Microfluidic Device For Separation Research Articles

Microfluidic separation device for blood components with lipids and cancer cells

Microfluidic separation device for blood components with lipids and cancer cells

Three-dimensional FSI simulation of cell entrapment utilizing acoustic interparticle force in a standing acoustic field

Abstract In recent years, there has been significant development in microfluidic devices for cell separation and sorting using acoustic methods in biomedical applications. The acoustic interparticle force (AIF) arises from particle interactions with the scattered field of other particles, influencing particle motion at close ranges and facilitating optimal trapping and separation. This study analyzes a two-particle system consisting of a fixed particle and a white blood cell (WBC) within a standing acoustic field and creeping flow using fluid-structure interaction (FSI). To reduce computational costs by decoupling the acoustics and FSI, the acoustic pressure equation (AcPr) was solved on the frequency domain to calculate the total acoustic radiation force in each time step. Model accuracy was assessed by evaluating interparticle (AIF) and primary acoustic radiation forces (ARF) on a polystyrene particle and comparing simulation results to analytical and experimental data. Results demonstrate precise ARF performance, with discrepancies in acoustic interparticle force attributed to viscous losses near the particle surface. Moreover, the higher density of the fixed particle compared to WBCs induces significant acoustic interparticle attraction at close distances. Consequently, cell entrapment occurs through strong attraction and collision with fixed aluminum and silicon particles in creeping flow in all three Reynolds numbers 1.4E-3, 2.1E-3, and 3E-3. Increasing Reynolds numbers augment the likelihood of cell separation from the fixed particle. These findings contribute to optimizing cell isolation and entrapment strategies.

Paper-Based Microfluidic Analytical Device Patterned by Label Printer for Point-of-Care Blood Glucose and Hematocrit Detection Using 3D-Printed Smartphone Cassette.

This study presents a portable, low-cost, point-of-care (POC) system for the simultaneous detection of blood glucose and hematocrit. The system consists of a disposable origami microfluidic paper-based analytical device (μPAD) for plasma separation, filtration, and reaction functions and a 3D-printed cassette for hematocrit and blood glucose detection using a smartphone. The origami μPAD is patterned using a cost-effective label printing technique instead of the conventional wax printing method. The 3D-printed cassette incorporates an array of LED lights, which mitigates the effects of intensity variations in the ambient light and hence improves the accuracy of the blood glucose and hematocrit concentration measurements. The hematocrit concentration is determined quantitatively by measuring the distance of plasma wicking along the upper layer of the origami μPAD, which is pretreated with sodium chloride and Tween 20 to induce dehydration and aggregation of the red blood cells. The filtered plasma also penetrates to the lower layer of the origami μPAD, where it reacts with embedded colorimetric assay reagents to produce a yellowish-brown complex. A color image of the reaction complex is captured using a smartphone inserted into the 3D-printed cassette. The image is analyzed using self-written RGB software to quantify the blood glucose concentration. The calibration results indicate that the proposed detection platform provides an accurate assessment of the blood glucose level over the range of 45-630 mg/dL (R2 = 0.9958). The practical feasibility of the proposed platform is demonstrated by measuring the blood glucose and hematocrit concentrations in 13 human whole blood samples. Taking the measurements obtained from commercial glucose and hematocrit meters as a benchmark, the proposed system has a differential of no more than 6.4% for blood glucose detection and 9.1% for hematocrit detection. Overall, the results confirm that the proposed μPAD is a promising solution for cost-effective and reliable POC health monitoring.

Polydimethylsiloxane Surface Modification of Microfluidic Devices for Blood Plasma Separation.

