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Fabrication of monodisperse, large-sized, functional biopolymeric microspheres using a low-cost and facile microfluidic device.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report a novel and facile method for fabricating coaxial microfluidic devices processing various dimensions at low cost, in which polypropylene hollow fibers or glass capillaries are used as the tip of the dispersed phase injection tube. With this coaxial microfluidic device, monodisperse biocompatible microspheres ranging from 300 to 800 mum were obtained by collecting oil-in-water or water-in-oil emulsions and solidifying the suspended microspheres. Microsphere size could be controlled by changing the tips or tuning the concentrations of the dispersed and continuous phases. By adding functional nanoparticles into the ...
Source: Biomedical Microdevices - November 19, 2009 Category: Biomedical Engineering Authors: Zhu L, Li Y, Zhang Q, Wang H, Zhu M Tags: Biomed Microdevices Source Type: journals

Tape underlayment rotary-node (TURN) valves for simple on-chip microfluidic flow control.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We describe a simple and reliable fabrication method for producing multiple, manually activated microfluidic control valves in polydimethylsiloxane (PDMS) devices. These screwdriver-actuated valves reside directly on the microfluidic chip and can provide both simple on/off operation as well as graded control of fluid flow. The fabrication procedure can be easily implemented in any soft lithography lab and requires only two specialized tools-a hot-glue gun and a machined brass mold. To facilitate use in multi-valve fluidic systems, the mold is designed to produce a linear tape that contains a series of plastic rotary nodes ...
Source: Biomedical Microdevices - October 27, 2009 Category: Biomedical Engineering Authors: Markov DA, Manuel S, Shor LM, Opalenik SR, Wikswo JP, Samson PC Tags: Biomed Microdevices Source Type: journals

Formation of biodegradable microcapsules utilizing 3D, selectively surface-modified PDMS microfluidic devices.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have successfully demonstrated the formation of biodegradable microcapsules utilizing PDMS double-emulsification devices. Specially designed 3D PDMS microchannels with surfaces selectively modified by a self-aligned photografting process are employed to generate monodisperse water-in-organic-solvent-in-water (W/O/W) emulsions in a controlled manner. Mainly by varying the outer and inner fluid flow-rates, the dimensions of resulting double emulsions can be adjusted as desired. Meanwhile, biodegradable materials are dissolved in the middle organic solvent (in this work ethyl acetate is used), and solidified into micro...
Source: Biomedical Microdevices - October 23, 2009 Category: Biomedical Engineering Authors: Liao CY, Su YC Tags: Biomed Microdevices Source Type: journals

Principle design and actuation of a dual chamber electromagnetic micropump with coaxial cantilever valves.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper deals with the design and characterization of an electromagnetic actuation micropump with superimposed dual chambers. An integral part of microfluidic system includes micropumps which have become a critical design focus and have the potential to alter treatment and drug delivery requirements to patients. In this paper, conceptual design of variable geometrical nozzle/diffuser elements, coaxial cantilever valve, is proposed. It takes advantages of cantilever fluctuating valves with preset geometry to optimize and control fluid flow. The integration of this conceptual valve into a dual chamber micropump has in...
Source: Biomedical Microdevices - October 16, 2009 Category: Biomedical Engineering Authors: Zordan E, Amirouche F, Zhou Y Tags: Biomed Microdevices Source Type: journals

Patterning alginate hydrogels using light-directed release of caged calcium in a microfluidic device.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper describes a simple reversible hydrogel patterning method for 3D cell culture. Alginate gel is formed in select regions of a microfluidic device through light-triggered release of caged calcium. In the pre-gelled alginate solution, calcium is chelated by DM-nitrophen (DM-n) to prevent cross-linking of alginate. After sufficient UV exposure the caged calcium is released from DM-n causing alginate to cross-link. The effect of using different concentrations of calcium and chelating agents as well as the duration of UV exposure is described. Since the cross-linking is based on calcium concentration, the cross-lin...
Source: Biomedical Microdevices - October 14, 2009 Category: Biomedical Engineering Authors: Chueh BH, Zheng Y, Torisawa YS, Hsiao AY, Ge C, Hsiong S, Huebsch N, Franceschi R, Mooney DJ, Takayama S Tags: Biomed Microdevices Source Type: journals

Water-assisted CO(2) laser ablated glass and modified thermal bonding for capillary-driven bio-fluidic application.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The glass-based microfluidic chip has widely been applied to the lab-on-a-chip for clotting tests. Here, we have demonstrated a capillary driven flow chip using the water-assisted CO(2) laser ablation for crackless fluidic channels and holes as well as the modified low-temperature glass bonding with assistance of adhesive polymer film at 300 degrees C. Effect of water depth on the laser ablation of glass quality was investigated. The surface hydrophilic property of glass and polymer film was measured by static contact angle method for hydrophilicity examination in comparison with the conventional polydimethylsiloxane (...
Source: Biomedical Microdevices - October 14, 2009 Category: Biomedical Engineering Authors: Chung CK, Chang HC, Shih TR, Lin SL, Hsiao EJ, Chen YS, Chang EC, Chen CC, Lin CC Tags: Biomed Microdevices Source Type: journals

