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Centrifugal separation is a highly efficient technique for accelerating the sedimentation of blood constituents in a cylindrical container through highspeed spin-up rotation. Few studies have reported on the separation of different blood constituents from homogeneous mixture of whole blood. In this study, the process through which blood constituent sedimentation occurs in a spin-up rotating cylindrical container is numerically investigated. Whole blood is considered a homogeneous mixture of red blood cells (RBC) and plasma, which are both considered incompressible viscous liquids. The Euler multi-fluid VOF (volume of fluid) model is introduced to simulate the separation of RBCs and plasma. The effects of the rotation speed and the geometric construction of the cylindrical container on the sedimentation and stratification of different blood constituents are studied. A stable interface between the RBC layer and plasma layer forms earlier in a high position. With an increase in the rotation speed, the interface between the RBCs and plasma layers forms more quickly. In the cylindrical container with a helical groove on the outer wall, a stable vortex occurs near the groove, which forces red blood cells to move toward the lower location of the groove, resulting in a conical distribution of the RBC layer and a larger volume fraction of plasma near the exit at the top. This allows for sufficient precipitation of the plasma, improving the separation efficiency. [ABSTRACT FROM AUTHOR]

Centrifugal separation is a highly efficient technique for accelerating the sedimentation of blood constituents in a cylindrical container through high-speed spin-up rotation. Few studies have reported on the separation of different blood constituents from homogeneous mixture of whole blood. In this study, the process through which blood constituent sedimentation occurs in a spin-up rotating cylindrical container is numerically investigated. Whole blood is considered a homogeneous mixture of red blood cells (RBC) and plasma, which are both considered incompressible viscous liquids. The Euler multi-fluid VOF (volume of fluid) model is introduced to simulate the separation of RBCs and plasma. The effects of the rotation speed and the geometric construction of the cylindrical container on the sedimentation and stratification of different blood constituents are studied. A stable interface between the RBC layer and plasma layer forms earlier in a high position. With an increase in the rotation speed, the interface between the RBCs and plasma layers forms more quickly. In the cylindrical container with a helical groove on the outer wall, a stable vortex occurs near the groove, which forces red blood cells to move toward the lower location of the groove, resulting in a conical distribution of the RBC layer and a larger volume fraction of plasma near the exit at the top. This allows for sufficient precipitation of the plasma, improving the separation efficiency.

Microplastics have emerged as ubiquitous contaminants, attracting increasing global attention. Recent evidence confirms the presence of microplastics in human blood, suggesting their potential to interact with cells and induce adverse physiological reactions in various organs as blood circulates. To quantify the distribution of microplastics and assess their potential effects on human health, the effective separation of microplastics from blood is crucial. However, current methods for separating microplastics from blood are limited in effectiveness and simplicity. This study proposes a microfluidic device that utilizes traveling surface acoustic waves to separate microplastics from blood. While traveling surface acoustic waves have been employed to separate various particles, a systematic study on the separation of microplastics from blood samples has not been previously reported. Specifically, the theoretical values of the acoustic radiation factor for various types of microplastics and blood cells were investigated. The significant differences in resonant frequencies indicated the feasibility of separating microplastics of different sizes and types from blood cells. Experimental validation was performed using a polydimethylsiloxane microfluidic device on a piezoelectric lithium niobate substrate. The device successfully separated 5- and 10-micrometer polystyrene microplastics from blood samples. The effects of power and flow rate on separation efficiency were also systematically investigated. This study provides a novel approach for the effective separation of microplastics from blood, contributing to the assessment of their distribution and potential health impacts.

Microplastics have emerged as ubiquitous contaminants, attracting increasing global attention. Recent evidence confirms the presence of microplastics in human blood, suggesting their potential to interact with cells and induce adverse physiological reactions in various organs as blood circulates. To quantify the distribution of microplastics and assess their potential effects on human health, the effective separation of microplastics from blood is crucial. However, current methods for separating microplastics from blood are limited in effectiveness and simplicity. This study proposes a microfluidic device that utilizes traveling surface acoustic waves to separate microplastics from blood. While traveling surface acoustic waves have been employed to separate various particles, a systematic study on the separation of microplastics from blood samples has not been previously reported. Specifically, the theoretical values of the acoustic radiation factor for various types of microplastics and blood cells were investigated. The significant differences in resonant frequencies indicated the feasibility of separating microplastics of different sizes and types from blood cells. Experimental validation was performed using a polydimethylsiloxane microfluidic device on a piezoelectric lithium niobate substrate. The device successfully separated 5- and 10-micrometer polystyrene microplastics from blood samples. The effects of power and flow rate on separation efficiency were also systematically investigated. This study provides a novel approach for the effective separation of microplastics from blood, contributing to the assessment of their distribution and potential health impacts. [ABSTRACT FROM AUTHOR]

The separation of bio-suspensions, such as blood, is of great interest for many biomedical applications, such as the extraction of leucocytes from whole blood, the laboratory analysis of specific cells or a mixed cell suspensions from bioreactors or the preparation of cellular products for cellbased therapy. In particular, mechanical separation processes have been established for the rapid separation of biosuspensions. The principle of mechanical separation is based on the specific density of the particles or the particle size. Thus, the corresponding processes are based on centrifugation and/or filtration. The standard process to prepare blood products from whole blood donations contains several steps. First the blood is separated into different phases by centrifugation and then further separated by filters containing specific filtration layers. The shortcomings of this process is the low yield due to bio-particles remaining in the filter and the high costs for equipment due to the use of multiple devices for centrifugation and filtration. Here we present the proof of principle of an adaptive, size-selective filter that addresses the above mentioned shortcomings. The filter is designed to combine the filtration and centrifugation process within one step. Therefore a novel filtration device was designed that can be used within a standard centrifugation tube. During centrifugation, the centrifugal force changes the filtration coefficient of the filter. This can be used to separate different sized of bio-particles at different centrifugation speeds. Moreover, the cells that were hold back in the filter can be removed afterwards by increasing the centrifugation speed. In this way, the filter is created to gradually release cells of a specific size yielding in a high purity of different cell fractions.

