Disposable Chamber Research Articles

DNA-Binding Magnetic Nanoreactor Beads for Digital PCR Analysis.

Digital PCR (dPCR) is based on the separation of target amplification reactions into many compartments with randomly distributed template molecules. Here, we present a novel digital PCR format based on DNA binding magnetic nanoreactor beads (mNRBs). Our approach relies on the binding of all nucleic acids present in a sample to the mNRBs, which both provide a high-capacity binding matrix for capturing nucleic acids from a sample and define the space available for PCR amplification by the internal volume of their hydrogel core. Unlike conventional dPCR, this approach does not require a precise determination of the volume of the compartments used but only their number to calculate the number of amplified targets. We present a procedure in which genomic DNA is bound, the nanoreactors are loaded with PCR reagents in an aqueous medium, and amplification and detection are performed in the space provided by the nanoreactor suspended in fluorocarbon oil. mNRBs exhibit a high DNA binding capacity of 1.1 ng DNA/mNRB (95% CI 1.0-1.2) and fast binding kinetics with ka = 0.21 s-1 (95% CI 0.20-0.23). The dissociation constant KD was determined to be 0.0011 μg/μL (95% CI 0.0007-0.0015). A simple disposable chamber plate is used to accommodate the nanoreactor beads in a monolayer formation for rapid thermocycling and fluorescence detection. The performance of the new method was compared with conventional digital droplet PCR and found to be equivalent in terms of the precision and linearity of quantification. In addition, we demonstrated that mNRBs provide quantitative capture and loss-free analysis of nucleic acids contained in samples in different volumes.

Performance comparison of piezo actuated valveless micropump with central excitation and annular excitation for biomedical applications

In recent years, microfluidic devices, particularly micropumps, are extensively utilized in biomedical applications. The micropump used in biomedical applications needs to possess precise delivery of fluids at requires rate and pressure. The present work proposes a valveless mechanical micropump with a disposable chamber integrated with a novel concept of annular excitation of the diaphragm to fulfil the need for precise delivery of fluids in biomedical applications. The proposed design of the micropump involves a reusable configuration of the amplified piezoelectric actuator (APA) for micropump actuation and a disposable pump chamber. The pumping of the fluids occurs through the oscillation of the silicone rubber bossed diaphragm. The performance of a mechanical micropump depends on the oscillation amplitude of the diaphragm. Thus, the conventional approach of central excitation of the bossed diaphragm is replaced by a novel approach of annular excitation intended to enhance the deflection range, thus the volumetric performance of the micropump. An experimental comparative study is carried out to assess the deflection characteristics of central excitation and annular excitation of the bossed diaphragm. The maximum deflection measured with the annularly excited configuration of the bossed diaphragm is about 1953.4 ± 8.00 µm at 150 V, 43.5 Hz, which is superior to the maximum deflection of centrally excited configuration delivering 717.99 ± 4.00 µm at 150 V, 9.5 Hz. Further, the experimental studies aimed to fabricate and characterize the micropump with central and annular excitation approaches. The proposed micropump with central excitation delivered the maximum water flow rate of about 7.192 ± 0.147 ml min−1 and backpressure of 0.294 kPa at 150 V, 5 Hz. However, the enhancement of the deflection characteristics of the bossed diaphragm under annular excitation leads to performance enhancement of the micropump with the flow rate of 95.10 ± 0.444 ml min−1 and backpressure of 1.472 kPa at 150, 30 Hz

Performance analysis of valveless micropump with disposable chamber actuated through Amplified Piezo Actuator (APA) for biomedical application