Over the last decade, researchers have developed a variety of new analytical and clinical diagnostic devices. These devices are predominantly based on microfluidic technologies, where biological samples can be processed and manipulated for the collection and detection of important biomolecules. Polydimethylsiloxane (PDMS) is the most commonly used material in the fabrication of these microfluidic devices. However, it has a hydrophobic nature (contact angle with water of 110°), leading to poor wetting behavior and issues related to the mixing of fluids, difficulties in obtaining uniform coatings, and reduced efficiency in processes such as plasma separation and molecule detection (protein adsorption). This work aimed to consider the fabrication aspects of PDMS microfluidic devices for biological applications, such as surface modification methods. Therefore, we studied and characterized two methods for obtaining hydrophilic PDMS surfaces: surface modification by bulk mixture and the surface immersion method. To modify the PDMS surface properties, three different surfactants were used in both methods (Pluronic® F127, polyethylene glycol (PEG), and polyethylene oxide (PEO)) at different percentages. Water contact angle (WCA) measurements were performed to evaluate the surface wettability. Additionally, capillary flow studies were performed with microchannel molds, which were produced using stereolithography combined with PDMS double casting and replica molding procedures. A PDMS microfluidic device for blood plasma separation was also fabricated by soft lithography with PDMS modified by PEO surfactant at 2.5% (v/v), which proved to be the best method for making the PDMS hydrophilic, as the WCA was lower than 50° for several days without compromising the PDMS's optical properties. Thus, this study indicates that PDMS surface modification shows great potential for enhancing blood plasma separation efficiency in microfluidic devices, as it facilitates fluid flow, reduces cell aggregations and the trapping of air bubbles, and achieves higher levels of sample purity.

Low-cost inertial microfluidic device for microparticle separation: A laser-Ablated PMMA lab-on-a-chip approach without a cleanroom

Although microparticles are frequently used in chemistry and biology, their effectiveness largely depends on the homogeneity of their particle size distribution. Microfluidic devices to separate and purify particles based on their size have been developed, but many require expensive cleanroom manufacturing processes. A cost-effective, passive microfluidic separator is presented, capable of efficiently sorting and purifying particles spanning the size range of 15 µm to 40 µm. Fabricated from Polymethyl Methacrylate (PMMA) substrates using laser ablation, this device circumvents the need for cleanroom facilities. Prior to fabrication, rigorous optimization of the device's design was carried out through computational simulations conducted in COMSOL Multiphysics. To gauge its performance, chitosan microparticles were employed as a test case. The results were notably promising, achieving a precision of 96.14 %. This quantitative metric underscores the device's precision and effectiveness in size-based particle separation.This low-cost and accessible microfluidic separator offers a pragmatic solution for laboratories and researchers seeking precise control over particle sizes, without the constraints of expensive manufacturing environments. This innovation not only mitigates the limitations tied to traditional cleanroom-based fabrication but also widens the horizons for various applications within the realms of chemistry and biology.

Isolation and Detection of Exosomal Mir210 Using Carbon Nanomaterial-Coated Magnetic Beads.

MicroRNAs (miRNAs) are short non-coding RNAs that are found in various cellular compartments and play an important role in regulating gene expression. Extracellular miRNAs, such as those found within extracellular vesicles such as exosomes are involved in cell-to-cell communication. The intercellular transfer of miRNAs has been implicated in various diseases' pathogenesis including cancer and has been studied extensively as potential cancer biomarkers. However, the extraction of miRNA from exosomes is still a challenging task. The current nucleic acid extraction assays are expensive and labor-intensive. In this study, we demonstrated a microfluidic device for aptamer-based magnetic separation of the exosomes and subsequent detection of the miRNA using a fluorescence switching assay, which was enabled by carbon nanomaterials coated on magnetic beads. In the OFF state, the fluorophore-labelled cDNA is quenched using carbon nanomaterials. However, when the target miRNA210 is introduced, the cDNA detaches from the bead's surface, which leads to an increase in the fluorescence intensity (ON state). This increment was found to be proportional to miRNA concentration within the dynamic range of 0-100 nM with a detection limit of 5 pM. The assay was validated with spiked miRNA using the standard RT-PCR method. No notable cross-reactivity with other closely related miRNAs was observed. The developed method can be utilized for the minimally invasive detection of cancer biomarkers.