In this paper, we report a point-of-care (POCT) testing strip based on a porous membrane structure for whole blood separation and colorimetric analysis without external supporting equipment. Conventional blood tests rely on large instruments for blood pretreatment and separation to improve measurement accuracy. Cellulose acetate (CA) membranes with different pore diameters and structures were prepared via a non-solvent method for the separation of whole blood. Among them, CA@PEG-2000 membranes with nano-pores on the surface and micro-pores in the interior facilitated the capture of blood cells on the surface, as well as the free diffusion of plasma through the porous interior structure. The fluid flow of blood in the asymmetric porous structure can be theoretically estimated using the Lucas-Washburn equation. Compared with the conventional paper strips and other porous membranes, the CA@PEG-2000 membrane with an immobilized sensing layer exhibited efficient blood separation, a short response time (less than 2 min), an ultralow dosage volume (5 μL), and high sensitivity. The fabricated blood separation membranes can be further used for the detection of various biomarkers in whole blood, providing additional options for rapid quantitative POCT tests. [ABSTRACT FROM AUTHOR]

In recent years, viscoelastic particle manipulation within microfluidic systems has received much attention due to the ease with which micron-sized objects may be maneuvered and isolated on the basis of size. While several factors, including both fluid and particle properties, regulate the precise locations and trajectories of micron-sized species flowing along a microchannel, the role of channel cross-section shape is critical, since it directly influences the fluid velocity profile and thus the direction and magnitude of hydrodynamic forces. It is therefore surprising that this parameter has not been comprehensively investigated for cell-based separations, especially since most viscoelastic microfluidic systems are only able to efficiently sperate cells over limited size ranges. To address this shortcoming, we present a viscoelastic microfluidic system integrating a triangular cross-section microchannel, for efficient and tunable size-based separations of micron-sized species. We find that particle focusing patterns can be controlled by simple variation of volumetric flow rates, which allows for the efficient separation of particles and cells of variable size. To showcase the efficacy of the approach, we present a size-based separation of various blood components, including white blood cells, platelets, and rare cells. By quantifying the number of particles collected at the outlets, we achieve recovery efficiencies of over 98%. • Viscoelastic particle manipulation is used to separate micron-sized particles. • A triangular cross-section microfluidic channel design is used for particle separation. • Passive separation of different blood components at low blood dilutions. • Size-selective separation of blood components via tunable viscoelastic focusing. [ABSTRACT FROM AUTHOR]

In this article, we introduce the importance of blood processing for human consumption while also presenting the methodology of porcine blood membrane separation to plasma and red blood cell fractions, as well as the membrane purification after porcine blood separation. Basic analytical measurements were carried out to investigate the blood product attributes, which relate to technological and nutritional quality depending on the separation parameters. Next, we present how the relevant hydrodynamical parameters were calculated during the experiments. Membrane separation was realized by crossflow microfiltration with pore size of 0.8 μm or 1.2 μm, retentate flow rate of 200 l·h-1 or 300 l·h-1 and with transmembrane pressure of 1 x 105 Pa, 2 x 105 Pa or 3 x 105 Pa. The experimental design was analysed, the parameters of the objective function and effect sizes were estimated and the global minimum of the objective function was successfully identified. The results of this optimization can be applied in practice. The membrane separation parameters were then optimized according to a model based on the observed data. An optimum was detected within the examined factor levels and experimental conditions at the lowest transmembrane pressure and at the highest membrane pore size. [ABSTRACT FROM AUTHOR]

Objectives: Our objectives were to determine the separation characteristics and blood product quality of a gravity‐driven microfiltration blood separation system (HemoClear, The Netherlands). Background: A range of centrifugal blood separation devices, including intraoperative cell salvage devices (cell savers) and apheresis machines, are available to assist in preparing both allogenic and autologous blood products. These devices are expensive to operate and require extensive training. Methods and Materials: Nine whole blood units were collected under standard conditions and analysed for haematological parameters, thromboelastographic properties, platelet morphology and activation, and red blood cell (RBC) deformability and morphology. Three whole blood units were separated by means of the HemoClear device, into a liquid and cellular component. The cellular component was diluted with SAGM and cold stored for 14 days. To simulate cell salvage six whole blood units were diluted with isotonic saline, followed by multiple HemoClear separation rounds. Results: The recovery of both RBCs (100 ± 1.6%) and white blood cells (99 ± 4.5%) after undiluted filtration were very high, while platelet recovery was high (83 ± 3.0%). During the filtration, and cold storage after filtration storage both the non‐deformable RBC fraction and the RBC maximum elongation remained stable. Parameters of thromboelastography indicated that platelets remain functional after filtration and after 7 days of cold storage. In the cell salvage simulation the total protein load in the cellular fraction was reduced by 65 ± 4.1% after one washing round and 84 ± 1.9% after two consecutive washing rounds. Conclusion: The novel blood filter studied effectively separates whole blood into diluted plasma and platelet‐rich RBCs. Moreover, the device effectively washed diluted whole blood, driving over 80% of proteins to the liquid component. [ABSTRACT FROM AUTHOR]

