BMF Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Facebook Podcast Flickr Twitter UniPHY Group iResearch App

Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Jun 2010

Volume 4, Issue 2, Articles (02xxxx)

Page 1 of 2 Pages Next Page | Jump to Page
back to top
RSS Feeds
FREE

Announcement: Fabrication and Laboratory Methods Section

James Friend

Biomicrofluidics 4, 020201 (2010); http://dx.doi.org/10.1063/1.3435331 (1 page)

Online Publication Date: 3 June 2010

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Show PACS
99.10.Np Editorial note
back to top
RSS Feeds

Dielectrophoretic separation of mouse melanoma clones

Ahmet C. Sabuncu, Jie A. Liu, Stephen J. Beebe, and Ali Beskok

Biomicrofluidics 4, 021101 (2010); http://dx.doi.org/10.1063/1.3447702 (7 pages) | Cited 3 times

Online Publication Date: 16 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dielectrophoresis (DEP) is employed to differentiate clones of mouse melanoma B16F10 cells. Five clones were tested on microelectrodes. At a specific excitation frequency, clone 1 showed a different DEP response than the other four. Growth rate, melanin content, recovery from cryopreservation, and in vitro invasive studies were performed. Clone 1 is shown to have significantly different melanin content and recovery rate from cryopreservation. This paper reports the ability of DEP to differentiate between two malignant cells of the same origin. Different DEP responses of the two clones could be linked to their melanin content.
Show PACS
87.85.-d Biomedical engineering
82.45.-h Electrochemistry and electrophoresis
87.80.-y Biophysical techniques (research methods)
87.17.-d Cell processes
back to top
RSS Feeds

Preface to Special Topic: Dielectrophoresis

Ronald Pethig

Biomicrofluidics 4, 022701 (2010); http://dx.doi.org/10.1063/1.3457488 (2 pages) | Cited 2 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This Special Topic section is on dielectrophoresis, a growing area of widespread interest and relevance to the microfluidics and nanofluidics community.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects
87.15.Tt Electrophoresis

Dynamic double layer effects on ac-induced dipoles of dielectric nanocolloids

Sagnik Basuray, Hsien-Hung Wei, and Hsueh-Chia Chang

Biomicrofluidics 4, 022801 (2010); http://dx.doi.org/10.1063/1.3455720 (7 pages) | Cited 3 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Normal and tangential surface ionic currents around low-permittivity nanocolloids with surface charges are shown to produce three different conductive mechanisms for ac-induced dipoles, all involving dynamic space charge accumulation at the double layer/bulk interface with a conductivity jump. However, the distinct capacitor dimensions and diffusive contributions produce three disparate crossover frequencies at which the induced dipole reverses direction relative to the bulk field. A highly conducting collapsed diffuse layer, with bulk ion mobility, renders the particle conductive and produces an ionic strength independent crossover frequency for weak electrolytes. A precipitous drop in crossover frequency occurs at high ionic strengths when charging occurs only at the poles through field focusing around the insulated colloid. A peculiar maximum in crossover frequency exists between these two asymptotes for colloids smaller than a critical size when normal charging of the diffuse layer occurs over the entire surface. The crossover frequency data for latex nanocolloids of various sizes in different electrolytes of wide ranging ionic strengths are collapsed by explicit theoretical predictions without empirical parameters.
Show PACS
82.45.Un Dielectric materials in electrochemistry
82.45.Yz Nanostructured materials in electrochemistry
77.22.Jp Dielectric breakdown and space-charge effects
82.70.Dd Colloids
82.45.Gj Electrolytes

Interaction between cells in dielectrophoresis and electrorotation experiments

Miguel Sancho, Genoveva Martínez, Sagrario Muñoz, José L. Sebastián, and Ronald Pethig

