An AC electrokinetic funnel flow is generated by a planar micro-coil resister design capable of sustaining 3500V without Faradaic reactions. The final line of the serpentine coil exhibits a transverse electro-osmotic slip velocity exceeding 1 cm/sec. Due to side boundaries, a large back pressure is established in the slip direction to ...

In this work we report a microfluidic platform capable of trapping and concentrating a trace amount of DNA molecules efficiently. Our strategy invokes nonlinear electro-osmotic flow induced by charge polarization under high-frequency ac fields. With the asymmetric quadrupole electrode design, a unique converging flow structure can be created for generating focusing effects on ...

Alternating current (AC) electrokinetic motion of colloidal particles suspended in an aqueous medium and subjected to a spatially nonuniform AC electric field are examined using a simple theoretical model that considers the relative magnitudes of dielectrophoresis, electrophoresis, AC-electroosmosis, and Brownian ...

... 4. TITLE AND SUBTITLE Biosensor Assay Enhancement Through Ac ... useful in portable field-based medical biosensors, or environmental, or food ...

Alternating current (ac) electrokinetic motion of colloidal particles suspended in an aqueous medium and subjected to a spatially nonuniform ac electric field are examined using a simple theoretical model that considers the relative magnitudes of dielectrophoresis, electrophoresis, ac-electroosmosis, and Brownian ...

Orthogonal electrodes have been reported to produce high velocity microflows when excited by ac signals, showing potential for micropumping applications. This paper investigates the microflow reversal phenomena in such orthogonal electrode micropumps. Three types of microflow fields were observed by changing the applied electric signals. Three ac ...

... microstirring is a tool that can be incorporated in existing devices, to speed up, for example, food-borne pathogen detection, or portable medical ...

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bearings will be important in the development of micro- coolers, micropumps, microgenerators, and other

Electrokinetic boundary conditions are derived for ac electrokinetic phenomena over leaky dielectric (i.e., semiconducting) surfaces. Such boundary conditions correlate the electric potentials across a semiconductor-electrolyte interface (consisting of an electric double layer inside the electrolyte solution and a space charge layer ...

Electrokinetic boundary conditions are derived for ac electrokinetic phenomena over leaky dielectric (i.e., semiconducting) surfaces. Such boundary conditions correlate the electric potentials across a semiconductor-electrolyte interface (consisting of an electric double layer inside the electrolyte solution and a space charge layer ...

The field of AC electrokinetics is rapidly growing due to its ability to perform dynamic fluid and particle manipulation on the micro- and nano-scale, which is essential for Lab-on-a-Chip applications. AC electrokinetic phenomena use electric fields to generate forces that act on fluids or suspended particles ...

A microstirring tool is developed to improve binding rates in biosensor devices by an order of magnitude. AC electric fields generate fluid motion through the well documented but unexploited phenomenon, Electrothermal Flow, where the circulating flow redi...

Orthogonal electrodes have been reported to produce high velocity microflows when excited by ac signals, showing potential for micropumping applications. This paper investigates the microflow reversal phenomena in such orthogonal electrode micropumps. Three types of microflow fields were observed by changing the applied electric signals. Three ac ...

, universal decay of the mobility with bulk concentration c0, observed in KCl for ACEO micropumps [11. Lett. 100 058302 [10] Olesen L H, Bruus H and Ajdari A 2006 AC electrokinetic micropumps: the effect and Chang H C 2004 Electrokinetic micropump and micromixer design based on ac Faradaic polarization J. Appl

This paper investigates the phenomenon of Faradaic charging in ac electrokinetics. Faradaic reactions were suggested as a key effect responsible for the reversal of pumping direction in ac micropumps. However, this hypothesis has yet to be proven convincingly and directly. Here we present an ion detection strategy to determine the ...

The AC electrokinetic movement of fluids has its origin in two different physical mechanisms: AC electroosmosis, the interaction of the Electrical Double Layer induced on microelectrodes by an applied potential and the generated electric field; and electrothermal Electro-hydrodynamics, the interaction of an electric field with ...

The area of 'laboratory-on-a-chip', miniaturised or microfluidic analysis systems, is a rapidly developing field. At the microscale, electrokinetic processes become enhanced, and the advent of AC electrokinetics (EK) in recent years further promotes the development of electrokinetic devices for microfluidics. ACEK ...

The kinesin-microtubule system plays an important role in intracellular transport and is a model system for integrating biomotor-driven transport into microengineered devices. AC electrokinetics provides a novel tool for manipulating and organizing microtubules in solution, enabling new experimental geometries for investigating and controlling the ...

