Pressure-driven System Research Articles

Design and fabrication of a novel microswitch made in LTCC-PDMS technology applicable to micro total analysis systems

AbstractThe physical design and implementation of an LTCC on–off microswitch device is demonstrated. One model was used to describe microchannel fluidic behavior, especially those with rectangular cross-section, routinely used in microfluidic devices. Another model to describe PDMS microbridge deformation was applied, allowing for estimating the elastic stiffness of several manufactured membranes. From this approach, microswitch design was conducted regarding the simulation results associated with both models, aiming at miniaturization. Applying LTCC-PDMS fabrication methodology, the fluidic devices were manufactured as established by theoretical design and an experimental setup was proposed in order to evaluate system performance. Experimental investigations indicate that a weight of 120 g was necessary to reduce the water flow rate of the normally open LTCC-PDMS microswitch from 0.42 mL/min to 50 μL/min when submitted to a controllable pressure-driven system. The leakage observed when testing the fabricated microswitches regards the rough way in which the PDMS membrane was attached to the LTCC body. However, experimental results suggest that the novel microswitch can operate satisfactorily regarding micro total analysis applications.

Enhanced Pulley Effect for Translocation: The Interplay of Electrostatic and Hydrodynamic Forces.

Solid-state nanopore sensors remain a promising solution to the rising global demand for genome sequencing. These single-molecule sensing technologies require single-file translocation for high resolution and accurate detection. In a previous publication, we discovered a hairpin unraveling mechanism, namely, the pulley effect, in a pressure-driven translocation system. In this paper, we further investigate the pulley effect in the presence of pressure-driven fluid flow and an opposing force provided by an electrostatic field as an approach to increase single-file capture probability. A hydrodynamic flow is used to move the polymer forward, and two oppositely charged electrostatic square loops are used to create an opposing force. By optimizing the balance between forces, we show that the single-file capture can be amplified from about 50% to almost 95%. The force location, force strength, and flow rate are used as the optimizing variables.

Fluidization regimes of dense suspensions of Geldart group A fluidized particles in a high aspect ratio column

Fluidization regimes were studied in numerous papers with applications in risers in which gas velocity is the main driving force. The situation is different when a tube is immersed in a fluidized bed vessel in which a pressure is imposed to move the particle upward. The particle-in-tube solar receiver concept is based on this latter operation mode with the aim to heat particles at high temperature with concentrated solar energy. This study identifies the fluidization regimes in a pressure-driven system that includes a secondary aeration to control the air velocity in the tube. Bubbling, slugging, turbulent and fast fluidization regimes are determined thanks to temporal pressure signal processing methods and a regime map is plotted. The transition velocities are significantly lower than in classical risers. The local slip velocity is defined as the governing parameter of the flow structure and the variation of the local particle volume fraction is discussed.

Perfusion culture of endothelial cells under shear stress on microporous membrane in a pressure-driven microphysiological system

This paper reports perfusion culture of human umbilical vein endothelial cells (HUVECs) on a microporous membrane in a pressure-driven microphysiological system (PD-MPS), which we developed previously as a multi-throughput perfusion culture platform. We designed fluidic culture unit with microporous membrane to culture HUVECs under fluidic shear stress and constructed a perfusion culture model in the PD-MPS platform. Four fluidic culture units were arranged in the microplate-sized device, which enables four-throughput assay for characterization of HUVECs under flow. Medium flow was generated above and below the membrane by sequential pneumatic pressure to apply physiological shear stress to HUVECs. HUVECs exhibited aligned morphology to the direction of the flow with shear stress of 11.5-17.7dyn/cm2 under the flow condition, while they randomly aligned under static culture condition in a 6 well plate. We also observed 3.3- and 5.0-fold increase in the expression levels of the thrombomodulin and endothelial nitric oxide synthase mRNAs, respectively, under the flow condition in the PD-MPS compared to the static culture in 6 well plate. We also observed actin filament aligned to the direction of flow in HUVECs cultured under the flow condition.