Droplet position control in digital microfluidic systems.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Research on so called digital microfluidic systems (DMS) capable of manipulating individual microdroplets on a cell-based structure has enormously increased in the past few years, mainly due to the demand of the technology-dependent biomedical applications. Significant research in this area has been related to the simulation and modeling of droplet motion, demonstration of different drop actuation techniques on laboratory-scale prototypes, and droplet routing and scheduling for more efficient assay procedures. This paper introduces the basics of the control analysis and design of a DMS, which is a relatively unexplored...
Source: Biomedical Microdevices - October 12, 2009 Category: Biomedical Engineering Authors: Bhattacharjee B, Najjaran H Tags: Biomed Microdevices Source Type: journals

Construction of a laser combiner for dual fluorescent single molecule imaging of pRNA of phi29 DNA packaging motor.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A customized laser combiner was designed and constructed for dual channel single molecule imaging. The feasibility of a combiner-incorporated imaging system was demonstrated in studies of single molecule FRET. Distance rulers made of dual-labeled dsDNA were used to evaluate the system by determining the distance between one FRET pair. The results showed that the system is sensitive enough to distinguish between distances differing by two base pair and the distances calculated from FRET efficiencies are close to those documented in the literature. The single molecule FRET with the dual-color imaging system was also appl...
Source: Biomedical Microdevices - October 6, 2009 Category: Biomedical Engineering Authors: Zhang H, Shu D, Browne M, Guo P Tags: Biomed Microdevices Source Type: journals

3D microfabricated bioreactor with capillaries.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present in this paper the implementation of an innovative three dimensional (3D) microfabrication technology coupled with numerical simulation to enhance the mass transport in 3D cell culture. The core of this microfabrication technology is a high-resolution projection micro stereolithography (PmuSL) using a spatial light modulator as a dynamic mask which enables a parallel fabrication of highly complex 3D microstructures. In this work, a set of poly (ethylene glycol) microfabricated bioreactors are demonstrated with PmuSL technology. We observed both experimentally and numerically the regulation of metabolism and the g...
Source: Biomedical Microdevices - October 5, 2009 Category: Biomedical Engineering Authors: Xia C, Fang NX Tags: Biomed Microdevices Source Type: journals

A microfluidic chip for permeability assays of endothelial monolayer.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Endothelial cell monolayer (EM), acting as a barrier between blood and tissue, plays an important role in pathophysiological processes. Here we describe a novel microfluidic chip that is applied for convenient and high throughput in vitro permeability assays of EM. The chip included a gradient generator and an array of cell culture chambers. A microporous membrane as a scaffold component was built between a polydimethylsiloxane (PDMS) layer and a glass substrate to grow EM. Cell culture chambers were separated by microchannels and microvalves. The concentration gradient of compound solutions could be generated automati...
Source: Biomedical Microdevices - October 2, 2009 Category: Biomedical Engineering Authors: Shao J, Wu L, Wu J, Zheng Y, Zhao H, Lou X, Jin Q, Zhao J Tags: Biomed Microdevices Source Type: journals

Nanostructured conducting polymer based reagentless capacitive immunosensor.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nanostructured polyaniline (PANI) film electrophoretically fabricated onto indium-tin-oxide (ITO) coated glass plate has been utilized for development of an immunosensor based on capacitance change of a parallel plate capacitor (PPC) by covalently immobilizing anti-human IgG (Anti-HIgG) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. These fabricated PANI/ITO and Anti-HIgG/PANI/ITO plates have been characterized using scanning electron microscopy, cyclic voltammetry, differential pulse voltammetry and Fourier transform infra-red studies. The capacitance measurements indicate th...
Source: Biomedical Microdevices - September 30, 2009 Category: Biomedical Engineering Authors: Bandodkar AJ, Dhand C, Arya SK, Pandey MK, Malhotra BD Tags: Biomed Microdevices Source Type: journals

Preferential vitrification of water in small alginate microcapsules significantly augments cell cryopreservation by vitrification.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The morphological changes of small (~100 microm) alginate microcapsules and the biophysical alterations of water in the microcapsules during cryopreservation were studied using cryomicroscopy and scanning calorimetry. It was found that water in the small microcapsules can be preferentially vitrified over water in the bulk solution in the presence of 10% (v/v) or more dimethylsulfoxide (DMSO, a cryoprotectant), which resulted in an intact morphology of the microcapsules post cryopreservation with a cooling rate of 100 degrees C/min. A small amount of Ca(2+) (up to 0.15 M) was also found to help maintain the microcapsule...
Source: Biomedical Microdevices - September 28, 2009 Category: Biomedical Engineering Authors: Zhang W, Yang G, Zhang A, Xu LX, He X Tags: Biomed Microdevices Source Type: journals

Functional endothelialized microvascular networks with circular cross-sections in a tissue culture substrate.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Functional endothelialized networks constitute a critical building block for vascularized replacement tissues, organ assist devices, and laboratory tools for in vitro discovery and evaluation of new therapeutic compounds. Progress towards realization of these functional artificial vasculatures has been gated by limitations associated with the mechanical and surface chemical properties of commonly used microfluidic substrate materials and by the geometry of the microchannels produced using conventional fabrication techniques. Here we report on a method for constructing microvascular networks from polystyrene substrates ...
Source: Biomedical Microdevices - September 28, 2009 Category: Biomedical Engineering Authors: Borenstein JT, Tupper MM, Mack PJ, Weinberg EJ, Khalil AS, Hsiao J, García-Cardeña G Tags: Biomed Microdevices Source Type: journals

