AC Electrokinetic Pumps for Micro/NanoFluidics

2004 ◽  
Author(s):  
Junqing Wu ◽  
Gaurav Soni ◽  
Dazhi Wang ◽  
Carl D. Meinhart
Keyword(s):  
Electric Fields ◽  
Fluid Motion ◽  
Lab On A Chip ◽  
Dna Amplification ◽  
Aqueous Fluid ◽  
Working Fluid ◽  
High Frequencies ◽  
Electrode Surfaces ◽  
Ac Electric Fields ◽  
Micro Channels

We have developed micropumps for microfluidics that use AC electric fields to drive aqueous fluid motion through micro channels. These pumps operate at relatively low voltages (~5–10Vrms), and high frequencies (~100kHz). They have several distinct advantages over the DC electrokinetic pumps. The low voltages make the pumps well suited for a wide variety of biosensor and “Lab-on-a-Chip” applications (e.g. PCR chip for DNA amplification). The high frequencies minimize electrolysis, so that bubbles do not form on the electrode surfaces, and do not contaminate the working fluid. The pumps can also be used as active valves or precision micro-dispensers.

AC Electrokinetics for Biosensors

2004 ◽  
Author(s):  
M. Sigurdson ◽  
C. Meinhart ◽  
D. Wang
Keyword(s):  
Electric Fields ◽  
Dna Hybridization ◽  
Fluid Motion ◽  
Diffusive Transport ◽  
Analyte Concentration ◽  
Ac Electrokinetics ◽  
Ac Electric Fields ◽  
Binding Rate ◽  
Electrothermal Flow ◽  
Biosensor Device

We develop here tools for speeding up binding in a biosensor device through augmenting diffusive transport, applicable to immunoassays as well as DNA hybridization, and to a variety of formats, from microfluidic to microarray. AC electric fields generate the fluid motion through the well documented but unexploited phenomenon, Electrothermal Flow, where the circulating flow redirects or stirs the fluid, providing more binding opportunities between suspended and wall-immobilized molecules. Numerical simulations predict a factor of up to 8 increase in binding rate for an immunoassay under reasonable conditions. Preliminary experiments show qualitatively higher binding after 15 minutes. In certain applications, dielectrophoretic capture of passing molecules, when combined with electrothermal flow, can increase local analyte concentration and further enhance binding.

AC electrohydrodynamic instabilities in thin liquid films

2009 ◽  
Vol 631 ◽  
pp. 255-279 ◽  
Author(s):  
SCOTT A. ROBERTS ◽  
SATISH KUMAR
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Electric Fields ◽  
Linear Stability Analysis ◽  
Floquet Theory ◽  
Thin Liquid Film ◽  
Liquid Films ◽  
Dielectric Films ◽  
High Frequencies ◽  
Ac Electric Fields

When DC electric fields are applied to a thin liquid film, the interface may become unstable and form a series of pillars. In this paper, we apply lubrication theory to examine the possibility of using AC electric fields to exert further control over the size and shape of the pillars. For perfect dielectric films, linear stability analysis shows that the influence of an AC field can be understood by considering an effective DC field. For leaky dielectric films, Floquet theory is applied to carry out the linear stability analysis, and it reveals that high frequencies may be used to inhibit the accumulation of interfacial free charge, leading to a lowering of growth rates and wavenumbers. Nonlinear simulations confirm the results of the linear stability analysis while also uncovering additional mechanisms for tuning overall pillar height and width. The results presented here may be of interest for the controlled creation of surface topographical features in applications such as patterned coatings and microelectronics.

Manipulation of Bio-Particles in Microelectrode Structures by Means of Non-Uniform AC Electric Fields

2002 ◽  
Author(s):  
Antonio Castellanos ◽  
Antonio Ramos ◽  
Antonio Gonza´lez ◽  
Hywel Morgan ◽  
Nicolas Green
Keyword(s):  
Electric Fields ◽  
Mass Density ◽  
Fluid Motion ◽  
Electrode System ◽  
Viscous Drag ◽  
Diffuse Double Layer ◽  
Ac Electroosmosis ◽  
Ac Electric Fields ◽  
High Electric Fields ◽  
And Diffusion

Non-uniform ac electric fields induce movement of polarizable particles. This phenomenon, known as dielectrophoresis, is useful to manipulate bioparticles. High electric fields when used in bio-separation systems give rise to fluid motion, which in turn results in a viscous drag on the particle. These fields generate heat, leading to volume forces in the liquid. Gradients in conductivity and permittivity rise to electrothermal forces; gradients in mass density to buoyancy. Also non-uniform ac electric fields produce forces on the induced charges in the diffuse double layer on the electrodes, and the resulting steady fluid motion has been termed ac electroosmosis. The effects of Brownian motion and diffusion are also discussed in this context. The orders of magnitude of the various forces experienced by a submicrometre particle in a model electrode system are calculated. The results are compared with experiments and the relative influence of each type of force is described.

