Microfluidic Passive Valve Regulator for Controlling Flow Rates

Microfluidic Passive Valve Regulator for Controlling Flow Rates | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Microfluidic Passive Valve Regulator for Controlling Flow Rates Hitham Thabet This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5379769/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In microfluidic applications where cost effectiveness and miniaturization are key, the use of passive microvalve offers significant benefits. This study introduces an innovative passive microfluidic valve design comprising a fluid chamber, a flexible membrane, and a rectangular control chamber, enabling effective flow rate management at exceptionally pressures. The model was created using the 3D photolithography method, and the passive microvalve was evaluated under pressure circumstances that are both constant and time-dependent. In the experiment, the microfluidic passive valve demonstrated a constant flow rate when the pressure ranged from 40 kPa to 70 kPa. This regulator can achieve a consistent delivery flow rate of up to 53 ± 2.5µL/min with deviations under 4.5%, as demonstrated by the testing outcomes. Furthermore, the microfluidic passive valve has demonstrated the capability to maintain a stable liquid flow rate under fluctuating conditions, specifically under square wave pressure variations over time. The suggested microfluidic passive valve device may be used in portable, low-cost Lab-on-a-Chip (LoC) applications to precisely control flow. We anticipate this innovative passive microfluidic valve will work well for regulating fluid flow in systems with broader applications or portable microfluidic devices. Passive valve Microfluidic Flow rate Pressure Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction Biological cell separation is one of the point-of-care test (POCT) applications for microfluidics, also known as lab-on-a-chip (Zhang et al. 2016 ; Murray et al. 2018 ), nucleic acid diagnostics (Kim et al. 2014 ; Zhang et al. 2018 ), bacteria detection, etc. (Czilwik et al. 2015 ; Houssin et al. 2016 ), often call for mobility, autonomous actuation, and high-throughput processing. Microfluidic POCT systems require a micro-scaled liquid-pushing pumping mechanism that satisfies the system's technical requirements. Nowadays, complicated flow control in pumping units is often achieved by using microvalves, and their usefulness in applications with limited resources is greatly influenced by their actuation mechanism and valve structure. In general, the microvalve's shape needs to be planned for a possible large-scale integration. For convenient actuation, the total force used to regulate the liquid in the microvalve should be kept to a minimum. Additionally, the microvalve should be fully operated on-chip with energy efficiency for mobility and cost-effectiveness. Numerous microvalves possessing on-chip actuation capability have been documented in the literature, especially those with types of elastomeric membranes, which are acknowledged as a fundamental technology for facilitating a range of applications in microfluidic systems (Oh and Ahn 2006 ; Au et al. 2011 ). These membrane valves have flexible actuation, are readily fabricated using conventional manufacturing techniques, and may be downsized for use in biological and biochemical microfluidic systems. Three layers make up a typical structural membrane valve a thin elastic membrane, a fluidic channel, and a control channel that may be reversibly deflected to Switch the fluidic channel on or off. to control flow (Unger et al. 2000 ). Poly (dimethyl siloxane) (PDMS) is the most widely utilized membrane material because of its strong elasticity for significant deformations and good optical transparency (Whitesides et al. 2001 ). In some circumstances, other materials are also utilized, including shape memory alloy (Cheng et al. 2018 ; Guevara-Pantoja et al. 2018 ), glass (Takehara et al. 2013 ), thermal plastic polymer ( Pourmand et al. 2018 ), and more. Numerous processes have been postulated to explain the membrane's deflection, including mechanical (Chen et al. 2009 ; Zheng et al. 2009 ), electrostatic (Anjewierden et al. 2012 ; Kim et al. 2014 ), pneumatic (Zhang et al. 2009 ; Fordyce et al. 2012 ), magnetic (Harper et al. 2016 ; Pugliese et al. 2017 ), piezoelectric (Lv et al. 2013 ), and thermal (Bazargan and Stoeber 2010 ). Pneumatic actuation appears to be the most often utilized technique among actuation systems. Pneumatically operated active valves frequently make use of off-chip components such air compressors, pressure regulators, etc., to regulate air pressure and accomplish the necessary flow control. Complex microfluidic devices like peristaltic pumps (Anjewierden et al. 2012 ; Cheng et al. 2018 ) and mixers (Zhang et al. 2007 ). Can be created by combining several valves. Still, the active technology can be deemed too much for a portable, low-cost microfluidic system that demands full on-chip activation, like in POCT applications. A passive valve, in contrast to an active valve, adjusts the flow resistance on its own to control the liquid flow rate without the need for additional power. Furthermore, the valve with a preset threshold pressure may achieve a constant flow rate because it can realize self-adaptive resistance fluctuations that fully compensate the fluidic pressure variations (Zhang et al. 2017 ; Zhang and Zhang 2019 ). A silicon membrane valve for medicine administration was created by (Cousseau et al. 2001 ). The valve was made out of a bottom layer with a spiral channel, a silicon membrane, and a glass cover. Between 20 and 50 kPa of working pressure, the valve kept the liquid flow rate constant at 0.022 mL/min. A PDMS press-up valve with a fluidic channel and membrane, and a detour control channel was suggested by (Kartalov et al. 2006 ). 