Experimental and numerical characterization of magnetophoretic separation for MEMS-based biosensor applications.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Magnetophoretic isolation of biochemical and organic entities in a microfluidic environment is a popular tool for a wide range of bioMEMS applications, including biosensors. An experimental and numerical analysis of magnetophoretic capture of magnetic microspheres in a microfluidic channel under the influence of an external field is investigated. For a given microfluidic geometry, the operating conditions for marginal capture is found to be interrelated in such a manner that a unique critical capture parameter [Formula: see text], that is proportional to the ratio of the magnetic force to viscous force, can be identifi...
Source: Biomedical Microdevices - September 28, 2009 Category: Biomedical Engineering Authors: Modak N, Kejriwal D, Nandy K, Datta A, Ganguly R Tags: Biomed Microdevices Source Type: journals

Fabrication of three-dimensional microarray structures by controlling the thickness and elasticity of poly(dimethylsiloxane) membrane.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper, we propose a method to construct three-dimensional curved microstructures with easy control of the size, position and shape, by exploiting the elasticity of poly(dimethylsiloxane) (PDMS) membranes and basic physics. For this end, we developed the method to handle thin PDMS membrane safely, and to replicate PDMS microstructure from the PDMS mold. Using this method, we demonstrated two potential applications: (1) the use of concave well for the formation of embryoid body (EB) to differentiate into neuronal cells, and (2) the fabrication of SU-8 and hydrogel microparticles having diverse curved shapes. The ...
Source: Biomedical Microdevices - September 23, 2009 Category: Biomedical Engineering Authors: Lee DH, Park JY, Lee EJ, Choi YY, Kwon GH, Kim BM, Lee SH Tags: Biomed Microdevices Source Type: journals

Erratum to: Microfabricated glass devices for rapid single cell immobilization in mouse zygote microinjection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19768547 [PubMed - as supplied by publisher] (Source: Biomedical Microdevices)
Source: Biomedical Microdevices - September 18, 2009 Category: Biomedical Engineering Authors: Liu X, Sun Y Tags: Biomed Microdevices Source Type: journals

Electroporation based on hydrodynamic focusing of microfluidics with low dc voltage.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, hydrodynamic focusing of fluids with different conductivities has been used for high through-put cell electroporation at low voltage (<3 V) of continuous direct current (dc) power. Simulation results showed that an input voltage of only 1.5 V could generate an electric field intensity of about 1.17 kV cm(-1) across the cell suspension flow in the squeezed area. The electropermeation of yeast cell was observed, showing a permeabilization percentage up to 70%. PMID: 19757070 [PubMed - as supplied by publisher] (Source: Biomedical Microdevices)
Source: Biomedical Microdevices - September 15, 2009 Category: Biomedical Engineering Authors: Zhu T, Luo C, Huang J, Xiong C, Ouyang Q, Fang J Tags: Biomed Microdevices Source Type: journals

Microtube-based electrode arrays for low invasive extracellular recording with a high signal-to-noise ratio.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report on the development of a microtube electrode array as a neural interface device. To combine the desired properties for the neural interface device, such as low invasiveness with a small needle and a good signal-to-noise ratio in neural recordings, we applied the structure of a glass pipette electrode to each microtube electrode. The device was fabricated as sub-5-mum-diameter out-of-plane silicon dioxide microtube arrays using silicon microneedle templates, which are grown by the selective vapor-liquid-solid method. The microtubes had inner diameters of 1.9-6.4 microm and a length of 25 microm. Impedances ranged f...
Source: Biomedical Microdevices - September 14, 2009 Category: Biomedical Engineering Authors: Takei K, Kawano T, Kawashima T, Sawada K, Kaneko H, Ishida M Tags: Biomed Microdevices Source Type: journals

Targeted cell adhesion on selectively micropatterned polymer arrays on a poly(dimethylsiloxane) surface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Herein, we introduce the fabrication of polymer micropattern arrays on a chemically inert poly(dimethylsiloxane) (PDMS) surface and employ them for the selective adhesion of cells. To fabricate the micropattern arrays, a mercapto-ester-based photocurable adhesive was coated onto a mercaptosilane-coated PDMS surface and photopolymerized using a photomask to obtain patterned arrays at the microscale level. Robust polymer patterns, 380 microm in diameter, were successfully fabricated onto a PDMS surface, and cells were selectively targeted toward the patterned regions. Next, the performance of the cell adhesion was observ...
Source: Biomedical Microdevices - September 14, 2009 Category: Biomedical Engineering Authors: Tang L, Min J, Lee EC, Kim JS, Lee NY Tags: Biomed Microdevices Source Type: journals