Pressure-driven dynamical microfluidic pumping system for droplet production

Compact and affordable microfluidic pumping is critical for point-of-care applications. Here we proposed a data driven dynamical system to build up a pressure-driven microfluidic pump with a small budget. Firstly, a precision flow sensor is required to obtain the dynamic flow rates as the responses to the driven pressures. Then the flow rate dataset under varying operation pressures is used for data training and model-based system identification. With a first-order or second-order transfer function model, the specifications of pressure-driven microfluidic pumping system are analyzed by the model-based system identification algorithm. Also, all the specifications including the gain, time constant, natural frequency, and damping ratio are updated online as new test data are introduced from more experimental trials. To perform a non-bulky design purpose, the data training system identification is taken on a commercial smartphone. Once the training performance is satisfied, the pressure-driven system could be operated without any flow sensors. The system is used for two-phase flow controls as a demonstration, showing a rapid response of pumping. Dynamic characteristics and the effects of flow resistance on the pumping performance are analyzed to verify its suitability for a wide range of microfluidic applications.

Perfusion culture of multi-layered HepG2 hepatocellular carcinoma cells in a pressure-driven microphysiological system

Here we report the perfusion culture of a multi-layered tissue composed of HepG2 cells (a human hepatoma line) in a pressure-driven microphysiological system (PD-MPS), which we developed previously as a multi-throughput perfusion culture platform. The perfusion culture of multi-layered tissue model was constructed by inserting a modified commercially available permeable membrane insert into the PD-MPS. HepG2 cells were layered on the membrane, and culture medium was perfused both through and below the membrane. The seeded density (number of cells/cm2) of the culture model is 70 times that of static culture in a conventional 35-mm culture dish. Pressure-driven circulation of the medium in our compact device (8.6× 7.0× 4.5cm3), which comprised two perfusion-culture modules and a pneumatic connection port, enabled perfusion culture of two multi-layered tissues (initially 1× 105cells). To obtain insight into the basic functionality of the multi-layered tissues as hepatocytes, we compared albumin production and urea synthesis between perfusion cultures and static cultures. The HepG2 cells grew and secreted increasing amounts of albumin throughout 20 days of perfusion culture, whereas albumin secretion did not increase under static culture conditions. In addition, on day 20, the amount of albumin secreted by the HepG2 cells in the microfluidic device was 68% of that in the conventional culture dish, which was seeded with the same number of cells but had a 70 times larger culture area. These features of high-density culture of functioning cells in a compact device support the application of PD-MPS in single- and multi-organ MPS.

Compaction of a Polymeric Membrane in Ultra-Low-Pressure Water Filtration.

Applications of ultra-low-pressure filtration systems are increasing as they offer enhanced sustainability due to lower energy input, almost no use of chemicals, and minimum operational expenditure. In many cases, they operate as a decentralized system using a gravity-driven membrane (GDM) filtration process. These applications are relatively new; hence, the fundamental knowledge of the process is still limited. In this study, we investigated the phenomenon of polymeric membrane compaction under an ultra-low-pressure system. The compaction phenomenon is well-recognized in the traditional pressure-driven system operating at high transmembrane pressures (ΔPs > 200 kPa), but it is less documented in ultra-low-pressure systems (ΔP < 10 kPa). A simple GDM filtration setup operated under a constant-pressure system was employed to investigate the compaction phenomena in a polymeric hollow fiber membrane for clean water filtration. Firstly, a short-term pressure stepping test was performed to investigate the occurrence of instantaneous compaction in the ΔP range of 1–10 kPa. The slow compaction was later investigated. Finally, the compaction dynamic was assessed under alternating high and low ΔP and relaxation in between the filtrations. The findings demonstrated the prominence of membrane compaction, as shown by the decreasing trend in clean water permeability at higher ΔPs (i.e., 3240 and 2401 L m−2 h−1 bar−1 at ΔPs of 1 and 10 kPa, respectively). We also found that the intrinsic permeability of the applied polymeric membrane was significantly higher than the apparent one (4351 vs. 2401 L m−2 h−1 bar−1), demonstrating >50% loss due to compaction. The compaction was mainly instantaneous, which occurred when the ΔP was changed, whereas only minor changes in permeability occurred over time when operating at a constant ΔP. The compaction was highly reversible and could be restored (i.e., decompaction) through relaxation by temporarily stopping the filtration. A small fraction of irreversible compaction could be detected by operating alternating filtrations under ΔPs of 1 and 10 kPa. The overall findings are essential to support emerging GDM filtration applications, in which membrane compaction has been ignored and confounded with membrane fouling. The role of compaction is more prominent for high-flux GDM filtration systems treating less-fouling-prone feed (i.e., rainwater, river water) and involving membrane cleaning (i.e., relaxation) in which both reversible and irreversible compaction occurred simultaneously.