Biomicrofluidics 4, 022802 (2010); http://dx.doi.org/10.1063/1.3454129 (11 pages) | Cited 8 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Progress in microelectrode-based technologies has facilitated the development of sophisticated methods for manipulating and separating cells, bacteria, and other bioparticles. For many of these various applications, the theoretical modeling of the electrical response of compartmentalized particles to an external field is important. In this paper we address the analysis of the interaction between cells immersed in rf fields. We use an integral formulation of the problem derived from a consideration of the charge densities induced at the interfaces of the particle compartments. The numerical solution by a boundary element technique allows characterization of their dielectric properties. Experimental validation of this theoretical model is obtained by investigating two effects: (1) The influence that dipolar “pearl chaining” has on the dielectrophoretic behavior of human T lymphocytes and (2) the frequency variation of the spin and orbital torques of approaching insulinoma β-cells in a rotating field.
Show PACS
87.80.-y Biophysical techniques (research methods)
87.17.-d Cell processes
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects
82.45.Fk Electrodes

Dielectrophoresis of DNA: Quantification by impedance measurements

Anja Henning, Frank. F. Bier, and Ralph Hölzel

Biomicrofluidics 4, 022803 (2010); http://dx.doi.org/10.1063/1.3430550 (9 pages) | Cited 7 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dielectrophoretic properties of DNA have been determined by measuring capacitance changes between planar microelectrodes. DNA sizes ranged from 100 bp to 48 kbp, DNA concentrations from below 0.1 to 70 μg/ml. Dielectrophoretic spectra exhibited maximum response around 3 kHz and 3 MHz. The strongest response was found for very long DNA (above 10 kbp) and for short 100 bp fragments, which corresponds to the persistence length of DNA. The method allows for an uncomplicated, automatic acquisition of the dielectrophoretic properties of submicroscopical objects without the need for labeling protocols or optical accessibility.
Show PACS
87.80.Kc Electrochemical techniques
87.15.Tt Electrophoresis
87.14.gk DNA
82.45.Tv Bioelectrochemistry

Fabrication and characterization of nanomaterial-based sensors using dielectrophoresis

Junya Suehiro

Biomicrofluidics 4, 022804 (2010); http://dx.doi.org/10.1063/1.3430535 (10 pages) | Cited 3 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dielectrophoresis (DEP) is an electrokinetic motion of dielectrically polarized materials in nonuniform electric fields. DEP has been successfully applied to manipulation of nanomaterials including carbon nanotubes (CNTs), metallic nanoparticles, and semiconducting nanowires. Under positive DEP force, which attracts nanomaterials toward the higher field region, nanomaterials are trapped in the electrode gap and automatically establish good electrical connections between them and the external measuring circuit. This feature allows us a fast, simple, and low-cost fabrication of nanomaterial-based sensors based on a bottom-up approach. This paper first presents a theoretical background of DEP phenomena and then reviews recent works of the present author, which were aimed to develop nanomaterial-based sensors, such as a CNT gas sensor and a ZnO nanowire photosensor, using DEP fabrication technique. It is also demonstrated that DEP technique enables self-formation of interfaces between various nanomaterials, which can be also applicable as novel sensing transducers.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
82.80.-d Chemical analysis and related physical methods of analysis
82.45.Yz Nanostructured materials in electrochemistry
85.35.Kt Nanotube devices
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.16.-c Methods of micro- and nanofabrication and processing
82.45.-h Electrochemistry and electrophoresis

Liquid dielectrophoresis and surface microfluidics

Karan V. I. S. Kaler, Ravi Prakash, and Dipankar Chugh

Biomicrofluidics 4, 022805 (2010); http://dx.doi.org/10.1063/1.3411003 (17 pages) | Cited 2 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Liquid dielectrophoresis (L-DEP), when deployed at microscopic scales on top of hydrophobic surfaces, offers novel ways of rapid and automated manipulation of very small amounts of polar aqueous samples for microfluidic applications and development of laboratory-on-a-chip devices. In this article we highlight some of the more recent developments and applications of L-DEP in handling and processing of various types of aqueous samples and reagents of biological relevance including emulsions using such microchip based surface microfluidic (SMF) devices. We highlighted the utility of these devices for on-chip bioassays including nucleic acid analysis. Furthermore, the parallel sample processing capabilities of these SMF devices together with suitable on- or off-chip detection capabilities suggest numerous applications and utility in conducting automated multiplexed assays, a capability much sought after in the high throughput diagnostic and screening assays.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.85.-g Applied fluid mechanics
82.45.Tv Bioelectrochemistry
07.10.Cm Micromechanical devices and systems

Trapping single human osteoblast-like cells from a heterogeneous population using a dielectrophoretic microfluidic device