Microfluidic gradient PCR (MG-PCR): a new method for microfluidic DNA amplification.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study develops a new microfluidic DNA amplification strategy for executing parallel DNA amplification in the microfluidic gradient polymerase chain reaction (MG-PCR) device. The developed temperature gradient microfluidic system is generated by using an innovative fin design. The device mainly consists of modular thermally conductive copper flake which is attached onto a finned aluminum heat sink with a small fan. In our microfluidic temperature gradient prototype, a non-linear temperature gradient is produced along the gradient direction. On the copper flake of length 45 mm, width 40 mm and thickness 4 mm, the temper...
Source: Biomedical Microdevices - September 14, 2009 Category: Biomedical Engineering Authors: Zhang C, Xing D Tags: Biomed Microdevices Source Type: journals

A self-contained fully-enclosed microfluidic cartridge for lab on a chip.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We describe a self-contained fully-enclosed cartridge for lab-on-a-chip applications where sample and reagents can be applied sequentially as is performed in a heterogeneous immunoassay, or nucleic acid extraction. Both the self-contained and fully-enclosed features of the cartridge are sought to ensure its safe use in the field by unskilled staff. Simplicity in cartridge design and operation is obtained via adopting a valveless concept whereby reagents are stored and used in the form of liquid plugs isolated by air spacers around a fluidic loop. Functional components integrated in the loop include a microfluidic chip spec...
Source: Biomedical Microdevices - September 14, 2009 Category: Biomedical Engineering Authors: Yobas L, Feng Cheow L, Tang KC, Yong SE, Kye-Zheng Ong E, Wong L, Cheng-Yong Teo W, Ji H, Rafeah S, Yu C Tags: Biomed Microdevices Source Type: journals

Triangular neuronal networks on microelectrode arrays: an approach to improve the properties of low-density networks for extracellular recording.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we followed an alternative strategy to increase the portion of neurons located at the electrodes by designing a network in confined geometries. Guided settlement and outgrowth of neurons is accomplished by taking control over the adhesive properties of the MEA surface. Using microcontact printing a triangular two-dimensional pattern of the adhesion promoter poly-D-lysine was applied to the MEA offering a meshwork that at the same time provides adhesion points for cell bodies matching the electrode positions and gives frequent branching points for dendrites and axons. Low density neocortical networks cultivat...
Source: Biomedical Microdevices - September 14, 2009 Category: Biomedical Engineering Authors: Jungblut M, Knoll W, Thielemann C, Pottek M Tags: Biomed Microdevices Source Type: journals

Disposable plastic microreactors for genomic analyses.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We show the design, development and assessment of disposable, biocompatible, fully plastic microreactors, which are demonstrated to be highly efficient for genomic analyses, such as amplification of DNA, quantitative analyses in real time, multiplex PCR (both in terms of efficiency and selectivity), as compared to conventional laboratory equipment for PCR. The plastic microreactors can easily be coupled to reusable hardware, enabling heating/cooling processes and, in the case of qPCR applications, the real-time detection of the signal from a suitable fluorescent reporter present in the reaction mixture during the analy...
Source: Biomedical Microdevices - September 3, 2009 Category: Biomedical Engineering Authors: Sabella S, Vecchio G, Pompa PP, Maruccio G, Sanarica L, Torre AD, De Bellis G, Caramenti G, Consolandi C, Severgnini M, Cingolani R, Rinaldi R Tags: Biomed Microdevices Source Type: journals

A microfluidic device for separation of amniotic fluid mesenchymal stem cells utilizing louver-array structures.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study presents a new microfluidic device for bead and cell separation utilizing a combination of T-junction focusing and tilted louver-like structures. For the first time, a microfluidic device is used for continuous separation of amniotic stem cells from amniotic fluids. An experimental separation efficiency as high as 82.8% for amniotic fluid mesenchymal stem cells is achieved. Furthermore, a two-step separation process is performed to improve the separation efficiency to 97.1%. These results are based on characterization experiments that show that this microfluidic chip is capable of separating beads with diameters...
Source: Biomedical Microdevices - September 2, 2009 Category: Biomedical Engineering Authors: Wu HW, Lin XZ, Hwang SM, Lee GB Tags: Biomed Microdevices Source Type: journals

Computational simulation of a magnetic microactuator for tissue engineering applications.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The next generation of tissue engineered constructs (TECs) requires the incorporation of a controllable and optimized microstructure if they are to chemically, mechanically, and biologically mimic tissue function. In order to obtain TECs with optimized microstructures, a combination of spatiotemporally regulated mechanical and biochemical stimuli is necessary during the formation of the construct. While numerous efforts have been made to create functional tissue constructs, there are few techniques available to stimulate TECs in a localized manner. We herein describe the design of a microdevice which can stimulate TECs...
Source: Biomedical Microdevices - August 13, 2009 Category: Biomedical Engineering Authors: Keyes J, Junkin M, Wong PK, Vande Geest JP Tags: Biomed Microdevices Source Type: journals