Continuous Flow Separation of Live and Dead Cells Using Gravity Sedimentation.

The separation of target cell species is an important step for various biomedical applications ranging from single cell studies to drug testing and cell-based therapies. The purity of cell solutions is critical for therapeutic application. For example, dead cells and debris can negatively affect the efficacy of cell-based therapies. This study presents a cost-effective method for the continuous separation of live and dead cells using a 3D resin-printed microfluidic device. Saccharomyces cerevisiae yeast cells are used for cell separation experiments. Both numerical and experimental studies are presented to show the effectiveness of the presented device for the isolation of dead cells from cell solutions. The experimental results show that the 3D-printed microfluidic device successfully separates live and dead cells based on density differences. Separation efficiencies of over 95% are achieved at optimum flow rates, resulting in purer cell populations in the outlets. This study highlights the simplicity, cost-effectiveness, and potential applications of the 3D-printed microfluidic device for cell separation. The implementation of 3D printing technology in microfluidics holds promise for advancing the field and enabling the production of customized devices for biomedical applications.

Development of a biodegradable microfluidic paper-based device for blood-plasma separation integrated with non-enzymatic electrochemical detection of ascorbic acid

In the present article, we developed an electrochemical microfluidic paper-based device (EμPAD) for the non-enzymatic detection of Ascorbic Acid (AA) concentration in plasma using whole human blood. We combined LF1 blood plasma separation membrane and Whatman grade 1 filter paper to separate plasma from whole blood through wax printing. A screen-printed electrode (SPE) was modified with spherical-shaped MgFe2O4 nanomaterial (n-MgF) to improve the catalytic properties of SPE. The n-MgF was prepared via hydrothermal method, and its material phase and morphology were confirmed via XRD, FTIR, TEM, SEM, and AFM analysis. The fabricated n-MgF/SPE/EμPAD exhibited detection of AA ranging from 0 to 80 μM. The obtained value of the detection limit, limit of quantification, sensitivity, and response time are 2.44 μM, 8.135 μM, 5.71 × 10−3 mA μM−1 cm−2, and 10 s, respectively. Our developed n-MgF/SPE/EμPAD shows marginal interference with the common analytes present in plasma, such as uric acid, glutamic acid, glucose, urea, lactic acid, and their mixtures. Overall, our low-cost, portable device with its user-friendly design and efficient plasma separation capability offers a practical and effective solution for estimating AA concentration from whole human blood in a single step.

Investigation on a cascaded inertial and acoustic microfluidic device for sheathless and label-free separation of circulating tumor cells

High-precision and high-purity acquisition of tumor cells from whole blood is vital for early disease detection and diagnosis. Here, we investigated a cascaded inertial and acoustic microfluidic device for sheathless and label-free separation of circulating tumor cells (CTCs) from the blood through numerical methods. We introduced a spiral microfluidics channel in the first stage (1st) for cell focusing and rough sorting to improve chip integration and reduce the dependence on sheath flow and extra syringe pumps. In the 1st, we simulated the spiral microfluidic with a rectangular cross section to determine the key parameters affecting the migration kinetics of blood cells and tumor cells. Under the influence of Dean drag force and inertial lift force, blood cells migrate toward the inner side of the channel, while CTCs flow out close to the outer side. A flow rate of 400 μl/min was optimized for the operating flow rate. To improve and further enhance the 1st sorting efficiency and purity, we introduced tilted angle standing surface acoustic wave (SSAW) in the second stage (2st). Based on the parametric study, the SSAW with 33.3 MHz, tilted angle with 5°, and acoustic pressure amplitude with 0.7 MPa was selected as the operating parameter. The product of the 1st is used as input for the 2st acoustofluidic unit, enabling a more accurate separation process to obtain CTCs. The simulation results show that the inertial microfluidic units arranged in the first stage help to improve throughput and assist in 2st acoustofluidic separation, and the cascaded chip has accomplished a separation performance of nearly 100% in terms of purity and efficiency.

