Manufacturing Of Microfluidic Devices Research Articles

The Importance of Dimensional Traceability in Microfluidic Systems

Dimensional measurements are fundamental in microfluidic device manufacturing and performance. The main focus of this study is the measurement of the connection port sizes in microfluidic devices and components and, accordingly, the possible existence of fluid leaks determined using the flow rate error. The sizes associated with three different microfluidic systems were determined using laser interferometry and through an optical measuring instrument, with metrological traceability to national length standards. It was possible to infer the method with the greatest accuracy and lowest measurement uncertainty for characterizing this kind of system. In conclusion, the results of this work directly address the current lack of dimensions measuring methods of microfluidic components by providing a comprehensive comparison of different protocols, ultimately suggesting a preferred option for immediate application within the microfluidic industry.

Evolution of 3d printing technology in fabrication of microfluidic devices and biological applications: a comprehensive review

Lab-on-a-chip or LOC is a term that is used to describe microfluidic devices that integrate multiple analyte detection, which are normally carried out in a laboratory, into one micro-chip unit and may have applications in diverse fields such as electronics, medicine and biomedical domains. Even though microfluidics has advanced greatly during the past decade due to increased needs for portability, reduced sample requirement and multiple analyte detection capabilities biological research has not adopted the technology at the required pace. This may be owing to the time-consuming and expensive process involved in the microfabrication of biochips, the requirement of specialised setup facilities and the extremely high cost associated with microfluidics as compared to conventional technologies. In recent years, three-dimensional (3D) printing has piqued curiosity in the scientific community. It has the potential to create complex, high-resolution structures and that too in a short timeframe depending upon device complexity. This could inspire progressive research in microfluidics, particularly finding applications in biomedical engineering and point-of-care diagnostics. This article gives an overview of how 3D printing aids in the manufacture of microfluidic devices for biological applications, as well as the existing 3D printing methods which are utilised for fabrication and the future perspective in the development of microfluidic devices.

Features of Vat-Photopolymerized Masters for Microfluidic Device Manufacturing.

The growing interest in advancing microfluidic devices for manipulating fluids within micrometer-scale channels has prompted a shift in manufacturing practices, moving from single-component production to medium-size batches. This transition arises due to the impracticality of lab-scale manufacturing methods in accommodating the increased demand. This experimental study focuses on the design of master benchmarks 1-5, taking into consideration critical parameters such as rib width, height, and the relative width-to-height ratio. Notably, benchmarks 4 and 5 featured ribs that were strategically connected to the inlet, outlet, and reaction chamber of the master, enhancing their utility for subsequent replica production. Vat photopolymerization was employed for the fabrication of benchmarks 1-5, while replicas of benchmarks 4 and 5 were generated through polydimethylsiloxane casting. Dimensional investigations of the ribs and channels in both the master benchmarks and replicas were conducted using an optical technique validated through readability analysis based on the Michelson global contrast index. The primary goal was to evaluate the potential applicability of vat photopolymerization technology for efficiently producing microfluidic devices through a streamlined production process. Results indicate that the combination of vat photopolymerization followed by replication is well suited for achieving a minimum rib size of 25 µm in width and an aspect ratio of 1:12 for the master benchmark.

Determination of Suitable Geometrical Ranges for the Manufacture of Microfluidic Channels by Low-Cost Additive Manufacturing Techniques

Additive manufacturing of microfluidic devices is a field of increasing interest due to the great variety of fields where they can be used, especially in physicochemical, biological and medical ones. These devices include internal channels whose manufacture can be challenging as it takes place close to or into the micro geometric scale. On the other hand, the use of low-cost techniques can provide access to certain services in depopulated areas in different fields, so this approach can be of interest in the development of new products under new production and living contexts. In this work, the geometrical ranges of practical application for the manufacture of microfluidic channels by two of the most common additive manufacturing techniques for polymeric materials (Fused Filament Fabrication and the Stereolithography) are analyzed by means of an evaluation of the dimensional accuracy obtained in samples with channels of circular section. The circular channels present diameters that vary from 2 mm to the minimal size feasible which each printer (a Markforged Onyx One, a Ultimaker S5 and a Formlabs Form3). The Ultimaker S5 (FFF) equipment is the one that presents the best results, being the dimensional deviations around 0.2 mm in a wide range 1 < dnom (mm) < 2; and contrary to the expectations, the SLA system provides the worst results, with a growing trend starting from deviations of 0.6 mm. An obturation effect in the channels has been also detected, being critical in the case of nominal diameters lower than 0.8 mm for the Ultimaker S5 system. In general, it can be concluded that the FFF technology is a more reliable option compared to SLA under the printing parameters considered in this work and for the materials used in this study.