0.033 mL/min was the steady flow rate that the valve maintained, and the threshold pressure required to attain the flow rate was 103 kPa. In order to create a confined fluid channel in a planar check valve, Yang et al. devised a stiff stopper and a compliant flap, The valve had a threshold pressure of 100 kPa and generated a high flow rate of 1.2 mL/min. (Yang and Lin 2007 ). Proposed the use of a parallel membrane valve to build a passive low threshold pressure valve with two vertical membranes, two control channels, and a fluidic channel (Doh and Cho 2009 ). At pressures as low as 15 kPa, the valve was able to control the flow of liquid in the fluidic channel by the independent deflection of both membranes. In this work, we created a novel passive microfluidic valve that will better regulate the flow rate performance of passive microfluidic valves. In addition, the presented microfluidic passive valve offers a promising solution for achieving precise and controllable fluidic manipulations in miniaturized analytical systems. Its simple design, ease of fabrication, and reliable operation make it a valuable component for advancing the capabilities of lab-on-a-chip devices, contributing to the ongoing progress in microfluidics and point of care diagnostics. 2. Materials and Method 2.1. The Device's Working Principle An elastic membrane, a liquid chamber, and a control chamber component of the valve. (Fig. 1 a) displays the proposed passive valve concept's structural schematic. The membrane will deform towards the control chamber in response to liquid pressure in order to regulate the rate of output flow. The control chamber features a rectangular surface with four angles for liquid to flow through. The flow resistance of the valve increases when the inlet liquid pressure is raised to deflect the membrane, as shown in (Fig. 1 b), because the membrane deforms and reduces the volume of the control chamber. The main equation for flow rate of valve is: $$\varvec{Q}=\frac{\varvec{P}}{\varvec{R}}=\frac{\varvec{P}+\varDelta\:\varvec{P}}{\varvec{R}+\varDelta\:\varvec{R}}$$ 1 Q In fluid dynamics, this is usually used to describe the flow rate, which is the volume of fluid flowing per unit time. where the valve's initial flow resistance is R , the resistance increment is ΔR , the initial inlet pressure is P , and the pressure gradient is ΔP . According to Eq. ( 1 ), the resistance increase ΔR automatically adjusts for the pressure modify ΔP when the input pressure rises above a certain threshold. We performed numerical research on the valve using the Fluid-Structure Interaction (FSI) module in COMSOL Multiphysics® (Version 6.0, COMSOL Inc., Stockholm, Sweden), based on the previously mentioned idea. This module enabled us to examine the reciprocal interaction between the elastic properties of the valve and the fluid dynamics. The membrane and the liquid are seen in (Fig. 2 a). The incompressible Navier-Stokes model was used to build the liquid domain of the FSI model, and the dynamic viscosity of water was fixed at 0.001 Pa.s. In contrast, a solid stress-strain model created especially for the PDMS membrane was used to build the solid domain. This model assumed a Young's modulus of 266 kPa and a Poisson's ratio of 0.49 (Locascio and Chemical and Biological Microsystems Society. 2008). The simulation was conducted by gradually increasing the inflow pressure until the membrane came into contact with the wall of the control chamber. The strong non-linear link between the flow rate and the input pressure seen throughout the simulation, as illustrated in (Fig. 2 b), was caused by the self-adaptive resistance change of the valve. Initially, the membrane exhibited a minor deformation as the inlet pressure increased, resulting in a steep slope of the Q(P) curve. Upon reaching a specific threshold value of Pt, the membrane underwent significant deformation, causing it to come into close proximity with the wall of the control chamber. 2.2. Device Design We designed our valve by using software programs. In the beginning, we started with AutoCAD 2023, a leading computer-aided design (CAD) software by using AutoCAD 2023, we created the basic geometry and provided the measurement. After the first step in AutoCAD 2023, we imported our design to SolidWorks 2023 for further refinement, and this step might include adding complex features. The final and crucial step involves simulating the valve performance by using COMSOL Multiphysics 6.0 by this software, we simulate our valve to see how it works under various conditions and get an idea of what the results will be like during the laboratory experiment. (Fig. 3 ) depicts the microfluidic flow-regulating device's schematic structure. The apparatus consisted of two separate components, the membrane and the glass base. We use normal glass, and under liquid pressure, the membrane was very elastic and flexible. The channel has length of 10000 µm, a width of 500 µm, and the height of 100 µm. In addition, we designed two holes for the inlet and outlet. 2.3. Device Fabrication The functional components of the valve were constructed using a multi-layer manufacturing technique. The first part involved fabricating the membrane with PDMS film, and in the second part, we used a piece of glass that was regular and transparent. The membrane was designed by AutoCAD software in 2023 and transferred to the photolithography method to make the mold. After obtaining the mold from the printing machine, we made the channel mixture in order to pour it into the mold, which is PDMS at a ratio of 20/1. After casting, we inserted the mold into an air bubble absorber, then took it out to the furnace at under 80 degrees for 60 minutes, and then we extracted the channel pieces from the mold. We removed any impurities from it using alcohol, then we drilled two holes with a diameter of 2000 µm, one for the liquid to enter and the other for the liquid to exit, and we put it into the oxygen plasma device with a piece of clear glass for three minutes. Then we took them out, immediately integrated the channel with the piece of glass, and inserted them into the furnace again for 20 minutes to adhere well and avoid leakage in the channel. 