Inertial microfluidic-assisted rapid detection of chemical contaminant in foods using quantum dots-based molecularly imprinted sensor

Integration of sample pretreatment, separation and detection in simple steps for food chemical contaminant analysis is challenging due to the complexity of food matrices. A novel analytical approach of using quantum dots-based molecular imprinting fluorescence sensor (QDs@MIPs) combined with inertial separation microfluidic device for separation and detection of enrofloxacin is presented in this study. The microfluidic device was designed based on laminar flow principle combined with Dean-coupled inertial migration of particles in spiral microchannels. Micron-sized QDs@MIPs sensing particles were synthesized for selective separation and sensitive detection of enrofloxacin. Separation of QDs@MIPs was achieved via parallel migration from the original suspension solution to another buffer solution in the same spiral microchannel with a high separation efficiency of 97.7 ± 1.6%. Fluorescence intensity of QDs@MIPs was quenched in the presence of enrofloxacin and showed a linearity in the range of 0.1–50 µg/mL with limit of detection of 0.059 µg/mL. On-chip analyses were performed to detect enrofloxacin in both standard samples and contaminated swine muscle. This microfluidic-assisted fluorescence sensing system provides a solution to integrate sample pretreatment, separation and detection together to realize rapid analysis of food contaminants with high selectivity and sensitivity.

Effects of obstacles on inertial focusing and separation in sinusoidal channels: An experimental and numerical study

Inertial microfluidics manipulates and separates microparticles based on the finite inertia of the fluid at high flow speed. In inertial microfluidics, modifying the geometry by embedding periodic micro-obstacles into curvilinear channels is emerging as a promising strategy to improve inertial focusing and separation. This work systematically investigated the influence of micro-obstacles on inertial focusing and developed a high-resolution microfluidic device for particle and cell separation. First, we developed numerical modelling to simulate the migration trajectories of particles. Then, we studied the effects of various obstacles on the inertial focusing in the sinusoidal channels. The concave obstacles were more effective in tuning particle inertial focusing and separation than convex obstacles. Furthermore, the square concave obstacle channel could offer the highest separation resolution. Finally, we developed a microfluidic device based on square concave obstacle channel, and applied it for the high-efficiency separation of polystyrene beads and U87MG cancer cells from the blood.

Three-dimensional lab-on-a-foil device for dielectrophoretic separation of cancer cells.

A simple, low-cost, three-dimensional (3D) lab-on-a-foil microfluidic device for dielectrophoretic separation of circulating tumor cells (CTCs) is designed and constructed. Disposable thin films are cut by xurography and microelectrode array are made with rapid inkjet printing. The multilayer device design allows the studying of spatial movements of CTCs and red blood cells (RBCs) under dielectrophoresis (DEP). A numerical simulation was performed to find the optimum driving frequency of RBCs and the crossover frequency for CTCs. At the optimum frequency, RBCs were lifted 120µm in z-axis direction by DEP force, and CTCs were not affected due to negligible DEP force. By utilizing the displacement difference, the separation of CTCs (modeled with A549 lung carcinoma cells) from RBCs in z-axis direction was achieved. With the nonuniform electric field at optimized driving frequency, the RBCs were trapped in the cavities above the microchannel, whereas the A549 cells were separated with a high capture rate of 86.3%±0.2%. The device opens not only the possibility for 3D high-throughput cell separation but also for future developments in 3D cell manipulation through rapid and low-cost fabrication.

Experimental investigation on microfluidic devices for particle separation using standing surface acoustic waves

In this work, we designed and experimentally tested a microfluidic device for particle separation by using standing surface acoustic waves (SSAW). Emphasis is being placed on an effective microfluidic device being capable of continuous separation of particles in a microchannel design on its size. For this, we developed a miniaturized (e.g., lab-on-a-chip) system for biological and chemical analyses. For demonstration, we experimentally demonstrated that separation of dissimilarly-sized polystyrene particles suspended in water medium was successfully achieved. Numerical simulations were conducted by using COMOSL Multiphysics 5.0 to investigate the effects of sheath layer thickness and particle size on separation efficiency of the microfluidic device. The present numerical and experimental findings were then applied to propose an improved design and fabrication process of Standing surface acoustic waves devices, which has great potential for biological applications.