A monolithic polymeric microdevice for pH-responsive drug delivery.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A drug-delivery microdevice integrating pH-responsive nano-hydrogel particles functioning as intelligent nano valves is described. The polymeric microdevices are monolithic without requiring peripheral control hardware or additional components for controlling drug-release rates. pH-responsive nanoparticles were synthesized and embedded into a composite membrane. The resulting pH-responsive composite membranes were integrated with PDMS micro reservoirs via a room-temperature transfer bonding technique to form the proof-of-concept microdevices. In vitro release characterization of the microdevices was conducted in which ...
Source: Biomedical Microdevices - August 11, 2009 Category: Biomedical Engineering Authors: Chen J, Chu M, Koulajian K, Wu XY, Giacca A, Sun Y Tags: Biomed Microdevices Source Type: journals

Combinatorial targeting and nanotechnology applications.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The development of improved methods for targeted cell detection is of general interest in many fields of research and drug development. There are a number of well-established techniques for the study and detection of biomarkers expressed in living cells and tissues. Many of them rely on multi-step procedures that might not meet ideal assay requirements for speed, cost, sensitivity, and specificity. Here we report and further validate an approach that enables spontaneous molecular assembly to generate biologically active networks of bacteriophage (phage) assembled with gold (Au) nanoparticles (termed Au-phage nanoshuttl...
Source: Biomedical Microdevices - August 10, 2009 Category: Biomedical Engineering Authors: Souza GR, Staquicini FI, Christianson DR, Ozawa MG, Miller JH, Pasqualini R, Arap W Tags: Biomed Microdevices Source Type: journals

Electrical characterization of a single cell electroporation biochip with the 2-D scanning vibrating electrode technology.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Advancements in microfabrication technology have lead to the development of planar micro-pore electroporation technology. This technology has been shown to provide greater control in single cell manipulation, and electroporation which is independent from cell size. In this work we report direct and spatially resolved characterization of electric currents within a planar micropore electroporation biochip to better understand this phenomenon at the cellular level. This work was performed using a two-dimensional (2-D) vibrating probe (VP). Analysis of the spatial patterns of current density yielded a 4th order polynomial ...
Source: Biomedical Microdevices - August 3, 2009 Category: Biomedical Engineering Authors: Ul Haque A, Zuberi M, Diaz-Rivera RE, Marshall Porterfield D Tags: Biomed Microdevices Source Type: journals

Microfluidic cell sorter with integrated piezoelectric actuator.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We demonstrate a low-power (<0.1 mW), low-voltage (<10 V(p-p)) on-chip piezoelectrically actuated micro-sorter that can deflect single particles and cells at high-speed. With rhodamine in the stream, switching of flow between channels can be visualized at high actuation frequency (~1.7 kHz). The magnitude of the cell deflection can be precisely controlled by the magnitude and waveform of input voltage. Both simulation and experimental results indicate that the drag force imposed on the suspended particle/cell by the instantaneous fluid displacement can alter the trajectory of the particle/cell of any size, shape,...
Source: Biomedical Microdevices - July 31, 2009 Category: Biomedical Engineering Authors: Chen CH, Cho SH, Tsai F, Erten A, Lo YH Tags: Biomed Microdevices Source Type: journals

Cell encapsulation and oxygenation in nanoporous microcontainers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
With strides in stem cell biology, cell engineering and molecular therapy, the transplantation of cells to produce therapeutic molecules endogenously is an attractive and achievable alternative to the use of exogenous drugs. The encapsulation of such cell transplants in semi-permeable, nanoporous constructs is often required to protect them from immune attack and to prevent their proliferation in the host. However, effective graft immunoisolation has been mostly elusive owing to the absence of a high-throughput method to create precisely controlled, high-aspect-ratio nanopores. To address the clinical need for effectiv...
Source: Biomedical Microdevices - July 22, 2009 Category: Biomedical Engineering Authors: Gimi B, Kwon J, Liu L, Su Y, Nemani K, Trivedi K, Cui Y, Vachha B, Mason R, Hu W, Lee JB Tags: Biomed Microdevices Source Type: journals

A self-contained microfluidic cell culture system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conventional in vitro cell culture that utilizes culture dishes or microtiter plates is labor-intensive and time-consuming, and requires technical expertise and specific facilities to handle cell harvesting, media exchange and cell subculturing procedures. A microfluidic array platform with eight microsieves in each cell culture chamber is presented for continuous cell culture. With the help of the microsieves, uniform cell loading and distribution can be obtained. Within the arrays, cells grown to the point of confluency can be trypsinized and recovered from the device. Cells trapped in the microsieves after trypsiniz...
Source: Biomedical Microdevices - July 20, 2009 Category: Biomedical Engineering Authors: Zhang B, Kim MC, Thorsen T, Wang Z Tags: Biomed Microdevices Source Type: journals

Development of a novel intra-vaginal transducer with improved dynamic response.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Limitations of standard clinical pressure transducers have hampered our ability to provide reliable measurements of intra-abdominal pressure (IAP) during physical activities. To overcome these limitations, a novel intravaginal transducer (IVT) capable of accurate, reliable, and continuous IAP measurements during normal activity was developed. The design was validated through comparison with standard clinical pressure transducers in both bench top and clinical tests. The IVT demonstrated an improved dynamic response when compared to a standard rectal balloon catheter. Additionally, the radially symmetric design allows f...
Source: Biomedical Microdevices - July 20, 2009 Category: Biomedical Engineering Authors: Johnson PJ, Rosenbluth EM, Nygaard IE, Parikh MK, Hitchcock RW Tags: Biomed Microdevices Source Type: journals