This Special Topic section is a compilation of several original contributions covering both fundamental and practical aspects of electrokinetic microfluidic phenomena that were presented during the Electrokinetics and Microfluidics sessions held at the conference. PMID:20644663

This Special Topic section is a compilation of several original contributions covering both fundamental and practical aspects of electrokinetic microfluidic phenomena that were presented during the Electrokinetics and Microfluidics sessions held at the conference.

intensive. Such baffles are also problematic in chips that employ electroosmosis or electrophoresis as high than the linear scaling of the standard electroosmosis. Dukhin7 first offered an estimate to a combination of channel electroosmosis and the pH-gradient-induced backflows, is less significant than that due

AC electrokinetics is rapidly becoming a foundational tool for lab-on-a-chip systems due to its versatility and the simplicity of the components capable of generating them. Predicting the behavior of fluids and particles under non-uniform AC electric fields is important for the design of next generation devices. Though there are ...

Recent experiments have demonstrated that AC electrokinetic micropumps permit integrable, local, and fast pumping (velocities � mm/s) with low driving voltage of a few volts only. However, they also displayed many quantitative and qualitative discrepancies with existing theories. We therefore extend the latter theories to account for three experimentally ...

We demonstrate an opto-electrokinetic technique for non-invasive particle manipulation on the surface of a parallel-plate indium tin oxide (ITO) electrode that is biased with an alternating current (AC) signal and illuminated with near-infrared (1064 nm) optical landscapes. This technique can generate strong microfluidic vortices at higher ...

A microfluidic pump and mixer design based on ac faradaic polarization is proposed. Unlike ac electrokinetic devices based on capacitive charging of the electrodes, the design yields a net electro-osmotic flow for high-conductivity electrolytes at high voltages and frequencies without producing gas bubbles or generating pH gradients. ...

Micelles and polymers vesicles have been of increasing interest as drug delivery systems for controlled release, specific cell targeting, and medical diagnostics. In addition, AC-electrokinetic techniques have emerged as a viable option for colloidal and biocolloidal manipulation. In this work, we examine the dielectrophoresis (DEP) characteristics of complex micellar ...

This study reports a hybrid electrokinetic technique for label-free manipulation of pathogenic bacteria in biological samples toward medical diagnostic applications. While most electrokinetic techniques only function in low-conductivity buffers, hybrid electrokinetics enables effective operation in high-conductivity samples, such as ...

This study reports improved electrokinetically driven microfluidic T-mixers to enhance their mixing efficiency. Enhancement of electrokinetic microfluidic T-mixers is achieved using (i) an active approach of utilizing a pulsating EOF, and (ii) a passive approach of using the channel geometry effect with patterned blocks. PDMS-based ...

An ac electric field is applied to induce particle and fluid motion in a wedge-shaped microchannel. Micron-resolution particle image velocimetry (?-PIV) is used to determine spatially resolved particle velocity and fluid velocity fields. Under steady-state conditions, the particles experience a balance between dielectrophoretic forces induced by the nonuniform electric field ...

Electric field guided assembly of colloids is a new area of research in colloidal science where sub-micrometer particles, or colloids, are assembled using patterned electrodes. The design of these devices is often limited by an inability to characterize accurately forces and fluxes with linearized electrokinetic theory. The research presented in this dissertation describes an ...

and proteins. AC electroosmotic flow can be utilized to create micropumps for micro-bio- chips [1]. As a result electroosmotic micropumps. ICEO [4] refers to a phenomenon in which a DC or AC electric field induces charge electrokinetic micropumps: The effect of geometrical confinement, Faradaic current injection, and nonlinear

unsuitable for biological applica- tions. Due to such drawbacks, the use of electrokinetic EK micropumps- clude dc and ac micropumps. In a dc pump electro-osmotic EO flow is induced by an external tangential of directed flow over the activated micropump. For more information on EPAPS, see http://www. aip

Rapid cell separation and collection is demonstrated through the integration of electrokinetic pumps, dielectrophoretic (DEP) traps and field driven valves into a well designed microfluidic channel loop. We present the ground-up design and analysis of this fully functional microfluidic device for the rapid separation and collection of live and dead yeast cells and malaria red ...

Removal of Cu, Cr and As from utility poles treated with chromated copper arsenate (CCA) was investigated using different one- to three-step combinations of oxalic acid extraction and electrokinetic treatment. The experiments were carried out at room temperature, using 0.8% oxalic acid and 30 V (200 V/m) of direct current (DC) or alternating current in combination ...

Various electrokinetic phenomena in microfluidics have been utilised to manipulate microfluids and particles for lab-on-a-chip applications. Microfluidic channels with traditional planar floor configuration designs have limited pumping efficiency due to the fast backward flow over the electrode surface. This study reports optimal design of a microchannel with a microgrooved ...