Indications of ion dehydration in diffusion-only and pressure-driven nanofiltration

Recent insights into the permeation of small ions through polyamide membranes highlighted the role of ion dehydration in the transport and selectivity observed. However, such insights were a by-product of studies exploring different transport phenomena without a systematic methodology that focuses on ion dehydration itself. In this study, we quantified the intrinsic permeability and its underlying Eyring's enthalpy and entropy of activation for a systematic set of cations and anions in polyamide nanofiltration membranes to gain better understanding of ion dehydration. Our results in a diffusion-only system expose a distinct correlation between the hydration strength of the ions and the enthalpic barrier they experience during permeation, with a permeability order that is similar to the mobility order in solution. Smaller entropic losses are observed for smaller bare ions, indicating their higher freedom of motion after dehydration compared to larger bare ions. Comparing the measured activation enthalpies to quantum chemical calculations for the ions' hydration in solution suggests that ions are only partially dehydrated. Last, our simulated ion permeability at higher temperatures and experimental results in a pressure-driven system expose higher permeation rates with reversed ion-ion selectivity, indicating the activation of ion transport in the form of ion dehydration when additional energy is supplied. • Transport of monovalent ions is explored in diffusion-only and pressurized NF. • More strongly hydrated ions face higher enthalpic barrier during permeation. • Smaller bare ions face lower entropic losses during permeation. • Experimental barriers correlate to simulated stripping of 1–3 water molecules. • Diffusion-only and pressurized filtration expose reversed ion-ion selectivity.

Outside Front Cover: Volume 1 Issue 1

Interdisciplinary MaterialsVolume 1, Issue 1 p. i-i COVER IMAGEOpen Access Outside Front Cover: Volume 1 Issue 1 First published: 31 January 2022 https://doi.org/10.1002/idm2.12015AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Outside Front Cover: Liquid gating membrane is a new kind of structural materials, response to an applied force as a pressure-driven system. To address the long-term high consumption caused by traditional “experimental trial method”, a machine learning algorithm is trained to effectively integrate material structure, composition and performance. This cover shows machine learning technology, offers a promising approach to exchange negligible machine resources for valuable researcher time, thus accelerating and optimizing the development of liquid gating technology. Volume1, Issue1January 2022Pages i-i RelatedInformation

Properties of Plasma Clots in Adult Patients Following Fontan Procedure: Relation to Clot Permeability and Lysis Time-Multicenter Study.

Objectives: thromboembolic complications are a major cause of morbidity and mortality following Fontan (FO) surgery. It is also well established that altered FO circulation results in systemic complications, including liver and endothelium damage. We sought to evaluate whether dysfunctions of these sources of hemostatic factors may result in changes of fibrin clot properties. Methods: a permeation coefficient (Ks) and clot lysis time (CLT) were assessed in 66 FO patients, aged 23.0 years [IQR 19.3–27.0], and 59 controls, aged 24.0 years [IQR 19.0–29.0]. Ks was determined using a pressure-driven system. CLT value was measured according to assay described by Pieters et al. Endothelium and liver-derived hemostatic factors along with liver function parameters were evaluated. The median time between FO operation and investigation was 20.5 years [IQR 16.3–22.0]. Results: FO patients had lower Ks (p = 0.005) and prolonged CLT (p < 0.001) compared to that of controls. Ks correlated with CLT (r = −0.28), FVIII (r = −0.30), FIX (r = −0.38), fibrinogen (r = −0.41), ALT (r = −0.25), AST (r = −0.26), GGTP (r = −0.27) and vWF antigen (r = −0.30), (all p < 0.05). CLT correlated with the time between FO operation and investigation (r = 0.29) and FIX (r = 0.25), (all p < 0.05). After adjustment for potential cofounders, TAFI antigen and GGTP were independent predictors of reduced Ks (OR 1.041 per 1% increase, 95% CI 1.009–1.081, p = 0.011 and OR 1.025 per 1 U/L increase, 95% CI 1.005–1.053, p = 0.033, respectively). Protein C and LDL cholesterol predicted prolonged CLT (OR 1.078 per 1% increase, 95% CI 1.027–1.153, p = 0.001 and OR 6.360 per 1 μmol/L increase, 95% CI 1.492–39.894, p = 0.011, respectively). Whereas elevated tPA was associated with lower risk of prolonged CLT (OR 0.550 per 1 ng/mL, 95% CI 0.314–0.854, p = 0.004). GGTP correlated positively with time between FO surgery and investigation (r = 0.25, p = 0.045) and patients with abnormal elevated GGTP activity (n = 28, 42.4%) had decreased Ks, compared to that of the others (5.9 × 10−9 cm2 vs. 6.8 × 10−9 cm2, p = 0.042). Conclusion: our study shows that cellular liver damage and endothelial injury were associated with prothrombotic clot phenotype reflected by Ks and CLT.