2.4. Experimental setup As shown in (Fig. 5 ), we set up experimental apparatus to assess the flow rate resultant from the valve in order to explore the flow characteristics of the passive valve. The setup's power source was an air compressor that generated compressed air (CDA) for a pressure controller (OB1 Base MkIII, Elveflow). The output CDA was thereafter regulated by the pressure controller and poured into a sealed reservoir sample; after that, the sample liquid was driven out of the reservoir (deionized water) by gradually increasing the gas pressure within, passing it via a passive valve and a flow sensor in turn (MFS 5, Elveflow). The liquid eventually overflowed the valve and filled a waste reservoir. An electric cable was used to connect the flow sensor to the pressure controller for the purpose of measuring and recording the flow rate. This allowed the pressure controller to continuously receive feedback on flow rate. In addition, the pressure controller was connected to a computer monitor, which allowed the displayer to automatically show the test pressure and flow rate curves in real time. 3. Result and Discussion 3.1. Simulation forward flow rate and membrane deformation As previously mentioned, the deformations of the membrane function as an automatic regulator to manage the rate of flow across the valve. To evaluate the flow characteristics of the valve, we measured the prototype valve's flow rates at various liquid pressures at the intake. I Accordingly, the corresponding effects of various pressures on the flow rates were investigated and the flow variation was computed by determining the bilateral tolerance of the lowest to highest flow by the overall flow rate, where the flow variation is defined as the relative pulsation compared to the average flow rate. The experimental findings indicate that even if the valve solely controlled the steady flow when the pressure exceeded the minimum threshold of 40 kPa, it continued to demonstrate a considerable flow autoregulation capability for the inlet pressures between 40 kPa and 70 kPa. We created and evaluated a membrane-free straight-through device to verify the valve's ability to regulate flow. Throughout the test procedure, the device produced a steadily rising flow rate. 3.2. Characterizing the forward flow under static pressure conditions The system's capacity to sustain steady flow was confirmed by the static tests, which established the range of pressure for the stable flow phase, where average flow rates during pressure changes were 53 μL/min, which was relatively similar to the results of the static pressure tests. First, as indicated in (Fig.7), flow tests were conducted at statistically varying pressures where in the experiment, the valve's incoming liquid pressure was gradually raised by 5 kPa steps, from 5 kPa to 85 kPa. In sixty seconds, the flow rate at every test pressure was determined and noted. We divided the flow rate curve into three stages according to the flow performances brought on by the intake pressures in order to quantitatively investigate the link between the input pressure and the flow rate. During the initial stage, the flow rate was directly proportionate to the inlet pressure, and when the pressure rose from 5 kPa to 40 kPa, it did so gradually, and the flow rate and inlet pressure started to exhibit a notable nonlinear connection when the pressure exceeded 40 kPa. We discovered that the flow rate was becoming regulated in the 40 kPa to 70 kPa pressure stage because it remained almost constant despite pressure changes. To evaluate the valve's performance, we calculated the mean flow rate and the flow variance throughout the previously indicated pressure ranges. The flow rate then started to gradually increase when the intake pressure was raised from 70 kPa to 85 kPa, and it was no longer possible to maintain a steady flow rate during the test phase. During dynamic wave pressures, on the other hand, the standard deviation of the flow rate was 9.8 μL/min, or 18.5% of the total flow, emphasizing the effect of fluctuating pressures on system stability. 3.3. Characterizing the forward flow under dynamic pressure conditions Subsequently, we examined the fluid dynamics of the polymer film valve while subjecting it to dynamically changing pressures. The test pressures were periodically adjusted between 40 kPa and 70 kPa using square-wave modes, where the time periods for trials were 10 seconds and 5 seconds. (Fig. 8 ), displays the prototype valve's flow-regulating capabilities at various intake pressures. The flow rates continue to exhibit satisfactory stabilization, with average values ranging from 53 µL/min to 58 µL/min. In order to quantitatively analyze the flow and determine the increase in flow rate, we computed the ratio of the difference between the lowest and highest average flow rates to the lowest flow rate. Under the static tests, the range of pressure was established for the stable flow phase, where the average flow rates during pressure changes were 53 µL/min, which was fairly similar to the static pressure test results. During dynamic wave pressures, the flow rate's standard deviation was 9.8 µL/min, or 18.5% of the total flow. 3.4. Backward flow rate and simulation Both modeling and experimental investigations have shown that the backward flow rate is of utmost importance in understanding the static and effective properties of fluid systems. Backflow, also known as reverse flow or backward flow, refers to the movement of fluid in the opposite direction of the intended flow channel. Numerical models are used in simulation to evaluate the behavior of fluids, enabling researchers to forecast and optimize reverse flow rates in different conditions. These simulations assist in the design of systems that have enhanced resistance to unwanted backflows, guaranteeing the dependability and safety of fluid systems. In experimental studies, physical sets are used to measure and look at the rates of backward flow, and this provides real-world evidence to support the results of simulations. Accurate characterization of backward flow rates is crucial in diverse situations, and we did that and obtained results about how much flow there was, as (Fig. 9 ) below shows. 