共查询到20条相似文献,搜索用时 15 毫秒
1.
We report the successful fabrication and testing of 3D printed microfluidic devices with integrated membrane-based valves. Fabrication is performed with a low-cost commercially available stereolithographic 3D printer. Horizontal microfluidic channels with designed rectangular cross sectional dimensions as small as 350 μm wide and 250 μm tall are printed with 100% yield, as are cylindrical vertical microfluidic channels with 350 μm designed (210 μm actual) diameters. Based on our previous work [Rogers et al., Anal. Chem. 83, 6418 (2011)], we use a custom resin formulation tailored for low non-specific protein adsorption. Valves are fabricated with a membrane consisting of a single build layer. The fluid pressure required to open a closed valve is the same as the control pressure holding the valve closed. 3D printed valves are successfully demonstrated for up to 800 actuations. 相似文献
2.
Swastika S. Bithi William S. Wang Meng Sun Jerzy Blawzdziewicz Siva A. Vanapalli 《Biomicrofluidics》2014,8(3)
Multiwell plate and pipette systems have revolutionized modern biological analysis; however, they
have disadvantages because testing in the submicroliter range is challenging, and increasing the
number of samples is expensive. We propose a new microfluidic methodology that delivers the
functionality of multiwell plates and pipettes at the nanoliter scale by utilizing drop coalescence
and confinement-guided breakup in microfluidic parking networks (MPNs). Highly monodisperse arrays
of drops obtained using a hydrodynamic self-rectification process are parked at prescribed locations
in the device, and our method allows subsequent drop manipulations such as fine-gradation dilutions,
reactant addition, and fluid replacement while retaining microparticles contained in the sample. Our
devices operate in a quasistatic regime where drop shapes are determined primarily by the channel
geometry. Thus, the behavior of parked drops is insensitive to flow conditions. This insensitivity
enables highly parallelized manipulation of drop arrays of different composition, without a need for
fine-tuning the flow conditions and other system parameters. We also find that drop coalescence can
be switched off above a critical capillary number, enabling individual addressability of drops in
complex MPNs. The platform demonstrated here is a promising candidate for conducting multistep
biological assays in a highly multiplexed manner, using thousands of submicroliter samples. 相似文献
3.
Bacterial culture is a basic technique in both fundamental and applied microbiology. The excessive reagent consumption and laborious maintenance of bulk bioreactors for microbial culture have prompted the development of miniaturized on-chip bioreactors. With the minimal choice of two compartments (N = 2) and discrete time, periodic dilution steps, we realize a microfluidic bioreactor that mimics macroscopic serial dilution transfer culture. This device supports automated, long-term microbial cultures with a nanoliter-scale working volume and real-time monitoring of microbial populations at single-cell resolution. Because of the high surface-to-volume ratio, the device also operates as an effective biofilm-flow reactor to support cogrowth of planktonic and biofilm populations. We expect that such devices will open opportunities in many fields of microbiology. 相似文献
4.
Guillaume Mottet Karla Perez-Toralla Ezgi Tulukcuoglu Francois-Clement Bidard Jean-Yves Pierga Irena Draskovic Arturo Londono-Vallejo Stephanie Descroix Laurent Malaquin Jean Louis Viovy 《Biomicrofluidics》2014,8(2)
We present a low cost microfluidic chip integrating 3D micro-chambers for the capture and the
analysis of cells. This device has a simple design and a small footprint. It allows the
implementation of standard biological protocols in a chip format with low volume consumption. The
manufacturing process relies on hot-embossing of cyclo olefin copolymer, allowing the development of
a low cost and robust device. A 3D design of microchannels was used to induce high flow velocity
contrasts in the device and provide a selective immobilization. In narrow distribution channels, the
liquid velocity induces a shear stress that overcomes adhesion forces and prevents cell
immobilization or clogging. In large 3D chambers, the liquid velocity drops down below the threshold
for cell attachment. The devices can be operated in a large range of input pressures and can even be
handled manually using simple syringe or micropipette. Even at high flow injection rates, the 3D
structures protect the captured cell from shear stress. To validate the performances of our device,
we implemented immuno-fluorescence labeling and Fluorescence in Situ Hybridization
(FISH) analysis on cancer cell lines and on a patient pleural effusion sample. FISH is a Food and
Drug Administration approved cancer diagnostic technique that provides quantitative information
about gene and chromosome aberration at the single cell level. It is usually considered as a long
and fastidious test in medical diagnosis. This process can be easily implanted in our platform, and
high resolution fluorescence imaging can be performed with reduced time and computer intensiveness.