Coplanar semi-circular electrodes based multi-microchannel microfluidic network device for binary bio-cell separation

Coplanar semi-circular electrodes based multi-microchannel microfluidic network device for binary bio-cell separation

A microfluidic plasma separation device combined with a surface plasmon resonance biosensor for biomarker detection in whole blood.

Biomarker detection in whole blood enables understanding of the cause, progression, relapse or outcome of treatment of a disease. Conventional biomarker detection techniques, such as enzyme-linked immunosorbent assay, polymerase chain reaction, and immunofluorescence, require long assay time, costly laboratory instruments, large reagent volume and sample pre-processing. Hence, there is an unmet need for reliable capture and detection of biomarkers in unprocessed blood which are adaptable to point-of-care (POC) testing. Here, we present a simple, low-cost, and rapid protein detection device from whole blood samples which has the potential to be employed in a POC setting. The platform consists of two components: a plasma separation device that extracts plasma from whole blood without the application of any external active forces and a SPR sensor chip that uses a label-free optical technique for the detection of biomarkers in the extracted plasma. We have demonstrated the detection of IgG and IgM biomolecules in unprocessed blood at concentrations lower than the physiological value within 15 min. The proposed technique has the potential for improving the diagnosis and screening of many diseases, including cancer, influenza, human immunodeficiency virus, and SARS-Cov2 at POC.

Low-cost, high-throughput and rapid-prototyped 3D-integrated dielectrophoretic channels for continuous cell enrichment and separation.

Microfluidic devices for dielectrophoretic cell separation are typically designed and constructed using microfabrication methods in a clean room, requiring time and expense. In this paper, we describe a novel alternative approach to microfluidic device manufacture, using chips cut from conductor-insulator laminates using a cutter plotter. This allows the manufacture of microchannel devices with micron-scale electrodes along every wall. Fabrication uses a conventional desktop cutter plotter, and requires no chemicals, masks or clean-room access; functional fluidic devices can be designed and constructed within a couple of hours at negligible cost. As an example, we demonstrate the construction of a continuous dielectrophoretic cell separator capable of enriching yeast cells to 80% purity at 10 000 cells/s.

THE THREE MUSKETEERS: A RETROSPECTIVE COHORT STUDY EXAMINING EMBRYO QUALITY IN IVF-ICSI CYCLES USING VARYING SPERM SELECTION METHODS

The limited literature comparing testicular vs. ejaculated sperm for assisted reproduction technology (ART) is rife with heterogenous results. While a meta-analysis found that testicular sperm was superior to ejaculated sperm with respect to embryo quality and pregnancy rates, a well-designed recent study concluded that intracytoplasmic sperm injection (ICSI) outcomes with the use of Testicular Sperm Extraction (TESE) samples compared with ejaculated sperm were equivalent (1). Moreover, studies comparing Zymot™, a microfluidic sperm separation device vs standard density gradient centrifugation (DGC) remain conflicting (2).

A universal monoclonal antibody-aptamer conjugation strategy for selective non-invasive bioparticle isolation from blood on a regenerative microfluidic platform

