Microfluidic Parallel Form Mixer Utilizing Chaotic Electric Field

2007 ◽  
Vol 364-366 ◽  
pp. 449-453
Author(s):  
Her Terng Yau ◽  
Chieh Li Chen ◽  
Ching Chang Cho
Keyword(s):  
Electric Field ◽  
Chaotic Behavior ◽  
Channel Length ◽  
Mixing Efficiency ◽  
Successful Operation ◽  
Number Systems ◽  
Flow Mixing ◽  
Reagent Consumption ◽  
Electric Filed ◽  
High Degree

The past few years, have witnessed a rapid increase in the application of microfluidic devices to chemical and biological analyses. These devices offer significant advantages over their traditional counterparts, including reduced reagent consumption, a more rapid analysis and a significant improvement in performance. Species mixing is a fundamentally important aspect of these devices since it is this mixing which generates the biochemical reactions necessary for their successful operation. Many microfluidic applications require the mixing of reagents, but efficient mixing in these laminar (i.e., low Reynolds number) systems are typically difficult. Instead of using complex geometries and/or relatively long channels, an electric field is applied to drive flow mixing in microchannels. Generally, the fluid is driven by the application of an external periodic AC electric field. However, the chaotic AC electric filed is never used to drive flow mixing in microchannels. Chaotic behavior is a very interesting nonlinear effect. In some physical systems, chaos is a beneficial feature as it enhances mixing in chemical reactions. This paper presents a numerical investigation of electrokinetically-driven flow mixing in microchannels with chaotic electric field. The simulation results show that the application of a chaotic external field enables a reduction in the mixing channel length and a high degree of mixing efficiency. It is shown that a mixing performance as high as 90% can be achieved by chaotic external electric field.

scholarly journals Design of super-efficient mixer based on induced charge electroosmotic

2012 ◽  
Vol 16 (5) ◽  
pp. 1534-1538 ◽  
Author(s):  
Kai Zhang ◽  
Xiao-Jing Mi ◽  
Ming-Zhou Yu
Keyword(s):  
Electric Field ◽  
Effective Means ◽  
Mixing Enhancement ◽  
High Flux ◽  
Electrokinetic Flow ◽  
Local Flow ◽  
Conducting Cylinder ◽  
Flow Mixing ◽  
Induced Charge ◽  
Electric Filed

The super-efficient sample mixing induced by the induced-charge electrokinetic flow around conducting/Janus cylinder was numerically studied in a confined |U-shaped microchannel with suddenly applied DC weak electric filed. It?s found that there are four large circulations around the conducting cylinder and two smaller circulations around the Janus cylinder. The results show that samples can still be well mixed with high flux due to the induced electroosmosis. It is demonstrated that the local flow circulations provide effective means to enhance the flow mixing between different solutions. The dependence of the degree of mixing enhancement on the electric field is also predicted.

Dielectrophoretic Mixing With Novel Electrode Geometry

2009 ◽  
Author(s):  
G. Naga Siva Kumar ◽  
Sushanta K. Mitra ◽  
Subir Bhattacharjee
Keyword(s):  
Electric Field ◽  
Cell Activation ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Computational Domain ◽  
Element Analysis

Electrokinetic mixing of analytes at micro-scale is important in several biochemical applications like cell activation, DNA hybridization, protein folding, immunoassays and enzyme reactions. This paper deals with the modeling and numerical simulation of micromixing of two different types of colloidal suspensions based on principle of dielectrophoresis (DEP). A mathematical model is developed based on Laplace, Navier-Stokes, and convection-diffusion-migration equations to calculate electric field, velocity, and concentration distributions, respectively. Mixing of two colloidal suspensions is simulated in a three-dimensional computational domain using finite element analysis considering dielectrophoretic, gravitational and convective (advective)–diffusive forces. Phase shifted AC signal is applied to the alternating electrodes for achieving the mixing of two different colloidal suspensions. The results indicate that the electric field and DEP forces are maximum at the edges of the electrodes and become minimum elsewhere. As compared to curved edges, straight edges of electrodes have lower electric field and DEP forces. The results also indicate that DEP force decays exponentially along the height of the channel. The effect of DEP forces on the concentration profile is studied. It is observed that, the concentration of colloidal particles at the electrodes edges is very less compared to elsewhere. Mixing of two colloidal suspensions due to diffusion is observed at the interface of the two suspensions. The improvement in mixing after applying the repulsive DEP forces on the colloidal suspension is observed. Most of the mixing takes place across the slant edges of the triangular electrodes. The effect of electrode pairs and the mixing length on degree of mixing efficiency are also observed.