Standing Air Bubble-Based Micro-Hydraulic Capacitors for Flow Stabilization in Syringe Pump-Driven Systems.

Unstable liquid flow in syringe pump-driven systems due to the low-speed vibration of the step motor is commonly observed as an unfavorable phenomenon, especially when the flow rate is relatively small. Upon the design of a convenient and cost-efficient microfluidic standing air bubble system, this paper studies the physical principles behind the flow stabilization phenomenon of the bubble-based hydraulic capacitors. A bubble-based hydraulic capacitor consists of three parts: tunable microfluidic standing air bubbles in specially designed crevices on the fluidic channel wall, a proximal pneumatic channel, and porous barriers between them. Micro-bubbles formed in the crevices during liquid flow and the volume of the bubble can be actively controlled by the pneumatic pressure changing in the proximal channel. When there is a flowrate fluctuation from the upstream, the flexible air-liquid interface would deform under the pressure variation, which is analogous to the capacitive charging/discharging process. The theoretical model based on Euler law and the microfluidic equivalent circuit was developed to understand the multiphysical phenomenon. Experimental data characterize the liquid flow stabilization performance of the flow stabilizer with multiple key parameters, such as the number and the size of microbubbles. The developed bubble-based hydraulic capacitor could minimize the flow pulses from syringe pumping by 75.3%. Furthermore, a portable system is demonstrated and compared with a commercial pressure-driven flow system. This study can enhance the understanding of the bubble-based hydraulic capacitors that would be beneficial in microfluidic systems where the precise and stable liquid flow is required.

Experimental investigation on a novel pressure-driven heating system with Ranque–Hilsch vortex tube and ejector for pipeline natural gas pressure regulating process

In this work, a novel pressure-driven heating system with a Ranque–Hilsch vortex tube and ejector to recover pressure losses and absorb energy from the ambient environment to heat pipeline natural gas (PNG) is proposed to take the place of the conventional heating system with a boiler. A vortex tube to produce the high-temperature and low-temperature streams simultaneously with its energy separation effect and an ejector to drive the internal subcycle within the system to heat the low-temperature stream by the ambient air are installed. They regulate the PNG pressure and absorb heat from the ambient air while maintaining simplicity and reliability. To study the performance of this new system, an analogical experimental rig was established with pressurised air as the working fluid. The experimental results verified the heating capacity of the system, in which a significant temperature rise greater than 9 K was obtained with a small pressure drop of approximately 1.0 MPa. Compared with a sole throttling valve, an energy-saving ratio of no less than 0.35 was achieved.

On a silver platter

on a silver platter

A computational framework for predicting the combustion of energetic materials in an expanding chamber

PurposeVarious simplifications are introduced into the establishment of numerical models for problems with strong nonlinear interactions. The combustion of energetic materials in a chamber with moving boundaries is a typical example. This paper aims to establish a coupled numerical model for predicting the internal combustion in a launch process.Design/methodology/approachA two-fluid model is used to predict the fluid field induced by the propellant combustion. The moving boundary is located by using a finite element method. Based on a user subroutine interface in the commercial software ABAQUS, the development of the fluid field and the mechanical interactions is coupled with each other.FindingsThe paper is devoted to provide a coupled computational framework for predicting the propellant combustion in an expanding chamber. The coupling strategy is validated through predicting a pressure-driven piston system. Based on the validated computational framework, the two-phase reactive flows in a launch process is studied. The predicted parameters agree well with experimental measurements.Originality/valueThis paper provide a method to address the difficulties in realizing the dynamic interactions between multi-phase reactive flows and mechanical behaviors. The computational framework can be used as a research tool for investigating fluid field in a combustion chamber with moving boundaries.

