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Structure of a nozzle-diffuser piezoelectric valveless micropump. (a) Micropump after assembling. (b) Explosive view of a nozzle-diffuser piezoelectric valveless micropump. The microchannels are micromachined on PMMA boards. The top layer, the bottom layer, a piezoelectric membrane, an inlet and an outlet pipe are assembled with glue.
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Unexpected gas bubbles in microfluidic devices always bring the problems of clogging, performance deterioration, and even device functional failure. For this reason, the aim of this paper is to study the characterization variation of a valveless micropump under different existence conditions of gas bubbles based on a theoretical modeling, numerical...
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... micropump is laminated with two pieces of micromachined polymethyl methacrylate (PMMA), piezoelectric membrane, and auxiliary parts, as shown in Fig. 2. The microchannels and pump chamber in the micropump are directly micromachined with a home-made ultraprecise manufacturing machine on acrylic boards, and the piezoelectric diaphragm is bonded on top of the cover layer PMMA. Glues are used for assembling all the compo- nents to prevent the leakage and all the micropump parameters are ...
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Citations
... When the water reservoir is placed at the nozzle side that has 6 μm diameter orifices, a net flow occurs towards the diffuser direction that has an array of holes with a diameter of 50 μm. This mechanism is frequently used in nozzle-diffuser-type microfluidic pumps, but they implement an elastic membrane and an intermediate chamber (Singhal et al. 2004;Ahmadian and Mehrabian 2006;Nisar et al. 2008;Li et al. 2013;Zhao et al. 2017). In traditional nozzle-diffuser pumps, the chamber is first supplied with fluid by diffuser action during a chamber volume expansion, and then the fluid is pumped through the second diffuser during the chamber volume contraction. ...
Microfluidic flow control systems are critical components for on-chip biomedical applications. This study introduces a new micropump for on-chip sample preparation and analysis by using an acoustic nozzle diffuser mechanism. The micropump implements a commercially available transducer and control board kit with 3D-printed fluid reservoirs. In this micropump, conic-shaped micro-holes on the metal sheet cover of the transducer are employed as oscillating nozzle diffuser micro arrays to achieve directional flow control. The micropump is shown to efficiently pump water and particle mixtures exceeding flow rates of 515 µl/min at a 12-volt input voltage. In addition, owing to the small size of the nozzle hole opening, larger particles can also be filtered out from a sample solution during fluid pumping enabling a new function. Importantly, the micropump can be fabricated and assembled without needing a cleanroom, making it more accessible. This feature is advantageous for researchers and practitioners, eliminating a significant barrier to entry. By combining commercially available components with 3D printing technology, this micropump presents a cost-effective and versatile solution for on-chip applications in biomedical research and analysis.
... Similarly, dielectric and on-chip integrated peristaltic pumps involve the fabrication of intricate microfluidic geometries and metal electrodes to achieve on-chip flow control. Another group of microfluidic pumps are valveless diffuser/nozzle type systems that utilize piezoelectric actuators to continuously expand and contract a small volume and generate net flow by implementing the diffuser/nozzle type channels [32][33][34]. Tesla valve-based pumps also fall into this category, in which fluid flow is restricted in one dimension by implementing a tesla valve structure to obtain net flow in one direction [24]. These systems are relatively simple compared to the magnetic, acoustic, electrohydrodynamic, chemical, and dielectric-based pumps, but the valveless pumps usually still require microfabricated actuation layers and high driving voltages, which add further complexity. ...
Miniaturized fluid manipulation systems are an important component of lab-on-a-chip platforms implemented in resourced-limited environments and point-of-care applications. This work aims to design, fabricate, and test a low-cost and battery-operated microfluidic diffuser/nozzle type pump to enable an alternative fluid manipulation solution for field applications. For this, CNC laser cutting and 3D printing are used to fabricate the fluidic unit and casing of the driving module of the system, respectively. This system only required 3.5-V input power and can generate flow rates up to 58 µL/min for water. In addition, this portable pump can manipulate higher viscosity fluids with kinematic viscosities up to 24 mPa·s resembling biological fluids such as sputum and saliva. The demonstrated system is a low-cost, battery-powered, and highly versatile fluid pump that can be adopted in various lab-on-a-chip applications for field deployment and remote applications.
... In some applications, such as drug delivery [5] and oil recovery [6], the compound droplets often pass through channels with constrictions or expansion, such as blood capillaries in the human body or the porous material of the membrane filter. In some pumping systems [7,8], a compound droplet can experience such above-mentioned geometrical configurations of the pumps (Fig. 1). Therefore, it is important to understand the hydrodynamic behavior of compound droplets traveling through a channel or nozzle with constrictions or expansion to track and control the transit time, deformation, and breakup (if available). ...