These results demonstrate the potential of this chip as a low cost, robust, and versatile tool
adapted to complex and demanding protocols for medical diagnosis. 相似文献
5.
Deterministic lateral displacement (DLD) is a microfluidic size-based particle separation or filter technology with applications in cell separation and enrichment. Currently, there are no cost-effective manufacturing methods for this promising microfluidic technology. In this fabrication paper, however, we develop a simple, yet robust protocol for thermoplastic DLD devices using regulatory-approved materials and biocompatible methods. The final standalone device allowed for volumetric flow rates of 660 μl min−1 while reducing the manufacturing time to <1 h. Optical profilometry and image analysis were employed to assess manufacturing accuracy and precision; the average replicated post height was 0.48% less than the average post height on the master mold and the average replicated array pitch was 1.1% less than the original design with replicated posts heights of 62.1 ± 5.1 μm (mean ± 6 standard deviations) and replicated array pitches of 35.6 ± 0.31 μm. 相似文献
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A microfluidic device integrated with 3D thin film microelectrode arrays wrapped around serpentine-shaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each microelectrode array has 1015 discrete microelectrodes patterned on each side wall, and the adjacent microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the microelectrode arrays, cells are paired at the edge of each discrete microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the microelectrode arrays to induce electroporation and electrofusion. Compared to the design with thin film microelectrode arrays deposited at the bottom of the side walls, the 3D thin film microelectrode array could induce electroporation and electrofusion under a lower voltage. The staggered electrode arrays on opposing side walls induce inhomogeneous electric field distribution, which could avoid multi-cell fusion. The alignment and pairing efficiencies of K562 cells in this device were 99% and 70.7%, respectively. The electric pulse of low voltage (~9 V) could induce electrofusion of these cells, and the fusion efficiency was about 43.1% of total cells loaded into the device, which is much higher than that of the convectional and most existing microfluidics-based electrofusion devices. 相似文献
7.
Jacquelyn A. Brown Virginia Pensabene Dmitry A. Markov Vanessa Allwardt M. Diana Neely Mingjian Shi Clayton M. Britt Orlando S. Hoilett Qing Yang Bryson M. Brewer Philip C. Samson Lisa J. McCawley James M. May Donna J. Webb Deyu Li Aaron B. Bowman Ronald S. Reiserer John P. Wikswo 《Biomicrofluidics》2015,9(5)
The blood-brain barrier (BBB) is a critical structure that serves as the gatekeeper between the central nervous system and the rest of the body. It is the responsibility of the BBB to facilitate the entry of required nutrients into the brain and to exclude potentially harmful compounds; however, this complex structure has remained difficult to model faithfully in vitro. Accurate in vitro models are necessary for understanding how the BBB forms and functions, as well as for evaluating drug and toxin penetration across the barrier. Many previous models have failed to support all the cell types involved in the BBB formation and/or lacked the flow-created shear forces needed for mature tight junction formation. To address these issues and to help establish a more faithful in vitro model of the BBB, we have designed and fabricated a microfluidic device that is comprised of both a vascular chamber and a brain chamber separated by a porous membrane. This design allows for cell-to-cell communication between endothelial cells, astrocytes, and pericytes and independent perfusion of both compartments separated by the membrane. This NeuroVascular Unit (NVU) represents approximately one-millionth of the human brain, and hence, has sufficient cell mass to support a breadth of analytical measurements. The NVU has been validated with both fluorescein isothiocyanate (FITC)-dextran diffusion and transendothelial electrical resistance. The NVU has enabled in vitro modeling of the BBB using all human cell types and sampling effluent from both sides of the barrier. 相似文献
8.