Simultaneous isolation of various circulating tumor cell (CTC) subtypes from whole blood is useful in cancer diagnosis and prognosis. Microfluidic affinity separation devices are promising for CTC separation because of their high throughput capacity and automatability. However, current affinity agents, such as antibodies (mAbs) and aptamers (Apts) alone, are still suboptimal for efficient, consistent, and versatile cell analysis. By introducing a hybrid affinity agent, i.e., an aptamer-antibody (Apt-mAb) conjugate, we developed a universal and regenerative microchip with high efficiency and non-invasiveness in the separation and profiling of various CTCs from blood. The Apt-mAb conjugate consists of a monoclonal antibody that specifically binds the target cell receptor and a surface-bound aptamer that recognizes the conserved Fc region of the mAb. The aptamer then indirectly links the surface functionalization of the microfluidic channels to the mAbs. This hybrid affinity agent and the microchip platform may be widely useful for various bio-particle separations in different biological matrices. Further, the regeneration capability of the microchip improves data consistency between multiple uses and minimizes plastic waste while promoting environmental sustainability. Statement of significanceA hybrid affinity agent, Apt-mAb, consisting of a universal aptamer (Apt) that binds the conserved Fc region of monoclonal antibodies (mAbs) was developed. The invented nano-biomaterial combines the strengths and overcomes the weakness of both Apts and mAbs, thus changing the paradigm of affinity separation of cell subtypes. When Apt-mAb was used to fabricate microfluidic chips using a “universal screwdriver” approach, the microchip could be easily tuned to bind any cell type, exhibiting great universality. Besides high sensitivity and selectivity, the superior regenerative capacity of the microchips makes them reusable, which provides improved consistency and repeatability in cell profiling and opens a new approach towards in vitro diagnostic point-of-care testing devices with environmental sustainability and cost-effectiveness.

In silico simulation and in vitro validation of a continuous microfluidic device for separation of magnetic nanoparticles

Magnetic separation is introduced to separate paramagnetic or superparamagnetic particles and beads from a suspension by implementing an external magnetic field gradient. The strength of this magnetic field declines with rising distance. Batch containers commonly separate nanoparticles from a fluid by imposing an external magnetic field gradient using a permanent magnet. In this system, magnetic particles aggregate the container's wall or bottom, therefore creating a continuous process without any aggregation is desired. In this paper, COMSOL Multiphysics ver. 5.6 (FEM) has been utilized to simulate a continuous microfluidic device with two geometrical designs, linear design (LD) and curved design (CD). The variables are the velocity of the primary fluid and buffer and the channel's width. The optimal designs of both microfluidic devices have been achieved by changing the variables in a specific range without aggregating them to the device's wall. The optimal structures for both designs were built and tested in the laboratory. The optimal velocity was 0.1 mm/s, the optimal channel width was 200 µm for LD, and it was 0.1 mm/s and 400 µm for CD, respectively. The separation percentage in the simulation was 63 %, the spectrophotometry result was 64.08 for LD, and CD showed better results in simulation (85 %) and laboratory experiment (80.24 %). So, this method can be used to optimize nanoparticle separation in microfluidic.

Microfluidic Approaches for Affinity-Based Exosome Separation.

As a subspecies of extracellular vesicles (EVs), exosomes have provided promising results in diagnostic and theranostic applications in recent years. The nanometer-sized exosomes can be extracted by liquid biopsy from almost all body fluids, making them especially suitable for mainly non-invasive point-of-care (POC) applications. To achieve this, exosomes must first be separated from the respective biofluid. Impurities with similar properties, heterogeneity of exosome characteristics, and time-related biofouling complicate the separation. This practical review presents the state-of-the-art methods available for the separation of exosomes. Furthermore, it is shown how new separation methods can be developed. A particular focus lies on the fabrication and design of microfluidic devices using highly selective affinity separation. Due to their compactness, quick analysis time and portable form factor, these microfluidic devices are particularly suitable to deliver fast and reliable results for POC applications. For these devices, new manufacturing methods (e.g., laminating, replica molding and 3D printing) that use low-cost materials and do not require clean rooms are presented. Additionally, special flow routes and patterns that increase contact surfaces, as well as residence time, and thus improve affinity purification are displayed. Finally, various analyses are shown that can be used to evaluate the separation results of a newly developed device. Overall, this review paper provides a toolbox for developing new microfluidic affinity devices for exosome separation.