scholarly journals Material- and Size-selective Separation Mechanism of Micro Particles in Frequency-modulated Dielectrophoretic Particle Chromatography

2021 ◽  
Author(s):  
Jasper Giesler ◽  
Laura Weirauch ◽  
Jorg Thöming ◽  
Michael Baune ◽  
Georg R. Pesch
Keyword(s):  
Surface Functionalization ◽  
Selective Separation ◽  
Separation Mechanism ◽  
Separation Techniques ◽  
Retention Mechanisms ◽  
Biological Particles ◽  
Micro Particles ◽  
Good Agreement

Abstract Separation of (biological) particles (<< 10 µm) according to size or other properties is an ongoing challenge in a variety of technical relevant fields. Dielectrophoresis is one method to separate particles according to a diversity of properties, and within the last decades a pool of dielectrophoretic separation techniques has been developed. However, many of them either suffer selectivity or throughput. We use simulation and experiments to investigate retention mechanisms in a novel DEP scheme, namely, frequency-modulated DEP. Results from experiments and simulation show a good agreement for the separation of binary PS particles mixtures with respect to size and more importantly, for the challenging task of separating equally sized microparticles according to surface functionalization alone. The separation with respect to size was performed using 2 µm and 3 µm sized particles, whereas separation with respect to surface functionalization was performed with 2 µm particles. The results from this study can be used to solve challenging separation tasks, for example to separate particles with distributed properties.

scholarly journals Separating microparticles by material and size using dielectrophoretic chromatography with frequency modulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jasper Giesler ◽  
Laura Weirauch ◽  
Jorg Thöming ◽  
Michael Baune ◽  
Georg R. Pesch
Keyword(s):  
Surface Functionalization ◽  
Frequency Modulation ◽  
Separation Techniques ◽  
Retention Mechanisms ◽  
Biological Particles ◽  
Good Agreement

AbstractSeparation of (biological) particles ($$\ll {10}~{\upmu }\text {m}$$ ≪ 10 μ m ) according to size or other properties is an ongoing challenge in a variety of technical relevant fields. Dielectrophoresis is one method to separate particles according to a diversity of properties, and within the last decades a pool of dielectrophoretic separation techniques has been developed. However, many of them either suffer selectivity or throughput. We use simulation and experiments to investigate retention mechanisms in a novel DEP scheme, namely, frequency-modulated DEP. Results from experiments and simulation show a good agreement for the separation of binary PS particles mixtures with respect to size and more importantly, for the challenging task of separating equally sized microparticles according to surface functionalization alone. The separation with respect to size was performed using 2 $${\upmu }$$ μ m and 3 $${\upmu }$$ μ m sized particles, whereas separation with respect to surface functionalization was performed with 2 $${\upmu }$$ μ m particles. The results from this study can be used to solve challenging separation tasks, for example to separate particles with distributed properties.

scholarly journals Investigation on Inertial Sorter Coupled with Magnetophoretic Effect for Nonmagnetic Microparticles

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 566 ◽  
Author(s):  
Jiayou Du ◽  
Long Li ◽  
Qiuyi Zhuo ◽  
Ruijin Wang ◽  
Zefei Zhu
Keyword(s):  
Magnetic Field ◽  
Structural Parameters ◽  
Expansion Ratio ◽  
Numerical Results ◽  
Lateral Migration ◽  
Sheath Flow ◽  
Micro Particles ◽  
Micro Piv ◽  
Sorting Efficiency ◽  
Good Agreement

The sizes of most prokaryotic cells are several microns. It is very difficult to separate cells with similar sizes. A sorter with a contraction–expansion microchannel and applied magnetic field is designed to sort microparticles with diameters of 3, 4 and 5 microns. To evaluate the sorting efficiency of the designed sorter, numerical simulations for calculating the distributions of microparticles with similar sizes were carried out for various magnetic fields, inlet velocities, sheath flow ratios and structural parameters. The numerical results indicate that micro-particles with diameters of 3, 4 and 5 microns can be sorted efficiently in such a sorter within appropriate parameters. Furthermore, it is shown that a bigger particle size and more powerful magnetic field can result in a greater lateral migration of microparticles. The sorting efficiency of microparticles promotes a lower inlet velocity and greater sheath flow ratios. A smaller contraction–expansion ratio can induce a greater space between particle-bands. Finally, the micro particle image velocity (micro-PIV) experiments were conducted to obtain the bandwidths and spaces between particle-bands. The comparisons between the numerical and experimental results show a good agreement and make the validity of the numerical results certain.

