Diaphragm Micropump Research Articles

Impact of gravity on the performance of multi-inlets and multi-outlets valveless diaphragm micropumps

The influence of gravity plays a crucial role in micropumps’ fluid dynamics. Gravitational forces have an intricate effect on the fluid flow of the micropump. Understanding gravity’s influence on micropump fluid dynamics is critical for improving the fine design features and operational efficacy of the microscale pumping systems. This study conducted thorough a numerical analysis on the Single Inlet Double Outlet Diaphragm (SIDOD) micropump and the Double Inlet Single Outlet Diaphragm (DISOD) micropump to determine how gravity influences the performance. In this research, the optimal frequency is identified as 3 Hz. At this frequency, the SIDOD flow rate increases from 313 μl min−1 without gravity to 327.77 μl min−1 with gravity, marking an increase of 4.77%. Similarly, the DISOD flow rate rises from 177.78 μl min−1 without gravity to 184 μl min−1 with gravity, reflecting an approximate 3.56% increase. A comprehensive understanding of gravity impact is crucial for aerospace applications, where micropumps may operate under fluctuating gravitational conditions. The potential applications of micropumps in medical devices, particularly drug delivery systems, experience gravitational variations.

Design and validation of a piezoelectric diaphragm micropump for drug delivery

There is a common eye ailment called Dry Eye Disease (DED) that causes symptoms of discomfort, visual disturbance, and tear film instability, which cause damage to the ocular surface. For treatment of this illness, the application of artificial tear fluid is usually prescribed. This work presents the design process of a piezoelectric micropump to become part of an automatic pumping system for delivering artificial tear fluid to people suffering from DED. Low polarizing voltage, portability, and achieving a variable output flow rate in the range of 1 µl/min, which is the necessary range needed by a person suffering from DED, are the focus of this design. Standard microfabrication techniques widely used in the CMOS industry and for MEMS development will be used for manufacturing the proposed micropump. For this reason, the materials and manufacturing processes involved must be CMOS-compliant. For the piezoelectric actuator, zinc oxide (ZnO) was selected due to its compatibility with CMOS technology and because it is readily available in thin film form through a sputtering process. Other materials involved in the device are silicon and aluminum. The design was validated through finite element analysis software, COMSOL Multiphysics®. The maximum flow rate obtained by a single micropump device was 2.51µl/min operating at 20V peak with a frequency of 900Hz. Also, the flow rate is controllable through variations in frequency, thus making it suitable for the application previously described.

Employing fluorescence analysis for real-time determination of the volume displacement of a pneumatically driven diaphragm micropump

In this work, we propose a new optical measurement method and setup to investigate the dynamic behavior of a pneumatically driven diaphragm micropump in a microfluidic system. The presented method allows a contact-free spatially and temporally resolved determination of the membrane displacement. Hence, it enables to derive the volume flow rate, generated by the micropump. The method is based on the Lambert–Beer law, which describes the intensity weakening of light traveling through a medium with an absorbing substance. The fluorescence emission of a medium can thus be related to the light traveling length. The measurement method is used to deduce the flow rate profile generated by the micropump of the Lab-on-Chip system Vivalytic from Bosch Healthcare Solutions. We further quantify effects of fluidic components and system parameters on the transient flow rates. This allows the determination of maximum flow rates and pumping cycle durations as a basis for the implementation of fluidic processes on the system. The presented method requires neither additional, integrated sensor components nor a complex measurement setup. It can be implemented in any microfluidic system with membrane-based, optically accessible micropumps without major hardware modifications.

Outside Front Cover: Vacuum‐driven fluid manipulation by a piezoelectric diaphragm micropump for microfluidic droplet generation with a rapid system response time

DOI: 10.1002/elps.201800357 The cover picture shows vacuum-driven microfluidic manipulation with a piezoelectric diaphragm micropump for droplet generation. Stepwise changes to peak-to-peak voltage applied to the pump during water-in-oil droplet creation showed that drive voltage reproducibly controls the droplet generation rate with a rapid system response time (i.e., within <0.5 s after input of a new voltage). The current system can be used not only for droplet production but also for rapid droplet screening.

Vacuum-driven fluid manipulation by a piezoelectric diaphragm micropump for microfluidic droplet generation with a rapid system response time.