4. Conclusion In conclusion, we designed and made a novel passive microfluidic valve to provide steady flow regulation in a microfluidic setting. The valve was made up of two flexible micro holes for the intake and outflow in the membrane, as well as a rectangular control chamber. When pressurized liquid passed through the micro-channel, the membrane would deflect, altering the control chamber's flow resistance and allowing the flow rate to remain constant regardless of the varied inlet pressures. We used photolithography printing methods to create a prototype microvalve and analyzed its flow rates based on the parameters of the intake pressure in order to study the flow performance of the valve. The prototype was able to achieve a practically constant flow rate and good throughput during threshold pressure, according to the experimental results. The device was found to maintain a constant flow rate in the forward mode at pressures between 40 and 70 kPa, where the microfluidic flow regulation device's regulatory feature makes it perfect for small-scale, low-cost microfluidic devices and portable in situ monitoring applications. Declarations Funding: The authors did not receive support from any organization for the submitted work. Author Contribution All this work did by first author (1) References Anjewierden D, Liddiard GA, Gale BK (2012) An electrostatic microvalve for pneumatic control of microfluidic systems. Journal of Micromechanics and Microengineering 22:025019 Au AK, Lai H, Utela BR, Folch A (2011) Microvalves and micropumps for BioMEMS. Micromachines (Basel) 2:179–220 Bazargan V, Stoeber B (2010) Flow control using a thermally actuated microfluidic relay valve. Journal of microelectromechanical systems 19:1079–1087 Chen C-F, Liu J, Chang C-C, DeVoe DL (2009) High-pressure on-chip mechanical valves for thermoplastic microfluidic devices. Lab Chip 9:3511–3516 Cheng C, Nair AR, Thakur R, Fridman G (2018) Normally closed plunger-membrane microvalve self-actuated electrically using a shape memory alloy wire. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5379769","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":375150400,"identity":"8dc096e5-4f68-4012-b1fe-6137553697d8","order_by":0,"name":"Hitham 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structure.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/f18fc2090b186a4ee5a9922a.jpg"},{"id":69806821,"identity":"d43e6940-2c84-43df-bbfa-4a1f58989bc6","added_by":"auto","created_at":"2024-11-25 12:02:16","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":44400,"visible":true,"origin":"","legend":"\u003cp\u003eFabrication steps.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/16f85337173449fdc0bc2efe.jpg"},{"id":69806824,"identity":"b200d302-390a-4808-8c80-8534015f5b58","added_by":"auto","created_at":"2024-11-25 12:02:16","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":33595,"visible":true,"origin":"","legend":"\u003cp\u003eDiagram showing the flow rate experimental setup.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/9763560891f3c47e4e0fa5f8.jpg"},{"id":69806823,"identity":"773fb351-b036-473a-984f-e746fce302dc","added_by":"auto","created_at":"2024-11-25 12:02:16","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":54060,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Membrane deformations at various inlet liquid pressures: \u003cstrong\u003e10 kPa\u003c/strong\u003e,\u003cstrong\u003e 30 kPa\u003c/strong\u003e,\u003cstrong\u003e \u003c/strong\u003eand \u003cstrong\u003e50 kPa.\u003c/strong\u003e \u003cstrong\u003e(b)\u003c/strong\u003e Membrane deformations at various stress levels: \u003cstrong\u003e10 kPa\u003c/strong\u003e,\u003cstrong\u003e 30 kPa\u003c/strong\u003e,\u003cstrong\u003e \u003c/strong\u003eand \u003cstrong\u003e50 kPa.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/8986c832d9f698b0256d90d7.jpg"},{"id":69806828,"identity":"90fe1f97-e87b-4f1d-8d4c-81bf847ffafe","added_by":"auto","created_at":"2024-11-25 12:02:16","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":45477,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Schematic of the flow performances for 20:1 PDMS. \u003cstrong\u003e(b)\u003c/strong\u003e Deflects the membrane under pressure\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/7f8962b64c881b54b55978ac.jpg"},{"id":69806825,"identity":"272e2309-49e3-403c-ba43-82ca8c629294","added_by":"auto","created_at":"2024-11-25 12:02:16","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":84434,"visible":true,"origin":"","legend":"\u003cp\u003eFlow rate under dynamic pressure\u003cstrong\u003e (a)\u003c/strong\u003e At \u003cstrong\u003e5\u003c/strong\u003e seconds. \u003cstrong\u003e(b)\u003c/strong\u003eAt \u003cstrong\u003e10\u003c/strong\u003e seconds.\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/b70be7f2ea73abe66a65199f.jpg"},{"id":69806826,"identity":"6a25be5e-b675-47c4-b0d0-6390623718b4","added_by":"auto","created_at":"2024-11-25 12:02:16","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":48842,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Structural schematic deflects the membrane. \u003cstrong\u003e(b)\u003c/strong\u003e Schematic of the flow performances. \u003cstrong\u003e(c)\u003c/strong\u003e Valve shape in the experiment under flow pressure. \u003cstrong\u003e(d)\u003c/strong\u003e Membrane deformation stress. \u003cstrong\u003e(e)\u003c/strong\u003e Valve shape in the simulation under flow pressure.