Electrostatic and Capillary Effects on the Detachment of Particles With Surface Deformation in Turbulent Flows

2010 ◽  
Author(s):  
Xinyu Zhang ◽  
Goodarz Ahmadi
Keyword(s):  
Turbulent Flows ◽  
Surface Deformation ◽  
Coulomb Force ◽  
Capillary Forces ◽  
Work Of Adhesion ◽  
Airflow Velocity ◽  
Micro Particles ◽  
Elastic Interface ◽  
Thermodynamic Work Of Adhesion ◽  
Good Agreement

Rolling detachment of micro particles in turbulent flows under the presence of electrostatic and capillary forces was studied. The maximum adhesion resistance model and the effective thermodynamic work of adhesion including the effects of electrostatic and capillary forces were used in the analysis. The JKR and DMT models for elastic interface deformations and the Maugis-Pollock model for the plastic deformation were extended to include the effect of electrostatic and capillary forces. The turbulence burst model was used to evaluate the airflow velocity near the substrate. The critical shear velocities for removal of particles of different sizes were evaluated and the results were compared with those without electrostatic and capillary forces. The relative critical shear velocities as well as the material dependence were also studied. The effect of the direction of the combined Coulomb force was also included. The predictions of the electric detachment fields for particles were compared with the available experimental data and good agreement was observed.

scholarly journals High-throughput dielectrophoretic filtration of sub-micron and micro particles in macroscopic porous materials

2020 ◽  
Vol 412 (16) ◽  
pp. 3903-3914 ◽  
Author(s):  
Malte Lorenz ◽  
Daniel Malangré ◽  
Fei Du ◽  
Michael Baune ◽  
Jorg Thöming ◽  
...  
Keyword(s):  
High Throughput ◽  
Parameter Study ◽  
Separation Mechanism ◽  
Electric Field Gradients ◽  
Major Step ◽  
Micro Particles ◽  
Field Gradients ◽  
Theoretical Predictions ◽  
Porous Microstructures ◽  
Real Complex

Abstract State-of-the-art dielectrophoretic (DEP) separation techniques provide unique properties to separate particles from a liquid or particles with different properties such as material or morphology from each other. Such separators do not operate at throughput that is sufficient for a vast fraction of separation tasks. This limitation exists because high electric field gradients are required to drive the separation which are generated by electrode microstructures that limit the maximum channel size. Here, we investigate DEP filtration, a technique that uses open porous microstructures instead of microfluidic devices to easily increase the filter cross section and, therefore, also the processable throughput by several orders of magnitude. Previously, we used simple microfluidic porous structures to derive design rules predicting the influence of key parameters on DEP filtration in real complex porous filters. Here, we study in depth DEP filtration in microporous ceramics and underpin the previously postulated dependencies by a broad parameter study (Lorenz et al., 2019). We will further verify our previous claim that the main separation mechanism is indeed positive DEP trapping by showing that we can switch from positive to negative DEP trapping when we increase the electric conductivity of the suspension. Two clearly separated trapping mechanisms (positive and negative DEP trapping) at different conductivities can be observed, and the transition between them matches theoretical predictions. This lays the foundation for selective particle trapping, and the results are a major step towards DEP filtration at high throughput to solve existing separation problems such as scrap recovery or cell separation in liquid biopsy.

Micro Particle Detachment in Turbulent Flows With Electrostatic and Capillary Effects and Surface Deformation

2009 ◽  
Author(s):  
Xinyu Zhang ◽  
Goodarz Ahmadi
Keyword(s):  
Turbulent Flows ◽  
Surface Deformation ◽  
Capillary Forces ◽  
Work Of Adhesion ◽  
Micro Particles ◽  
Model Predictions ◽  
Large Particles ◽  
Elastic Interface ◽  
Thermodynamic Work Of Adhesion ◽  
Good Agreement

Rolling detachment of micro particles in the presence of electrostatic and capillary forces based on the maximum adhesion resistance was studied. The effective thermodynamic work of adhesion including the effects of electrostatic and capillary forces was used in the analysis. The JKR and DMT models for elastic interface deformations and the Maugis-Pollock model for the plastic deformation were extended to include the effect of electrostatic and capillary forces. Under turbulent flow conditions, the turbulence burst model was used to evaluate the airflow velocity near the substrate. The critical shear velocities for removal of particles of different sizes were evaluated and the results were compared with those without electrostatic and capillary forces. It shows that the capillary forces significantly increases the critical shear velocities for particles of all sizes, while the electrostatic forces only have major effects on large particles. The model predictions were compared with the available experimental data and good agreement was observed.

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