We present here a study on overlooked aspects of alternating current (AC) electrokinetics-AC electrophoretic (ACEP) phenomena. The dynamics of a particle with both polarizability and net charges in a non-uniform AC electric trapping field is investigated. It is found that either electrophoretic (EP) or dielectrophoretic (DEP) effects ...

We present here a study on overlooked aspects of alternating current (AC) electrokinetics�AC electrophoretic (ACEP) phenomena. The dynamics of a particle with both polarizability and net charges in a non-uniform AC electric trapping field is investigated. It is found that either electrophoretic (EP) or dielectrophoretic (DEP) effects ...

Motivated by the growing interest in ac electroosmosis as a reliable no moving parts strategy to control fluid motion in microfluidic devices for biomedical applications, such as lab-on-a-chip, we study transient and steady-state electrokinetic phenomena (electroosmosis and streaming currents) in infinitely extended rectangular charged microchannels. With ...

The recognition and manipulation of biomolecules on the microscale is a fundamental requirement for the development of lab on a chip devices. AC electrokinetic approaches are ideally suited to manipulating particles in such systems. Unfortunately, these approaches cannot recognize isolated macromolecules with high discrimination because molecular ...

Iontophoretic and electroporation transdermal delivery modes of ionic drugs have been utilized in a number of clinical and biomedical devices. However, applications of these methods have been found challenging for the delivery of many non polar and high molecular weight clinically important drugs. The main goal of the present study is to investigate whether transdermal transport of non polar ...

In this work, we explore the rich AC-electrokinetic effects to manipulate micelles of varied chemical structures and examine their stability in response to applied AC-electric fields. We investigate the AC-field induced transport and instability of sodium dodecyl sulfate (SDS) micelles and cetyl trimethylammonium bromide (CTAB) ...

Recent experiments have demonstrated that ac electrokinetic micropumps permit integrable, local, and fast pumping (velocities �mm/s ) with low driving voltage of a few volts only. However, they also displayed many quantitative and qualitative discrepancies with existing theories. We therefore extend the latter theories to account for three ...

This paper reports dramatic improvements in flow rate over conventional alternating current (ac) electrokinetic micropumps by exploiting asymmetry in electric potentials over the electrodes. A micropump consisting of a planar asymmetric electrode array was tested using ac signals with and without a direct current (dc) bias. All ...

We demonstrate an optically induced electrokinetic technique that continuously concentrates nanoparticles on the surface of a parallel plate electrode that is biased with an AC signal. A highly focused beam of near-infrared light (1064 nm) was applied, inducing an electrothermal microfluidic vortex that carried nanoparticles to its center where they were ...

Forces experienced by colloidal particles in an AC electric field such as dielectrophoresis (DEP) and AC electro-osmosis (ACEO) have been widely investigated for their application in microfluidic devices. In order to provide a more complete theoretical basis for such AC electrokinetic mechanisms, we propose a ...

Lab-on-a-chip devices require integrated pumping and fluid control in microchannels. A recently developed mechanism that can produce fluid flow is an integrated ac-electro-osmosis micropump. However, like most electrokinetic pumps, ac-electro-osmotic pumps are incapable of handling backpressure as the pumping force mechanism acts on ...

The ability of electrokinetics to manipulate biological microparticles, such as cells and bacteria, has great applications in Lab-on-a-chip devices, and micro-total analysis systems (mTAS). In these methods, non-uniform AC electric fields interact with the dielectric properties of suspended biological microparticles to induce forces and torques on the ...

This paper reports on the integration of thick carbon-polydimethylsiloxane (C-PDMS) electrodes in microfluidic systems for electrokinetic operations. The C-PDMS material, obtained by mixing carbon nanopowder and PDMS, preserves PDMS processing properties such as O2 plasma activation and soft-lithography patternability in thick or 3D electrodes. Conductivity in the order of 10 ...

Microscale electrodes supplied with an AC field can generate rotational fluid patterns known as AC electroosmosis. In the present study, this effect was used to improve antibody binding on a biosensor surface. Antibodies, like many other large, slow moving biomolecules, tend to suffer from transport limitations during a reaction with a surface-bound ...

The classical theory of electrokinetic phenomena assumes a dilute solution of point-like ions in chemical equilibrium with a surface whose double-layer voltage is of order the thermal voltage, kBT/e=25 mV. In nonlinear 'induced-charge' electrokinetic phenomena, such as ac electro-osmosis, several volts ?100kBT/e are applied to the ...