Recently, we developed a convenient microfluidic droplet generation device based on vacuum-driven fluid manipulation with a piezoelectric diaphragm micropump. In the present study built on our previous work, we investigate the influence of settings applied to the piezoelectric pump, such as peak-to-peak drive voltage (Vp-p ) and wave frequency, on droplet generation characteristics. Stepwise adjustments to the drive voltage in ±10-Vp-p increments over the range of 200-250 Vp-p during droplet creation revealed that the droplet generation rate could be reproducibly controlled at a specific drive voltage. The droplet generation rate switched within <0.5s after the input of a new voltage. Although the droplet generation rate depended on the drive voltage, this setting had almost no influence on droplet size. The frequency over the selected range (50-60Hz) did not markedly influence the droplet generation rate or droplet size. We show that the current fluid manipulation system can be conveniently used for both droplet generation and for rapid droplet reading, which is required in many microfluidic-based applications.

Modeling of compliant flexure diaphragm for micropump

A number of mechanical micropumps have been proposed, many of those have been designed using plane diaphragms. Diaphragm is the essential part in mechanical type of micropump. Performance of the diaphragm can be improved by varying diaphragm geometry; use of compliant flexure in the diaphragm will improve the diaphragm deflection. In this paper, we present a FE analysis of stainless steel flexure diaphragm with different number of rectangular flexures using ANSYS. Simulations have been performed and results obtained for different flexure diaphragm from the Finite element modeling (FEM) compared with the plane diaphragm to decide the better diaphragm for piezoelectric mechanical type micropump. The central deflection is studied for driving voltage of 90-120V. Single layer PVDF actuator of 52µm thickness is considered for simulation. The great advantage of using compliant flexure in micropump diaphragm is that it can achieve higher deflection at a low driving voltage.

Modeling, control and experimental investigation of time-average flow rate of a DEAP actuator based diaphragm pump

Over the past three decades, micropumps have been intensively interested to handle and to carry small and precise volumes of liquid in many fields of modern industry. Especially, smart actuator based diaphragm micropumps have received considerable attention because of its simple structure and operation precisely. However, hysteresis phenomenon in the smart actuator is the barrier which prevents the system functioning correctly. This study deals with a mitigation strategy of the hysteresis effects for a typical dielectric electro-active polymer actuator based diaphragm micropump in order to improve the performance of the micropump. Firstly, the forward and inverse hysteresis models are designed and optimized to describe the rate-dependent hysteresis behavior of the actuation system. The model-based control method is then developed and validated to drive the system precisely at high frequencies. Finally, experiments have been conducted to demonstrate the effectiveness of the control strategy in a real application. As a result, the hysteresis behaviors of the smart actuator are effectively compensated at the frequencies up to 1Hz and a maximum time average flow rate of 1.443 mL/min and maximum backpressure of 833.5 Pa at room temperature are recorded.

A compact and facile microfluidic droplet creation device using a piezoelectric diaphragm micropump for droplet digital PCR platforms.

We have exploited a compact and facile microfluidic droplet creation device consisting of a poly(dimethylsiloxane) microfluidic chip possessing T-junction channel geometry, two inlet reservoirs, and one outlet reservoir, and a piezoelectric (PZT) diaphragm micropump with controller. Air was evacuated from the outlet reservoir using the PZT pump, reducing the pressure inside. The reduced pressure within the outlet reservoir pulled oil and aqueous solution preloaded in the inlet reservoirs into the microchannels, which then merged at the T-junction, successfully forming water-in-oil emulsion droplets at a rate of ∼1000 per second with minimal sample loss. We confirmed that the onset of droplet formation occurred immediately after turning on the pump (<1s). Over repeated runs, droplet formation was highly reproducible, with droplet size purity (polydispersity, <4%) comparable to that achieved using other microfluidic droplet preparation techniques. We also demonstrated single-molecule PCR amplification in the created droplets, suggesting that the device could be used for effective droplet digital PCR platforms in most laboratories without requiring great expense, space, or time for acquiring technical skills.