Rupert S. W. Thomas, Peter D. Mitchell, Richard O. C. Oreffo, and Hywel Morgan

Biomicrofluidics 4, 022806 (2010); http://dx.doi.org/10.1063/1.3406951 (9 pages) | Cited 7 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe a system for the isolation, concentration, separation, and recovery of human osteoblast-like cells from a heterogeneous population using dielectrophoretic ring traps. Cells flowing in a microfluidic channel are immobilized inside an electric field cage using negative dielectrophoresis. A planar ring electrode creates a closed trap while repelling surrounding cells. Target cells are identified by fluorescent labeling, and are trapped as they pass across a ring electrode by an automated system. We demonstrate recovery of small populations of human osteoblast-like cells with a purity of 100%, which in turn demonstrates the potential of such a device for cell selection from a heterogeneous population.
Show PACS
87.85.Ox Biomedical instrumentation and transducers, including micro-electro-mechanical systems (MEMS)
87.80.Ek Mechanical and micromechanical techniques
87.17.-d Cell processes

A miniaturized continuous dielectrophoretic cell sorter and its applications

Ana Valero, Thomas Braschler, Nicolas Demierre, and Philippe Renaud

Biomicrofluidics 4, 022807 (2010); http://dx.doi.org/10.1063/1.3430542 (9 pages) | Cited 10 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
There is great interest in highly sensitive separation methods capable of quickly isolating a particular cell type within a single manipulation step prior to their analysis. We present a cell sorting device based on the opposition of dielectrophoretic forces that discriminates between cell types according to their dielectric properties, such as the membrane permittivity and the cytoplasm conductivity. The forces are generated by an array of electrodes located in both sidewalls of a main flow channel. Cells with different dielectric responses perceive different force magnitudes and are, therefore, continuously focused to different equilibrium positions in the flow channel, thus avoiding the need of a specific cell labeling as discriminating factor. We relate the cells’ dielectric response to their output position in the downstream channel. Using this microfluidic platform that integrates a method of continuous-flow cell separation based on multiple frequency dielectrophoresis, we succeeded in sorting viable from nonviable yeast with nearly 100% purity. The method also allowed to increase the infection rate of a cell culture up to 50% of parasitemia percentage, which facilitates the study of the parasite cycle. Finally, we prove the versatility of our device by synchronizing a yeast cell culture at a particular phase of the cell cycle avoiding the use of metabolic agents interfering with the cells’ physiology.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects
87.50.cj Electroporation/membrane effects
87.17.-d Cell processes
87.16.D- Membranes, bilayers, and vesicles
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Dielectrophoretic cell trapping and parallel one-to-one fusion based on field constriction created by a micro-orifice array

Murat Gel, Yuji Kimura, Osamu Kurosawa, Hidehiro Oana, Hidetoshi Kotera, and Masao Washizu

Biomicrofluidics 4, 022808 (2010); http://dx.doi.org/10.1063/1.3422544 (8 pages) | Cited 7 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
Micro-orifice based cell fusion assures high-yield fusion without compromising the cell viability. This paper examines feasibility of a dielectrophoresis (DEP) assisted cell trapping method for parallel fusion with a micro-orifice array. The goal is to create viable fusants for studying postfusion cell behavior. We fabricated a microfluidic chip that contained a chamber and partition. The partition divided the chamber into two compartments and it had a number of embedded micro-orifices. The voltage applied to the electrodes located at each compartment generated an electric field distribution concentrating in micro-orifices. Cells introduced into each compartment moved toward the micro-orifice array by manipulation of hydrostatic pressure. DEP assisted trapping was used to keep the cells in micro-orifice and to establish cell to cell contact through orifice. By applying a pulse, cell fusion was initiated to form a neck between cells. The neck passing through the orifice resulted in immobilization of the fused cell pair at micro-orifice. After washing away the unfused cells, the chip was loaded to a microscope with stage top incubator for time lapse imaging of the selected fusants. The viable fusants were successfully generated by fusion of mouse fibroblast cells (L929). Time lapse observation of the fusants showed that fused cell pairs escaping from micro-orifice became one tetraploid cell. The generated tetraploid cells divided into three daughter cells. The fusants generated with a smaller micro-orifice (diameter ∼ 2 μm) were kept immobilized at micro-orifice until cell division phase. After observation of two synchronized cell divisions, the fusant divided into four daughter cells. We conclude that the presented method of cell pairing and fusion is suitable for high-yield generation of viable fusants and furthermore, subsequent study of postfusion phenomena.
Show PACS
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects
87.80.Ek Mechanical and micromechanical techniques
87.17.Ee Growth and division
47.85.Np Fluidics
07.10.Cm Micromechanical devices and systems