In this paper, we report a point-of-care (POCT) testing strip based on a porous membrane structure for whole blood separation and colorimetric analysis without external supporting equipment. Conventional blood tests rely on large instruments for blood pretreatment and separation to improve measurement accuracy. Cellulose acetate (CA) membranes with different pore diameters and structures were prepared via a non-solvent method for the separation of whole blood. Among them, CA@PEG-2000 membranes with nano-pores on the surface and micro-pores in the interior facilitated the capture of blood cells on the surface, as well as the free diffusion of plasma through the porous interior structure. The fluid flow of blood in the asymmetric porous structure can be theoretically estimated using the Lucas-Washburn equation. Compared with the conventional paper strips and other porous membranes, the CA@PEG-2000 membrane with an immobilized sensing layer exhibited efficient blood separation, a short response time (less than 2 min), an ultralow dosage volume (5 μL), and high sensitivity. The fabricated blood separation membranes can be further used for the detection of various biomarkers in whole blood, providing additional options for rapid quantitative POCT tests.

Separation of blood plasma or serum from blood is essential for accurate analysis. Conventional blood separation requires instrumentation, reagents, and large sample volumes, limiting this process to laboratory environments with trained personnel. Full implementation of effective blood separation and analysis on microliter sample volumes for point of care (POC) diagnostics has proven extremely challenging resulting in a growing market demand, with common challenges such as expensive device fabrication processes or devices being comprised of materials which are not easily disposable. We developed a membrane-based wicking microfluidic device which is made using a simple fabrication process. This device uses a unique 3D flow channel geometry, fabricated in a polycaprolactone-filled glass microfiber membrane, to efficiently separate microliter sample volumes of blood. Colorimetric assay chemistries were integrated to demonstrate utility of these devices in POC diagnostics. The devices are capable of separating both fresh and anticoagulant-treated blood at microscale sample volumes (<15.0 μL). Modifications to the base device are also reported herein which increased sample volume capacity and separation efficiency. Integrated colorimetric assay enabled semi-quantitative detection of conjugated bilirubin in real blood samples (1.0–1.5 mg/dL). These blood separation devices, fabricated on polycaprolactone-filled glass microfiber, enabled effective blood plasma (anticoagulant-treated blood) and serum (fresh blood) separation with microscale sample volumes. Sample volume capacity and separation efficiency are customizable for specific applications and devices can be integrated with downstream assay chemistries to develop complete POC devices that offer blood separation and diagnostics at the same time on a single membrane. [ABSTRACT FROM AUTHOR]

In this paper, we describe two fabrication methods (well array-based and biopsy punching-based) of gel disks to construct a gel-based point-of-care (POC) diagnosis device for direct colorimetric measurement of human whole blood glucose without any extra blood separation step. The gel disks are made of Polyethylene glycol (PEG) diacrylate (PEG-DA) containing immobilized glucose colorimetric assay reagents. The performances of three types of PEG-DA gel (molecular weight: 575, 3,400, and 10,000) based sensors as well as the two fabrication methods were investigated. • The fabricated devices enabled colorimetric whole blood glucose sensing assay without the need for blood cell separation • The biopsy punching-based gel disk fabrication method provided less variation on the fabricated gel disks

Dynamic and on‐site analysis of serum from human blood is crucial, however, state‐of‐the‐art blood‐assay methods can only collect single or discrete data of physiological analytes; thus, the online reports of the dynamic fluctuation of key analytes remains a great challenge. Here, we propose a novel separation‐sensing membrane by constructing a heterogeneous‐nanostructured architecture, wherein a surface nanoporous layer continuously extracts serum, while the biosensing nanochannels underneath dynamically recognise biotargets, thereby achieving a continuous testing of vital clinical indices as blood is drawn. By precisely controlling the pore structure and nanoshape of biosensing crystals, this membrane achieved accurate and online glucose and lactate monitoring in patients with a variety of medical conditions within 1 min, which is one order of magnitude faster than state‐of‐the‐art techniques. Moreover, various kinds of bio‐recognisers can be introduced into this membrane to accurately detect glutamate, transaminase, and cancer biomarkers. [ABSTRACT FROM AUTHOR]

In this paper, we report on the development of a microfluidic device, which extracts plasma from low‐volume whole blood (10 μL), and is aimed at integration with microfluidic system for micro analytical systems. The device autonomously separates blood cells and transfers the separated plasma by steady rotation. Based on the original autonomous fluidic control theory, we developed the principle of automatic timed injection of pressurizing medium into the separation chamber. This realizes the transferring of separated plasma from blood separation chamber to the other place, after separating blood cells by centrifugal force. Through the demonstration on a polydimethylsiloxane microfluidic device, we confirmed that the automatic plasma extraction was successfully implemented as designed. The efficiency of separation was evaluated on the basis of the concentrations of blood cells in samples before and after extraction, and the rate of blood cell removal was 98.5%. [ABSTRACT FROM AUTHOR]