A Two-Step Global Maximum Error Controller-Based TPWL MOR with POD Basis Vectors and Its Applications to MEMS

In our previous study, we have proposed a linearization point (LP) selection method based on a global maximum error controller for the trajectory piecewise-linear (TPWL) method. It has been demonstrated that this method has many advantages over other existing methods. In this paper, a more efficient version of this method is presented, which introduces a preliminary LP selection procedure and constructs projection matrix by the proper orthogonal decomposition (POD) method. Compared with the original method, the improved method takes much less time for extracting a reduced-order model (ROM) of similar quality and gets some other benefits (such as being easier to implement, having lower memory requirement, and enhanced flexibility). The effectiveness of the new method is fully demonstrated by a diode transmission line RLC circuit. And then, the method is applied to three more complicated microelectromechanical systems (MEMS) devices, which are a micromachined switch, an electrostatic micropump diaphragm, and a thermomechanical in-plane microactuator.

Portable Optoelectronic Nose for Monitoring Meat Freshness

A disposable colorimetric sensor array (CSA) made from printing various chemically responsive dyes was combined with a hand-held device for on-site assessment and monitoring of the freshness of five meat products: beef, chicken, fish, pork, and shrimp. The hand-held device takes advantage of an on-board diaphragm micropump and a commercial 1D CMOS camera (CIS) which enables the real-time collection of colorimetric data. The sensor array shows excellent sensitivity to gaseous analytes, especially amines and sulfides at low ppb levels; excellent discrimination among meat volatiles in terms of meat type and storage time was demonstrated with multiple chemometric approaches including principle component analysis, hierarchical cluster analysis, and support vector machine analysis. This optoelectronic nose proves to be a promising supplement to other available techniques for meat product inspection.

Fabrication of a diaphragm micropump system utilizing the ionomer-based polymer actuator

This paper introduces an easy method for the fabrication of a diaphragm micropump using an ionomer-based polymer actuator. The polymer actuator was fabricated by electroless plating of platinum onto a Nafion-117 film. The electrode that serves as the diaphragm has a simple circular shape without any modification of the electrode surface and was punched from the polymer actuator film in a single step. The whole body of the micropump was designed to be the size of a credit card and was fabricated by the lamination of 13 layers to construct a three-dimensional flow path inside the body. The actuator assembly was embedded at the bottom of the pump to facilitate the exchange of the diaphragm. A square polarization waveform with amplitudes of +2.0V and −2.0V was applied to the pump, and the diaphragm micropump transported water at ∼5μL/s with no water leakage. The results presented in this work are an important demonstration that a diaphragm micropump can be easily fabricated for many micro-total analysis system (micro-TAS) applications using the nature of an ionomer-based polymer actuator as a flexible and large deformation available property in aqueous media.

Coupled vibrations of a magneto-electro-elastic micro-diaphragm in micro-pumps

Reciprocating diaphragm micro-pumps are the most common type among indirectly driven micro-pumps. The elastic diaphragm is deflected using different excitation mechanisms to produce a flow rate. This paper addresses the possible use of magneto-electro-elastic (MEE) materials as micro-pump diaphragm with a central discharge opening. It is assumed that the diaphragm is made from transversely isotropic MEE material with different volume fractions (VFs) of piezoelectric phase. Taking into account the Kirchhoff’s plate theory and the constitutive relations of the MEE materials and Maxwell’s theory, Hamilton’s variational principle is employed to derive the governing equations of axisymmetric vibration of the diaphragm. It is assumed that the MEE diaphragm is polarized in the thickness direction when the external magnetic and electric potentials are applied. The fluid pressure exerted upon the diaphragm is formulated using linear Bernoulli’s equation. In addition, the kinematic and compatibility conditions are incorporated into the elastic vibration of the diaphragm to extract the eigen-matrix equation. Employing different MEE materials, the stability and thresholds of the magnetic and electric potentials are evaluated. Natural frequencies of the coupled system are presented for different VFs of piezoelectric phase. Finally, the effects of the operating fluid density and the applied external magnetic and electric potentials on the natural frequencies are investigated.