Abstract A027: A novel two-step tumor cell isolation system, combining acoustophoresis and negative selection of white blood cells using CD45-conjugated elastomeric particles

Abstract Introduction: Circulating tumor cells (CTCs) are a promising tool for disease monitoring and for better-targeted therapies for patients with disseminating tumors. However, isolation of CTCs is challenging, due to their scarcity, heterogeneous size, and lack of universal expression markers. We employ a novel ultrasonic standing wave-based microfluidic technique (acoustophoresis) to enable unbiased, label-free isolation of circulating tumor cells (CTCs). The cell separation is based on intrinsic cell properties, such as size, morphology, density, and compressibility. During acoustophoresis cells/particles get positioned to nodes or antinodes depending on their acoustic contrast factor. The contrast factor depends on the density and compressibility ratios between the particles and the surrounding medium. Both cancer cells and subpopulations of white blood cells (WBCs) partly possess positive acoustic factors and are therefore positioned to pressure nodes during acoustophoresis. By employing negative contrast CD45-conjugated elastomeric particles (EPs) to capture the contaminating WBCs, a negative acoustic complex can be formed that positions the remaining WBCs to the antinodes. This cell separation technique is gentle towards the target cells and tunable to fit various situations, depending on whether throughput, cancer cell recovery, or purity is of major importance. Both paraformaldehyde (PFA) fixed cells and fresh blood can be processed through acoustophoresis. However, acoustophoretic cancer cell separation from fresh blood generates higher WBC contamination than processing of PFA fixed cells, due to overlapping acoustic properties. Therefore, an additional purification step is needed to remove excess contaminating WBCs. Hence, we have added an additional purging step after acoustophoresis, employing CD45-conjugated negative selection of WBCs using negative acoustic contrast EPs. Material and Methods: The acoustic separation device is a glass/silicon microchip connected to a pressure-driven system. For optimal separation performance, the system is temperature controlled and a prefocusing step is included before the main separation in the first cell separation step. The setup can process samples up to 10 mL, with a processing speed of 1 mL sample in 13 minutes without compromising the cell separation capacity. To evaluate the system performance, 1 mL model samples were processed, consisting of 10,000 DU145 prostate cancer cells spiked in 0.5 mL red blood cell (RBC) lysed blood from healthy donors. Results and Discussion: In the primary acoustic separation step, an average of 93% of the DU145 cancer cells were collected at the central outlet, whereas 7% were found in the side fraction. A 20-fold WBC depletion was achieved after the primary acoustophoresis-based tumor cell separation step. The central fraction output was subjected to a subsequent one-hour incubation with CD45-conjugated EPs in room temperature. The incubated samples were processed by acoustophoresis to negatively select EP/WBC complexes from cancer cells into separate outlet fractions, with subsequent flow cytometry analysis. Result showed a 98% cancer cell separation efficiency and a total 250-fold WBC depletion from the starting WBC concentration. Although the separation efficiency in the two steps was high, there was some cell loss in the total system, which needs to be further addressed. We propose a two-step acoustic-based microfluidic technology, consisting of an upstream primary label-free acoustophoretic separation of cancer cells from blood and a subsequent negative WBC depletion. This may lay the foundation for future analytical and clinical studies aimed to validate novel biomarkers for effective treatment management of cancer patients. Citation Format: Cecilia Magnusson, Eva Undvall, Thomas Laurell, Hans Lilja. A novel two-step tumor cell isolation system, combining acoustophoresis and negative selection of white blood cells using CD45-conjugated elastomeric particles [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A027.

Combination of low-pressure UF membranes with conventional water treatment systems

The purpose of the study was to improve drinking water quality of conventional treatment processes by combining with UF-membrane systems. Performances of two membrane systems were evaluated in two different full-scale conventional water treatment plants in Istanbul. Low-pressure UF membranes were combined after settling and filtration units of Büyükçekmece and Emirli water treatment plants. Low-pressure UF systems were operated under vacuum and pressure conditions. The experimental results indicated that combining UF systems enhanced drinking water quality with respect to turbidity, TOC and UV254 removal. In all cases, vacuum-driven UF membranes provided higher treatment performance and low energy consumption comparing to pressure-driven system. Combination with UF membranes also reduced disinfection by-products.