Cell Patterning Technology on Polymethyl Methacrylate through Controlled Physicochemical and Biochemical Functionalization.

In recent years, innovative cell-based biosensing systems have been developed, showing impact in healthcare and life science research. Now, there is a need to design mass-production processes to enable their commercialization and reach society. However, current protocols for their fabrication employ materials that are not optimal for industrial production, and their preparation requires several chemical coating steps, resulting in cumbersome protocols. We have developed a simplified two-step method for generating controlled cell patterns on PMMA, a durable and transparent material frequently employed in the mass manufacturing of microfluidic devices. It involves air plasma and microcontact printing. This approach allows the formation of well-defined cell arrays on PMMA without the need for blocking agents to define the patterns. Patterns of various adherent cell types in dozens of individual cell cultures, allowing the regulation of cell-material and cell-cell interactions, were developed. These cell patterns were integrated into a microfluidic device, and their viability for more than 20 h under controlled flow conditions was demonstrated. This work demonstrated the potential to adapt polymeric cytophobic materials to simple fabrication protocols of cell-based microsystems, leveraging the possibilities for commercialization.

Comparison between Injection Molding (IM) and Injection‐Compression Molding (ICM) for Mass Manufacturing of Thermoplastic Microfluidic Devices

AbstractPoint‐of‐care (PoC) and organ‐on‐chip (OoC) devices represent promising microfluidic applications for in vitro analysis and miniaturized analytical studies, reducing the need for traditional animal‐based tests for drug discovery and toxicity studies. Using thermoplastics in microfluidic device manufacturing provides interesting functionalities for expansion of these devices into market. However, market growth requires manufacturing large quantities for low cost, which can be achieved using injection molding techniques. This work involves the design of a microfluidic device with different aspect ratio channels to compare injection molding (IM) and injection‐compression molding (ICM) processes, as well as the design and manufacturing of a metallic insert containing machined inverted microstructures. Injected parts are validated visually, dimensionally, and functionally. The differences between both techniques and two grades of cyclic olefin copolymer materials are analyzed to evaluate microfluidic device mass production feasibility concluding that although the machining process for inverted high aspect ratio microstructures is not mature yet, both IM and ICM processes allow the mass manufacturing of microfluidic devices in thermoplastic. Parts processed by ICM show better replicability of microfluidic structures and less internal stresses generate during the injection process than IM parts, highlighting the potential of this process to achieve thermoplastic microfluidic devices to market.

Aryl-diazonium salts offer a rapid and cost-efficient method to functionalize plastic microfluidic devices for increased immunoaffinity capture.

Microfluidic devices have been used for decades to isolate cells, viruses, and proteins using on-chip immunoaffinity capture using biotinylated antibodies, proteins, or aptamers. To accomplish this, the inner surface is modified to present binding moieties for the desired analyte. While this approach has been successful in research settings, it is challenging to scale many surface modification strategies. Traditional polydimethylsiloxane (PDMS) devices can be effectively functionalized using silane-based methods; however, it requires high labor hours, cleanroom equipment, and hazardous chemicals. Manufacture of microfluidic devices using plastics, including cyclic olefin copolymer (COC), allows chips to be mass produced, but most functionalization methods used with PDMS are not compatible with plastic. Here we demonstrate how to deposit biotin onto the surface of a plastic microfluidic chips using aryl-diazonium. This method chemically bonds biotin to the surface, allowing for the addition of streptavidin nanoparticles to the surface. Nanoparticles increase the surface area of the chip and allow for proper capture moiety orientation. Our process is faster, can be performed outside of a fume hood, is very cost-effective using readily available laboratory equipment, and demonstrates higher rates of capture. Additionally, our method allows for more rapid and scalable production of devices, including for diagnostic testing.