Separation by dielectrophoresis of dormant and nondormant bacterial cells of Mycobacterium smegmatis

Ke Zhu, Arseny S. Kaprelyants, Elena G. Salina, and Gerard H. Markx

Biomicrofluidics 4, 022809 (2010); http://dx.doi.org/10.1063/1.3435335 (11 pages) | Cited 5 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dielectrophoretic behavior of active, dead, and dormant Mycobacterium smegmatis bacterial cells was studied. It was found that the 72-h-old dormant cells had a much higher effective particle conductivity (812±10 μS cm−1), almost double that of active cells (560±20 μS cm−1), while that of dead (autoclaved) M. smegmatis cells was the highest (950±15 μS cm−1) overall. It was also found that at 80 kHz, 900 μS cm−1 dead cells were attracted at the edges of interdigitated castellated electrodes by positive dielectrophoresis, but dormant cells were not. Similarly, at 120 kHz, 2 μS cm−1 active cells were attracted and dormant cells were not. Using these findings a dielectrophoresis-based microfluidic separation system was developed in which dead and active cells were collected from a given cell suspension, while dormant cells were eluted.
Show PACS
87.16.-b Subcellular structure and processes
87.80.-y Biophysical techniques (research methods)
87.50.C- Static and low-frequency electric and magnetic fields effects
82.45.-h Electrochemistry and electrophoresis

Construction by dielectrophoresis of microbial aggregates for the study of bacterial cell dormancy

Ke Zhu, Arseny S. Kaprelyants, Elena G. Salina, Martin Schuler, and Gerard H. Markx

Biomicrofluidics 4, 022810 (2010); http://dx.doi.org/10.1063/1.3435336 (13 pages) | Cited 3 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A study of the effect of aggregate size on the resuscitation of dormant M. smegmatis was conducted by constructing cell aggregates with defined sizes and shapes using dielectrophoresis and monitoring the resuscitation process under controlled laboratorial conditions in a long-term cell feeding system. Differently sized cell aggregates were created on the surface of indium tin oxide coated microelectrodes, their heights and shapes controlled by the strength of the induced electric field and the shape of the microelectrodes. Both two-dimensional (ring-patterned) and three-dimensional cell aggregates were produced. The cell aggregates were maintained under sterile conditions at 37 °C for up to 14 days by continuously flushing Sauton’s medium through the chamber. Resuscitation of dormant M. smegmatis was evaluated by the production of the fluorescent dye 5-cyano-2,3-ditolyltetrazolium chloride. The results confirm that the resuscitation of dormant M. smegmatis is triggered by the accumulation of a resuscitation promoting factor inside the aggregates by diffusion limitation.
Show PACS
87.16.-b Subcellular structure and processes
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects

Review Article—Dielectrophoresis: Status of the theory, technology, and applications

Ronald Pethig

Biomicrofluidics 4, 022811 (2010); http://dx.doi.org/10.1063/1.3456626 (35 pages) | Cited 48 times