\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/c9294427ab52720061ef171b.jpg"},{"id":74569700,"identity":"3cb6c18a-c770-45f9-90fd-9d998f722e5b","added_by":"auto","created_at":"2025-01-23 14:09:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":966500,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5379769/v1/6cc20b49-ca5b-4c82-a90f-222ce1d7d63a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Microfluidic Passive Valve Regulator for Controlling Flow Rates","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eBiological cell separation is one of the point-of-care test (POCT) applications for microfluidics, also known as lab-on-a-chip (Zhang et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Murray et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), nucleic acid diagnostics (Kim et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Zhang et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), bacteria detection, etc. (Czilwik et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Houssin et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), often call for mobility, autonomous actuation, and high-throughput processing. Microfluidic POCT systems require a micro-scaled liquid-pushing pumping mechanism that satisfies the system's technical requirements. Nowadays, complicated flow control in pumping units is often achieved by using microvalves, and their usefulness in applications with limited resources is greatly influenced by their actuation mechanism and valve structure. In general, the microvalve's shape needs to be planned for a possible large-scale integration. For convenient actuation, the total force used to regulate the liquid in the microvalve should be kept to a minimum. Additionally, the microvalve should be fully operated on-chip with energy efficiency for mobility and cost-effectiveness. Numerous microvalves possessing on-chip actuation capability have been documented in the literature, especially those with types of elastomeric membranes, which are acknowledged as a fundamental technology for facilitating a range of applications in microfluidic systems (Oh and Ahn \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Au et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). These membrane valves have flexible actuation, are readily fabricated using conventional manufacturing techniques, and may be downsized for use in biological and biochemical microfluidic systems. Three layers make up a typical structural membrane valve a thin elastic membrane, a fluidic channel, and a control channel that may be reversibly deflected to Switch the fluidic channel on or off. to control flow (Unger et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Poly (dimethyl siloxane) (PDMS) is the most widely utilized membrane material because of its strong elasticity for significant deformations and good optical transparency (Whitesides et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). In some circumstances, other materials are also utilized, including shape memory alloy (Cheng et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Guevara-Pantoja et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), glass (Takehara et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), thermal plastic polymer ( Pourmand et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), and more. Numerous processes have been postulated to explain the membrane's deflection, including mechanical (Chen et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Zheng et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), electrostatic (Anjewierden et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Kim et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), pneumatic (Zhang et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Fordyce et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), magnetic (Harper et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Pugliese et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), piezoelectric (Lv et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), and thermal (Bazargan and Stoeber \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Pneumatic actuation appears to be the most often utilized technique among actuation systems. Pneumatically operated active valves frequently make use of off-chip components such air compressors, pressure regulators, etc., to regulate air pressure and accomplish the necessary flow control. Complex microfluidic devices like peristaltic pumps (Anjewierden et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Cheng et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and mixers (Zhang et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Can be created by combining several valves. Still, the active technology can be deemed too much for a portable, low-cost microfluidic system that demands full on-chip activation, like in POCT applications. A passive valve, in contrast to an active valve, adjusts the flow resistance on its own to control the liquid flow rate without the need for additional power. Furthermore, the valve with a preset threshold pressure may achieve a constant flow rate because it can realize self-adaptive resistance fluctuations that fully compensate the fluidic pressure variations (Zhang et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Zhang and Zhang \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). A silicon membrane valve for medicine administration was created by (Cousseau et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). The valve was made out of a bottom layer with a spiral channel, a silicon membrane, and a glass cover. Between 20 and 50 kPa of working pressure, the valve kept the liquid flow rate constant at 0.022 mL/min. A PDMS press-up valve with a fluidic channel and membrane, and a detour control channel was suggested by (Kartalov et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). 0.033 mL/min was the steady flow rate that the valve maintained, and the threshold pressure required to attain the flow rate was 103 kPa. In order to create a confined fluid channel in a planar check valve, Yang et al. devised a stiff stopper and a compliant flap, The valve had a threshold pressure of 100 kPa and generated a high flow rate of 1.2 mL/min. (Yang and Lin \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Proposed the use of a parallel membrane valve to build a passive low threshold pressure valve with two vertical membranes, two control channels, and a fluidic channel (Doh and Cho \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). At pressures as low as 15 kPa, the valve was able to control the flow of liquid in the fluidic channel by the independent deflection of both membranes.