Valveless 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.

Towards personalized microfluidics: 3D printing of high-performance micropumps by control and optimization of fabrication-induced surface roughness

Additive fabrication technologies are very attractive for use in the realization of customized medical diagnostic and point-of-care devices in the rapidly growing field of personalized healthcare. However, non-idealities in additive manufacturing processes, such as the enhanced roughness that is inherent to many such processes, limit the use of these fabrication technologies in real products. In this work, the effect of additive fabrication-induced surface roughness on fluid flow within material extrusion (MEX) 3D-printed microfluidic devices is modeled and experimentally validated. An optimization process to eliminate such effects in functional 3D-printed devices is developed. By the resulting careful model-driven optimization, high-performance printed glass and Acrylonitrile butadiene styrene (ABS) valveless micropumps are demonstrated in this work for the first time. Water flow rates of 210 µl min−1 and 140 µl min−1 for the ABS and the glass micropumps respectively, and a maximum working backpressure of 978 Pa at an actuation signal of 68 Hz and 120 Vpp are achieved, attesting to the viability of additive fabrication to realize functional microfluidic devices.

Simulation and experiment of valveless micropumps driven by piezoelectric-heating coupling for microfluidics

Simulation and experiment of valveless micropumps driven by piezoelectric-heating coupling for microfluidics

Synergistic Integration of Hydrogen Peroxide Powered Valveless Micropumps and Membraneless Fuel Cells: A Comprehensive Review

AbstractCatalytic valveless micropumps, and membraneless fuel cells are the class of devices that utilize the decomposition of hydrogen peroxide (H2O2) into water and oxygen. Nonetheless, a significant obstacle that endures within the discipline pertains to the pragmatic open circuit potential (OCP) of hydrogen peroxide FCs (H2O2 FCs), which fails to meet the theoretical OCP. Additionally, bubble formation significantly contributes to this disparity, as it disrupts the electrolyte's uniformity and interferes with reaction dynamics. In addition, issues such as catalyst degradation and poor kinetics can impact the overall cell efficiency. The development of high‐performance H2O2‐FCs necessitates the incorporation of selective electrocatalysts with a high surface area. However, porous micro‐structures of the electrode impedes the transport of fuel and the removal of reaction byproducts, thereby hindering the attainment of technologically significant rates. To address these challenges, including bubble formation, the review highlights the potential of integrating electrokinetic and bubble‐driven micropumps. An alternative approach involves the spatiotemporal separation of fuel and oxidizer through the use of laminar flow‐based fuel cell (LFFC). The present review addresses multifaceted challenges of H2O2‐powered FCs, and proposes integration of electrokinetic and bubble‐driven micropumps, emphasizing the critical role of bubble management in improving H2O2 FC performance.

Computational analysis of a four-flap valveless micropump (FFVM) for low reynolds number applications in microfluidic systems

Microfluidic systems are crucial in various fields including biological fluid handling and microelectronic cooling. Micropumps play a vital role in microfluidics. Valveless micropumps are the preferred choice in microfluidics because of their ability to minimize the risk of clogging and gently handle biological materials. In this comprehensive Four-Flap Valveless Micropump (FFVM) simulation, the fluid flow and associated deformation in the valveless micropump are analyzed. The oscillatory fluid motion generated by a straightforward reciprocating pumping mechanism is transformed into a unidirectional net flow by the micropump. This pump eliminates the need for intricate actuation mechanisms found in valve-based pumps while offering precise direction control. The input is given in terms of the Reynolds number or inflow velocity. In this study, the Reynolds numbers were changed from 16 to 50, which resulted in a positive correlation with the net flow rates, yielding a maximum net flow rate of 20.81 μl min−1 at a Reynolds number of 50. The influence of the average flow velocity is evident, with a peak net flow rate of 29.16 μl min−1 at 50 cm s−1. The FFVM showcases adaptability by delivering fluid within microfluidic pathways, holding promising applications in precision drug delivery systems.

Research on internal flow characteristics of the planar conical tube for valveless piezoelectric micropump

Abstract As the most commonly used driving and executing components in microfluidic systems, valveless piezoelectric micropumps have broad application prospects in numerous fields. The steady and unsteady characteristics of planar conical tubes for valveless piezoelectric micropumps were simulated using CFX software at different pressure amplitudes and driving frequencies. The aim was to obtain the factors affecting the flow performance of the valveless piezoelectric micropump. The results show that the numbers of Remax in both diffusion and contraction directions of the planar conical tube increase with increasing pressure. When the number of Wo is lower, the number of Remax under a steady state is approximately equal to that under an unsteady state, and the maximum relative deviation is only 0.25%. The greater the Wo number, the smaller the velocity on the minimum flow section, and the more significant the velocity change. The rectification efficiency η of the valveless piezoelectric micropump and the efficiency λ of the planar conical tube both increase with increasing pressure under steady conditions, and the maximum values can be reached at 11.2% and 1.56, respectively.