Mass producible and biocompatible microneedle patch and functional verification of its usefulness for transdermal drug delivery.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The key issues in the development of a microneedle patch as a tool for transdermal drug delivery are safety and delivery performance in addition to economical production. In this paper, novel fabrication methods for an inexpensive microneedle patch made of biocompatible polymer are reported, along with functional verifications for the fabricated microneedle patch through animal models. We combined the merits of in-line microneedles, i.e., easy and economical production, with the superior performance of two-dimensionally arrayed microneedles. One-dimensionally fabricated microneedles were assembled to make two-dimension...
Source: Biomedical Microdevices - July 15, 2009 Category: Biomedical Engineering Authors: Jin CY, Han MH, Lee SS, Choi YH Tags: Biomed Microdevices Source Type: journals

Influence of PEG chain on the complement activation suppression and longevity in vivo prolongation of the PCL biomedical nanoparticles.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The process of opsonization is the major biological barrier to the injectable polymeric nanoparticles (NPs). Complement protein is one kind of opsonins and it can be activated potentially by the negative charged particles. The fragment C3b generated by complement activation could subsequently induce the opsonization on the NPs surface. The aim of our work was to examine the relationship between the hydrophilic poly(ethylene glycol) (PEG) chain on the surface of NPs and particles longevity in vivo from the biological point of view such as complement activation (C3 cleavage) as well as uptake by macrophages. The studies ...
Source: Biomedical Microdevices - July 15, 2009 Category: Biomedical Engineering Authors: Shan X, Yuan Y, Liu C, Tao X, Sheng Y, Xu F Tags: Biomed Microdevices Source Type: journals

Finger-actuated, self-contained immunoassay cassettes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The building blocks for an inexpensive, disposable, luminescence-based microfluidic immunoassay cassette are described, and their integration in a point-of-care diagnostic system is demonstrated. Fluid motion in the cassette is driven by depressing finger-actuated pouches. All reagents needed for the immunoassay can be stored in the cassette in liquid form. Prior to use, the cassette consists of two separate parts. A top storage component contains pouches, sealed storage chambers, a metering chamber, and needle seats. The bottom processing component contains connection needles, a mixing chamber, and a detection chamber...
Source: Biomedical Microdevices - July 13, 2009 Category: Biomedical Engineering Authors: Qiu X, Thompson JA, Chen Z, Liu C, Chen D, Ramprasad S, Mauk MG, Ongagna S, Barber C, Abrams WR, Malamud D, Corstjens PL, Bau HH Tags: Biomed Microdevices Source Type: journals

Microfabricated glass devices for rapid single cell immobilization in mouse zygote microinjection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents the design and microfabrication of a vacuum-based cell holding device for single-cell immobilization and the use of the device in mouse zygote microinjection. The device contains many through-holes, constructed via two-sided glass wet etching and polydimethylsiloxane (PDMS)-glass bonding. Experimental results of mouse zygote immobilization and microinjection demonstrate that the device is effective for rapid cell immobilization and does not produce negative effect on embryonic development. PMID: 19578992 [PubMed - as supplied by publisher] (Source: Biomedical Microdevices)
Source: Biomedical Microdevices - July 3, 2009 Category: Biomedical Engineering Authors: Liu X, Sun Y Tags: Biomed Microdevices Source Type: journals

A microperfused incubator for tissue mimetic 3D cultures.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
High density, three-dimensional (3D) cultures present physical similarities to in vivo tissue and are invaluable tools for pre-clinical therapeutic discoveries and development of tissue engineered constructs. Unfortunately, the use of dense cultures is hindered by intra-culture transport limits allowing just a few layer thick cultures for reproducible studies. In order to overcome diffusion limits in intra-culture nutrient and gas availability, a simple scalable microfluidic perfusion platform was developed and validated. A novel perfusion approach maintained laminar flow of nutrients through the culture to meet metabo...
Source: Biomedical Microdevices - June 26, 2009 Category: Biomedical Engineering Authors: Vukasinovic J, Cullen DK, Laplaca MC, Glezer A Tags: Biomed Microdevices Source Type: journals

Microfluidic compartmentalized co-culture platform for CNS axon myelination research.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents a circular microfluidic compartmentalized co-culture platform that can be used for central nervous system (CNS) axon myelination research. The microfluidic platform is composed of a soma compartment and an axon/glia compartment connected through arrays of axon-guiding microchannels. Myelin-producing glia, oligodendrocytes (OLs), placed in the axon/glia compartment, interact with only axons but not with neuronal somata confined to the soma compartment, reminiscent to in vivo situation where many axon fibres are myelinated by OLs at distance away from neuronal cell bodies. Primary forebrain neurons fr...
Source: Biomedical Microdevices - June 24, 2009 Category: Biomedical Engineering Authors: Park J, Koito H, Li J, Han A Tags: Biomed Microdevices Source Type: journals