Fluid Mixing Control Inside a Y-Shaped Microchannel by Using Electrokinetic Instability

2007 ◽  
Author(s):  
Zheyan Jin ◽  
Hui Hu
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Fluid Mixing ◽  
Critical Voltage ◽  
Mixing Efficiency ◽  
Mixing Process ◽  
Static Electric Field ◽  
Electrokinetic Instability ◽  
Mixing Control ◽  
Static Electric Fields

An experimental study was conducted to further our understanding about the fundamental physics of electrokinetic instability (EKI) and to explore the effectiveness to enhance fluid mixing inside a Y-shaped microchannel by manipulating convective EKI waves. The dependence of the critical voltage of applied static electric field to trig EKI to generate convective EKI waves on the conductivity ratio of the two adjacent streams was quantified at first. The effect of the strength of the applied static electric field on the evolution of the convective EKI waves and fluid mixing process were assessed in terms of scalar concentration fields, shedding frequency of the convective EKI waves and scalar mixing efficiency. The effectiveness of manipulating the convective EKI waves by introducing alternative electric perturbations to the applied static electric fields was also explored for the further enhancement of the fluid mixing process inside the Y-shaped microchannel.

scholarly journals Numerical Investigation of Liquid–Liquid Mixing in Modified T Mixer with 3D Obstacles

2021 ◽  
pp. 25-32
Author(s):  
Md. Readul Mahmud
Keyword(s):  
Numerical Investigation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Channel Length ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Wide Range

The fluids inside passive micromixers are laminar in nature and mixing depends primarily on diffusion. Hence mixing efficiency is generally low, and requires a long channel length and longtime compare to active mixers. Various designs of complex channel structures with/without obstacles and three-dimensional geometries have been investigated in the past to obtain an efficient mixing in passive mixers. This work presents a design of a modified T mixer. To enhance the mixing performance, circular and hexagonal obstacles are introduced inside the modified T mixer. Numerical investigation on mixing and flow characteristics in microchannels is carried out using the computational fluid dynamics (CFD) software ANSYS 15. Mixing in the channels has been analyzed by using Navier–Stokes equations with water-water for a wide range of the Reynolds numbers from 1 to 500. The results show that the modified T mixer with circular obstacles has far better mixing performance than the modified T mixer without obstacles. The reason is that fluids' path length becomes longer due to the presence of obstacles which gives fluids more time to diffuse. For all cases, the modified T mixer with circular obstacle yields the best mixing efficiency (more than 60%) at all examined Reynolds numbers. It is also clear that efficiency increase with axial length. Efficiency can be simply improved by adding extra mixing units to provide adequate mixing. The value of the pressure drop is the lowest for the modified T mixer because there is no obstacle inside the channel. Modified T mixer and modified T mixer with circular obstacle have the lowest and highest mixing cost, respectively. Therefore, the current design of modified T with circular obstacles can act as an effective and simple passive mixing device for various micromixing applications.

scholarly journals Perspectives of pulsed electric field application for larvae biomass drying

2020 ◽  
Vol 10 (4) ◽  
pp. 12-21
Author(s):  
I.A. Shorstky ◽  
◽  
O. Parniakov ◽  
S. Smetana ◽  
◽  
...  
Keyword(s):  
Electric Field ◽  
Specific Energy ◽  
Energy Input ◽  
Pulsed Electric Field ◽  
Field Application ◽  
Specific Energy Input ◽  
Drying Time ◽  
Drying Temperature ◽  
Electric Filed ◽  
Pulsed Electric Field Treatment

The perspectives of pulsed electric field (PEF) application for larvae biomass drying are considered. Drying process optimization was carried out using two-way analysis of variance in the range of applied specific energy input of from 0 up to 20 kJ/kg and drying temperature of from 50 up to 90°С. It was found out that application of pulsed electric field treatment allowed marked decreasing of larvae biomass drying time from 183 to 124 minutes for the samples treated with electric filed intensity of E = 2 kV/cm and specific energy of 20 kJ/kg. Based on the obtained experimental data the optimal drying and PEF treatment parameters for larvae biomass were determined for the ranges of drying temperature – 82–85℃ and specific energy input – 4.1–6.6 kJ/kg.

scholarly journals Centeral Electric Field and Threshold Voltage in Accumulation Mode Junctionless Cylindrical Surrounding Gate MOSFET

2018 ◽  
Vol 8 (2) ◽  
pp. 673
Author(s):  
Hakkee Jung
Keyword(s):  
Electric Field ◽  
Threshold Voltage ◽  
Oxide Thickness ◽  
Channel Length ◽  
Accumulation Mode ◽  
Transfer Characteristics ◽  
Threshold Voltages ◽  
Analytical Potential ◽  
Surrounding Gate ◽  
Dimensional Simulation

Transfer characteristics is presented using analytical potential distribution of accumulation-mode junctionless cylindrical surrounding-gate (JLCSG) MOSFET, and deviation of center electric field at threshold voltage is analyzed for channel length and oxide thickness. Threshold voltages presented in this paper is good agreement with results of other compared papers, and transfer characteristics is agreed with those of two-dimensional simulation. The most important factor to determine threshold voltage is center electric field at source because the greater part of electron flows through center axis of JLCSG MOSFET. As a result of analysis for center electric field at threshold voltage, center electric field is decreased with reduction of channel length due to drain induced barrier lowering. Center electric field is increased with decrease of oxide thickness, and deviation of center electric field for channel length is significantly occurred with decrease of oxide thickness.