Design of a Simple Valveless Micropump Using Piezoelectric Actuators

Abstract An open valveless micropump pumped by a disc-shaped piezoelectric actuator was developed, and its working principles were investigated. The electrode of the pump buzzer was divided into two semicircles as piezoelectric actuators, and single-phase or dual-phase AC driving potential was applied. The flow rate of the pump was analyzed when actuated in basic symmetric (W00) and anti-symmetric (W01) modes. The finite element package software ANSYS was used to analyze the resonant frequency and mode of the buzzer under fluid loading, and the vibration displacement generated by the single-phase and dual-phase time-harmonic actuation was both simulated by using an additional mass method and experimentally investigated. The experimental results show that the resonant frequency of the disc-shaped actuator decreased due to the fluid loading effect and as the gap distance between the conduit and the actuator decreased. The maximum flow rates of the W00 and W01 mode actuated pumps were 133.13 and 9.63 mL/min, respectively. The driving frequency with the highest pump efficiency was slightly lower than the resonance frequency of the fluid-loaded buzzer. Applying a hydrophobic treatment to the back of the buzzer decreased the resonance frequency under fluid loading. The results show that simulating the structural resonance frequency for various fluid loads by the additional mass method is feasible. The flow direction could be controlled by activating the W01 mode.

Research on unsteady characteristics of valveless piezoelectric micropump with planar conical tube

The model of valveless piezoelectric micropump with planar conical tube is established in this paper, and dynamic mesh technology is used to simulate the unsteady characteristics of the micropump at different pressure amplitudes and driving frequencies for different diffusion angles. The elements affecting the output performance of the micropump are analyzed. The research indicates that the longer the conical tube, the smaller the flux that flows into the cavity of the micropump during inhalation. While the longer the conical tube, the greater the flux that flows out of the cavity of the micropump during expulsion. The net output flux of the valveless piezoelectric micropump increases with the length of the conical tube. The rectification efficiencies of micropump with tube length of 1mm, 3mm, and 5mm are 8.77%, 14.58%, and 18%, respectively.

Internal flow characteristics of the valveless piezoelectric micropump with the diffusion/nozzle tube

A simulation was conducted to research the unsteady flow properties of the valveless piezoelectric micropump with diffusion/nozzle tube at different angles in the case of various driving frequencies using CFX software in this study. The purpose was to obtain the factors that affect the performance of the micropump under unsteady conditions. The results show that the rate of flow of the valveless piezoelectric micropump with different diffusion angles increases with the increase of frequency. The micropump with a diffusion angle of 10° has the best performance and the maximum rate of flow within the frequency range of 100 Hz~500 Hz, and the efficiency of the micropump can be reached 16.98%. The vortex motion generated due to flow separation has a notable effect on the performance of the micropump.

Drive simulation analysis of piezoelectric valveless micropump based on ZnO nanorod array

In this paper, ZnO nanorods are combined with the driving mechanism of a piezoelectric micropump to design a valveless piezoelectric micropump. The ZnO nanorods were prepared by the magnetron sputtering method to grow the ZnO seed crystal layer on the silicon surface and then by hydrothermal method. The growth of ZnO nanorods under different solution concentrations, solution temperatures, and growth times was investigated, and analytical methods for analyzing the surface morphology and elemental content of ZnO nanorods. Then, the simulation of the valveless micropump using ZnO nanorods prepared under optimal conditions as piezoelectric oscillators were carried out using COMSOL finite element analysis software, and the maximum output flow rate of about 14.40 μL/s was achieved at 100 V50 Hz.

Analytical and experimental study of a valveless piezoelectric micropump with high flowrate and pressure load

Miniaturized gas pumps based on electromagnetic effect have been intensively studied and widely applied in industries. However, the electromagnetic effect-based gas pumps normally have large sizes, high levels of noises and high power consumption, thus they are not suitable for wearable/portable applications. Herein, we propose a high-flowrate and high-pressure load valveless piezoelectric micropump with dimensions of 16 mm*16 mm*5 mm. The working frequency, vibration mode and displacement of the piezoelectric actuator, the velocity of gas flow, and the volume flowrate of the micropump are analyzed using the finite element analysis method. The maximum vibration amplitude of the piezoelectric actuator reaches ~29.4 μm. The output gas flowrate of the pump is approximately 135 mL/min, and the maximum output pressure exceeds 40 kPa. Then, a prototype of the piezoelectric micropump is fabricated. Results show that performance of the micropump is highly consistent with the numerical analysis with a high flowrate and pressure load, demonstrated its great potential for wearable/portable applications, especially for blood pressure monitoring.