Nonlinear electrokinetic pumps are attractive in the development of portable and flexible microfluidic analysis systems, since they operate without moving parts using low (battery powered) alternating potentials. Since the discovery of AC electro-osmosis (ACEO) in the late 1990s, there has been much work in designing and building two-dimensional, periodic ...

AC electrokinetic phenomena, i.e., electrorotation, dielectrophoresis and traveling wave dielectrophoresis, have gained an increasing amount of attention. This is due to their wide range of applications from cancer research to identifying and separating parasites, cell populations and viruses, and even to design of nanomotors. Despite the number of ...

Electrokinetic microstirring is used to improve the sensitivity of microfluidic heterogeneous immuno-sensors by enhancing the transport in diffusion-limited reactions. The AC electrokinetic force, Electrothermal Flow, is exploited to create a circular stirring fluid motion, thereby providing more binding opportunities between suspended ...

concentrator, micro-pumps and mixers by ACEO. Electro-osmosis typically refers to using DC potential to moving is important for optimizing the micropump and particle transportation. In contrast to electrophoretic AC Electrochemical Micropump, AIChE annual meeting 2004, Nov. 7 � 12, Austin, TX. 361 #12;

with electrokinetic flow [19]. Microvortices to rehomoge- nize the blood cell distribution can also be utilized. Work the loading of microliter of blood sample is the goal of our cur- rent efforts. Acknowledgments This work ac- knowledge the blood supply by Jason Gordon from Andre F. Palmer's group at Notre Dame. References

. A slip silicone cover (SA8R-0.5, Grace Bio-Labs, USA) is sealed on the glass slide to form the chamber Erms is applied over a fluid body, energy is dissipated as 2 rmsEP = ( : electrolyte conductivity at high frequency. ACET effect occurs owing to the resistive property of the fluid, so its flow velocity

DESIGN AND MODELING OF A PETAL-SHAPE, CONJUGATED POLYMER-ACTUATED MICROPUMP Yang Fang and Xiaobo the micropump, it is important to make the prototypes of different diaphragms for comparisons and predict the performance of the micropump. In this paper, a petal-shape design is proposed for the pump- Proceedings

--We have developed micropumps for microfluidics that use AC electric fields to drive aqueous fluid motion, micropump I. INTRODUCTION Electrokinetic phenomena are important at micro/nanoscales, and can be used micropumps by taking advantage of these phenomena. IMECE2004-61836 2004 ASME International Mechanical

of moving parts and the favorable velocity profile have made electrokinetic means such as electroosmosis) electroosmosis, a series of novel techniques have been developed to generate bulk flow using ac fields electroosmosis has a number of applications in microfluidic and micro- electromechanical system (MEMS) devices.1

Recommended Construction and Installation Instructions for the Extended Funnel Bycatch Reduction Device

Try a simple experiment with a ping pong and a funnel, with explanation of Bernoulli's principle for what happens.

An air funnel assembly is described between an air inlet and a carburetor, comprising an elastic air funnel extending between the inlet and the carburetor; an air funnel cover extending about at least a portion of the elastic air funnel, the air funnel cover being rigid, the elastic air ...

A novel microstirring strategy is applied to accelerate the digestion rate of the substrate N(alpha)-benzoyl-L-arginine-4-nitroanilide (L-BAPA) catalyzed by sol-gel encapsulated trypsin. We use an ac nonlinear electrokinetic vortex flow to stir the solution in a microfluidic reaction chamber to reduce the diffusion length between the immobilized enzyme and ...

A novel microstirring strategy is applied to accelerate the digestion rate of the substrate N_?-benzoyl-L-arginine-4-nitroanilide (L-BAPA) catalyzed by sol-gel encapsulated trypsin. We use an ac nonlinear electrokinetic vortex flow to stir the solution in a microfluidic reaction chamber to reduce the diffusion length between the ...

The control and handling of fluids and fluid-based samples is central to the majority of applications in the areas of Micro Analysis systems and the Lab-on-a-chip. As a result, there is a great deal of research and industrial interest in developing specific technologies for this purpose: micropumps, micromixers, microstirrers, etc. One widely used technology in these systems is ...

In biomedical research and diagnostics it is a challenge to isolate and detect low levels of nanoparticles and nanoscale biomarkers in blood and other biological samples. While highly sensitive epifluorescent microscope systems are available for ultra low level detection, the isolation of the specific entities from large sample volumes is often the bigger limitation. AC ...

AC electrokinetics has shown great potential for microfluidic functions such as pumping, mixing and concentrating particles. So far, electrokinetics are typically applied on fluids that are not too conductive (<0.02 S/m), which excludes most biofluidic applications. To solve this problem, this paper seeks to apply ...