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1.
Experimental investigations are performed to determine the influence of electrical excitation and geometrical parameters on
the performance of piezoelectric valveless micropumps fabricated on printed circuit board substrates. Strain gauges and shunt
resistor are used in conjunction with a data acquisition system to form an effective transducer, capable of providing magnitude
and phase response information pertaining to fluid–structure interaction. Effect of conical diffuser geometry on the displacement
response and pressure flow characteristics are studied. With suitable variations in the design of the diffuser element and
input excitation parameters, the ability of the valveless micropump can be extended to include forward, reversed and bidirectional
flow features. The characteristic signatures of single and two peaks in flowrate or pressure data are captured in the displacement
phase response. System identification approach is proposed to model and predict the performance of valveless micropumps. 相似文献
2.
A PMMA valveless micropump using electromagnetic actuation 总被引:4,自引:0,他引:4
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. 相似文献
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5.
The concept of a valveless acoustic micropump was investigated. Two-dimensional, time-varying, axisymmetric, incompressible
viscous flows through a planar diffuser-nozzle element were analyzed for applications in valveless acoustic micropumps. The
diffuser divergence half-angles (θ), and the maximum pressure amplitudes (P) were independently varied. The inflow was periodic and the excitation frequency (f) was varied over the range 10 kHz ≤ f ≤ 30 kHz. The net time-averaged volume flux and the rectification capability of the diffuser were found as functions of
θ, f, and P. The phase difference between pressure and velocity waveforms, the life time and the size of large scale flow recirculation
regions inside the microdiffuser, and energy losses were found to be strongly frequency dependent. 相似文献
6.
Ching-Jiun Lee Horn-Jiunn Sheen Zhi-Kai Tu U. Lei Cheng-Ying Yang 《Microsystem Technologies》2009,15(7):993-1000
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. 相似文献
7.
H.K. MaAuthor Vitae H.C. SuAuthor VitaeJ.Y. WuAuthor Vitae 《Sensors and actuators. A, Physical》2011,171(2):297-305
Previous studies have indicated that a one-sided actuating piezoelectric micropump (OAPMP) combined with two valves may enhance the liquid flow rate to 4.1 ml/s and make it possible to reach the maximum pump head of 9807 Pa in a limited space. In this study, an innovative one-sided actuating piezoelectric valveless micropump (OAPMP-valveless) has been developed to actuate fluid at a higher flow rate in one direction by adding a secondary chamber. The secondary chamber plays a key role in the application of the valveless micropump: the flow rate of the pump can reach 0.989 ml/s by adding a secondary chamber. The maximum pump head is 1522.5 Pa when using the 0.3 mm-thick secondary diaphragm and the 0.5 mm-thick primary diaphragm. In addition, if a nozzle/diffuser element is applied to the OAPMP-valveless with a secondary chamber, the flow rate can be further improved to 1.183 ml/s at a frequency of 150 Hz. A three-dimensional numerical model of the valveless micropump has been built to compare the measured results with the simulated results. 相似文献
8.
Current micropump technologies and their biomedical applications 总被引:6,自引:2,他引:4
9.
Flow characterization of valveless micropump using driving equivalent moment: theory and experiments 总被引:1,自引:0,他引:1
Il-Han Hwang Sung-Kil Lee Sang-Mo Shin Yong-Gu Lee Jong-Hyun Lee 《Microfluidics and nanofluidics》2008,5(6):795-807
A valveless micropump, actuated by a PZT disk bonded to a glass plate, can generate positive flow. In order to estimate flow
characteristics of micropumps, it is necessary to theoretically analyze the radial expansion (more specifically, the equivalent
moment) of the PZT disk according to the voltage input. Using the equivalent moment, deflection equations are derived for
the tri-layer disk (PZT, epoxy bonder and glass plate) and are confirmed to match well with experiments. The flow rate of
the valveless micropump is also theoretically and experimentally investigated in terms of input voltage and oscillation frequency.
The flow increased at a rate of 0.1 μL/min/V, and the maximum flow rate was obtained at the driving frequency of around 225 Hz. 相似文献
10.