Despite the stereotype that secondary flow fields induced by surface grooves are effective for microfluidic mixing and increase the entropy of different fluid flows, many efforts have been made to utilize the grooves for particle separation and focusing, decreasing the entropy of particle distribution. As part of these efforts, hydrophoresis has been proposed to define deterministic particle trajectories in grooved microchannels. Due to the simple, cloggingfree, and high-throughput characteristics, hydrophoresis has become increasingly promising for blood separation in clinical applications and sheathless particle focusing in flow cytometric applications. In this review, I introduce and summarize the basic physics, design parameters, design principles, and applications of hydrophoresis to improve the fundamental understanding of hydrophoresis and expand its use. I also discuss the challenges of hydrophoresis and forecast its future direction. [ABSTRACT FROM AUTHOR]

Experiments are done with separated human blood decelerated at constant rates to determine the maximum deceleration rate while avoiding remixing of the layers, which have different densities and viscosities. The deceleration rate affects both the stability and separation of particles through sedimentation. The velocity at onset of instability for a constant deceleration rate is experimentally determined for a 12‐cm‐diameter disk. Parameters of cell pack thickness, plasma thickness, and total thickness are investigated experimentally, and the only statistically significant parameter to affect stability is rate of deceleration. The data describe a correlation separating regions of stability and instability. To understand stability in decelerating flow of separated blood plasma and cells, the equations of motion are solved for a two‐layer fluid flow with a moving boundary and free surface. Inclusion of non‐Newtonian rheology of blood predicts large discontinuities in the shear rate, which is proposed as the cause of the interfacial instabilities. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1376–1386, 2019 [ABSTRACT FROM AUTHOR]

Abstract A microfluidic SERS chip integrated with blood separation and in-situ detection was designed and fabricated for the rapid detection of clinical blood samples. Each functional unit in the microfluidic SERS chip consist of separation-decantation cavity based on centrifugal separation principle, mixing channels and SERS detection chamber built with integrated nano-Au on Ag film microstructure. The serum creatinine was selected as a typical sample to demonstrate the capability of microfluidic SERS chip. It was found that the creatinine SERS characteristic peaks at 678 cm−1 can be effectively identified and the detection limit could be as low as 4.42 × 10−3 μmol mL−1 in water. The blood samples were also tested in microfluidic SERS chip. The whole separation and test process could be completed within 2 min, which is a significant improvement in the field of creatinine detection. The whole blood of six cases clinical blood samples were also tested, and the results were consistent with the enzymatic results. The developed microfluidic SERS chip has advantages including reduction of the required quantity of blood sample, reusable and easy to operate. It is expected to provide a new method for rapid diagnostics. Graphical abstract fx1 Highlights • Nano-Au on Ag film taken as SERS substrate was prepared in-situ in the detecting chamber for detection. • The serum separated by microchannels was directly injected into the chamber on the designed chip for SERS detection. • The integrated microfluidic SERS chip was applied to detect rapidly the clinical serum creatinine within 2 min. [ABSTRACT FROM AUTHOR]

Excellent detection capability, a simple assay procedure, and easy device acquisition are three key factors to analyze biomarkers for disease diagnosis using a point-of-care device in resource-limited settings or in emergency situations. However, constructing a platform with the simultaneous presence of these factors to sense multiple biomarkers remains a challenge. In the spirit of "frugal science", a simple method is developed by combining a low-cost portable paper centrifuge with surface-enhanced Raman scattering (SERS) immunoassay for sample pretreatment and multiple-cytokine (IL-6, IL-1, and TNF-α) detection. The paper centrifuge can achieve rapid blood separation as a commercial centrifuge and also concentrate sandwich immune composites to generate abundant hot spots, thus enhancing the SERS signal. By analyzing three prospective cytokines (IL-6, IL-1, and TNF-α) closely related to tumors, the combined paper centrifugation–SERS immunoassay method realizes sensitive assays with detection limits down to 0.86, 0.42 and 0.22 pg/mL. Meanwhile, the proposed approach possesses capabilities of specific recognition and accurate quantitative detection for three cytokines in serum. Hence, the constructed multifunctional SERS platform is expected to be applied in the development of decentralized and battery-free diagnostic devices in facility-limited areas and field settings. [Display omitted] • A combined paper centrifugation–SERS immunoassay method is developed. • Paper centrifuge can achieve rapid blood separation as a commercial centrifuge. • Sensitive, quantitative, and specific detection for three cytokines are realized. [ABSTRACT FROM AUTHOR]

A microfluidic chip, which can separate and enrich leukocytes from whole blood, is proposed. The chip has 10 switchback curve channels, which are connected by straight channels. The straight channels are designed to permit the inertial migration effect and to concentrate the blood cells, while the curve channels allow the Dean flow to further classify the blood cells based on the cell sizes. Hydrodynamic suction is also utilized to remove smaller blood cells (e.g., red blood cell (RBC)) in the curve channels for higher separation purity. By employing the inertial migration, Dean flow force, and hydrodynamic suction in a continuous flow system, our chip successfully separates large white blood cells (WBCs) from the whole blood with the processing rates as high as 1 × 108 cells/sec at a high recovery rate at 93.2% and very few RBCs (~0.1%).