Caitlin M. Austin William Stoy Peter Su Marie C. Harber J. Patrick Bardill Brian K. Hammer Craig R. Forest 《Biomicrofluidics》2014,8(3)
Biosensors exploiting communication within genetically engineered bacteria are becoming
increasingly important for monitoring environmental changes. Currently, there are a variety of
mathematical models for understanding and predicting how genetically engineered bacteria respond to
molecular stimuli in these environments, but as sensors have miniaturized towards microfluidics and
are subjected to complex time-varying inputs, the shortcomings of these models have become apparent.
The effects of microfluidic environments such as low oxygen concentration, increased biofilm
encapsulation, diffusion limited molecular distribution, and higher population densities strongly
affect rate constants for gene expression not accounted for in previous models. We report a
mathematical model that accurately predicts the biological response of the autoinducer N-acyl
homoserine lactone-mediated green fluorescent protein expression in reporter bacteria in
microfluidic environments by accommodating these rate constants. This generalized mass action model
considers a chain of biomolecular events from input autoinducer chemical to fluorescent protein
expression through a series of six chemical species. We have validated this model against
experimental data from our own apparatus as well as prior published experimental results. Results
indicate accurate prediction of dynamics (e.g., 14% peak time error from a pulse input) and with
reduced mean-squared error with pulse or step inputs for a range of concentrations
(10 μM–30 μM). This model can help advance the design of
genetically engineered bacteria sensors and molecular communication devices. 相似文献
9.
We have investigated the bonding stability of various silane treatments for the integration of
track-etched membranes with poly(dimethylsiloxane) (PDMS) microfluidic devices. We compare various
treatments using trialkoxysilanes or dipodal silanes to determine the effect of the organofunctional
group, cross-link density, reaction solvent, and catalyst on the bond stability. We find that
devices made using existing silane methods delaminated after one day when immersed in cell culture
medium at 37 °C. In contrast, the dipodal silane, bis[3-(trimethoxysilyl)propyl]amine, is shown to
yield stable and functional integration of membranes with PDMS that is suitable for long-term cell
culture. To demonstrate application of the technique, we fabricated an open-surface device in which
cells cultured on a track-etched membrane can be stimulated at their basal side via embedded
microfluidic channels. C2C12 mouse myoblasts were differentiated into myotubes over the course of
two weeks on these devices to demonstrate biocompatibility. Finally, devices were imaged during the
basal-side delivery of a fluorescent stain to validate the membrane operation and long-term
stability of the bonding technique. 相似文献
10.
Fluid shear stress (FSS) plays a critical role in regulating endothelium function and maintaining vascular homeostasis. Current microfluidic devices for studying FSS effects on cells either separate high shear stress zone and low shear stress zone into different culturing chambers, or arranging the zones serially along the flow direction, which complicates subsequent data interpretation. In this paper, we report a diamond shaped microfluidic shear device where the high shear stress zone and the low shear stress zone are arranged in parallel within one culturing chamber. Since the zones with different shear stress magnitudes are aligned normal to the flow direction, the cells in one stress group are not substantially affected by the flow-induced cytokine/chemokine releases by cells in the other group. Cell loading experiments using human umbilical vein endothelial cells show that the device is able to reveal stress magnitude-dependent and loading duration-dependent cell responses. The co-existence of shear stress zones with varied magnitudes within the same culturing chamber not only ensures that all the cells are subject to the identical culturing conditions, but also allows the resemblance of the differential shear stress pattern in natural arterial conditions. The device is expected to provide a new solution for studying the effects of heterogeneous hemodynamic patterns in the onset and progression of various vascular diseases. 相似文献
11.