Fabrication of low-cost MEMS microfluidic devices using metal embossing technique on glass for lab-on-chip applications

This paper discusses a low-cost technology for the fabrication of microfluidic devices on glass substrate using metal embossing technique. The fabrication technique demonstrated is a much simpler approach of embossing on glass using thermo-compression process with a patterned metal layer to define device structure. Well established printed circuit board fabrication photo-process is used to realize the desired planar geometry on metal layer deposited over a glass substrate. The depth of the channel is defined by the thickness of the metal deposited by electro-plating. The embossing technology offers a relatively safer approach conducive to batch processing to enable repeatable, high-yield, low-cost devices fabricated using low-cost equipment. Major challenges of achieving adhesion of the deposited thick nickel layer without peel-off and control of the thermo-compression process to achieve reliable and repeatable embossing without structural distortions were addressed. To prove its suitability for manufacturing, experiments were carried out with full wafer of 6″ × 6″ square glass wafer and optimal process steps for low-cost microfluidic device manufacturing have been well established.

Sustainable mold biomachining for the manufacturing of microfluidic devices

Biomachining has been investigated as a sustainable and effective alternative to conventional prototyping techniques for molding polymeric materials for their subsequent use as microfluidic devices. A novel and simple process based on the combination of a Pressure Sensitive Adhesive mask and a varnish has been proposed for preparing metal workpieces as an alternative to photolithography, with the latter being the most widely used technique for protecting workpieces. As far as the bioprocess is concerned, it has been applied in successive mold-etching and oxidant bio-regeneration stages. Metal solubilization has proven to be repeatable in several consecutive mold-etching stages when using the regenerated oxidant solution. As a result, the lifespan of the biomachining medium has been prolonged, contributing to process sustainability. An equation with two restrictions has been proposed to predict the time required to obtain a mold with a fixed height, as metal solubilization evolves differently between the first and subsequent hours. Finally, the bio-engraved copper pieces have acted as effective molds in the fabrication of self-powered polydimethylsiloxane microfluidic devices. This new biomachining application is therefore an effective and ecofriendly process for producing microfluidic devices.

A Simple Method To Modify The PDMS Surface Wettability For Biomicrofluidic Applications

Polydimethylsiloxane (PDMS) is one of the most used materials for the manufacture of microfluidic devices. Recent studies have combined microfluidic devices and cell cultures to originate a new group of devices, the organs-on-achip (OoC). These devices replicate the microphysiological features that can be found in the human body so that healthy and pathological conditions can be easily studied. PDMS is also one of the materials of choice for the manufacture of the OoC, due to its mechanical and chemical properties, and due to the fact that is a biocompatible and inert material. However, the hydrophobic behavior of PDMS leads to the adsorption of unspecific molecules, hinders cell culture attachment and growth, and decreases the specificity of certain biochemical tests. Additionally, the hydrophobicity of microchannels walls of microfluidic devices difficult the fluid flow, making necessary the use of external sources for the flow control, such as syringe pumps. A common strategy to improve the wettability of the PDMS surface is to apply oxygen plasma. However, the effects of this technique only last a few hours. Another strategy is to alter the bulk of PDMS during manufacture by adding components such as surfactants. In this work, different compounds were combined with PDMS in concentrations of 1 and 2 wt.%. The changes in the wettability were verified on the day of sample manufacturing and one week later. Since the optical properties of PDMS can be important for some microfluidic studies, the changes in the transparency of the samples were also evaluated by measuring the respective transmittance spectrum. The results showed that two tested surfactants can improve the wettability of the PDMS surface to a hydrophilic behavior remaining for at least one week after fabrication. The transparency of the PDMS shows to be affected by one of those two surfactants while the other only led to a small decrease when used the higher concentration.

Role of microfluidics in accelerating new space missions.

Numerous revolutionary space missions have been initiated and planned for the following decades, including plans for novel spacecraft, exploration of the deep universe, and long duration manned space trips. Compared with space missions conducted over the past 50 years, current missions have features of spacecraft miniaturization, a faster task cycle, farther destinations, braver goals, and higher levels of precision. Tasks are becoming technically more complex and challenging, but also more accessible via commercial space activities. Remarkably, microfluidics has proven impactful in newly conceived space missions. In this review, we focus on recent advances in space microfluidic technologies and their impact on the state-of-the-art space missions. We discuss how micro-sized fluid and microfluidic instruments behave in space conditions, based on hydrodynamic theories. We draw on analyses outlining the reasons why microfluidic components and operations have become crucial in recent missions by categorically investigating a series of successful space missions integrated with microfluidic technologies. We present a comprehensive technical analysis on the recently developed in-space microfluidic applications such as the lab-on-a-CubeSat, healthcare for manned space missions, evaluation and reconstruction of the environment on celestial bodies, in-space manufacturing of microfluidic devices, and development of fluid-based micro-thrusters. The discussions in this review provide insights on microfluidic technologies that hold considerable promise for the upcoming space missions, and also outline how in-space conditions present a new perspective to the microfluidics field.