Shape-based separation capabilities of a novel pinched flow fractionation device with a tilted sidewall and vertical focusing channels (t-PFF-v) were demonstrated for (1) spherical and disc-shaped polystyrene (PS) particles; (2) platelets (PLT) and red blood cells (RBC); and (3) singlet, doublet, and triplet clusters of disc-shaped PS particles. The tilted sidewalls and vertical focusing channels of the t-PFF-v device allowed us to perform enhanced separation of non-spherical particles. Using this t-PFF-v device with a W p (pinched segment width) of 20 μm and 15 μm, not only spherical (diameter of 2 μm) and disc-shaped (thickness of ∼2 μm, diameter of ∼5.0 μm) PS particles but also PLTs and RBCs from diluted blood were well separated with good separation resolutions (R disc,sphere = 1.40 and R PLT,RBC = 1.28). Additionally, time-lapse images of flowing particles indicated that both disc-shaped PS particles and RBCs are probably having type I orientation in the pinched segment (i.e., leaning against the tilted sidewalls at the pinched segment). Moreover, we observed streamlines of singlet, doublet, and triplet clustered disc-shaped PS particles, which suggested that these clustered particles could be well separated according to their aspect ratio. The doublet or triplet clustered PS particles are probably lay on the floor and rotated at the pinched segment (type II orientation). We believe that this shape-based separation capability achieved by the t-PFF-v device can be utilized for many application areas, such as medical, biological, material and colloidal sciences. [ABSTRACT FROM AUTHOR]

Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and biological research. Yet, processing blood is not trivial. In the past decade, a flurry of new microfluidic based technologies has emerged to address this compelling problem. Microfluidics is an attractive solution for this application leveraging its numerous advantages to process clinical blood samples. This paper reviews the various microfluidic approaches realized to successfully fractionate one or more blood components. Techniques to separate plasma from hematologic cellular components as well as isolating blood cells of interest including certain rare cells are discussed. Comparisons based on common separation metrics including efficiency (sensitivity), purity (selectivity), and throughput will be presented. Finally, we will provide insights into the challenges associated with blood-based separation systems towards realizing true point-of-care (POC) devices and provide future perspectives.

This paper describes continuous sorting and washing of cancer cells from blood samples by three-dimensional rotating flows and hydrophoretic cell focusing in a microchannel with slant trenches. Sample preparation for analysis of cancer cells such as sorting and washing is an important pre-requisite for their downstream analysis ( i.e. enumeration or molecular characterization of cancer cells). Current cell separators, however, provide the capability of either sorting or washing. Washing process is routinely per- formed off-chip, preventing the automation of cell-based assays and point-of-care diagnostics. We present here a microfluidic method for on-chip cell sorting and washing. Slant trenches on a channel floor generate rotational flow streams and enable manipulation of the streams to passively cross cancer cells which remain focused in their equilibrium position by hydrophoresis. Using this device, we sorted cancer cells from contaminant particles and simultaneously washed them with a clean buffer, achieving high blood cell rejection efficiency of 99.3% and washing efficiency of 99.0%. The device enables simultaneous sorting and washing of cancer cells which can facilitate high-performance, automated cancer cell analysis. [ABSTRACT FROM AUTHOR]

A novel device of smart pipette has been suggested to extract and deliver plasma from whole blood in a disposable format. By operating an on-chip disposable micropump, approximately 30 μL of plasma was obtained from 100 μL of whole blood within 5 min without any external equipment for point-of-care blood analysis. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Evaluation and diagnosis of blood alterations is a common request for clinical laboratories, requiring a complex technological approach and dedication of health resources. In this paper, we present a microfluidic device that owing to a novel combination of hydrodynamic and dielectrophoretic techniques can separate plasma from fresh blood in a microfluidic channel and for the first time allows optical real-time monitoring of the components of plasma without pre- or post-processing. The microchannel is based on a set of dead-end branches at each side and is initially filled using capillary forces with a 2-μL droplet of fresh blood. During this process, stagnation zones are generated at the dead-end branches and some red blood cells (RBCs) are trapped there. An electric field is then applied and dielectrophoretic trapping of RBCs is used to prevent more RBCs entering into the channel, which works like a sieve. Besides, an electroosmotic flow is generated to sweep the rest of the RBCs from the central part of the channel. Consequently, an RBC-free zone of plasma is formed in the middle of the channel, allowing real-time monitoring of the platelet behavior. To study the generation of stagnation zones and to ensure RBC trapping in the initial constrictions, two numerical models were solved. The proposed experimental design separates up to 0.1 μL blood plasma from a 2-μL fresh human blood droplet. In this study, a plasma purity of 99 % was achieved after 7 min, according to the measurements taken by image analysis. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Blood is the richest source of diagnostic information. The growing interest in point-of-care analytics prompted several attempts to extract plasma from whole blood in simple diagnostic devices. The simplest method of separation is sedimentation. Here we show the first microfluidic system that uses sedimentation to extract plasma from undiluted blood and integrates execution of liquid assays on the extracted material. We present a microfluidic chip that accepts a small sample (27 μL) of whole blood, separates up to 6 μL of plasma, and uses metered volumes of plasma and of reagent (2-chloro-4-nitrophenyl-α-maltotrioside, CNP-G3) for a liquid enzymatic assay. With a custom designed channel, the system separates blood by sedimentation within few minutes of accepting the sample, mixes it with the reagent, and quantifies spectrophotometrically the product of the enzymatic reaction. As a model demonstration, we show a quantitative enzymatic α-amylase assay that is routinely used in diagnosis of pancreas diseases. The paper reports the design and characterization of the microfluidic device and the results of tests on clinically collected blood samples. The results obtained with the microfluidic system compare well to a reference bench-top analyzer. [ABSTRACT FROM AUTHOR]

