suppress the vibration of the micro-beam. It was observed that when the magnetic field rises from 0.25 Tesla to 0.5 Tesla, the amplitude of the micro-beam fluctuations will decrease from 6 × 10−13m to 3 × 10−13m. Assuming a laminar and incompressible flow, the finite volume method (FVM) is used to solve the governing equations. In the design of the micropump, the parameters studied are the value of the magnetic field, the amount of voltage applied to the micro-pump, the external force oscillation amplitude and the Reynolds number, and the effect of each parameter on the fluid and micro-beam behavior. The results show that with increasing fluid pressure in the micro-pump, the micro-beam vibration is suppressed. In addition, the pressure of the fluid along the micro-beam remains constant at 0.1 percent.

3-D Design and Simulation of a Piezoelectric Micropump.

The objective of this paper is to carefully study the performances of a new piezoelectric micropump that could be used, e.g., for drug delivery or micro-cooling systems. The proposed micropump is characterized by silicon diaphragms, with a piezoelectric actuation at a 60 V input voltage, and by two passive valves for flow input and output. By means of a 3-D Finite Element (FE) model, the fluid dynamic response during different stages of the working cycle is investigated, together with the fluid–structure interaction. The maximum predicted outflow is 1.62 μL min, obtained at 10 Hz working frequency. The computational model enables the optimization of geometrical features, with the goal to improve the pumping efficiency: The outflow is increased until 2.5 μL min.

Experimental investigation on performance of disposable micropump with retrofit piezo stack actuator for biomedical application

Extensive researches are being conducted to develop miniaturized pumping systems to fulfill the need for accurate delivery of fluids at required rates, particularly in the biomedical field. This paper presents the design, fabrication, and testing of novel valveless micropump actuated through an amplified piezo actuator. The proposed model of the micropump pump has the unique feature of a disposable chamber and employs low-cost polymeric materials, conventional molding and machining operations for fabrication. The disposable part of the pump consists of a laser-cut pump chamber with nozzle/diffuser made of Polymethyl methacrylate (PMMA) and conventionally molded silicone rubber diaphragm. The retrofit part includes the amplified piezo actuator and support structures build from PMMA. Systematic characterization of the pump was carried with water and blood mimicking fluid to understand the effect of operating parameters such as driving frequency and actuation voltage on flow rate and back pressure of the micropump. Experimental results show that the proposed design was capable of pumping 3.3–3.4 ml/min of dye solution and 1.7–1.75 ml/min of blood mimicking fluid at a driving frequency of 5 Hz and actuation voltage of 150 V. The corresponding computed volume resolution/stroke of the pump was found to about 5.75 µl and 11.25 µl of blood mimicking fluid and dye solution, respectively. The proposed pump was found to work effectively against a maximum back pressure of 156 Pa with blood mimicking fluid and 250 Pa with the dye solution as the working fluid under the same operating condition of 5 Hz and 150 V.

Design and Development of Piezoelectric Composite-Based Micropump

Valveless micropumps are extensively used in micro fluidic systems, including health care monitoring and diagnostic devices, computer devices, and so on, as it forms the critical component in the microsystem for precise and controlled fluid handling. This paper proposes the design and development of a novel, significantly low cost, planar micropump with piezoelectric polymer composite, consisting of lead zirconate titanate and polyvinylidene fluoride, for actuation. The novelty lies in the synthesis and use of the piezoelectric polymer composite as the actuating mechanism and the diffuser/nozzle design around the line of appreciable stall to achieve maximum flow rate for the given boundary conditions. The parametric study on the micropump geometry, including, chamber depth and diameter as well as diffuser/nozzle was carried out by using numerical simulations in COMSOL multiphysics, to analyze the fluid flow rate. The response of piezoelectric polymer to the applied sinusoidal voltage causes flow rectification in the micropump. An aspect ratio (diffuser length/diffuser width) of 15 produces maximum fluid flow rate. The designed micropump can achieve maximum fluid flow rate at low applied voltage and frequency of operation. [2018-0166]

Biofluid pumping and mixing by an AC electrothermal micropump embedded with a spiral microelectrode pair in a cylindrical microchannel.