The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable actuator with the proposed micropump allows the actuator to be reused and eliminates the possibility of infection or contagion. The micropump was fabricated using low-cost polymeric materials like Polymethylmethacrylate (PMMA), Silicone rubber through CNC milling, Laser Cutting, conventional moulding operation. The micropump chamber, nozzle/diffusers, and a bossed diaphragm constituted disposable part and Amplified Piezo Actuator with structural support formed the reusable part of the micropump. The bossed diaphragm of the pump chamber consists of a central cylindrical protrusion to reduce the force of adhesion on the diaphragm and transmit force required for micropump actuation. A theoretical analysis was performed to assess the effect of diaphragm thickness and the bossed region on the effective stiffness of the diaphragm, which in turn influences the deflection achieved. Besides, an analytical approach has been presented to address the effect of adhesive force on the diaphragm surface due to the residual fluid and chamber depth. The experimental characterization of the micropump was carried out to determine the optimal performance parameters with water, fluids mimicking blood plasma, and whole blood. Based on the experimental results, the pumping rate and head developed by the micropump have been significantly affected by factors such as bossed ratio, diaphragm thickness, depth of the micropump chamber, and viscosity of the fluid. The optimum configuration of the micropump cosidered silicone rubber diaphragm with thickness of 0.20 mm having a bossed ratio of 0.33 and a chamber depth of 1.25 mm. With the optimal operating parameters of 150 V sinusoidal input of frequency 5 Hz, the proposed micropump was capable of delivering 7.192 ml/min, 6.108 ml/min, and 5.013 ml/min of water and blood plasma, whole blood mimicking fluid with the maximum backpressure of 294.00 Pa, 226.243 Pa, and 204.048 Pa respectively. The corresponding resolution, i.e., pumping volume/stroke of the micropump was about 23.972 µl, 20.358 µl, and 16.708 µl, respectively.

Experimental investigation on performance of disposable micropump with retrofit piezo stack actuator for biomedical application

Extensive researches are being conducted to develop miniaturized pumping systems to fulfill the need for accurate delivery of fluids at required rates, particularly in the biomedical field. This paper presents the design, fabrication, and testing of novel valveless micropump actuated through an amplified piezo actuator. The proposed model of the micropump pump has the unique feature of a disposable chamber and employs low-cost polymeric materials, conventional molding and machining operations for fabrication. The disposable part of the pump consists of a laser-cut pump chamber with nozzle/diffuser made of Polymethyl methacrylate (PMMA) and conventionally molded silicone rubber diaphragm. The retrofit part includes the amplified piezo actuator and support structures build from PMMA. Systematic characterization of the pump was carried with water and blood mimicking fluid to understand the effect of operating parameters such as driving frequency and actuation voltage on flow rate and back pressure of the micropump. Experimental results show that the proposed design was capable of pumping 3.3–3.4 ml/min of dye solution and 1.7–1.75 ml/min of blood mimicking fluid at a driving frequency of 5 Hz and actuation voltage of 150 V. The corresponding computed volume resolution/stroke of the pump was found to about 5.75 µl and 11.25 µl of blood mimicking fluid and dye solution, respectively. The proposed pump was found to work effectively against a maximum back pressure of 156 Pa with blood mimicking fluid and 250 Pa with the dye solution as the working fluid under the same operating condition of 5 Hz and 150 V.

A miniature circular pump with a piezoelectric bimorph and a disposable chamber for biomedical applications

Piezoelectric miniature pumps provide excellent stability and accuracy, and thus, have been used in fluid handling and medical applications. In the current study, a separable piezoelectric miniature pump was developed by combining a piezoelectric bimorph actuator and a disposable pumping chamber. By employing a single-use disposable pumping chamber the cross-contamination issues caused by repeated uses of the pumping chamber can be easily avoided, making the pump ideal for biological fluid transmission process. The pumping in the proposed miniature pump was indirectly driven by a circular piezoelectric bimorph actuator through a pillar structure that connects the actuator with the covering PET diaphragm of the pumping chamber. The pumping efficiency of the proposed miniature pump was investigated with respect to several parameters, such as the diaphragm thickness, the chamber diameter and the pillar-to-chamber ratio. A maximum flow rate of 9.1mL/min was achieved by using the proposed pump structure with 10mm chamber diameter and a pillar-to-chamber ratio of 0.9.