SUMMARY Background The ErySep system represents an alternative to centrifuge-based whole blood ( WB) separation, using gravity and filtration through hollow-fibres (0·2 µm pore size) to produce red blood cell ( RBC) and plasma components. The aim of this study was to characterise the quality of ErySep RBC and plasma units compared with standard products from WB held overnight. Methods/Materials Two ABO-compatible WB units ( n = 24) were pooled and split to produce matched products. One of the WB units was separated into components using the ErySep system ( ErySep; n = 12), whereas the other units were separated by centrifugation (control; n = 12). RBC units were stored at 2-6 °C and assessed for in vitro quality over 42 days of storage. Plasma was frozen at −30 °C and tested upon thawing. Results Processing WB with the ErySep system took longer than controls. The ErySep RBC units were of an appropriate volume (307 ± 17 mL) and contained sufficient Hb (50 ± 2 g unit−1). ErySep RBC components contained more microparticles relative to controls at expiry. The plasma volume, total protein, coagulation factor activity (fibrinogen, FV, FVIII) and number of microparticles was lower in the ErySep units compared with controls. Conclusion Following overnight hold of WB, the ErySep system was capable of producing RBC components that met specifications. However, the ErySep plasma components did not meet quality specifications. [ABSTRACT FROM AUTHOR]

In this paper, a microfluidic chip inspired by fish gills has been designed and fabricated in order to separate blood cells from serum. This microchip is modeled after fish gills which filter particles from fluids. In this way, the blood passes through a reservoir that contains several parallel rows of filter columns, which perform the filtering action. COMSOL Multiphysics software was used to conduct several simulations to optimize the pressure and velocity parameters of blood entering the microchip, and these parameters were used to determine the appropriate dimensions of the microchip. The simulation results indicate that the microchip is able to completely separate the cells from the serum, assuming a blood flow rate of 134 μl/s. With the help of the proposed filter, blood cells are separated from the plasma after 20 s and the aggregation occurs in the outlet reservoirs. In order to fabricate the microchip, the filter component made of polydimethylsiloxane (PDMS) was bonded to the copper substrate. In this paper a new copper to PDMS bonding process is proposed. Copper was chosen as the substrate because it allows the application of voltage to separate particles through the Dielectrophoresis method. The chemical etching method reinforced with noble metals was used to create micro holes on the silicon wafer, which are used to mold PDMS filters with a diameter of several micrometers. The main reservoir with a depth of 20 µm was created by the wet etching method. The reservoir was coated with silane coating and the oxygen plasma was utilized to bond the PDMS filters and the main reservoir. The copper substrate allows the microchip to be used with other electronic devices and circuits on printed circuit boards. Scanning Electron Microscopy (SEM) was used to observe the silane-coated copper surface, the micro holes on the silicon wafer, and the PDMS pillars. The topography and roughness of the copper surface before and after silane coating was evaluated through Atomic Force Microscopy (AFM). Optical Microscopy (OM) was utilized to observe the separation of the cells from the plasma. The results showed acceptable adhesion between copper and PDMS and good results for serum separation from blood cells. [Display omitted] • Design and simulation of Microfluidic Chip inspiring fish gill geometry. • Ag Assisted Chemical Etching of Si for fabrication of mold of PDMS micro pillars. • Proposing Silane intermediate layer to bond PDMS and copper. • Proposing a process for implementation of microfluidic chips with electronics, all in one. [ABSTRACT FROM AUTHOR]

Micro-manufacturing is a fast developing area due to the increasing demand for components and systems of high precision and small dimensions. A number of challenges are yet to be overcome before the full potential of such techniques is realised. Examples of such challenges include limitations in component geometry, material selection and suitability for mass production. Some micro-manufacturing techniques are still at early development stages, while other techniques are at higher stage of manufacturing readiness level but require adaptation in part design or manufacturing procedure to overcome such limitations. This article presents a case study, where the design of a micro-scale, biomedical device is adapted for functionality and manufacturability by a high-volume micro-fabrication technique. Investigations are described towards a disposable three-dimensional, polymer-based device for the separation of blood cells and plasma. The importance of attempting a three-dimensional device design and fabrication route was to take advantage of the high-throughput per unit volume that such systems can, in principle, allow. The importance of a micro-moulding fabrication route was to allow such blood-containing devices to be cheaply manufactured for disposability. Initial device tests showed separation efficiency up to approximately 80% with diluted blood samples. The produced prototype indicated that the process flow was suitable for high-volume fabrication of three-dimensional microfluidics. [ABSTRACT FROM PUBLISHER]

Abstract: The plasma separation rate is enhanced significantly, as much as 8 times faster for whole blood, by simple change of the channel geometry in a rotating disc. It was enhanced in the channels with narrower channel widths and larger tilt angles with respect to the radial direction but independent of the channel depth or spin direction. A modified Ponder-Nakamura-Kuroda (PNK) theory could nicely fit all of the experimental data to a linear line, which data were obtained from spinning discs with various channel designs and blood samples with broad hematocrit range. To the best of our knowledge, this is the first investigation of geometry effects on the particle separation rate on a rotating disc and it will potentially contribute to the further performance enhancement of centrifugal microfluidic devices. [Copyright &y& Elsevier]