Junzhen Ren Pengqing Bi Jianqi Zhang Jiao Liu Jingwen Wang Ye Xu Zhixiang Wei Shaoqing Zhang Jianhui Hou 《国家科学评论(英文版)》2021,8(8)
Developing photovoltaic materials with simple chemical structures and easy synthesis still remains a major challenge in the industrialization process of organic solar cells (OSCs). Herein, an ester substituted poly(thiophene vinylene) derivative, PTVT-T, was designed and synthesized in very few steps by adopting commercially available raw materials. The ester groups on the thiophene units enable PTVT-T to have a planar and stable conformation. Moreover, PTVT-T presents a wide absorption band and strong aggregation effect in solution, which are the key characteristics needed to realize high performance in non-fullerene-acceptor (NFA)-based OSCs. We then prepared OSCs by blending PTVT-T with three representative fullerene- and NF-based acceptors, PC71BM, IT-4F and BTP-eC9. It was found that PTVT-T can work well with all the acceptors, showing great potential to match new emerging NFAs. Particularly, a remarkable power conversion efficiency of 16.20% is achieved in a PTVT-T:BTP-eC9-based device, which is the highest value among the counterparts based on PTV derivatives. This work demonstrates that PTVT-T shows great potential for the future commercialization of OSCs. 相似文献
12.
While advances in genomics have enabled sensitive and highly parallel detection of nucleic acid targets, the isolation and extraction of the nucleic acids remain a critical bottleneck in the workflow. We present here a simple 3D printed microfluidic chip that allows for the vortex and centrifugation free extraction of nucleic acids. This novel microfluidic chip utilizes the presence of a water and oil interface to filter out the lysate contaminants. The pure nucleic acids, while bound on cellulose particles, are magnetically moved across the oil layer. We demonstrated efficient and rapid extraction of spiked Human Papillomavirus (HPV) 18 plasmids in specimen transport medium, in under 15 min. An overall extraction efficiency of 61% is observed across a range of HPV plasmid concentrations (5 × 101 to 5 × 106 copies/100 μl). The magnetic, interfacial, and viscous drag forces inside the microgeometries of the chip are modeled. We have also developed a kinetics model for the adsorption of nucleic acids on cellulose functionalized superparamagnetic beads. We also clarify here the role of carrier nucleic acids in the adsorption and isolation of nucleic acids. Based on the various mechanistic insights detailed here, customized microfluidic devices can be designed to meet the range of current and emerging point of care diagnostics needs. 相似文献
13.
A method to easily manufacture and assemble a polydimethylsiloxane (PDMS) based microfluidic device is described. The method uses low cost materials and re-usable laser cut polymethyl methacrylate (PMMA) parts. In addition, the thickness of PDMS layers can be controlled and both PDMS layer surfaces are flat, which allows for multi-layer PDMS structures to be assembled. The use of mechanical clamping to seal the structure allows for easy cleaning and re-use of the manufactured part as it can be taken apart at any time. In this way, selected layers can be re-used or replaced. The process described can be easily adopted and utilised without the need for any costly clean room facilities or equipment such as oxygen bonders, making it ideal for laboratories, universities, and classrooms exploring microfluidics applications. 相似文献
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根据多基线合成孔径雷达(SAR)三维成像的信号模型,得到了利用高度向观测数据实现目标三维成像的矩阵方程,并引入QR分解算法求解矩阵方程,形成了多基线SAR三维成像的QR分解算法.使用该算法对多基线SAR仿真数据进行了三维成像实验. 相似文献
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On the one hand, lensless imaging technology has become one of the key technologies to achieve point-of-care testing; on the other hand, microfluidic technology has shown great application potential in the field of biological detection. Using mainstream lensless imaging technology to achieve biological cell imaging in microfluidic chips has technical limitations. In particular, it is more difficult to achieve lensless imaging for non-spherical cells in microfluidic chips such as red blood cells. Achieving red blood cell recognition and posture estimation in a microfluidic chip under the lensless imaging, combined with mainstream lensless imaging technology, can provide more effective red blood cell morphological parameters for medical diagnosis. In this paper, the method for red blood cell recognition and posture estimation in microfluidic chips based on lensless imaging is given. First, the relevant theoretical basis is introduced. Then, the models of red blood cell recognition and posture estimation in microfluidic chips based on lensless imaging are given. The effect of red blood cell flipping on lensless imaging is analyzed in the modeling process. Finally, the effectiveness of the proposed method is verified by experiments. Experiments show that the proposed method can well achieve red blood cell recognition and posture estimation through the shape characteristics of red blood cells. 相似文献
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