This study’s aim is to improve the understanding of the dynamical behavior of a multi-core compound droplet traveling in an axisymmetric channel consisting of a diffuser element. The compound droplet typically consisting of two inner droplets distributed one after another is initially located at a certain distance from the entrance of the channel. A front-tracking method is used to handle the movement and deformation of the droplet. The numerical simulation results show that the compound droplet is stretched in the channel, and it takes a certain time, “the transit time”, to pass through the diffuser. The compound droplet has the largest deformation in the diffuser region and tends to return to its nearly original shape after leaving the diffuser. The deformation and transit time of the compound droplet are affected by some typical parameters, such as the capillary number and the diffuser angle. For small capillary numbers, the leading inner droplet takes a shorter transit time than the rear one does. The transit time also increases with an increase in the diffuser angle and the number of inner droplets enclosed in the compound droplet.
... 18 Undesired air bubbles in microfluidic devices are not rare for many applications and can enter a system through many processes such as liquid heating during PCR reaction thermocycling, 20,21 cell culture, 22,23 vacuum pressure driven flow, and directly introduced with the liquid during pumping. 24 Various strategies utilizing gas-permeable membranes [25][26][27] or porous structures 28,29 were invented in air bubble removal/trapping apparatuses. Yet, all of these developed techniques serve as assisted modules in addition to the liquid pumping equipment, not intrinsically built-in to the functions. ...
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... The effect of geometry and working conditions on flow rectification achieved in valveless micropumps has been investigated by several researchers [1,4,[10][11][12][13][14][15][16][17][18][19]. However, the micropump system analysis is a sophisticated multi-disciplinary problem with various field couplings [20]. Though several studies have been carried out, the working of a micropump is still not clearly understood, as it involves significant fluid-structure interaction. ...
... The variation in the chamber pressure at different operating frequencies (1,2,3,5,10,15,20,25Hz,30, and 50 Hz) are as presented in figure 8. The y-axis represents the pressure (kPa) and the x-axis represents the arbitrary time of the micropump operation in seconds. ...
A lot of work has gone into the study of valveless micropumps for various applications. However, the complex fluid-structure interactional physics and associated phenomena such as cavitation affects the characterization of valveless micropumps, for applying them reliably in any real-time applications. This paper presents a method of characterization of valveless micropump performance through dynamic measurement of chamber pressure. Experimental investigation has been carried out to study the micropump behavior through pressure measurement under both cavitation and non-cavitation conditions, and the results show that this technique is useful for the characterization of micropump.
Both authors have contributed equally. Piezoelectric materials, capable of converting mechanical energy into electrical energy and vice versa, have emerged as promising candidates for designing intelligent drug delivery vehicles. Leveraging their inherent electrical properties, these materials respond to external stimuli, such as mechanical forces and electrical signals, to control drug release. By integrating piezoelectric materials into drug delivery systems, we can achieve exacting control over drug-release mechanisms. Piezoelectric materials hold enormous promise as smart delivery vehicles in cancer treatment, responding to mechanical and electrical cues, enabling site-specific drug release, reducing systemic toxicity and enhancing therapeutic effectiveness. Further advancements in the field are expected to lead to innovative piezoelectric-based systems that can revolutionize cancer treatment strategies, as explored in this review article. 2 | P a g e
Seawater axial piston pump (SWAPP) has been widely used as the power component in the seawater reverse osmosis (SWRO) desalination systems, whose flow quality could result in significant influences on the performance of RO membranes and SWRO system. This thesis proposed an efficient fully parameterized mathematical approach for the flow and pressure characteristics of SWAPP that is modeled by lumped parameter techniques considering gaseous and vaporous cavitation simultaneously. To address the complex structure of the port plate in SWAPP, especially silencing groove, an innovative model based on the Monte Carlo method was originally proposed, and In-depth comparison with piecewise functions validated the accuracy, efficient and convenient of Monte Carlo approach for calculating the flow area of SWAPP. Particularly, the influence of shaft rotational speed and inlet pressure on the instantaneous discharge flow and pressure of SWAPP was comparatively studied. In addition, a SWRO desalination system was constructed to evaluate the effect of discharge pressure of SWAPP on the RO concentrated brine pressure. The results indicate that the presented model can precisely capture the instantaneous discharge pressure and flow of SWAPP. Besides, increasing the shaft rotational speed and inlet pressure are reliable solutions to enhance the flow performance of SWRO system.
We report a planar solenoid actuated valveless micropump with multiple inlet-outlet configurations. The self-priming characteristics of the multiple inlet-multiple outlet micropump are studied. The filling dynamics of the micropump chamber during start-up and the effects of fluid viscosity, voltage and frequency on the dynamics are investigated. Numerical simulations for multiple inlet-multiple outlet micropumps are carried out using fluid structure algorithm. With DI water and at 5.0 Vp-p, 20 Hz frequency, the two inlet-two outlet micropump provides a maximum flow rate of 336 μl min⁻¹ and maximum back pressure of 441 Pa. Performance characteristics of the two inlet-two outlet micropump are studied for aqueous fluids of different viscosity. Transport of biological cell lines and diluted blood samples are demonstrated; the flow rate-frequency characteristics are studied. Viability of cells during pumping with multiple inlet multiple outlet configuration is also studied in this work, which shows 100% of cells are viable. Application of the proposed micropump for simultaneous pumping, mixing and distribution of fluids is demonstrated. The proposed integrated, standalone and portable micropump is suitable for drug delivery, lab-on-chip and micro-total-analysis applications.