\u003c/p\u003e \u003cp\u003eIn this work, we created a novel passive microfluidic valve that will better regulate the flow rate performance of passive microfluidic valves. In addition, the presented microfluidic passive valve offers a promising solution for achieving precise and controllable fluidic manipulations in miniaturized analytical systems. Its simple design, ease of fabrication, and reliable operation make it a valuable component for advancing the capabilities of lab-on-a-chip devices, contributing to the ongoing progress in microfluidics and point of care diagnostics.\u003c/p\u003e"},{"header":"2. Materials and Method","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. The Device's Working Principle\u003c/h2\u003e \u003cp\u003eAn elastic membrane, a liquid chamber, and a control chamber component of the valve. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea) displays the proposed passive valve concept's structural schematic. The membrane will deform towards the control chamber in response to liquid pressure in order to regulate the rate of output flow. The control chamber features a rectangular surface with four angles for liquid to flow through. The flow resistance of the valve increases when the inlet liquid pressure is raised to deflect the membrane, as shown in (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), because the membrane deforms and reduces the volume of the control chamber. The main equation for flow rate of valve is:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\varvec{Q}=\\frac{\\varvec{P}}{\\varvec{R}}=\\frac{\\varvec{P}+\\varDelta\\:\\varvec{P}}{\\varvec{R}+\\varDelta\\:\\varvec{R}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003eQ\u003c/b\u003e In fluid dynamics, this is usually used to describe the flow rate, which is the volume of fluid flowing per unit time. where the valve's initial flow resistance is \u003cb\u003eR\u003c/b\u003e, the resistance increment is \u003cb\u003eΔR\u003c/b\u003e, the initial inlet pressure is \u003cb\u003eP\u003c/b\u003e, and the pressure gradient is \u003cb\u003eΔP\u003c/b\u003e. According to Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), the resistance increase \u003cb\u003eΔR\u003c/b\u003e automatically adjusts for the pressure modify \u003cb\u003eΔP\u003c/b\u003e when the input pressure rises above a certain threshold.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe performed numerical research on the valve using the Fluid-Structure Interaction (FSI) module in COMSOL Multiphysics\u0026reg; (Version 6.0, COMSOL Inc., Stockholm, Sweden), based on the previously mentioned idea. This module enabled us to examine the reciprocal interaction between the elastic properties of the valve and the fluid dynamics. The membrane and the liquid are seen in (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). The incompressible Navier-Stokes model was used to build the liquid domain of the FSI model, and the dynamic viscosity of water was fixed at 0.001 Pa.s. In contrast, a solid stress-strain model created especially for the PDMS membrane was used to build the solid domain. This model assumed a Young's modulus of 266 kPa and a Poisson's ratio of 0.49 (Locascio and Chemical and Biological Microsystems Society. 2008). The simulation was conducted by gradually increasing the inflow pressure until the membrane came into contact with the wall of the control chamber. The strong non-linear link between the flow rate and the input pressure seen throughout the simulation, as illustrated in (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb), was caused by the self-adaptive resistance change of the valve. Initially, the membrane exhibited a minor deformation as the inlet pressure increased, resulting in a steep slope of the Q(P) curve. Upon reaching a specific threshold value of Pt, the membrane underwent significant deformation, causing it to come into close proximity with the wall of the control chamber.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Device Design\u003c/h2\u003e \u003cp\u003eWe designed our valve by using software programs. In the beginning, we started with AutoCAD 2023, a leading computer-aided design (CAD) software by using AutoCAD 2023, we created the basic geometry and provided the measurement. After the first step in AutoCAD 2023, we imported our design to SolidWorks 2023 for further refinement, and this step might include adding complex features. The final and crucial step involves simulating the valve performance by using COMSOL Multiphysics 6.0 by this software, we simulate our valve to see how it works under various conditions and get an idea of what the results will be like during the laboratory experiment. (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) depicts the microfluidic flow-regulating device's schematic structure. The apparatus consisted of two separate components, the membrane and the glass base. We use normal glass, and under liquid pressure, the membrane was very elastic and flexible. The channel has length of 10000 \u0026micro;m, a width of 500 \u0026micro;m, and the height of 100 \u0026micro;m. In addition, we designed two holes for the inlet and outlet.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Device Fabrication\u003c/h2\u003e \u003cp\u003eThe functional components of the valve were constructed using a multi-layer manufacturing technique. The first part involved fabricating the membrane with PDMS film, and in the second part, we used a piece of glass that was regular and transparent. The membrane was designed by AutoCAD software in 2023 and transferred to the photolithography method to make the mold. After obtaining the mold from the printing machine, we made the channel mixture in order to pour it into the mold, which is PDMS at a ratio of 20/1. After casting, we inserted the mold into an air bubble absorber, then took it out to the furnace at under 80 degrees for 60 minutes, and then we extracted the channel pieces from the mold. We removed any impurities from it using alcohol, then we drilled two holes with a diameter of 2000 \u0026micro;m, one for the liquid to enter and the other for the liquid to exit, and we put it into the oxygen plasma device with a piece of clear glass for three minutes. Then we took them out, immediately integrated the channel with the piece of glass, and inserted them into the furnace again for 20 minutes to adhere well and avoid leakage in the channel.