In this paper, we numerically investigated a multifunctional AC electrothermal (ACET) micropump embedded with an asymmetric spiral microelectrode pair in a cylindrical microchannel for simultaneous pumping and mixing in high-conductivity fluids, which makes the pump useful for biofluid applications. When an AC signal was applied to the asymmetric spiral electrode pair, the vortices induced on the electrode surfaces with centerlines along the corresponding spiral electrode length exhibit a spiral distribution, and the net flow in the cylindrical microchannel is generated by the ACET effect. The vorticity field distribution can explain the mechanism of simultaneous pumping and mixing. Because the vorticity field is inclined against the microchannel direction, vortices on top of the spiral electrodes can affect the ACET flow in the following two aspects at the same time: one is pumping the flow in the microchannel direction, and the other is mixing the samples by stirring the flow. We also determined that the geometric ratios of the electrode width to the gap or slant angle of the spiral electrodes can feasibly be used to control the relative strength of the pumping and mixing capabilities, and we achieved an optimal design that gives both desirable pumping and mixing efficiencies. This study shows that the spiral ACET micropump design can rapidly drive the high-conductivity fluids and efficiently mix samples simultaneously. The numerical simulation of the spiral ACET micropump is of significant importance for practical, chemical and biological applications, and feasible fabrication techiniques should be experimentally investigated in future studies.

A novel micropump design: Investigation of the voltage effect on the net flow rate

A low cost piezoelectric micropump was designed and fabricated to supply fluid flow rate in micro-sizes and for use in medical purposes. It was designed as disposable in order to prevent contamination and infection. The micropump was fabricated with the Objet260 Connex3 multi-material 3D printer, which was very precise and sensitive. The piezoelectric was selected as an actuator to drive the diaphragm of this micropump. The piezoelectric diameter was 14mm, the thickness was 200 µm and the operating voltages were between 5V-55V. According to the experiments results, the air in the chamber caused reduction of the net flow rate of the micropump. Therefore, we eliminated the air inside the chamber with ethanol before the experiments. In the proposed micropump, we obtained the highest net flow rate and the maximum displacement of diaphragm at 55V that were 40.3ml/min and 2.64µm respectively.

Finite element analysis of effects of Joule heating, electro-osmosis and slip conditions on the performance of magnetohydrodynamic (MHD) micropumps

Magnetohydrodynamic (MHD) micropump which is energy saving and less pollution has been widely investigated by researchers in recent years. Based on the finite element analysis (FEA) of numerical model of 3D MHD micropump, we investigated the comprehensive effects of Joule heating, electro-osmosis and slip condition at walls on flow performance. This paper presents a new method for solving the full 3D MHD equations by coupling multi-physics fields, and gives a more comprehensive analysis of fundamental principles of MHD micropump. The temperature distribution under different flow channel geometries, the electro-osmotic velocity in MHD micropump, and the influence of slip condition at walls on flow velocity are analyzed in detail. The flow velocity slightly increases when taking the effect of Joule heating into account. In addition, the flow velocity is hardly affected by electron-osmosis in this work. It should be pointed out that the mean temperature of MHD micropump decreases with driven voltage increasing. With the advantage of fast and accurate analysis of MHD micropump performance, this study holds promising potential for the optimal design and fundamental research of MHD micropump.

Design and operation of a bio-inspired micropump based on blood-sucking mechanism of mosquitoes

The study is to develop a novel bionic micropump, mimicking blood-suck mechanism of mosquitos with a similar efficiency of 36%. The micropump is produced by using micro-electro-mechanical system (MEMS) technology, PDMS (polydimethylsiloxane) to fabricate the microchannel, and an actuator membrane made by Fe-PDMS. It employs an Nd-FeB permanent magnet and PZT to actuate the Fe-PDMS membrane for generating flow rate. A lumped model theory and the Taguchi method are used for numerical simulation of pulsating flow in the micropump. Also focused is to change the size of mosquito mouth for identifying the best waveform for the transient flow processes. Based on computational results of channel size and the Taguchi method, an optimization actuation waveform is identified. The maximum pumping flow rate is 23.5 [Formula: see text]L/min and the efficiency is 86%. The power density of micropump is about 8 times of that produced by mosquito’s suction. In addition to using theoretical design of the channel size, also combine with Taguchi method and asymmetric actuation to find the optimization actuation waveform, the experimental result shows the maximum pumping flowrate is 23.5 [Formula: see text]L/min and efficiency is 86%, moreover, the power density of micropump is 8 times higher than mosquito’s.