Integration of Glucose Biofuel Cells with a MEMS Diaphragm Micropump

Enzymatic biofuel cells (BFCs) that utilize enzymes as electrocatalysts instead of metals have attracted attention as ubiquitous sustainable power devices that can generate electricity directly from the blood or bodily fluids [1]. A characteristic feature of BFCs is their ability to generate power using various kinds of fuels, such as glucose, lipids, and hydrogen. In other words, a wide range of fuel choices is possible because they do not require an ion-exchange membrane. Many biofuel cells are safe and biocompatible, utilizing enzymes as biological catalysts. In addition, they function under mild conditions from room temperature to human body temperature under neutral pH conditions. Microelectromechanical system (MEMS) technologies have been applied to realize compact, high-output power sources toward the commercialization of BFCs. For example, Choban et al. reported a BFC with a Y-shaped channel that used formic acid and oxygen [2]. It utilized laminar flows of the two fuels without mixing for efficient reactions at each electrode. Togo et al. built hydrophobic pillars in a flow path, and fed air individually into three cells [3]. Fukushi et al. reported a flexible biofuel cell equipped with a microchannel which mimicked the blood vessels in the human body [4]. However, these biofuel cells equipped with microchannels require large external flow systems that include tubing and pumps to supply the fuels. Compact fuel transport mechanisms would be more desirable. Micropumps fabricated with MEMS technology have been considered for use in such fuel transport mechanisms [5,6]. Liu et al. reported polyimide (PI) diaphragm micropumps (15 × 15 mm2) fabricated using MEMS technology [7]. Such micropumps should be able to deliver enough glucose fuel solution to continuously generate power in a BFC. In this paper, a new BFC equipped in the fluid reservoir of the micropump is reported, and its power generation performance and lifetime are discussed. We fabricated a micropump with a polyimide (PI) diaphragm (53 μm thick, 7 mm diameter) on a silicon chip using microfabrication processes, and a glucose biofuel cell was inserted into the fluid chamber of the micropump. The biofuel cell was fabricated on another PI film, with glucose oxidase immobilized on its porous carbon anode and bilirubin oxidase immobilized on the porous carbon cathode. Each semicircular electrode area was 14.1 mm2 with a radius of 3 mm, and the gap between the anode and cathode was 1 mm. The device generated electricity by feeding an aqueous solution of glucose directly onto the electrodes in the micropump chamber. The maximum generated power, 0.076 μW at 98 mV, corresponding to a power density of 0.556 μW/cm2, was realized when a 100 mM glucose solution was introduced under diaphragm pressures alternating between 0 and 30 kPa at a pumping frequency of 3 Hz. A longer power generation lifetime was observed under fuel flow driven by micropump operation. [1] H. Becker and U. Heim, Sensors Actuators: A Phys., 83 (2000) 130. [2] E. R. Choban, J. S. Spendelow, L. Gancs, A. Wieckowski and P. J. Kenis, Electrochim. Acta, 50 (2005) 5390. [3] M. Togo, K. Morimoto, T. Abe, H. Kaji and M. Nishizawa, TRANSDUCERS 2009–15th Int. Conf. Solid-State Sensors, Actuators Microsystems (2009) pp. 2102–2105. [4] Y. Fukushi, S. Koide, R. Ikoma, W. Akatsuka, S. Tsujimura and Y. Nishioka, J. Photopolym. Sci. Technol., 26 (2013) 303. [5] A. Zebda, L. Renaud, M. Cretin, C. Innocent, F. Pichot, R. Ferrigno and S. Tingry, J. Power Sources, 193 (2009) 602. [6] W. L. Benard, H. Kahn, A. H. Heuer and M. A. Huff, J. Microelectromechanical Syst., 7 (1998) 245. [7] Y. Liu, H. Komatsuzaki, S. Imai and Y. Nishioka, Sens. Actuators A: Phys., 169 (2011) 259.

A Glucose Biofuel Cell Equipped in the Fluid Reservoir of a Polyimide Diaphragm Micropump

A Glucose Biofuel Cell Equipped in the Fluid Reservoir of a Polyimide Diaphragm Micropump

A modeling and vibration analysis of a piezoelectric micro-pump diaphragm

The vibration analysis of a micro-pump diaphragm is presented. A piezoelectric micro-pump is studied. For this purpose, a dynamic model of the micro-pump is derived. The micro-pump diaphragm is modeled as circular double membranes, a piezoelectric one as actuator and a silicon one for representing the membrane for pumping action. The damping effect of the fluid is introduced into the equations. Vibration analysis is established by explicitly solving the dynamic model. The natural frequencies and mode shapes are calculated. The orthogonality conditions of the system are discussed. To verify the results, the finite-element micro-pump model is developed in ANSYS software package. The results show that the two methods are well comparable.