Online Publication Date: 29 June 2010

Full Text: Read Online (HTML) | Download PDF


See Also: Publisher's Note

Show Abstract
A review is presented of the present status of the theory, the developed technology and the current applications of dielectrophoresis (DEP). Over the past 10 years around 2000 publications have addressed these three aspects, and current trends suggest that the theory and technology have matured sufficiently for most effort to now be directed towards applying DEP to unmet needs in such areas as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation to describe the DEP force acting on a particle subjected to a nonuniform electric field has evolved to include multipole contributions, the perturbing effects arising from interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations that must be considered for nanoparticles. Theoretical modelling of the electric field gradients generated by different electrode designs has also reached an advanced state. Advances in the technology include the development of sophisticated electrode designs, along with the introduction of new materials (e.g., silicone polymers, dry film resist) and methods for fabricating the electrodes and microfluidics of DEP devices (photo and electron beam lithography, laser ablation, thin film techniques, CMOS technology). Around three-quarters of the 300 or so scientific publications now being published each year on DEP are directed towards practical applications, and this is matched with an increasing number of patent applications. A summary of the US patents granted since January 2005 is given, along with an outline of the small number of perceived industrial applications (e.g., mineral separation, micropolishing, manipulation and dispensing of fluid droplets, manipulation and assembly of micro components). The technology has also advanced sufficiently for DEP to be used as a tool to manipulate nanoparticles (e.g., carbon nanotubes, nano wires, gold and metal oxide nanoparticles) for the fabrication of devices and sensors. Most efforts are now being directed towards biomedical applications, such as the spatial manipulation and selective separation/enrichment of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP is able to manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP as a tool to address an unmet need in stem cell research and therapy.
Show PACS
87.80.-y Biophysical techniques (research methods)
82.45.-h Electrochemistry and electrophoresis
87.50.ch Electrophoresis/dielectrophoresis and other mechanical effects
87.17.-d Cell processes
back to top
RSS Feeds

A prototypic microfluidic platform generating stepwise concentration gradients for real-time study of cell apoptosis

Wen Dai, Yizhe Zheng, Kathy Qian Luo, and Hongkai Wu

Biomicrofluidics 4, 024101 (2010); http://dx.doi.org/10.1063/1.3398319 (14 pages) | Cited 11 times

Online Publication Date: 16 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This work describes the development of a prototypic microfluidic platform for the generation of stepwise concentration gradients of drugs. A sensitive apoptotic analysis method is integrated into this microfluidic system for studying apoptosis of HeLa cells under the influence of anticancer drug, etoposide, with various concentrations in parallel; it measures the yellow fluorescent protein/cyan fluorescent protein fluorescence resonance energy transfer (FRET) signal that responds to the activation of caspase-3, an indicator of cell apoptosis. Sets of microfluidic valves on the chip generate stepwise concentration gradient of etoposide in various cell-culture microchambers. The FRET signals from multiple chambers are simultaneously monitored under a fluorescent microscope for long-time observation and the on-chip results are compared with those from 96-well plate study and the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. The microfluidic platform shows several advantages including high-throughput capacity, low drug consumption, and high sensitivity.
Show PACS
87.85.Ox Biomedical instrumentation and transducers, including micro-electro-mechanical systems (MEMS)
87.80.Ek Mechanical and micromechanical techniques
87.64.M- Optical microscopy
87.64.kv Fluorescence
87.19.xj Cancer
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Fast and reliable droplet transport on single-plate electrowetting on dielectrics using nonfloating switching method

Jun Kwon Park, Seung Jun Lee, and Kwan Hyoung Kang

Biomicrofluidics 4, 024102 (2010); http://dx.doi.org/10.1063/1.3398258 (8 pages) | Cited 3 times

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In a droplet transport based on electrowetting on dielectrics, the parallel-plate configuration is more popular than the single-plate one because the droplet transport becomes increasingly difficult without cover plate. In spite of the improved transport performance, the parallel-plate configuration often limits the access to the peripheral components, requesting the removal of the cover plate, the single-plate configuration. We investigated the fundamental features of droplet transport for the single-plate configuration. We compared the performance of several switching methods with respect to maximum speed of successive transport without failure and suggested nonfloating switching method which is inherently free from the charge-residue problem and exerts greater force on a droplet than conventional switching methods. A simple theory is provided to understand the different results for the switching methods.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.55.dr Interactions with surfaces
47.65.-d Magnetohydrodynamics and electrohydrodynamics
47.85.Np Fluidics
68.08.Bc Wetting

Amplification of SPPS150 and Salmonella typhi DNA with a high throughput oscillating flow polymerase chain reaction device

D. Sugumar, Asma Ismail, Manickam Ravichandran, Ismail Aziah, and L. X. Kong

Biomicrofluidics 4, 024103 (2010); http://dx.doi.org/10.1063/1.3422524 (12 pages) | Cited 3 times