Overcoming the limitations of COVID-19 diagnostics with nanostructures, nucleic acid engineering, and additive manufacturing

The COVID-19 pandemic revealed fundamental limitations in the current model for infectious disease diagnosis and serology, based upon complex assay workflows, laboratory-based instrumentation, and expensive materials for managing samples and reagents. The lengthy time delays required to obtain test results, the high cost of gold-standard PCR tests, and poor sensitivity of rapid point-of-care tests contributed directly to society’s inability to efficiently identify COVID-19-positive individuals for quarantine, which in turn continues to impact return to normal activities throughout the economy. Over the past year, enormous resources have been invested to develop more effective rapid tests and laboratory tests with greater throughput, yet the vast majority of engineering and chemistry approaches are merely incremental improvements to existing methods for nucleic acid amplification, lateral flow test strips, and enzymatic amplification assays for protein-based biomarkers. Meanwhile, widespread commercial availability of new test kits continues to be hampered by the cost and time required to develop single-use disposable microfluidic plastic cartridges manufactured by injection molding. Through development of novel technologies for sensitive, selective, rapid, and robust viral detection and more efficient approaches for scalable manufacturing of microfluidic devices, we can be much better prepared for future management of infectious pathogen outbreaks. Here, we describe how photonic metamaterials, graphene nanomaterials, designer DNA nanostructures, and polymers amenable to scalable additive manufacturing are being applied towards overcoming the fundamental limitations of currently dominant COVID-19 diagnostic approaches. In this paper, we review how several distinct classes of nanomaterials and nanochemistry enable simple assay workflows, high sensitivity, inexpensive instrumentation, point-of-care sample-to-answer virus diagnosis, and rapidly scaled manufacturing.

Manufacturing of Microfluidic Devices with Interchangeable Commercial Fiber Optic Sensors.

In situ measurements are highly desirable in many microfluidic applications because they enable real-time, local monitoring of physical and chemical parameters, providing valuable insight into microscopic events and processes that occur in microfluidic devices. Unfortunately, the manufacturing of microfluidic devices with integrated sensors can be time-consuming, expensive, and “know-how” demanding. In this article, we describe an easy-to-implement method developed to integrate various “off-the-shelf” fiber optic sensors within microfluidic devices. To demonstrate this, we used commercial pH and pressure sensors (“pH SensorPlugs” and “FOP-MIV”, respectively), which were “reversibly” attached to a glass microfluidic device using custom 3D-printed connectors. The microfluidic device, which serves here as a demonstrator, incorporates a uniform porous structure and was manufactured using a picosecond pulsed laser. The sensors were attached to the inlet and outlet channels of the microfluidic pattern to perform simple experiments, the aim of which was to evaluate the performance of both the connectors and the sensors in a practical microfluidic environment. The bespoke connectors ensured robust and watertight connection, allowing the sensors to be safely disconnected if necessary, without damaging the microfluidic device. The pH SensorPlugs were tested with a pH 7.01 buffer solution. They measured the correct pH values with an accuracy of ±0.05 pH once sufficient contact between the injected fluid and the measuring element (optode) was established. In turn, the FOP-MIV sensors were used to measure local pressure in the inlet and outlet channels during injection and the steady flow of deionized water at different rates. These sensors were calibrated up to 140 mbar and provided pressure measurements with an uncertainty that was less than ±1.5 mbar. Readouts at a rate of 4 Hz allowed us to observe dynamic pressure changes in the device during the displacement of air by water. In the case of steady flow of water, the pressure difference between the two measuring points increased linearly with increasing flow rate, complying with Darcy’s law for incompressible fluids. These data can be used to determine the permeability of the porous structure within the device.

Portable Pathogen Diagnostics Using Microfluidic Cartridges Made from Continuous Liquid Interface Production Additive Manufacturing.