Design and analysis of MEMS based piezoelectric micro pump integrated with micro needle

This paper presents the design and simulation of piezoelectric micro pump integrated with micro needle. The proposed micro pump adopted rectangular piezoelectric vibrator supplied with an external alternating current voltage. It has four primary components: electrodes, piezoelectric plate, PDMS (polydimethylsiloxane) membrane and channel with inlet and outlet bottom up and whole setup is constructed on a glass base. The simulations are carried out by subjecting the developed model to voltage changes, material changes which shows the satisfactory results. The micro pump possesses a flow rate of 4.1 ml/min at an input voltage 10 V with frequency 300 Hz while it is integrated with Micro Needle is having 4.67 ml/min. High pumping rates at low applied voltages making the proposed model significantly important for Transdermal controlled drug delivery applications.

A rotary ferrofluidic vane micropump with C shape baffle

This paper presents a prototype design, fabrication and characterization of a rotary ferrofluidic vane micropump with C shape baffle. The new ferrofluid micropump mainly consists of a glass substrate, a PDMS chip and some ferrofluid actuated with an external permanent magnet. The ferrofluid in the microchamber is used as a rotary vane to pump the working fluid. The combination of the ferrofluid and the novel C shape baffle in the microchamber served as a valve to stop the reverse flow between the inlet and the outlet. The volumetric flow rate and the backpressure were characterized with different actuation speeds. The maximum pumping flow rate is about 49.32 μL/min and the maximum backpressure is about 1125.9 Pa. The advantages are that the fewer components in the micropump not only reduce the complex of the fabrication process and the cost, but also improve the reliability of the micropump. The proposed ferrofluid micropump can be easily integrated with other PDMS-glass-based microfluidic system and can also be used in many applications when microfluidic systems need to be disposable and low cost.

Design and experimental investigation of a bi-directional valveless electromagnetic micro-pump

In this paper, a design of a novel electromagnetic micro-actuator prototype is presented. This prototype is fabricated using conventional elements for a novel working principle as bi-directional valveless micro-pump for biomedical applications. The proposed micro-pump includes two unfixed permanent magnets placed in opposite polarities in a cylindrical channel. The channel is placed between two fixed coaxial coils as external electromagnets. The electromagnetic actuating depends on moving both unfixed permanent magnets vertically via the interaction of their magnetic fields and that resulting from coils. The actuation of magnets is produced with a periodic movement and consists mainly of three main modes. By selecting a suitable coil’s driving currents, the actuation can be controlled either to change fluid flow direction or the actuation speed. An experimental test shows the high performance of the proposed micro-pump, a flow rate of 37 ml/mn and maximum back pressure of 1.98 kPa are attained.

Design and Numerical Study of Micropump Based on Induced Electroosmotic Flow

Induced charge electroosmotic flow is a new electric driving mode. Based on the Navier–Stokes equations and the Poisson–Nernst–Planck (PNP) ion transport equations, the finite volume method is adopted to calculate the equations and boundary conditions of the induced charge electroosmotic flow. In this paper, the formula of the induced zeta potential of the polarized solid surface is proposed, and a UDF program suitable for the simulation of the induced charge electroosmotic is prepared according to this theory. At the same time, on the basis of this theory, a cross micropump driven by induced charge electroosmotic flow is designed, and the voltage, electric potential, charge density, and streamline of the induced electroosmotic micropump are obtained. Studies have shown that when the cross-shaped micropump is energized, in the center of the induction electrode near the formation of a dense electric double layer, there exist four symmetrical vortices at the four corners, and they push the solution towards both outlets; it can be found that the average velocity of the solution in the cross-flow microfluidic pump is nonlinear with the applied electric field, which maybe helpful for the practical application of induced electroosmotic flow in the field of micropump.

The Design, Fabrication, and Testing of an Electromagnetic Micropump with a Matrix-Patterned Magnetic Polymer Composite Actuator Membrane.