Evaluation on suitability of osmotic dewatering through forward osmosis (FO) for xylose concentration

Abstract Forward osmosis (FO) has great potential for sustainable osmotic dewatering, which can attain several goals including low energy use, high water recovery, and low membrane fouling. However, this technology still involves critical issues that should be explored to achieve successful functioning of osmotic dehydration process, such as feed characteristics, FO membrane performance, and draw solution selection. In this study, the effectiveness of FO for osmotic dehydration was demonstrated by adopting xylose solution as model feed. Aside from current energy intensive evaporation methods, this widely used sweetener needs an advanced and energy-efficient concentration method such as FO. The stable performance showed xylose can be sustainably concentrated with a consistently high dewatering rate, whereas the recovery rate using a pressure-driven membrane system was constrained by the bursting pressure of nanofiltration membrane. Lastly, high-quality of concentrated product can be obtained by selecting a suitable draw solution of which its reversely diffused salts barely affect the xylose solution or are used to enhance the xylose quality. Employing Poly (aspartic acid) sodium salt or sugar-based solutes as draw help to preserve the purity of enriched xylose. These results suggest that FO can provide a feasible solution for food processing which requires product concentration through dewatering while preserving and improving its quality.

Weak solutions for Euler systems with non-local interactions

We consider several modifications of the Euler system of fluid dynamics, including its pressureless variant driven by non-local interaction repulsive–attractive and alignment forces in the space dimension N = 2 , 3 . These models arise in the study of self-organization in collective behavior modeling of animals and crowds. We adapt the method of convex integration to show the existence of infinitely many global-in-time weak solutions for any bounded initial data. Then we consider the class of dissipative solutions satisfying, in addition, the associated global energy balance (inequality). We identify a large set of initial data for which the problem admits infinitely many dissipative weak solutions. Finally, we establish a weak–strong uniqueness principle for the pressure-driven Euler system with non-local interaction terms as well as for the pressureless system with Newtonian interaction.

Shear stress in a pressure-driven membrane system and its impact on membrane fouling from a hydrodynamic condition perspective: a review

Pressure-driven membrane technology has gained increasing popularity in municipal/domestic and industrial wastewater treatment, desalination, and water reclamation. Careful manipulation of surface shear stress, which plays a vital role in membrane fouling control from a purely hydrodynamic perspective, can minimise concentration polarisation of solute on flat sheet membranes, or enhance the particle back transport from hollow fibre membranes. This review considers the techniques to generate turbulence and shear at the membrane surface, the magnitude of shear stress, and the experimental, as well as numerical methods for evaluation of shear stress. The findings are presented in terms of the amount of shear stress reported to control membrane fouling in these systems. Operational disadvantages of fouling control via application of shear stress occur while changing the properties of the solute or particles, such as cell breakup, bacterial population change, or shear stress classification. The literature teaches that future developments on shear stress for membrane systems must be addressed, in addition to energy consumption, shear stress distribution and the development of combined analytical methods to characterise and visualise shear in situ for different membrane configurations. © 2016 Society of Chemical Industry

A microfluidic gas damper for stabilizing gas pressure in portable microfluidic systems.

Pressure fluctuations, which invariably occur in microfluidic systems, usually result in the unstable fluid delivery in microfluidic channels. In this work, a novel microfluidic gas damper is proposed and applied for providing stable fluid-driving pressures. Then, a pressure-driven flow setup is constructed to investigate the gas damping characteristics of our damper. Since the pressure-driven flow setup functions as a resistor-capacitor low-pass filter, the damper significantly decreases the amplitude of the input pressures via self-regulating its pneumatic resistance. In addition, the gas volume and pressure frequency are found to have direct effects on the pressure fluctuations. The practical application of the gas damper is examined through a portable pressure-driven system, which consists of an air blower, a gas damper, and a centrifuge tube. By periodically pressing the air blower, precise flow rates with low throughput (∼9.64 μl min-1) and high throughput (∼1367.15 μl min-1) are successfully delivered. Future integration of our microfluidic gas damper with miniaturized pressure generators (e.g., peristaltic or pressure-driven micropumps) can fully exploit the potential of the gas damper for low-cost, portable microfluidics where stable pressures or flow rates are required.