The Vibration Pickup of Micro-Pump Diaphragm Based on MEMS Technology Design

This paper designs a micro-pump silicon diaphragm vibration pickup sensor. In this newsensor which is based on piezoresistive effect, four MOSFETs with nc-Si/c-Si heterojunction drainand source are manufactured on the surface of silicon wafer by using the technique of CMOS andPECVD, at edge of &lt;100&gt; orientation of the N-type silicon diaphragm rectangle, and using MEMStechnology, the back of the four MOSFETs device silicon substrate processed into silicon cup, whichconstitutes the vibration pickup sensor. The micro-pump silicon diaphragm vibration pickup sensornot only has all the advantages of conventional force sensitive resistance vibration pickup sensor, butalso has the advantages of small temperature drift, high detection precision, and it can satisfy themicro-pump silicon diaphragm vibration requirements.

Programmable active droplet generation enabled by integrated pneumatic micropumps

In this work we have investigated the integrated diaphragm micropump as an active fluidic control approach for the on-demand generation of droplets with precisely defined size, frequency and timing. In contrast to valve-actuated devices that only modulate the flow of the dispersed phase being continuously injected, this integrated micropump allows the combination of fluidic transport and modulation to achieve active control of droplet generation. A distinct characteristic of this method compared to the valve modulated droplet formation processes is that it enables independent control of droplet generation frequency by adjusting the pumping frequency and droplet size by flow conditions. We also demonstrated the generation of complex droplet patterns through programming the pumping configurations and the application to multi-volume digital PCR for precise and quantitative detection of genetic targets. Overall, our results suggest that the pump-based droplet microfluidics provide a robust platform for programmable active droplet generation which could facilitate the development of high-performance chemical and biological assays.

Simulation and verification of a piezoelectrically actuated diaphragm for check valve micropump design

This paper presents a design guideline for a piezoelectric actuated check valve diaphragm micropump for microfluidic applications. Diaphragm average displacement was adopted in analyzing a piezoelectrically actuated diaphragm. For the first time, the relationship between the stroke volume and backpressure of a check valve diaphragm micropump were simulated with a Finite Element Analysis (FEA) tool. The simulated results reasonably agreed to the experimental results of the micropump.

SU8 diaphragm micropump with monolithically integrated cantilever check valves

This paper presents a SU8 unidirectional diaphragm micropump with embedded out-of-plane cantilever check valves. The device represents a reliable and low-cost solution for integration of microfluidic control in lab-on-a-chip devices. Its planar architecture allows monolithic definition of its components in a single step and potential integration with previously reported PCR, electrophoresis and flow-sensing SU8 microdevices. Pneumatic actuation is applied on a PDMS diaphragm, which is bonded to the SU8 body at wafer level, further enhancing its integration and mass production capabilities. The cantilever check valves move synchronously with the diaphragm, feature fast response (10ms), low dead volume (86nl) and a 94% flow blockage up to 300kPa. The micropump achieves a maximum flow rate of 177 μl min(-1) at 6 Hz and 200 kPa with an effective area of 10 mm(2). The device is reliable, self-priming and tolerant to particles and big bubbles. To the knowledge of the authors, this is the first micropump in SU8 with monolithically integrated cantilever check valves.

A novel diaphragm micropump actuated by conjugated polymer petals: Fabrication, modeling, and experimental results

Micropumps have promising applications in biomedical devices and micro total analysis systems. Conjugated polymer actuators provide an important potential mechanism for realizing micropumps because of their amenability to miniaturization and low actuation voltages. In this paper we present a novel, conjugated polymer petal-actuated diaphragm micropump, which is in contrast to the typical diaphragm design of using a single piece of soft actuation material clamped at all edges. We show through analysis and experiments that the new design, by alleviating the edge constrains, can provide significantly larger diaphragm deformation and consequently higher flow rate. A physics-based, control-oriented model is developed to predict the diaphragm deformation and the flow rate given the actuation voltage input. Experiments conducted on a polypyrrole (PPy)-actuated micropump, fabricated through PDMS-based MEMS processes, have validated the dynamic model. A maximum flow rate of 1260 μ L / min is achieved for the petal-actuated diaphragm pump under an actuation voltage of 4 V, while in comparison, the pump with traditional diaphragm design generates no observable flow under the same voltage.