A valveless electromagnetic (EM) micropump with a matrix-patterned magnetic polymer composite actuator membrane structure was successfully designed and fabricated. The composite membrane structure is made of polydemethylsiloxane (PDMS) that is mixed with magnetic particles and patterned in matrix blocks. The matrix magnetic composite membrane was fabricated using a soft lithography process and expected to have a compact structure having sufficient magnetic force for membrane deformation and maintained membrane flexibility. The magnetic membrane was integrated with the microfluidic system and functionally tested. The experimental results show that a magnetic composite actuator membrane containing of 6% NdFeB is capable of producing a maximum membrane deflection up to 12.87 µm. The functionality test of the EM actuator for fluid pumping resulted in an extremely low sample injection flow rate of approximately 6.523 nL/min. It was also concluded that there is a correlation between the matrix structure of the actuator membrane and the fluid pumping flow rate. The injection flow rate of the EM micropump can be controlled by adjusting the input power supplied to the EM coil, and this is believed to improve the injection accuracy of the drug dosage and have potential in improving the proficiency of the existing drug delivery system.

Dual light-activated microfluidic pumps based on an optopiezoelectric composite

In this paper, a new type of microfluidic pump that can be activated and controlled by a masked light source is presented. The actuation of this micropump is based on an optopiezoelectric composite. This composite is constructed by having one of the electrodes of a piezoelectric PVDF (polyvinylidene fluoride) polymer replaced by a layer of TiOPc (titanyl phthalocyanine) photoconductive coating and an ITO (indium-tin-oxide) transparent electrode. This layer of photoconductive electrode provides the capability to activate multiple locations of this optopiezoelectric composite independently using a masked light source and a single voltage source. To verify the feasibility of this concept, dual light-activated microfluidic pumps based on this optopiezoelectric composite are implemented and studied. Experimental results verify that two microfluidic pumps can be created by one optopiezoelectric composite and that each pump can be optically turned on and off independently or be turned on simultaneously. These results suggest that integrating an optopiezoelectric composite into a lab-on-a-chip system can reduce the size and the number of driving units significantly, since every operation can be done optically and only one driving source is needed. The equivalent circuit, design, and implementation of dual light-activated optopiezoelectric micropumps are discussed in this paper.

Biocontractile microfluidic channels for peristaltic pumping

Bio-actuated micro-pumps do not need any external power source and pose no risk of electrical or heat shock for the biological materials in lab-on-chip systems. Several different designs of bio-actuated micro-pumps based on the use of the contractile force of cultured cardiomyocites have been proposed earlier. Here we present a novel type of a bio-actuated micro-pump representing a microfluidic channel with a contractile wall. The flow inside the channel is generated by the peristaltic movement of its wall caused by the propagation of an excitation-contraction wave along the channels surface. The directional flow generated by the pump was demonstrated by tracking of polystyrene microspheres, moving in the direction of the propagation of the excitation-contraction wave with an average velocity of 6-8μm/min. The suggested design of a micro-pump allows the control of pumping direction, which might be useful for targeted delivery of fluids and substances in lab-on-chip systems. Prospects of future development and implementation of this kind of bio-actuated peristaltic pumps are discussed.

Modeling and flow analysis of piezoelectric based micropump with various shapes of microneedle

Micropumps have been investigated as drug delivery and disease diagnostic devices. Many of these micropumps have been designed, considering primarily, available micro fabrication technologies rather than appropriate pump performance analysis. Piezoelectric and silicon based micro pumps are more popular as compared to other smart materials being explored. The microneedle is an integral part of these micropumps providing an interface between the drug reservoir and the patient’s body for extracting the blood for investigation. Blood collected in the pump chamber passes through the biosensor and gives the required investigation report. It is aimed to minimize the pain while the microneedle is inserted in the body without having any effect on the flow characteristics. Several factors affect the pain while inserting the needle, out of which shape and size of the microneedle are two important parameters. In this study we have investigated the effect of shape of the microneedle on the flow inside the micropump. A micropump design is based on the required flow at the biosensor point. All computations were carried out with water (Newtonian fluid) as the working fluid after carrying out a comparative analysis with human blood (non-Newtonian fluid). For the pentagonal shaped microneedle, the velocity at the top of the microneedle was minimum, which is beneficial in that fluid should remain in contact with the sensor for longer time.