Biomedical diagnostics based on microfluidic devices have the potential to significantly benefit human health; however, the manufacturing of microfluidic devices is a key limitation to their widespread adoption. Outbreaks of infectious disease continue to demonstrate the need for simple, sensitive, and translatable tests for point-of-care use. Additive manufacturing (AM) is an attractive alternative to conventional approaches for microfluidic device manufacturing based on injection molding; however, there is a need for development and validation of new AM process capabilities and materials that are compatible with microfluidic diagnostics. In this paper, we demonstrate the development and characterization of AM cartridges using continuous liquid interface production (CLIP) and investigate process characteristics and capabilities of the AM microfluidic device manufacturing. We find that CLIP accurately produces microfluidic channels as small as 400 μm and that it is possible to routinely produce fluid channels as small as 100 μm with high repeatability. We also developed a loop-mediated isothermal amplification (LAMP) assay for detection of E. coli from whole blood directly on the CLIP-based AM microfluidic cartridges, with a 50 cfu/μL limit of detection, validating the use of CLIP processes and materials for pathogen detection. The portable diagnostic platform presented in this paper could be used to investigate and validate other AM processes for microfluidic diagnostics and could be an important component of scaling up the diagnostics for current and future infectious diseases and pandemics.

Surface activation of poly(methyl methacrylate) for microfluidic device bonding through a H2O plasma treatment linked with a low-temperature annealing

This paper reports on a rapid, lossless process for the bonding of poly(methyl methacrylate) (PMMA) substrates for use in microfluidic devices for blood tests, utilizing H2O plasma, and H2O linked rapid thermal annealing (RTA) treatments. The bonding of PMMA produced with H2O plasma linked with RTA was analyzed, and its effect on the bonding of free radicals was investigated. The PMMA surface treatment was performed at constant RF power and H2O vapor flow but changing plasma treatment times in both processes. The surface modification of the PMMA subjected to the H2O plasma treatment was studied by optical emission spectroscopy, which confirmed that the relative intensity of hydroxyl radicals and oxygen emission peaks. The surface of the PMMA after being subjected to the plasma linked with RTA treatment was also characterized. The free energy increased with the plasma treatment time. The tensile test results revealed that the strength of OH bonds on the PMMA surface increased with a high plasma treatment time of 120 s. After bonding, UV–visible transmission spectrum measurements revealed that the transparency of the microfluidic device increased. We demonstrated the bonding of a microfluidic device with plasma treatment without deformation. This method provides an ideal bonding technique for the manufacture of microfluidic devices with PMMA. This technique has more advantages than other bonding techniques.

Adhesive wafer bonding for CMOS based lab-on-a-chip devices

Adhesive wafer bonding using laminated photosensitive dry-resist offers many advantages and can be used to realize advanced, CMOS integrated, lab-on-a-chip devices. The low bond-temperatures involved allow the hybrid integration of a range of substrates, e.g. CMOS wafers with structured MEMS glass wafers. The dry-film polymer functions as an adhesive interlayer and can be lithographically patterned to form sealed microfluidic fluid channels and chambers. This approach is well suited for low-cost R&D prototyping, and efforts reported in the past were often limited to proof-of-concept devices. However, all of the involved process steps do have the potential to be scaled up for an industrial volume production. We report on our activities to implement a baseline 8″ process flow, using the ORDYL SY300 series of permanent dry-film resist, to enable the commercial manufacturing of microfluidic devices based on this technology at a MEMS foundry. Advantages and disadvantages of the presented approach are discussed.

Fabrication of wavy micromixer using soft lithography technique

Microfluidic devices are enormously used in different engineering applications such as biological, chemical, electronics, mechanical, etc. Manufacturing of microfluidic devices becomes one of the emerging areas of research in the current times. Manufacturing of microfluidic devices is a challenging issue via general fabrication technologies. Several types of materials and methods are in use for fabricating microfluidic devices for different kinds of uses. Micromixer is an essential component to integrate any microfluidic device. In this paper, a fast process for the fabricating of micromixer with poly-di-methyl-siloxane (PDMS) is presented and elaborated. Two types of wavy micromixers, namely raccoon, and serpentine are fabricated. The complete fabrication process of the micromixer has been conducted with major two steps, namely, mold preparation, and fabrication. Initially, the mold of the micromixer of raccoon, and serpentine type with proper dimensions is produced using CO2 assisted laser machining on poly-methyl-meth-acrylate (PMMA), and then using these molds, micromixer of PDMS is prepared by soft lithography technique. Micromixer with accurate and precious dimensions as per the required design can be fabricated using the proposed process for different purposes. This article may be helpful for the researchers to get the proper knowledge related to the fabrication of wavy micromixer in a fast and cost-effective way.