Online Publication Date: 3 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper, a novel oscillating flow polymerase chain reaction (PCR) device was designed and fabricated to amplify SPPS150 and salmonella typhi. In this new design, the samples are shuttled (oscillating flow) inside a microfluidic chip to three different temperature zones required for DNA amplification. The amplification cycle time has markedly been reduced as the reagent volume used was only about 25% of that used in conventional PCRs. Bubble formation and adsorption issues commonly associated to chip based PCR were also eliminated. Based on the performance evaluated, it is demonstrated that this oscillating flow PCR has the advantages of both the stationary chamber and continuous flow PCR devices.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
87.14.gk DNA
87.15.R- Reactions and kinetics

Electric charge-mediated coalescence of water droplets for biochemical microreactors

Yong-Mi Jung (정용미) and In Seok Kang (강인석)

Biomicrofluidics 4, 024104 (2010); http://dx.doi.org/10.1063/1.3427356 (14 pages) | Cited 3 times

Online Publication Date: 4 May 2010

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
This work proposes the use of charged droplets driven by the Coulombic force as solution-phase reaction chambers for biological microreactions. A droplet can be charged near an electrode under dc voltage by direct contact to the electrode. This process is called electrical charging of droplet (ECOD). This charged droplet can then be transported rapidly between electrodes following the arc of an electric field line by exploiting electrostatic force. As on-demand electrocoalescence, both alkalization of phenolphthalein and bioluminescence reaction of luciferase in the presence of adenosine triphosphate are studied to test the feasibility of the biochemical microreactors using ECOD. Two oppositely charged droplets are merged to have a color change immediately after microchemical reaction. The applicability of an ECOD-driven droplet to measurement of glucose concentration is also tested. The glucose concentration is measured using a colorimetric enzyme-kinetic method based on Trinder’s reaction [ J. Clin. Pathol. 22, 158 (1969) ]. The color change in the merged droplet is detected with an absorbance measurement system consisting of a photodiode and a light emitting diode.
Show PACS
87.85.fk Biosensors
82.39.-k Chemical kinetics in biological systems
87.15.R- Reactions and kinetics
87.15.mq Luminescence
87.80.Ek Mechanical and micromechanical techniques

A simplified design of the staggered herringbone micromixer for practical applications

Yan Du, Zhiyi Zhang, ChaeHo Yim, Min Lin, and Xudong Cao

Biomicrofluidics 4, 024105 (2010); http://dx.doi.org/10.1063/1.3427240 (13 pages) | Cited 2 times

Online Publication Date: 7 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrated a simple method for the device design of a staggered herringbone micromixer (SHM) using numerical simulation. By correlating the simulated concentrations with channel length, we obtained a series of concentration versus channel length profiles, and used mixing completion length Lm as the only parameter to evaluate the performance of device structure on mixing. Fluorescence quenching experiments were subsequently conducted to verify the optimized SHM structure for a specific application. Good agreement was found between the optimization and the experimental data. Since Lm is straightforward, easily defined and calculated parameter for characterization of mixing performance, this method for designing micromixers is simple and effective for practical applications.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
47.85.Np Fluidics
47.63.-b Biological fluid dynamics

Acoustic driven flow and lattice Boltzmann simulations to study cell adhesion in biofunctionalized μ-fluidic channels with complex geometry

M. A. Fallah, V. M. Myles, T. Krüger, K. Sritharan, A. Wixforth, F. Varnik, S. W. Schneider, and M. F. Schneider

Biomicrofluidics 4, 024106 (2010); http://dx.doi.org/10.1063/1.3396449 (10 pages) | Cited 1 time

Online Publication Date: 19 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Accurately mimicking the complexity of microvascular systems calls for a technology which can accommodate particularly small sample volumes while retaining a large degree of freedom in channel geometry and keeping the price considerably low to allow for high throughput experiments. Here, we demonstrate that the use of surface acoustic wave driven microfluidics systems successfully allows the study of the interrelation between melanoma cell adhesion, the matrix protein collagen type I, the blood clotting factor von Willebrand factor (vWF), and microfluidic channel geometry. The versatility of the tool presented enables us to examine cell adhesion under flow in straight and bifurcated microfluidic channels in the presence of different protein coatings. We show that the addition of vWF tremendously increases (up to tenfold) the adhesion of melanoma cells even under fairly low shear flow conditions. This effect is altered in the presence of bifurcated channels demonstrating the importance of an elaborate hydrodynamic analysis to differentiate between physical and biological effects. Therefore, computer simulations have been performed along with the experiments to reveal the entire flow profile in the channel. We conclude that a combination of theory and experiment will lead to a consistent explanation of cell adhesion, and will optimize the potential of microfluidic experiments to further unravel the relation between blood clotting factors, cell adhesion molecules, cancer cell spreading, and the hydrodynamic conditions in our microcirculatory system.
Show PACS
87.19.rh Fluid transport and rheology
47.63.Jd Microcirculation and flow through tissues
87.17.Rt Cell adhesion and cell mechanics