Conceptual design and performance analysis of a novel flexible-valve micropump using magneto-fluid–solid interaction

An electromagnetic actuated micropump with flexible sequence of valves is presented and investigated in the present article. Two flexible valves are placed inside the microchannel in order to bidirectionalize flow, employing the idea of rectifying mechanism of lymphangion in the lymphatic transport system. A time-dependent magnetic field exerts force on the soft magnetorheological elastomer (SMRE) wall, and therefore, the enclosed fluid is forced to move. The valve series are embedded in such a way that prevent flow from leaving the left terminal, and stop fluid flow entering from the right terminal. Therefore some fluid move left to right, which is called VNet. The net volume is considered as the target design for the performance of the micropump. A fully coupled time-dependent magneto-fluid–solid interaction (MFSI) simulation of two-dimensional incompressible fluid flow is conducted. The finite element method is used to solve all physics involved. Simulation results indicate capability of the proposed mechanism to propel fluid in one direction. A parametric study is performed to investigate the effect of key geometric, magnetic, and structural parameters on the net transported volume. Results show that under optimum conditions the micropump is able to transmit a net volume of fluid nearly two times more than the basic design. The final model is able to pump 0.055 (μl) of water (at 25 °C) in 1 s. The proposed micropump can operate in a wide range of applications, such as artificial organs, organ-on-chip, and aerospace applications.

Effect of Cross Aspect Ratio on Flow in Diverging and Converging Microchannels

Aspect ratio is an important parameter in the study of flow through noncircular microchannel. In this work, three-dimensional numerical study is carried out to understand the effect of cross aspect ratio (height to width) on flow in diverging and converging microchannels. Three-dimensional models of the diverging and converging microchannels with angle: 2–14 deg, aspect ratio: 0.05–0.58, and Reynolds number: 130–280 are employed in the simulations with water as the working fluid. The effects of aspect ratio on pressure drop in equivalent diverging and converging microchannels are studied in detail and correlated to the underlying flow regime. It is observed that for a given Reynolds number and angle, the pressure drop decreases asymptotically with aspect ratio for both the diverging and converging microchannels. At small aspect ratio and small Reynolds number, the pressure drop remains invariant of angle in both the diverging and converging microchannels; the concept of equivalent hydraulic diameter can be applied to these situations. Onset of flow separation in diverging passage and flow acceleration in converging passage is found to be a strong function of aspect ratio, which has not been shown earlier. The existence of a critical angle with relevance to the concept of equivalent hydraulic diameter is identified and its variation with Reynolds number is discussed. Finally, the effect of aspect ratio on fluidic diodicity is discussed which will be helpful in the design of valveless micropump. These results help in extending the conventional formulae made for uniform cross-sectional channel to that for the diverging and converging microchannels.

Design and modelling of droplet based microfluidic system enabled by electroosmotic micropump

In this work, we have investigated the integration of an electroosmotic micropump allowing to generate droplets in two parallel flow focusing junctions. A novel design of the electroosmotic micropump with low voltage is proposed, acting as an active fluidic control to produce droplets of water-in-oil. Numerical studies are performed both on the micropump and the oil flow rate of the continuous phase. The simulations are conducted in terms of size and frequency of droplets issued from the device. Several ranges of applied voltage were applied to the micropump (2, 3.6, 5, and 10 V) for each oil flow rate value varying from 0.75 to 5.5 µl/min. Contrary to the pneumatic, piezoelectric or mechanical micropump, this integrated electroosmotic micropump is a versatile droplet generator allowing it to be used in microfluidic system.

On effect of viscoelastic characteristics of polymers on performance of micropump

Micropumps are the most important components of lab-on-a-chip devices, which are becoming popular recently due to their enormous advantages. Among the different designs of micropumps, the nozzle–diffuser valveless design is the most preferred one due to simplicity in manufacturing. For the simulation of these pumps, the local fluid–structure interaction modeling is important to get the performance accuracy. To capture fluid–structure interaction accurately, an appropriate selection of the fluid as well as the structural modeling approaches are very essential. It is well known that the polydimethylsiloxane materials behave as a viscoelastic material. However, most of the earlier studies on polydimethylsiloxane micropump modeling have considered polydimethylsiloxane as a linear elastic material. In this article, a nozzle–diffuser-based valveless micropump is modeled using a fluid–structure interaction approach along with a linear viscoelastic model for polydimethylsiloxane. The mechanical properties of the polydimethylsiloxane material are experimentally obtained using dynamic mechanical analysis for the range of micropump operating frequencies. These viscoelastic properties of polydimethylsiloxane, with varying proportionate of curing agent, are introduced in the fluid–structure interaction model of micropump using the Kelvin–Voigt model. The results are presented in the form of micropump performance parameters such as diaphragm deflection, von-Mises stresses, swept volume, and fluid flow rate.