Разработка практикума по микрофлюидике для англоязычного модуля «Smart Materials»

The article is devoted to the analysis of development and testing of experimental practicums for foreign students based on modern techniques. It is of special importance for programs in chemical engineering and material’s science as respective practicums provide students with opportunities to learn more about cutting-edge interdisciplinary methods used for development and investigation of modern materials properties. The purpose of the article is to develop an interdisciplinary experimental practicum on microfluids for a Master’s degree program «Smart Materials» in English. Methods. The analysis was carried out on the basis of Kazan National Research Technological University (KNRTU). The development of the experimental practicum was carried out on the basis of the KNRTU international partners’ experience: the University of Regensburg (Germany) and Carnegie Mellon University (USA) through a comparative analysis of master's programs at KNRTU and international partners, as well as teaching materials of relevant educational programs. It is concluded that microfluidic systems such as «lab-on–a–chip» devices are a promising technology for the implementation of various chemical and chemical-technological processes for the end user or group of users as well as an actual experimental environment for students studying natural sciences. The practicum was tested on Bachelor’s and Master’s students. The practicum was analyzed for its potential to be implemented as a component of short-term academic programs such as summer schools. The practicum aroused greater interest among students compared to traditional laboratory work due to the possibility of self-design and manufacture of microfluidic devices and control of the process of obtaining nanoparticles using a computer.

Does PDMS really interact with [18F]fluoride? Applications in microfluidic reactors for 18F-radiopharmaceuticals

Microfluidic devices used to synthesize radiopharmaceuticals for positron emission tomography (PET) are of increasing interest for the rapid preparation of on-demand doses, especially in medical centers that do not have a cyclotron. Polydimethylsiloxane (PDMS) is an inexpensive, easily available material used for the manufacturing of microfluidic devices. The literature often refers the interaction of this material with [18F]fluoride. Many authors discard PDMS as a suitable material because of these interactions, while others suggest the use of a thin fluoropolymer coating to reduce the adsorption of [18F]fluoride. The objective of this work was to evaluate the retention of [18F]fluoride within a PDMS reaction chamber without further treatment, under heating and vacuum in a range of activities that would allow to obtain enough product for two or three human doses of a radiopharmaceutical. Under these conditions, which are commonly used in radiosynthesis with [18F]fluoride, we found that [18F]fluoride was almost non-adsorbed into PDMS, making PDMS suitable for 18-F radiochemistry on single-use lab-on-chip devices, even uncoated.

Extrusion-based printing of sacrificial Carbopol ink for fabrication of microfluidic devices

Current technologies for manufacturing of microfluidic devices include soft-lithography, wet and dry etching, thermoforming, micro-machining and three-dimensional (3D) printing. Among them, soft-lithography has been the mostly preferred one in medical and pharmaceutical fields due to its ability to generate polydimethylsiloxane (PDMS) devices with resin biocompatibility, throughput and transparency for imaging. It is a multi-step process requiring the preparation of a silicon wafer pattern, which is fabricated using photolithography according to a defined mask. Photolithography is a costly, complicated and time-consuming process requiring a clean-room environment, and the technology is not readily accessible in most of the developing countries. In addition, generated patterns on photolithography-made silicon wafers do not allow building 3D intricate shapes and silicon direct bonding is thus utilized for closed fluid channels and complex 3D structures. 3D Printing of PDMS has recently gained significant interest due to its ability to define complex 3D shapes directly from user-defined designs. In this work, we investigated Carbopol as a sacrificial gel in order to create microfluidic channels in PDMS devices. Our study demonstrated that Carbopol ink possessed a shear-thinning behavior and enabled the extrusion-based printing of channel templates, which were overlaid with PDMS to create microfluidic devices upon curing of PDMS and removal of the sacrificial Carbopol ink. To demonstrate the effectiveness of the fabricated devices, channels were lined up with human umbilical vein endothelial cells (HUVECs) and human bone marrow endothelial cells (BMECs) in separate devices, where both HUVECs and BMECs demonstrated the formation of endothelium with highly aligned cells in the direction of fluid flow. Overall, we here present a highly affordable and practical approach in fabrication of PDMS devices with closed fluid channels, which have great potential in a myriad of applications from cancer treatments to infectious disease diagnostics to artificial organs.