Abstract: To set up a point-of-care whole-blood immunoassay system, sample preparation and on-chip storage of conjugate reagents are indispensable functional units. Here, we merge these functions into a deposited microbead plug (DMBP) to simultaneously play the roles of a blood filter and a conjugate reagent carrier. The DMBP was easily fabricated by the use of natural deposition of beads without the need of weirs. Conjugate reagents (FITC labeled antibodies used here) were incorporated into the DMBP during the assembly of the DMBP. To demonstrate the ability of the DMBP, we constructed a DMBP-based microfluidic chip and used it for the detection of human IgG (hIgG). The DMBP enabled to remove blood cells from whole blood and provide the pure plasma for the downstream on-chip immunoreactions. The release of reconstituted FITC labeled antibodies from the DMBP was controlled in a passive fashion. Dry FITC labeled antibodies retained at least 81% of their activity after 60 days of storage at the room temperature. The DMBP presented here makes an important step towards the development of the self-contained, integrated, sample-to-answer microfluidic chips for point-of-care diagnostics. [Copyright &y& Elsevier]

Abstract: When aiming a complete microfluidic analysis system for human blood tests the blood plasma separation should be preferably also integrated in the device. The sensitivity of the analysis is significantly affected by the sample quality, so in this work the efficiency of the Zweifach-Fung effect based microfluidic separation systems was characterized. The microstructures were fabricated by simple replication in polydimethylsilixane applying SU-8 photoresist master beside extensive variation of the geometric parameters. [Copyright &y& Elsevier]

Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and biological research. Yet, processing blood is not trivial. In the past decade, a flurry of new microfluidic based technologies has emerged to address this compelling problem. Microfluidics is an attractive solution for this application leveraging its numerous advantages to process clinical blood samples. This paper reviews the various microfluidic approaches realized to successfully fractionate one or more blood components. Techniques to separate plasma from hematologic cellular components as well as isolating blood cells of interest including certain rare cells are discussed. Comparisons based on common separation metrics including efficiency (sensitivity), purity (selectivity), and throughput will be presented. Finally, we will provide insights into the challenges associated with blood-based separation systems towards realizing true point-of-care (POC) devices and provide future perspectives. [ABSTRACT FROM AUTHOR]

Abstract: A major requirement for the development of point-of-care tests for the detection of disease analytes is the need to separate plasma from whole blood in an efficient and rapid manner. Furthermore, the separated plasma must be able to elute efficiently the analyte of interest and serve effectively as a physical matrix to deliver the equivalent of neat plasma for downstream diagnostic analysis. Additionally, many applications require the use of heat shock to liberate immunocomplexed antigen found in the collected plasma. A membrane-based filter method is reported for rapid and efficient collection of plasma from a whole blood sample that is compatible with heat shock. Using pediatric human immunodeficiency virus as an example, this device elutes 100% of the input p24 core antigen post-collection and enables heat shock of plasma samples identical to neat plasma treatment. [Copyright &y& Elsevier]

Abstract: This paper presents a microfluidic device that can separate and extract blood plasma from several microliters of blood without external mechanical driving sources such as a centrifugal machine and a syringe pump. This device consists of a main-channel, many side-channels, a reservoir, and two electrodes. After blood was automatically injected into the main-channel by capillary force, blood cells blocked the side-channel entrances and prevented blood plasma from entering them. Next, when AC voltage application between the two electrodes separated blood into cells and plasma by dielectrophoresis (DEP), cells were removed from the side-channel entrances. This permitted plasma to be injected into the side-channels connecting to the reservoir. Experiments using diluted blood samples (dilution 1:9) showed that blood cell removal and blood plasma extraction were affected by channel geometry and magnitude/frequency of applied AC voltage. In case of applied AC voltage of 10V and 1MHz, blood cells were removed by about 97%, and blood plasma of about 300nL was extracted from 5μL blood. Moreover, we found that optimal dimension of the side-channels for blood plasma extraction is 5μm wide and 2μm deep. [Copyright &y& Elsevier]

Real-time quantitative polymerase chain reaction (RQ-PCR) has been accepted as integral part of the management of patients with hematologic malignancies. Whereas standardization efforts of RQ-PCR, initiated by Europe Against Cancer (EAC) group, have been gradually widespread in the world, Japanese laboratories use their individual protocol for RQ-PCR analysis. Therefore, we assessed the variability of quantitative results obtained from 4 different laboratories in Japan, including 3 companies and Tohoku University Hospital, using identical peripheral blood or bone marrow samples of patients in chronic myeloid leukemia (CML; n = 11) and acute myeloid leukemia (AML; n = 2). RQPCR was designed to quantify the copy numbers of disease-specific fusion chimeras; BCRABL (CML) and AML1-ETO (AML). In 5 out of 13 samples, the quantitative results from 4 laboratories varied more than 10 times (up to 712 times). Thus, we next sought to determine factors affecting the variability of RQ-PCR results across laboratories, by sending back RNA and cDNA samples from each company to Tohoku University, and they were further proceed to yield quantitative data. The main difference between companies and Tohoku University was probably due to the difference of blood separation method (Blood lysis or Ficoll-Hypaque). On the other hand, the variability among 4 laboratories was the most noticeable in the PCR step, mainly attributable to the difference of primer/probe sequence among laboratories. In conclusion, our analyses indicate the importance to limit both preanalytical (sample processing) and analytical (RQ-PCR) interlaboratory variability for RQ-PCR protocol, and the need of further efforts on standardization program in Japan. [ABSTRACT FROM AUTHOR]