Differences in CASA output according to the chamber type when analyzing frozen-thawed bull sperm

As demonstrated by some authors, the type of analyzing chamber can greatly influence the results of computer-assisted sperm analysis (CASA). This study aimed to compare three of the disposable chamber types currently available on the market and to determine whether the CASA output may be significantly different among them. The semen from five Fleckvieh bulls was analyzed by CASA using three different disposable chambers: Leja (20μm), MofA (20μm) and Minitube (20μm), at three different time points: immediately after filling the chamber, at 6min, and also at 12min after filling. Sperm concentration was also determined using the Nucleocounter® NC-100™ device and the hemocytometer as standard methods. The results showed higher values in terms of total and progressive sperm motility for MofA compared to the other two chambers immediately after filling (p<0.05), but higher values for Leja and Minitube after 6 and 12min (p<0.05). All three disposable chambers offered lower values for sperm concentration compared to standard methods (Leja: 68.4±4.9×106/mL; MofA: 80.8±9.6×106/mL; Minitube: 67.3±5.4×106/mL; Nucleocounter: 86.5×106/mL; Hemocytometer: 84.0×106/mL). We conclude that for rapid analyses the MofA chambers provide superior results when compared to the other types that we tested. However, when the analysis requires a longer duration, the Minitube type, and especially the Leja type provide a greater degree of confidence. Further, for determining sperm concentration we think that examiners would be more accurate using the Nucleocounter or the hemocytometer and should make use of CASA only when the other methods are not available.

Comparison of different counting chambers using a computer-assisted semen analyzer

A routine computer-assisted sperm analysis is an important diagnostic test in the andrology laboratory. To evaluate the accuracy and precision of the different types of counting chambers for human semen analysis in combination with a computer-assisted semen analyzer (CASA), a quality-control study that compared human sperm analysis results obtained using different counting chambers (Makler chamber, disposable 8-cell GoldCyto chamber, disposable 4-cell Leja chamber, a plain glass slide, and a tissue culture dish cover with a 24 × 24 mm2 coverslip) in conjunction with the CASA systems was performed. Significantly higher counts of sperm concentration were obtained from the reusable Makler chamber than from the other counting chambers. Sperm motility from drop loaded counting chambers was significantly higher than that of capillary-loaded chambers. A plain glass slide and a tissue culture dish cover used with a coverslip showed rather better performance in semen assessment. Disposable chambers are suitable for routine semen analysis with CASA in a diagnostic andrology setting. With the proper workflow and quality control, a plain glass slide and the tissue culture dish cover are acceptable alternatives for routine counting chambers with CASA as necessary. The type of counting chamber should be specified in test reports.

Membrane-based, sedimentation-assisted plasma separator for point-of-care applications.

Often, high-sensitivity, point-of-care (POC) clinical tests, such as HIV viral load, require large volumes of plasma. Although centrifuges are ubiquitously used in clinical laboratories to separate plasma from whole blood, centrifugation is generally inappropriate for on-site testing. Suitable alternatives are not readily available to separate the relatively large volumes of plasma from milliliters of blood that may be needed to meet stringent limit-of-detection specifications for low-abundance target molecules. We report on a simple-to-use, low-cost, pump-free, membrane-based, sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes. This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a "blood in-plasma out" capability, consistently extracting 275 ± 33.5 μL of plasma from 1.8 mL of undiluted whole blood within less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3500, and 350 copies/mL, respectively. The separation process is self-terminating to prevent excessive hemolysis. The HIV-laden plasma was then injected into our custom-made microfluidic chip for nucleic acid testing and was successfully subjected to reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP), demonstrating that the plasma is sufficiently pure to support high-efficiency nucleic acid amplification.

Evaluation of a disposable plastic Neubauer counting chamber for semen analysis

To evaluate whether disposable plastic counting chambers effectively could replace nondisposable, time-consuming, and potentially dangerous glass hemocytometers. Evaluation of equipment in modern laboratory andrology. Comparison of results obtained with plastic chambers with results obtained with "gold-standard" glass hemocytometer counts. Diagnostic laboratory for andrology. Twenty-one patients undergoing investigation for infertility problems. No interventions with patients; sperm in diluted semen samples were used when patients had allowed the use for research and training. Sperm concentration, difference from results obtained with standard equipment. In the first three experimental series, with use of standard routine phase-contrast microscopy, significantly lower count results were obtained consistently from the plastic chambers than from standard chambers. In the fourth series, with use of specialized equipment, equivalent results were obtained but with a considerably greater time commitment because of difficulties in distinguishing sperm adjacent to the gridlines in the plastic chambers. The plastic disposable chamber type was not suitable for routine semen analysis because results are variable depending on the microscope used, and increased time is necessary to do the assessment accurately.