An optofluidic volume refractometer using Fabry–Pérot resonator with tunable liquid microlenses

L. K. Chin, A. Q. Liu, C. S. Lim, C. L. Lin, T. C. Ayi, and P. H. Yap

Biomicrofluidics 4, 024107 (2010); http://dx.doi.org/10.1063/1.3430605 (7 pages) | Cited 6 times

Online Publication Date: 24 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter reports the development of an optofluidic Fabry–Pérot (FP) resonator, which consists of a microcavity and a pair of liquid microlenses. The microcavity forms part of the microchannel to facilitate sample injection. The liquid microlenses are used for efficient light coupling from the optical fiber to the microcavity. The liquid microlens collimates the diverging light from the optical fiber into the FP cavity, which provides real-time tuning to obtain the highest possible finesse up to 18.79. In volume refractive index measurement, a sensitivity of 960 nm per refractive index unit (RIU) and a detection range of 0.043 RIU are achieved.
Show PACS
87.85.Ox Biomedical instrumentation and transducers, including micro-electro-mechanical systems (MEMS)
87.80.Ek Mechanical and micromechanical techniques
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.60.Hv Refractometers and reflectometers
42.79.Bh Lenses, prisms and mirrors
47.85.Np Fluidics

A polymeric micro-optical interface for flow monitoring in biomicrofluidics

Francesca Sapuppo, Andreu Llobera, Florinda Schembri, Marcos Intaglietta, Victor J. Cadarso, and Maide Bucolo

Biomicrofluidics 4, 024108 (2010); http://dx.doi.org/10.1063/1.3435333 (13 pages) | Cited 1 time

Online Publication Date: 24 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe design and miniaturization of a polymeric optical interface for flow monitoring in biomicrofluidics applications based on polydimethylsiloxane technology, providing optical transparency and compatibility with biological tissues. Design and ray tracing simulation are presented as well as device realization and optical analysis of flow dynamics in microscopic blood vessels. Optics characterization of this polymeric microinterface in dynamic experimental conditions provides a proof of concept for the application of the device to two-phase flow monitoring in both in vitro experiments and in vivo microcirculation investigations. This technology supports the study of in vitro and in vivo microfluidic systems. It yields simultaneous optical measurements, allowing for continuous monitoring of flow. This development, integrating a well-known and widely used optical flow monitoring systems, provides a disposable interface between live mammalian tissues and microfluidic devices making them accessible to detection/processing technology, in support or replacing standard intravital microscopy.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
87.50.wf Biophysical mechanisms of interaction
87.19.U- Hemodynamics

Highly accurate deterministic lateral displacement device and its application to purification of fungal spores

David W. Inglis, Nick Herman, and Graham Vesey

Biomicrofluidics 4, 024109 (2010); http://dx.doi.org/10.1063/1.3430553 (8 pages) | Cited 4 times

Online Publication Date: 24 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have designed, built, and evaluated a microfluidic device that uses deterministic lateral displacement for size-based separation. The device achieves almost 100% purity and recovery in continuously sorting two, four, and six micrometer microspheres. We have applied this highly efficient device to the purification of fungal (Aspergillus) spores that are spherical ( ∼ 4 μm diameter) with a narrow size distribution. Such separation directly from culture using unfiltered A. niger suspensions is difficult due to a high level of debris. The device produces a two to three increase in the ratio of spores to debris as measured by light scatter in a flow cytometer. The procedure is feasible at densities up to 4.4×106 spores/ml. This is one of the first studies to apply microfluidic techniques to spore separations and has demonstrated that a passive separation system could significantly reduce the amount of debris in a suspension of fungal spores with virtually no loss of spore material.
Show PACS
87.80.Ek Mechanical and micromechanical techniques
82.70.Kj Emulsions and suspensions