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Experimental setup\u003c/h2\u003e \u003cp\u003eAs shown in (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), we set up experimental apparatus to assess the flow rate resultant from the valve in order to explore the flow characteristics of the passive valve. The setup's power source was an air compressor that generated compressed air (CDA) for a pressure controller (OB1 Base MkIII, Elveflow). The output CDA was thereafter regulated by the pressure controller and poured into a sealed reservoir sample; after that, the sample liquid was driven out of the reservoir (deionized water) by gradually increasing the gas pressure within, passing it via a passive valve and a flow sensor in turn (MFS 5, Elveflow). The liquid eventually overflowed the valve and filled a waste reservoir.\u003c/p\u003e \u003cp\u003eAn electric cable was used to connect the flow sensor to the pressure controller for the purpose of measuring and recording the flow rate. This allowed the pressure controller to continuously receive feedback on flow rate. In addition, the pressure controller was connected to a computer monitor, which allowed the displayer to automatically show the test pressure and flow rate curves in real time.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"3. Result and Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Simulation forward flow rate and membrane deformation\u003c/h2\u003e \u003cp\u003eAs previously mentioned, the deformations of the membrane function as an automatic regulator to manage the rate of flow across the valve. To evaluate the flow characteristics of the valve, we measured the prototype valve's flow rates at various liquid pressures at the intake. I Accordingly, the corresponding effects of various pressures on the flow rates were investigated and the flow variation was computed by determining the bilateral tolerance of the lowest to highest flow by the overall flow rate, where the flow variation is defined as the relative pulsation compared to the average flow rate. The experimental findings indicate that even if the valve solely controlled the steady flow when the pressure exceeded the minimum threshold of 40 kPa, it continued to demonstrate a considerable flow autoregulation capability for the inlet pressures between 40 kPa and 70 kPa. We created and evaluated a membrane-free straight-through device to verify the valve's ability to regulate flow. Throughout the test procedure, the device produced a steadily rising flow rate.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Characterizing the forward flow under static pressure conditions\u003c/h2\u003e \u003cp\u003eThe system\u0026apos;s capacity to sustain steady flow was confirmed by the static tests, which established the range of pressure for the stable flow phase, where average flow rates during pressure changes were 53 \u0026mu;L/min, which was relatively similar to the results of the static pressure tests. First, as indicated in (Fig.7), flow tests were conducted at statistically varying pressures where in the experiment, the valve\u0026apos;s incoming liquid pressure was gradually raised by 5 kPa steps, from 5 kPa to 85 kPa. In sixty seconds, the flow rate at every test pressure was determined and noted. We divided the flow rate curve into three stages according to the flow performances brought on by the intake pressures in order to quantitatively investigate the link between the input pressure and the flow rate. During the initial stage, the flow rate was directly proportionate to the inlet pressure, and when the pressure rose from 5 kPa to 40 kPa, it did so gradually, and the flow rate and inlet pressure started to exhibit a notable nonlinear connection when the pressure exceeded 40 kPa. We discovered that the flow rate was becoming regulated in the 40 kPa to 70 kPa pressure stage because it remained almost constant despite pressure changes. To evaluate the valve\u0026apos;s performance, we calculated the mean flow rate and the flow variance throughout the previously indicated pressure ranges. The flow rate then started to gradually increase when the intake pressure was raised from 70 kPa to 85 kPa, and it was no longer possible to maintain a steady flow rate during the test phase. During dynamic wave pressures, on the other hand, the standard deviation of the flow rate was 9.8 \u0026mu;L/min, or 18.5% of the total flow, emphasizing the effect of fluctuating pressures on system stability.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Characterizing the forward flow under dynamic pressure conditions\u003c/h2\u003e \u003cp\u003eSubsequently, we examined the fluid dynamics of the polymer film valve while subjecting it to dynamically changing pressures. The test pressures were periodically adjusted between 40 kPa and 70 kPa using square-wave modes, where the time periods for trials were 10 seconds and 5 seconds. (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e), displays the prototype valve's flow-regulating capabilities at various intake pressures. The flow rates continue to exhibit satisfactory stabilization, with average values ranging from 53 \u0026micro;L/min to 58 \u0026micro;L/min. In order to quantitatively analyze the flow and determine the increase in flow rate, we computed the ratio of the difference between the lowest and highest average flow rates to the lowest flow rate. Under the static tests, the range of pressure was established for the stable flow phase, where the average flow rates during pressure changes were 53 \u0026micro;L/min, which was fairly similar to the static pressure test results. During dynamic wave pressures, the flow rate's standard deviation was 9.8 \u0026micro;L/min, or 18.5% of the total flow.