Recycling nebulization system with a disposable spray chamber for analysis of sub-milligram samples of geological materials using inductively coupled plasma mass spectrometry

A recycling nebulization system with a disposable spray chamber was developed and evaluated for inductively coupled plasma mass spectrometry (ICP-MS). With the recycling nebulization system, 0.5 g of sample solution is sufficient for 8 min of data acquisition. The sensitivity of the recycling nebulization system was similar to a conventional Scott spray chamber system. Twenty-six trace elements were determined by ICP-MS using four internal standards (Ge, In, Re and Bi) to correct for matrix effects, instrumental drift and enrichment of the sample solution by evaporation. The ability to analyse mineral separates weighing less than 0.1 mg is demonstrated with detection limits similar to conventional procedures. Analyses of selected geological reference materials: Canada Centre for Energy and Mineral Technology (CANMET) SY-2 Syenite Rock, United States Geological Survey (USGS) reference material BCR-1 and W-1 and Centre de Recherches Petrographiques et Geochimiques (CRPG) reference material BR indicate good limits of detection, good accuracy and precision, a very low memory effect and low consumption of sample solution. Results compare well with data reported using conventional ICP-MS analysis. Analysis of the USGS geological reference material, PCC-1, for 14 rare earth elements, at ultra-trace concentration levels using cation-exchange preconcentration, is demonstrated, with limits of detection for solids of from 0.01 to 1 ng g–1 and relative standard deviations of less than 15%.

The influence of chamber characteristics on the reliability of sperm concentration and movement measurements obtained by manual and videomicrographic analysis

To assess the influence of chamber design and depth on the accuracy and precision of sperm measurements, manual counting of a standardized latex bead solution and automated sperm motility measurements were made using a Makler chamber (Sefi Medical Industries, Haifa, Israel), Neubauer hemocytometer (American Optical Company, Buffalo, NY), and a new, disposable device (Micro-Cell; Cyto Fluidics, Inc., Silver Spring, MD). Bead counts obtained with the Micro-Cell chamber or hemocytometer were not statistically different from those determined by electronic particle counting, whereas Makler chamber counts were 62% higher. Makler counts had a significantly higher standard deviation, suggesting that counts made with this device are less reproducible. Analyzing live sperm samples, the percentage of motile sperm determined using Micro-Cell and Makler chambers were similar. However, significant differences in sperm concentration and mean velocity were found. The Micro-Cell disposable chamber provided consistent and accurate data on sperm concentration, percent motility, and mean velocity. These differences in sperm measurements emphasize the importance of sampling chamber characteristics on data reliability.

A pulsatile pump for cardiopulmonary bypass and its clinical use.

A pulsatile pump driven by a coil spring, which was designed and constructed by us, is described in this report. It consists of two main parts, a disposable blood chamber and a driving section. The blood chamber has two leaflet valves and a piston, which is covered with two bellofram rolling diaphragms and moves into the housing to draw in and eject the blood. The driving section consists of three cams, an electric motor and a coil spring. The ejection force is wholly produced by the compressed coil spring and is transmitted to the piston in the blood chamber by a rod. This pump allows the ejection pressure, the beat rates, and the stroke volume all to be changed independently. The performance of the pump was tested by using a circulation model where the beat rate was adjusted from 30 to 250 bpm. The output subsequently increased from 0.8 l/min to 5.7 l/min and the stroke volume, from 20.4 ml to 36.7 ml. This new pump has been used for clinical cardiopulmonary bypasses in 24 patients of open heart surgery and the pressure traces during perfusion resembled those of the patients' own hearts.

Disposable organ chamber for perfusion of the ex vivo liver and its use in the treatment of hepatic coma.

A disposable organ chamber for the perfusion of the ex vivo liver has been designed for use in the treatment of patients in hepatic coma by extracorporeal hepatic assist, and in exp