Dual Synthetic Jets Actuator and Its Applications Part V: Novel Valveless Continuous Micropump Based on Dual Synthetic Jets with a Tesla Structure

The valveless micropump based on dual synthetic jets is a potential fluid pumping device that has the ability to transport fluid continuously. In order to improve the performance of this device, a novel valveless continuous micropump based on dual synthetic jets with a Tesla structure was proposed by combining a double Tesla symmetrical nozzle and a dual synthetic jets actuator. The mechanism of the novel micropump and its flow field characteristics were analyzed, combined with numerical simulation and a PIV experiment. The performance of the novel micropump was compared with that of a dual synthetic jet micropump based on a traditional shrinking nozzle. The novel micropump achieved continuous flow with a larger and more stable flow rate in one cycle. The maximum pump flow speed reached 12 m/s. Compared with the traditional type, the pump flow rate was increased by 5.27% and the pump flow pulsation was reduced by 214.93%. The backflow and vortex inside the nozzle were prevented and inhibited effectively by the Tesla structure. The velocity and influence range of the pump flow increased with the intensification of driving voltage in a certain range.

Design and development of a piezoelectric driven micropump integrated with hollow microneedles for precise insulin delivery

A significant rise in diabetes has spurred researchers to develop more painless, patient-friendly, precise therapeutic products for insulin delivery. There is extensive use of valveless micropumps in numerous medical devices since they constitute the key component in the microsystem for fluid control and precision delivery. This study reports a novel integrated insulin delivery device consisting of a valveless piezoelectric-driven micropump, a hollow microneedle array, and a fluid reservoir. At first, a simple, low-cost micropump driven by a piezoelectric disc is fabricated using 3D printing technology. Nozzle/diffuser elements are used instead of any active valves in order to avoid leakage and other complexities. To investigate the viability of the micropump, an analysis of the vibrational performance of the piezoelectric actuator is performed. COMSOL Multiphysics is used to perform the transient analysis of the piezoelectric actuator of the micropump. Further, simulation-based flow analyses are carried out to verify the outcomes of the experimental studies. The experimental results indicate that the maximum flow rate of the micropump is achieved at 400 Hz for insulin. To realize the final aim of this work, an array of hollow SU-8 microneedles is fabricated and then finally integrated with the piezoelectric-driven valveless micropump and fluid reservoir. This integrated insulin delivery device is tuneable and can achieve a maximum flow rate of 120.5 µl min−1 for insulin at 60Vpp, 400 Hz sine wave.

Unsteady characteristics of the diffusion/nozzle tube for valveless piezoelectric micropumps at a lower frequency

In this study, transient flow performance of the diffusion/nozzle tube with diffusion angle of 10° under different Wo numbers was studied using ANSYS CFX software. The purpose of this work is to obtain the factors which influence the flow characteristics of the diffusion/nozzle tube for valveless piezoelectric micropumps under unsteady conditions. A time-dependent sinusoidal pressure is exerted for the entrance as the boundary condition, and the pressure amplitudes P0 are 50Pa, 100Pa, 500Pa, 1000Pa and 5000Pa. The simulation results show that the change of flow lags behind the variation of pressure under unsteady flow conditions. The greater the Wo numbers, the smaller the pressure amplitude P0 , and the greater the phase difference. Both the loss coefficient of pressure in the diffusion ξd , and the nozzle ξn increase with increasing Wo numbers, and decrease with increasing P0 . The vortex has a great influence on the flow characteristics of the valveless piezoelectric micropumps.

A bi-directional valveless piezoelectric micropump based on the Coanda effect

A bi-directional valveless piezoelectric micropump based on the Coanda effect

A Novel Integrated Transdermal Drug Delivery System with Micropump and Microneedle Made from Polymers.