Quantitative analysis of single bacterial chemotaxis using a linear concentration gradient microchannel.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A microfluidic device to quantify bacterial chemotaxis has been proposed, which generates a linear concentration gradient of chemoattractant in the main channel only by convective and molecular diffusion, and which enables the bacteria to enter the main channel in a single file by hydrodynamic focusing technique. The trajectory of each bacterium in response to the concentration gradient of chemoattractant is photographed by a CCD camera and its velocity is acquired by a simple PTV (Particle Tracking Velocimetry) algorithm. An advantage of this assay is to measure the velocity of a single bacterium and to quantify the d...
Source: Biomedical Microdevices - June 22, 2009 Category: Biomedical Engineering Authors: Jeon H, Lee Y, Jin S, Koo S, Lee CS, Yoo JY Tags: Biomed Microdevices Source Type: journals

Alginate-PLL cell encapsulation system Co-entrapping PLGA-microspheres for the continuous release of anti-inflammatory drugs.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In spite of advances in cell microencapsulation technology in the past three decades, this approach still suffers from obstacles associated with its biocompatibility. We hypothesized that encapsulation system, which incorporates polymeric particles releasing anti-inflammatory drug in addition to the encapsulated cells, will result in improved biocompatibility, thus improving therapeutic efficacy. We have developed, optimized and studied a combined microencapsulation system in which Ibuprofen loaded PLGA microspheres (MS) are co-entrapped with cells. The combined system was developed and optimized in terms of Ibuprofen ...
Source: Biomedical Microdevices - June 10, 2009 Category: Biomedical Engineering Authors: Baruch L, Benny O, Gilert A, Ukobnik M, Ben Itzhak O, Machluf M Tags: Biomed Microdevices Source Type: journals

Novel PEG-coated niosomes based on bola-surfactant as drug carriers for 5-fluorouracil.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Innovative niosomes made up of alpha,omega-hexadecyl-bis-(1-aza-18-crown-6) (bola), Span 80(R) and cholesterol (2:5:2 molar ratio) are proposed as suitable delivery systems for the administration of 5-fluorouracil (5-FU), an antitumoral compound largely used in the treatment of breast cancer. The bola-niosomes, after sonication procedure, showed mean sizes of ~200 nm and a loading capacity of ~40% with respect to the amount of 5-FU added during the preparation. Similar findings were achieved with PEG-coated bola-niosomes (bola, Span 80(R), cholesterol, DSPE-mPEG2000, 2:5:2:0.1 molar ratio respectively). 5-FU-loaded PEG...
Source: Biomedical Microdevices - June 8, 2009 Category: Biomedical Engineering Authors: Cosco D, Paolino D, Muzzalupo R, Celia C, Citraro R, Caponio D, Picci N, Fresta M Tags: Biomed Microdevices Source Type: journals

Gradient lithography of engineered proteins to fabricate 2D and 3D cell culture microenvironments.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Spatial patterning of proteins is a valuable technique for many biological applications and is the prevailing tool for defining microenvironments for cells in culture, a required procedure in developmental biology and tissue engineering research. However, it is still challenging to achieve protein patterns that closely mimic native microenvironments, such as gradient protein distributions with desirable mechanical properties. By combining projection dynamic mask lithography and protein engineering with non-canonical photosensitive amino acids, we demonstrate a simple, scalable strategy to fabricate any user-defined 2D ...
Source: Biomedical Microdevices - June 2, 2009 Category: Biomedical Engineering Authors: Wang S, Wong Po Foo C, Warrier A, Poo MM, Heilshorn SC, Zhang X Tags: Biomed Microdevices Source Type: journals

Multicoils-based inductive links dedicated to power up implantable medical devices: modeling, design and experimental results.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present in this paper a new topology of inductively-coupled links based on a monolithic multi-coils receiver. A model is built to characterize the proposed structure using Matlab and is verified employing simulation tools under ADS electromagnetic environment. This topology accounts for the losses associated with the receiver micro-coil including substrate and oxide layers. The geometry of micro-coils significantly desensitizes the link to both angular and side misalignments. A custom fabrication process using 1 micron metal thickness is also presented by which two sets of micro-coils varying in the number of coils are ...
Source: Biomedical Microdevices - June 1, 2009 Category: Biomedical Engineering Authors: Sawan M, Hashemi S, Sehil M, Awwad F, Hajj-Hassan M, Khouas A Tags: Biomed Microdevices Source Type: journals

An open-access microfluidic model for lung-specific functional studies at an air-liquid interface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In an effort to improve the physiologic relevance of existing in vitro models for alveolar cells, we present a microfluidic platform which provides an air-interface in a dynamic system combining microfluidic and suspended membrane culture systems. Such a system provides the ability to manipulate multiple parameters on a single platform along with ease in cell seeding and manipulation. The current study presents a comparison of the efficacy of the hybrid system with conventional platforms using assays analyzing the maintenance of function and integrity of A549 alveolar epithelial cell monolayer cultures. The hybrid syst...
Source: Biomedical Microdevices - May 29, 2009 Category: Biomedical Engineering Authors: Nalayanda DD, Puleo C, Fulton WB, Sharpe LM, Wang TH, Abdullah F Tags: Biomed Microdevices Source Type: journals