scholarly journals Theoretical Study of High-Frequency Response of InGaAs/AlAs Double-Barrier Nanostructures

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Konstantin S. Grishakov ◽  
Vladimir F. Elesin ◽  
Mikhail M. Maslov ◽  
Konstantin P. Katin
Keyword(s):  
Energy Level ◽  
Electric Fields ◽  
Field Amplitude ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Resonant Energy ◽  
High Frequencies ◽  
High Frequency Response ◽  
Ac Electric Fields ◽  
Wide Range

The presented article contains the numerical calculations of the InGaAs/AlAs resonant tunneling diode’s (RTD) response to the AC electric field of a wide range of amplitudes and frequencies. These calculations have been performed within the coherent quantum-mechanical model that is based on the solution of the time-dependent Schrödinger equation with exact open boundary conditions. It is shown that as the field amplitude increases, at high frequencies, where ħω>Γ (Γ is the width of the resonant energy level), the active current can reach high values comparable to the direct current value in resonance. This indicates the implementation of the quantum regime for RTD when radiative transitions are between quasi-energetic levels and the resonant energy level. Moreover, there is an excitement of higher quasi-energetic levels in AC electric fields, which in particular results in a slow droop of the active current as the field amplitude increases. It also results in potentially abrupt changes of the operating point position by the ħω value. This makes it possible to achieve relatively high output powers of InGaAs/AlAs RTD having an order of 105 W/cm2 at high frequencies.

LBE for Generalized Hydrodynamics

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Potential Energy ◽  
Electric Fields ◽  
Chemical Reactions ◽  
Soft Matter ◽  
Fluid Motion ◽  
Life Sciences ◽  
Scientific Discipline ◽  
The Past ◽  
Generalized Hydrodynamics ◽  
Internal Forces

This chapter presents the main techniques to incorporate the effects of external and/or internal forces within the LB formalism. This is a very important task, for it permits us to access a wide body of generalized hydrodynamic applications whereby fluid motion couples to a variety of additional physical aspects, such as gravitational and electric fields, potential energy interactions, chemical reactions and many others. It should be emphasized that while hosting a broader and richer phenomenology than “plain” hydrodynamics, generalized hydrodynamics still fits the hydrodynamic picture of weak departure from suitably generalized local equilibria. This class is all but an academic curiosity; for instance, it is central to the fast-growing science of Soft Matter, a scientific discipline which has received an impressive boost in the past decades, under the drive of micro- and nanotechnological developments and major strides in biology and life sciences at large.

Fabrication of ZrO 2 /rGO nanocomposites by flash sintering under AC electric fields

2021 ◽  
Author(s):  
Xinghua Su ◽  
Mengying Fu ◽  
Gai An ◽  
Zhihua Jiao ◽  
Qiang Tian ◽  
...  
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields ◽  
Flash Sintering

Simulation on the Flow and Heat Transfer Characteristics of Confined Bubbles in Micro-Channels

2012 ◽  
Author(s):  
Qingming Liu ◽  
Björn Palm ◽  
Henryk Anglart
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Phase Interface ◽  
Working Fluid ◽  
Initial Shape ◽  
Thin Film Evaporation ◽  
Flow And Heat Transfer ◽  
Vof Model ◽  
Micro Channels

3D simulations on confined bubbles in micro-channels with diameter of 1.24 mm were conducted. The working fluid is R134a with a mass flux range from 125kg/m2s to 375kg/m2s. The VOF model is chosen to capture the 2 phase interface while the geo-construction method was used to re-construct the 2-phase interface. A heated boundary wall with heat flux varying from 15kW/m2 to 102kW/m2 is supplied. The wall temperature was calculated. The effects of mass flux and heat flux are studied. The shape of the bubble was predicted by the simulation successfully and the results show that they are independent of the initial shape. Both thin film evaporation and micro convection enhance the heat transfer. However, the micro convection which is caused by bubble motion has greater contribution to the total heat transfer at the stage of bubble growth studied.

scholarly journals Spinning Janus doublets driven in uniform ac electric fields

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
Alicia Boymelgreen ◽  
Gilad Yossifon ◽  
Sinwook Park ◽  
Touvia Miloh
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields
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