Transdermal drug delivery (TDD), which enables targeted delivery with microdosing possibilities, has seen much progress in the past few years. This allows medical professionals to create bespoke treatment regimens and improve drug adherence through real-time monitoring. TDD also increases the effectiveness of the drugs in much smaller quantities. The use of polymers in the drug delivery field is on the rise owing to their low cost, scalability and ease of manufacture along with drug and bio-compatibility. In this work, we present the design, development and characterization of a polymer-based TDD platform fabricated using additive manufacturing technologies. The system consists of a polymer based micropump integrated with a drug reservoir fabricated by 3D printing and a polymer hollow microneedle array fabricated using photolithography. To the best of our knowledge, we present the fabrication and characterization of a 3D-printed piezoelectrically actuated non-planar valveless micropump and reservoir integrated with a polymer hollow microneedle array for the first time. The integrated system is capable of delivering water at a maximum flow rate of 1.03 mL/min and shows a maximum backpressure of 1.37 kPa while consuming only 400 mW. The system has the least number of moving parts. It can be easily fabricated using additive manufacturing technologies, and it is found to be suitable for drug delivery applications.

Design and Analysis of Multiple Inlet–Multiple Outlet Piezoelectric Actuated Valveless Micropump for Micro Drug Delivery Application

Design and Analysis of Multiple Inlet–Multiple Outlet Piezoelectric Actuated Valveless Micropump for Micro Drug Delivery Application

A SUPERIMPOSED VALVELESS MICROPUMP USING NEW CHANNELS FOR OPTIMAL DRUG DELIVERY

In this paper, we propose a valveless micropump with an improved inlet/outlet channel configuration for biomedical applications. To do so, we added curved parts known as "ears" to a standard diffuser/nozzle shape. This new design will enlarge the flow rate values between both directions for the purpose of improving the valveless micropump efficiency. After that, the new channel is incorporated into a double valveless micropump superimposed on each other making the diaphragm in sandwich. This kind of micropump shows no reflux at its common outlet and good reliability due to the new design of the diffuser/nozzle channel. COMSOL Multiphysics software is used to model and simulate, under Fluid-Structure Interaction (FSI) physic, the complete system of the superimposed valveless micropump (SVM). The results are promising and show that our kind of micropump is necessary for medication injection because of the no backflow at its common outlet, and also because of the increase in its efficiency.

Implantable double-layer pump chamber piezoelectric valveless micropump with adjustable flow rate function

The piezoelectric valveless micropump with the characteristics of precise liquid delivery is widely utilized in the field of biomedicine. However, the improvement of the flow rate of the piezoelectric micropump relies on the increase in size and driving voltage, which hinders its application in the implantable medical field. This article proposes a double-layer chamber valveless piezoelectric micropump, which has the obvious advantages of small size and adjustable flow rate, and is expected to be applied to the treatment of implantable hydrocephalus. The overall size of the micropump is 10 mm × 10 mm × 4 mm, which can be implanted in the cerebral cortex. Combined with polydimethylsiloxane-polyethylene glycol terephthalate bonding technology, the double-layer chamber micropump solves the contradiction between miniaturization and large flow range. The flow rate generated by micropump under low voltage can be adjusted according to the amount of hydrocephalus. In order to reveal the mechanism of increasing the flow rate, the working efficiencies of the microvalve and micropump are studied in this article. The electric-solid-fluid coupling simulation and experimental tests obtained the optimal structural parameters: the divergence angle is 30°, the throat width is 300 μm, and the upper chamber depth is 100 μm. The proposed micropump can achieve the tunable flow rate of 2.16–51.74 μl min−1.

Achieving Full Forward Flow of Valveless Piezoelectric Micropump Used for Micro Analysis System

The valveless piezoelectric micropump has the advantages of simple structure, high precision and low cost, which can realize the directional transport of micro-fluid and wildly be applied in a micro analysis system. However, backflow at the outlet cannot be avoided due to the limitation of its working mechanism. Large reflux rate can increase the volume control accuracy per cycle, but reduces the stability of the micro analysis system. In order to achieve a full forward flow, which reduce the influence of backflow on the system’s stability, the reflux characteristics of the designed valveless piezoelectric micropump were studied. The condition proposed, which should be satisfied for obtaining full forward flow, is that the reflux rate should be less than 50%. The influence of relations between the size of the key structures and pumping characteristics are established, and the references for structural parameter selection to reduce backflow and achieve full forward flow are given. This paper highlights the methods of controlling the pumping performance and achieving full forward flow, based on structural parameter selection analysis and adjusting excitation. The reflux rate can be reduced to 5% when the inlet angle is increased to 9°. The experimental results verify the validity of the obtained results and the proposed methods of control. This work provides important references for applying valveless piezoelectric micropumps in micro analysis and precision-driven systems.