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Backward flow rate and simulation\u003c/h2\u003e \u003cp\u003eBoth modeling and experimental investigations have shown that the backward flow rate is of utmost importance in understanding the static and effective properties of fluid systems. Backflow, also known as reverse flow or backward flow, refers to the movement of fluid in the opposite direction of the intended flow channel. Numerical models are used in simulation to evaluate the behavior of fluids, enabling researchers to forecast and optimize reverse flow rates in different conditions. These simulations assist in the design of systems that have enhanced resistance to unwanted backflows, guaranteeing the dependability and safety of fluid systems. In experimental studies, physical sets are used to measure and look at the rates of backward flow, and this provides real-world evidence to support the results of simulations. Accurate characterization of backward flow rates is crucial in diverse situations, and we did that and obtained results about how much flow there was, as (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e) below shows.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eIn conclusion, we designed and made a novel passive microfluidic valve to provide steady flow regulation in a microfluidic setting. The valve was made up of two flexible micro holes for the intake and outflow in the membrane, as well as a rectangular control chamber. When pressurized liquid passed through the micro-channel, the membrane would deflect, altering the control chamber's flow resistance and allowing the flow rate to remain constant regardless of the varied inlet pressures. We used photolithography printing methods to create a prototype microvalve and analyzed its flow rates based on the parameters of the intake pressure in order to study the flow performance of the valve. The prototype was able to achieve a practically constant flow rate and good throughput during threshold pressure, according to the experimental results. The device was found to maintain a constant flow rate in the forward mode at pressures between 40 and 70 kPa, where the microfluidic flow regulation device's regulatory feature makes it perfect for small-scale, low-cost microfluidic devices and portable in situ monitoring applications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThe authors did not receive support from any organization for the submitted work.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll this work did by first author (1)\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAnjewierden D, Liddiard GA, Gale BK (2012) An electrostatic microvalve for pneumatic control of microfluidic systems. Journal of Micromechanics and Microengineering 22:025019\u003c/li\u003e\n\u003cli\u003eAu AK, Lai H, Utela BR, Folch A (2011) Microvalves and micropumps for BioMEMS. 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Lab Chip 18:662\u0026ndash;669\u003c/li\u003e\n\u003cli\u003eHarper JC, Andrews JM, Ben C, et al (2016) Magnetic-adhesive based valves for microfluidic devices used in low-resource settings. Lab Chip 16:4142\u0026ndash;4151\u003c/li\u003e\n\u003cli\u003eHoussin T, Cramer J, Grojsman R, et al (2016) Ultrafast, sensitive and large-volume on-chip real-time PCR for the molecular diagnosis of bacterial and viral infections. Lab Chip 16:1401\u0026ndash;1411\u003c/li\u003e\n\u003cli\u003eKartalov EP, Walker C, Taylor CR, et al (2006) Microfluidic vias enable nested bioarrays and autoregulatory devices in Newtonian fluids. Proceedings of the National Academy of Sciences 103:12280\u0026ndash;12284\u003c/li\u003e\n\u003cli\u003eKim H, Astle AA, Najafi K, et al (2014) An integrated electrostatic peristaltic 18-stage gas micropump with active microvalves. 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Lab Chip 9:469\u0026ndash;472\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Passive valve, Microfluidic, Flow rate, Pressure","lastPublishedDoi":"10.21203/rs.3.rs-5379769/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5379769/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn microfluidic applications where cost effectiveness and miniaturization are key, the use of passive microvalve offers significant benefits. This study introduces an innovative passive microfluidic valve design comprising a fluid chamber, a flexible membrane, and a rectangular control chamber, enabling effective flow rate management at exceptionally pressures. The model was created using the 3D photolithography method, and the passive microvalve was evaluated under pressure circumstances that are both constant and time-dependent. In the experiment, the microfluidic passive valve demonstrated a constant flow rate when the pressure ranged from 40 kPa to 70 kPa. This regulator can achieve a consistent delivery flow rate of up to 53\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u0026micro;L/min with deviations under 4.5%, as demonstrated by the testing outcomes. Furthermore, the microfluidic passive valve has demonstrated the capability to maintain a stable liquid flow rate under fluctuating conditions, specifically under square wave pressure variations over time. The suggested microfluidic passive valve device may be used in portable, low-cost Lab-on-a-Chip (LoC) applications to precisely control flow. We anticipate this innovative passive microfluidic valve will work well for regulating fluid flow in systems with broader applications or portable microfluidic devices.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e","manuscriptTitle":"Microfluidic Passive Valve Regulator for Controlling Flow Rates","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-25 12:02:11","doi":"10.21203/rs.3.rs-5379769/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4dff048d-d535-4544-bbdb-f72f6a190c5f","owner":[],"postedDate":"November 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-01-23T14:09:00+00:00","versionOfRecord":[],"versionCreatedAt":"2024-11-25 12:02:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5379769","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5379769","identity":"rs-5379769","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}