Effect of electrode geometry on performance of EWOD device driven by battery-based system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study develops a driving system for an electrowetting-on-dielectric (EWOD) device comprising a 9 V battery, an ATmega8535 microprocessor, a DC/DC converter, two regulator ICs and a switch circuit. The driving system greatly improves the portability of the EWOD device and is capable of generating a square wave with voltages ranging from 50~100 V(pp) and frequencies in the range 1~5 kHz. A series of experimental and numerical investigations are performed to investigate the effect of the conducting electrode geometry on the droplet velocity in the EWOD device. Three different electrode configurations are considered, name...
Source: Biomedical Microdevices - May 28, 2009 Category: Biomedical Engineering Authors: Jang LS, Hsu CY, Chen CH Tags: Biomed Microdevices Source Type: journals

Performance of nanoliter-sized droplet-based microfluidic PCR.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A microfluidic device was used to characterize PCR in aqueous-in-oil droplets for potential point-of-care applications. Droplets with a volume range of 5-250 nL can be formed on-chip reproducibly, and PCR in the droplets shows amplification efficiencies comparable to benchtop reactions with no evaporation loss. A higher polymerase concentration is required in the reaction droplet while the optimal Magnesium ion concentration is the same for both on-chip and benchtop systems. The optimal hold time is 9 s and 30 s for denaturation and annealing/extension in thermal cycling, respectively. With the optimized cycling parame...
Source: Biomedical Microdevices - May 27, 2009 Category: Biomedical Engineering Authors: Wang F, Burns MA Tags: Biomed Microdevices Source Type: journals

Melt-extruded guides for peripheral nerve regeneration. Part I: Poly(epsilon-caprolactone).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Melt-extruded guides for peripheral nerve repair based on poly(epsilon-caprolactone) (PCL) were realised and their physico-chemical properties were evaluated. Preliminarily, PCL cast films were found to support the attachment and proliferation of Neonatal Olfactory Bulb Ensheating Cells (NOBEC). S5Y5 neuroblastoma cells were cultured inside PCL guides in their uncoated form or coated with a non-specific adhesion protein (gelatin) and a specific peptide for nerve regeneration (poly(L-lysine)). Coating increased cell density (gelatin) and/or the cell density rate on substrates (poly(L-lysine); gelatin) as compared to unc...
Source: Biomedical Microdevices - May 27, 2009 Category: Biomedical Engineering Authors: Chiono V, Vozzi G, Vozzi F, Salvadori C, Dini F, Carlucci F, Arispici M, Burchielli S, Di Scipio F, Geuna S, Fornaro M, Tos P, Nicolino S, Audisio C, Perroteau I, Chiaravalloti A, Domenici C, Giusti P, Ciardelli G Tags: Biomed Microdevices Source Type: journals

Neuronal cell biocompatibility and adhesion to modified CMOS electrodes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The use of CMOS (Complementary Metal Oxide Semiconductor) integrated circuits to create electrodes for biosensors, implants and drug-discovery has several potential advantages over passive multi-electrode arrays (MEAs). However, unmodified aluminium CMOS electrodes may corrode in a physiological environment. We have investigated a low-cost electrode design based on the modification of CMOS metallisation to produce a nanoporous alumina electrode as an interface to mammalian neuronal cells and corrosion inhibitor. Using NG108-15 mouse neuroblastoma x rat glioma hybrid cells, results show that porous alumina is biocompati...
Source: Biomedical Microdevices - May 20, 2009 Category: Biomedical Engineering Authors: Graham AH, Bowen CR, Taylor J, Robbins J Tags: Biomed Microdevices Source Type: journals

A physiologically realistic in vitro model of microvascular networks.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Existing microfluidic devices, e.g. parallel plate flow chambers, do not accurately depict the geometry of microvascular networks in vivo. We have developed a synthetic microvascular network (SMN) on a polydimethalsiloxane (PDMS) chip that can serve as an in vitro model of the bifurcations, tortuosities, and cross-sectional changes found in microvascular networks in vivo. Microvascular networks from a cremaster muscle were mapped using a modified Geographical Information System, and then used to manufacture the SMNs on a PDMS chip. The networks were cultured with bovine aortic endothelial cells (BAEC), which reached co...
Source: Biomedical Microdevices - May 18, 2009 Category: Biomedical Engineering Authors: Rosano JM, Tousi N, Scott RC, Krynska B, Rizzo V, Prabhakarpandian B, Pant K, Sundaram S, Kiani MF Tags: Biomed Microdevices Source Type: journals

Extensional flow-based assessment of red blood cell deformability using hyperbolic converging microchannel.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The deformability of the red blood cell (RBC), is known to be closely related to microcirculation and diagnosis of specific diseases such as malaria, arterial sclerosis, sepsis, and so on. From the viewpoint of the flow type, conventional methods to measure the cell deformability have exploited simple shear or complex flow field with little focus on extensional flow field. In this paper, we present a new approach to assess cell deformability under the extensional flow field. For this purpose, a hyperbolic converging microchannel was designed, and the cell deformation in the extensional flow region was continuously moni...
Source: Biomedical Microdevices - May 11, 2009 Category: Biomedical Engineering Authors: Lee SS, Yim Y, Ahn KH, Lee SJ Tags: Biomed Microdevices Source Type: journals