An optical counting technique with vertical hydrodynamic focusing for biological cells

Stefano Chiavaroli, David Newport, and Bernie Woulfe

Biomicrofluidics 4, 024110 (2010); http://dx.doi.org/10.1063/1.3380598 (10 pages) | Cited 4 times

Online Publication Date: 15 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A barrier in scaling laboratory processes into automated microfluidic devices has been the transfer of laboratory based assays: Where engineering meets biological protocol. One basic requirement is to reliably and accurately know the distribution and number of biological cells being dispensed. In this study, a novel optical counting technique to efficiently quantify the number of cells flowing into a microtube is presented. REH, B-lymphoid precursor leukemia, are stained with a fluorescent dye and frames of moving cells are recorded using a charge coupled device (CCD) camera. The basic principle is to calculate the total fluorescence intensity of the image and to divide it by the average intensity of a single cell. This method allows counting the number of cells with an uncertainty ±5%, which compares favorably to the standard biological methodology, based on the manual Trypan Blue assay, which is destructive to the cells and presents an uncertainty in the order of 20%. The use of a microdevice for vertical hydrodynamic focusing, which can reduce the background noise of out of focus cells by concentrating the cells in a thin layer, has further improved the technique. Computational fluid dynamics (CFD) simulation and confocal laser scanning microscopy images have shown an 82% reduction in the vertical displacement of the cells. For the flow rates imposed during this study, a throughput of 100–200 cells/s is achieved.
Show PACS
87.63.L- Visual imaging
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
47.85.Np Fluidics
87.16.-b Subcellular structure and processes

Rapid magnetic heating treatment by highly charged maghemite nanoparticles on Wistar rats exocranial glioma tumors at microliter volume

Ioannis Rabias, Danai Tsitrouli, Eleni Karakosta, Thomas Kehagias, Georgios Diamantopoulos, Michael Fardis, Dimosthenis Stamopoulos, Thomas G. Maris, Polykarpos Falaras, Nikolaos Zouridakis, Nikolaos Diamantis, Georgios Panayotou, Dimitrios A. Verganelakis, Garyfalia I. Drossopoulou, Effie C. Tsilibari, et al.

Biomicrofluidics 4, 024111 (2010); http://dx.doi.org/10.1063/1.3449089 (8 pages) | Cited 1 time

Online Publication Date: 21 June 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
One of the most significant challenges implementing colloidal magnetic nanoparticles in medicine is the efficient heating of microliter quantities by applying a low frequency alternating magnetic field. The ultimate goal is to accomplish nonsurgically the treatment of millimeter size tumors. Here, we demonstrate the synthesis, characterization, and the in vitro as well as in vivo efficiency of a dextran coated maghemite (γ-Fe2O3) ferrofluid with an exceptional response to magnetic heating. The difference to previous synthetic attempts is the high charge of the dextran coating, which according to our study maintains the colloidal stability and good dispersion of the ferrofluid during the magnetic heating stage. Specifically, in vitro 2 μl of the ferrofluid gives an outstanding temperature rise of 33 °C within 10 min, while in vivo treatment, by infusing 150 μl of the ferrofluid in animal model (rat) glioma tumors, causes an impressive cancer tissue dissolution.
Show PACS
87.85.Rs Nanotechnologies-applications
75.50.Tt Fine-particle systems; nanocrystalline materials
87.55.-x Treatment strategy
87.85.J- Biomaterials
75.50.Mm Magnetic liquids
87.19.xj Cancer
87.85.D- Applied neuroscience
Page 1 of 2 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. Electrokinetic focusing and filtration of cells in a serpentine microchannel
  2. Pressure-driven transport of particles through a converging-diverging microchannel
  3. Enhanced discrimination of normal oocytes using optically induced pulling-up dielectrophoretic force
  4. Polydimethylsiloxane-based conducting composites and their applications in microfluidic chip fabrication
  5. Microfluidics as a functional tool for cell mechanics
Go to AIP Home
Copyright © American Institute of Physics
close