H. J. Sheen C. J. Hsu T. H. Wu C. C. Chang H. C. Chu C. Y. Yang U. Lei 《Microfluidics and nanofluidics》2008,4(4):331-342
In this paper, a PZT micropump excited by amplified squarewave signals with various frequencies was used to study the transient
flow behaviors in an obstacle-type valveless micropump. A micro-particle-image-velocimetry (micro-PIV) with an external trigger
was developed to obtain flow fields at the outlet and around the obstacle with various phases in a cycle. In comparison with
previous studies on the pump performance, such as pump pressure and volume flow rate, more detailed information about the
pump was obtained. The velocity profiles and periodic sectional mean velocities exhibited the unsteady flow nature. The total
net flow generation efficiency per cycle was obtained experimentally by integrating the phase-dependent velocities. The flow
recirculation around the obstacle was observed and quantified to investigate the influence on the pump performance. The duration,
circulation, and the size of the recirculation regions indicated that this flow behavior could enhance the flow-directing
capability. These results are very useful for the design and improvement of obstacle-type valveless micropumps. 相似文献
11.
This paper briefly overviews progress on the development of MEMS-based micropumps and their applications in drug delivery and other biomedical applications such as micrototal analysis systems (μTAS) or lab-on-a-chip and point of care testing systems (POCT). The focus of the review is to present key features of micropumps such as actuation methods, working principles, construction, fabrication methods, performance parameters and their medical applications. Micropumps have been categorized as mechanical or non-mechanical based on the method by which actuation energy is obtained to drive fluid flow. The survey attempts to provide a comprehensive reference for researchers working on design and development of MEMS-based micropumps and a source for those outside the field who wish to select the best available micropump for a specific drug delivery or biomedical application. Micropumps for transdermal insulin delivery, artificial sphincter prosthesis, antithrombogenic micropumps for blood transportation, micropump for injection of glucose for diabetes patients and administration of neurotransmitters to neurons and micropumps for chemical and biological sensing have been reported. Various performance parameters such as flow rate, pressure generated and size of the micropump have been compared to facilitate selection of appropriate micropump for a particular application. Electrowetting, electrochemical and ion conductive polymer film (ICPF) actuator micropumps appear to be the most promising ones which provide adequate flow rates at very low applied voltage. Electroosmotic micropumps consume high voltages but exhibit high pressures and are intended for applications where compactness in terms of small size is required along with high-pressure generation. Bimetallic and electrostatic micropumps are smaller in size but exhibit high self-pumping frequency and further research on their design could improve their performance. Micropumps based on piezoelectric actuation require relatively high-applied voltage but exhibit high flow rates and have grown to be the dominant type of micropumps in drug delivery systems and other biomedical applications. Although a lot of progress has been made in micropump research and performance of micropumps has been continuously increasing, there is still a need to incorporate various categories of micropumps in practical drug delivery and biomedical devices and this will continue to provide a substantial stimulus for micropump research and development in future. 相似文献
12.
Micropumps with various types of actuations have been used in lab-on-a-chip devices. In order to control the delivery of drug
particles both in space and time and avoid clogging, other types of actuation mechanisms may be needed. In this study, a valveless
micropump with novel actuation is proposed to transport particles for biomedical and environmental applications. The transport
of drug particles through the designed valveless micropump is carried out through computational fluid dynamics combined with
discrete particle transport methods. After convergence studies, the effects of actuation frequency, particle size and the
resident times on the particle transport are investigated. Interestingly, both the actuation frequency and particle size have
a strong effect in terms of resident times and the spatial distribution of the transported particles through the designed
micropump. Based on the results obtained, the relationship between actuation frequency, fluid flow, and particle transport
through the designed micropump is presented. The computational analysis presented demonstrates that it is possible to optimize
the proposed valveless micropump design for specific delivery of drug particles for separation and sorting applications. 相似文献
13.
Meiling Zhu Paul Kirby Martin Wacklerle Markus Herz Martin Richter 《Sensors and actuators. A, Physical》2009,149(1):130-135
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. 相似文献
14.
Steady and unsteady flow analysis in microdiffusers and micropumps: a critical review 总被引:3,自引:0,他引:3
Majid Nabavi 《Microfluidics and nanofluidics》2009,7(5):599-619
In recent research, there has been a growing interest in the analysis of flow through microdiffusers and micropumps in order
to characterize and optimize the performance of these devices. In this review, the recent advances in the numerical and experimental
analysis of the steady and pulsating flows through microdiffusers and valveless micropumps are surveyed. The differences between
the performance of microdiffusers and micropumps in steady and unsteady flow regimes are described. Qualitative and quantitative
discussions of the effects of different design parameters on the performance of microdiffusers and valveless micropumps in
both steady and unsteady flow regimes along with the contradictory results reported in the literature in this regard are provided.