The aim of this work is to construct a computational fluid dynamics model capable of simulating the transient non-Newtonian process of apheresis. A Lagrangian–Eulerian model has been developed which tracks the blood particles within a two-dimensional flow configuration. Within the Eulerian method, the fluid mass and momentum conservation equations within the separator are solved using the density and the viscosity is calculated from the blood particle concentrations. Subsequently, the displacement of the blood particles is calculated with a Lagrangian method. Hawksley's model for the density of supensions is used in the variable density calculation. The viscosity is calculated with two models based on Vand's rigid particle suspension viscosity concepts, followed by the flow field calculation in the separator. Simulations were performed for various inlet hematocrit values and separator lengths. The simulations are in satisfactory agreement with experimental results reported in literature, indicating a complete separation of plasma and red blood cells (RBCs), as well as nearly complete separation of red blood cells and platelets. No hemolysis was observed in the simulations because the shear rate remained under the critical value of 150 N/m2. [ABSTRACT FROM AUTHOR]

Abstract: None of the present magnetic separators is capable of achieving the classification of particles according to their magnetic susceptibility. We have developed a new apparatus to attain these magnetic classification goals. In this paper, the design of the continuous-mode large-scale prototype of the magnetic classifier is presented. Many areas of application are foreseen for this device, and we analyse two of them – health sciences and chemical engineering – presenting also some possible application cases within these areas. [Copyright &y& Elsevier]

The aim of this study was to assess the separation of whole blood into red cells and plasma by using the Sangofer® device, which is a gravity-fed, hollow-fibre system. The components would then be compared with those produced by the use of more elaborate technical equipment. Ten whole-blood units were leucoreduced by using a WBF2 filter and immediately separated into red cells and plasma by using the Sangofer® blood-separation device. Red cells were stored in additive solution and tested on days 1 and 42. The plasma was assayed for levels of various coagulation factors and for markers of both coagulation and complement activation. The red-cell parameters were similar to those obtained when routine centrifugation methods were used. The filter did not cause haemolysis. Levels of plasma factor VIII and factor XI were lower than those seen in routinely produced leucoreduced plasma units but there was no evidence of activation of the coagulation and complement systems. The Sangofer® device is simple and straightforward to use and eliminates the need for both centrifugation and automated separation steps during the processing of whole blood into red cells and plasma components. Minor changes are required to make the procedure easier to incorporate into routine use. [ABSTRACT FROM AUTHOR]

The aim of this work is to construct a computational fluid dynamics model capable of simulating the quasitransient process of apheresis. To this end a Lagrangian–Eulerian model has been developed which tracks the blood particles within a delineated two-dimensional flow domain. Within the Eulerian method, the fluid flow conservation equations within the separator are solved. Taking the calculated values of the flow field and using a Lagrangian method, the displacement of the blood particles is calculated. Thus, the local blood density within the separator at a given time step is known. Subsequently, the flow field in the separator is recalculated. This process continues until a quasisteady behavior is reached. The simulations show good agreement with experimental results. They shows a complete separation of plasma and red blood cells, as well as nearly complete separation of red blood cells and platelets. The white blood cells build clusters in the low concentrate cell bed. [ABSTRACT FROM AUTHOR]

Accurately monitoring blood glucose in real-time is highly required for diabetes. Utilizing membrane to realize fast separation of a trace of blood is significant for accurately testing blood glucose. In this work, we designed a Janus membrane with thin film composite structure by electrospinning polyurethane (PU) on Ca 3 (PO 4) 2 -coated nylon mesh. This Janus membrane exhibited directional liquid transport performance and liquid wastage reduction during separation through optimizing the surface wettability, pore parameters and asymmetric structures of membrane. When a trace of water with volume as small as 3 μL was dipped on the hydrophobic side with pore size of around 1.1 μm, this water droplet could easily penetrate through the Janus membrane within 2.9 s under only gravity and liquid wastage reduction was achieved at the same time (D 2 /D 1 = 1.27), suggesting an excellent liquid transportation performance. The blood glucose meter integrated with this Janus membrane could efficiently remove red blood cells from 10 μL blood within 7.2 s. As a result, the sensitivity of the blood glucose meter increased by 4.5%. Image 1 • Janus membrane was prepared via phase inversion assisted dip coating process combining electrospining process. • Directional transport of a trace of water with little wastage was realized on this membrane. • The Janus membrane could efficiently remove red blood cells from 10 μL blood within 7.2 s. • The sensitivity of blood glucose meter integrated with the Janus membrane was increased by 4.5%. [ABSTRACT FROM AUTHOR]

A microfluidic chip, which can separate and enrich leukocytes from whole blood, is proposed. The chip has 10 switchback curve channels, which are connected by straight channels. The straight channels are designed to permit the inertial migration effect and to concentrate the blood cells, while the curve channels allow the Dean flow to further classify the blood cells based on the cell sizes. Hydrodynamic suction is also utilized to remove smaller blood cells (e.g., red blood cell (RBC)) in the curve channels for higher separation purity. By employing the inertial migration, Dean flow force, and hydrodynamic suction in a continuous flow system, our chip successfully separates large white blood cells (WBCs) from the whole blood with the processing rates as high as 1 × 108 cells/sec at a high recovery rate at 93.2% and very few RBCs (~0.1%). [ABSTRACT FROM AUTHOR]