Study of Enhanced Self Mixing in Ferrofluid Flow in an Elbow Channel Under the Influence of Non-Uniform Magnetic Field

2019 ◽  
Author(s):  
Nadish Anand ◽  
Richard Gould
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Magnetization Vector ◽  
Field Vector ◽  
Mixing Efficiency ◽  
Mixing Enhancement ◽  
Initial Flow ◽  
Viscosity Term ◽  
Flow Mixing ◽  
The Magnetic Field

Abstract This paper investigates numerically the various parameters dictating the vortical (self)-mixing induced by a non-uniform magnetic field in a ferrofluid flow in an elbow channel. The elbow bend region of the channel has two current carrying conductors placed symmetrically and parametrically from the channel and are used to generate a non-uniform magnetic field. The ferrofluid is assumed to be pre-magnetized, isothermal and electrically non-conductive as it enters the channel and has a prescribed inlet magnetization and temperature. The mixing efficiency is characterized by introducing different mixing scalars based on velocity of the fluid and are compared in order to determine the overall suitability of each scalar to quantify the flow vortical (self)-mixing. Parametric studies were performed by varying parameters influencing the magnetic field and the initial flow field. This resulted in variations in non-dimensional groups which control different aspects of the flow and helped establish their relationship with mixing efficiency. It was found that at higher Reynolds numbers the flow mixing induced by the lateral gradient in the Kelvin Body Force (KBF) dissipates and higher electrical inputs are required to sustain mixing in the flow. The effects of mixing enhancement on the pressure gradient across the channel was also established, along with the introduction of an enhanced viscosity term which is due to the non-collinearity of the magnetization vector and the magnetic field vector.

Structure of Turbulent Flow in Subchannel of Rod Bundle Downstream of Spacer Grid With Hybrid Flow Mixing Device

2002 ◽  
Author(s):  
Dong Seok Oh ◽  
Wang Kee In ◽  
Tae Hyun Chun
Keyword(s):  
Rectangular Channel ◽  
Cross Flow ◽  
Mixing Efficiency ◽  
Lateral Velocity ◽  
Spacer Grid ◽  
Turbulent Diffusion Coefficient ◽  
Rod Bundle ◽  
Flow Mixing ◽  
A Cell ◽  
Rod Array

An experiment was performed in a wind tunnel to investigate the flow structure in a rod bundle with a hybrid vane grid. The hybrid vane is a flow-mixing device, which consists of two pairs of primary and secondary vanes in a cell. The test section is a rectangular channel (300 mm × 300 mm × 2400 mm) including 3 × 3 rod (75 mm diameter) array with a spacer grid. The pitch to diameter ratio of the rod array is 1.33. The flow structures downstream the grid are measured at Reynolds number of 1.2 × 105 for 35-degree deflecting angle of the hybrid flow-mixing vane. The data are obtained for the distributions of the time mean axial velocity, lateral velocity, and turbulent intensities in 3 component directions over a center subchannel along axial locations and compared with the previous results of split vane grid that has two vanes in a cell. The results show that the mixing efficiency of the hybrid vane grid could be similar with that of the split vane grid because swirl factor of the hybrid vane grid is higher than that of split vane grid and the magnitude of axial turbulent intensity, turbulent diffusion coefficient, and cross flow factor is similar to each other in spite of differences of the vane numbers and shape in a cell between hybrid and split vane grids.

scholarly journals Generalized Single Stage Class C Amplifier: Analysis from the Viewpoint of Chaotic Behavior

2020 ◽  
Vol 10 (15) ◽  
pp. 5025 ◽  
Author(s):  
Jiri Petrzela
Keyword(s):  
Chaotic Behavior ◽  
Building Blocks ◽  
Cubic Polynomial ◽  
Signal Path ◽  
Class C ◽  
Lc Tank ◽  
High Degree ◽  
Bias Point ◽  
Stage Class ◽  
Simple Network

This paper briefly describes a recent discovery that occurred during the study of the simplest mathematical model of a class C amplifier with a bipolar transistor. It is proved both numerically and experimentally that chaos can be observed in this simple network structure under three conditions: (1) the transistor is considered non-unilateral, (2) bias point provides cubic polynomial feedforward and feedback transconductance, and (3) the LC tank has very high resonant frequency. Moreover, chaos is generated by an autonomous class C amplifier; i.e., an isolated system without a driving force is analyzed. By the connection of a harmonic input signal, much more complex behavior can be observed. Additionally, due to the high degree of generalization of the amplifier cell, similar fundamental circuits can be ordinarily found as subparts of typical building blocks of a radio frequency signal path.

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