In addition, a summary of the latest micropump technologies along with the advantages and disadvantages of each mechanism
with the emphasis on the innovative and less-reviewed micropumps are presented. Two important types of fixed microvalves,
as part of valveless micropumps are described in details. Experimental flow visualization of steady and pulsating flows through
microdiffusers and micropumps as a useful tool for better understanding the underlying micro-fluid dynamics is discussed.
The present review reveals that there are many possible areas of research in the field of steady and unsteady flows through
microdiffusers and micropumps in order to understand the effects of all important design parameters on the performance of
these devices. 相似文献
15.
16.
Valveless micropump with acoustically featured pumping chamber 总被引:2,自引:2,他引:0
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. 相似文献
17.
Bonnie Tingting Chia Hsin-Hung Liao Yao-Joe Yang 《Sensors and actuators. A, Physical》2011,165(1):86-93
This work presents a novel thermo-pneumatic peristaltic micropump with low temperature elevation on working fluid. The proposed device, which consists of two separate zones for air-heating and fluid-squeezing, is realized by using micromachining techniques. Also, the device can be operated by using a small and simple actuation circuitry with low applied voltages. Under similar operational conditions, the proposed micropump shows similar fluid-pumping performance when compared with the conventional design of thermo-pneumatic micropumps. However, for the proposed design, the temperature elevation on the fluid-pumping area is as small as about 2.0 K, which is less than 8% of that generated by the conventional design. Furthermore, by applying higher voltages, larger flow rate can be achieved with relatively small increase in temperature elevation. Due to low temperature elevation on working fluid, the proposed device is suitable for the applications such as DNA chips or protein chips. In addition, because of its small size and simple actuation scheme, potentially the proposed device can be integrated into the devices for point-of-care applications. 相似文献
18.
Chih-Ming Cheng Cheng-Hsien Liu 《Journal of microelectromechanical systems》2007,16(5):1095-1105
A novel electrolysis-bubble-actuated micropump based on the roughness gradient design in the microchannel is reported in this paper. This micropump is implemented by taking advantage of both the electrolysis actuation and the surface tension effect. The surface tension effect is controlled via the periodic generation of electrolytic bubbles and the roughness gradient design of microchannel surface, which results in the specified variation of liquid contact angle along the microchannel. Our proposed micropump could resolve the disadvantages that exist in the early reported micropumps, such as the complicated time-sequence power control, the need of long nozzle-diffuser structure, and the choking/sticking phenomena of electrolytic bubbles in a microchannel. Due to the features of large actuation force, low-power consumption, and room temperature operation, our micropump is suitable for the development of low-power consumption and compact micropumps for various applications. Experimental results show that the liquid displacement and the pumping rate could be easily and accurately controlled by adjusting the amplitude and frequency of the applied voltage. With the applied voltage of 15 V at 4.5 Hz, a maximum pumping rate of 114 nl/min is achieved for one of our micropump designs with a microchannel of 100 x 20 mum. In this paper, we report the theoretical analysis, design, micromachining process, operating principles, characterization, and experimental demonstration of these micropumps. 相似文献
19.
Utilizing a solvent-assisted bonding process, two diffuser-type polymethylmethacrylate (PMMA) peristaltic micropumps are fabricated
with a linear array of circular microchambers with a depth and diameter of 15 m and 7 mm, respectively, actuated using either
square or circular PZT actuators. Experimental trials are performed to characterize the performance of the two micropumps
under driving frequencies ranging from 80 to 150 Vpp and actuation frequencies in the range of 10 Hz to 1 kHz. The results
reveal that the micropump with square PZT actuators generates a maximum pumping rate and back pressure of 217 l/min and 9.2 kPa,
respectively, while the micropump with circular actuators generates a maximum flow rate of 131 l/min and a back pressure of
2.7 kPa. ANSYS finite element simulations demonstrate two events. First, given an equivalent surface area, the circular actuators
undergo a greater displacement than the square actuators under given actuation conditions. In other words, the circular actuator
design is more efficient to represent a higher ratio of the displacement to the actuation area (d/A). However, the circular
actuators with the surface area of 38.47 mm2 are smaller than the square actuators (49 mm2). In addition, it is inferred that the relatively poorer performance of the circular actuators is due in part to thermal
damage of the PZT patches during their removal from the bulk PZT chip using a laser cutting device in the pump fabrication
process. Secondly, when the shape of the effective working area for the actuation is rectangular which is usual in a MEMS
design, the rectangular actuator with length of 7 mm has significantly higher displacement (0.71 m) than that of the circular
actuator with diameter of 7 mm (0.396 m). Consequently, a rectangular actuator design presents a more practical solution for
higher performance of micro-actuators. 相似文献
20.
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. 相似文献