Non-equilibrium analytical focusing field-flow fractionation using intrinsic hydrodynamic force and integral Doppler anemometry

Kononenko, V. L.; Shimkus, J. K.

doi:10.1016/0021-9673(90)85111-8

Cited by 20 publications

(6 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A critical factor in the operation of traditional hyperlayer FFF [42][43][44] is the use of the hydrodynamic lift force on particles, which was found to depend sensitively on the fluid-flow rate. 44,45 Our finding that the cell equilibrium heights in the DEP/G-FFF chamber were almost independent of the flow rate confirms that the applied DEP levitation forces were much stronger than this hydrodynamic lift force. This finding is in agreement with theoretical analyses of the hydrodynamic lift force.…”

Section: Resultsmentioning

confidence: 57%

Cell Separation on Microfabricated Electrodes Using Dielectrophoretic/Gravitational Field-Flow Fractionation

et al. 1999

View full text Add to dashboard Cite

Dielectrophoretic/gravitational field-flow fractionation (DEP/G-FFF) was used to separate cultured human breast cancer MDA-435 cells from normal blood cells mixed together in a sucrose/dextrose medium. An array of microfabricated, interdigitated electrodes of 50 microns widths and spacings, and lining the bottom surface of a thin chamber (0.42 mm H x 25 mm W x 300 mm L), was used to generate DEP forces that levitated the cells. A 10-microL cell mixture sample containing approximately 50,000 cells was introduced into the chamber, and cancerous and normal blood cells were levitated to different heights according to the balance of DEP and gravitational forces. The cells at different heights were transported at different velocities under the influence of a parabolic flow profile that was established in the chamber and were thereby separated. Separation performance depended on the frequency and voltage of the applied DEP field and the fluid-flow rate. It took as little as 5 min to achieve cell separation. An analysis of the DEP/G-FFF results revealed that the separation exploited the difference in dielectric and density properties between cell populations. The DEP/G-FFF technique is potentially applicable to many biological and biomedical problems, especially those related to microfluidic systems.

show abstract

Section: Resultsmentioning

confidence: 57%

Cell Separation on Microfabricated Electrodes Using Dielectrophoretic/Gravitational Field-Flow Fractionation

et al. 1999

View full text Add to dashboard Cite

show abstract

“…The concentration, C(r,t), is related to the self-intermediate scattering function, F s(q,t), through a Fourier transform. Fourier transformation and solution of the equations, subject to boundary condition of the probability at t ) 0 being 1, yields Since the macromolecules are not infinitely small, the velocity gradients in solution will exert a resultant intrinsic hydrodynamic force 24 due to shear that will depend on the size and the shape of the molecules. Because of this gradient, the drag on larger sized macromolecules should be greater than the drag on smaller counterparts, resulting in a velocity differential.…”

Section: Theory Derivation Of An Intensity-intensity Correlation Func...mentioning

confidence: 99%

“…Since the macromolecules are not infinitely small, the velocity gradients in solution will exert a resultant intrinsic hydrodynamic force due to shear that will depend on the size and the shape of the molecules. Because of this gradient, the drag on larger sized macromolecules should be greater than the drag on smaller counterparts, resulting in a velocity differential.…”

Section: Theorymentioning

confidence: 99%

Anomalous Dynamic Light Scattering from Solutions of Light Absorbing Polymers

Sehgal

Seery

1999

Macromolecules

View full text Add to dashboard Cite

Dynamic light scattering data from highly absorbing solutions exhibit intensity-intensity correlation functions characterized by a sum of exponential decays superposed with an oscillatory term. A new analytical treatment is proposed, which explains this behavior as arising from the heterodyning of scattered light from two distinct species in convective motion. Similar data were obtained both for solutions of polyaniline (PANI) as well as for a complex of cytochrome c and cytochrome c peroxidase in phosphate buffer. This suggests the generality of the phenomenon for polymers that both absorb light and aggregate, such as proteins and conducting polymers. Effects of laser power on convection, thermal lensing, and coning of the beam and concentration of absorbing species have been considered. The presence or absence of the oscillations is shown to be a sensitive indication of aggregation.

show abstract

“…The transformation of concentrational profiles with the increase of the distance z from the channel entrance is illustrated by Fig.3. These data show the development of the focusing process along the channel length, starting from the homogeneous distri- x/h (7) channel. However, If the particle's dimension becomes comparable with the channel width, this profile changes completely, and so does the expression for the transverse focusing force.…”

Section: Erythrocyte Concentration Profiles In Narrow Channel Flowsmentioning

confidence: 73%

Integral Doppler anemometry: an effective technique for rapid measurements of concentrational and velocity profiles in the flow exploiting biomedical instrumentation

Kononenko

Shimkus

1993

SPIE Proceedings

View full text Add to dashboard Cite

The flow velocity profiles and particles concentration profiles in a flow are often required for design and optimal operatioti of various flow-exploiting biomedical instruments. A new optical probing technique named Integral Doppler Anemometry (IDA) allows the fast and precise measurements of these profiles in narrow channels with the optically transparent walls and characteristic width from tens microns up to several millimeters. IDA is based on the laser Doppler method of measurement of the particle velocity, but registers all velocities simultaneously from the whole cross section of a flow. As a result, instead of a single Doppler line registered in conventional-type Doppler anemometry, a broad IDA spectrum is recorded. The shape of IDA spectrum is determined by the flow velocity profile and the concentrational profile of light scattering particles in a flow. These profiles can be reconstructed from the measured spectrum by means of special measuring and data processing procedures. The basic principles of IDA technique and the main requirements to IDA measurements are formulated. The analytical expressions giving the shape of IDA spectrum for the practically used optical arrangement of anemometer are presented. The algorithms of reccnstruction of flow velocity and particles concentration profiles from IDA spectra are discussed. Using IDA technique, the measurements were done of transverse concentration profiles in dilute (104÷106 cells/cm3) erythrocytes suspension flows in narrow (30-300 microns) channels at flow velocities 1+10 cm/s. The measurements showed an essentially nonuniform lateral distribution of erythrocytes in a flow in such channels, namely, the transverse hydrodynamic focusing of cells. The lateral focus positions were two noncentral symmetric planes in the flat channels, and a tubular surface in the round channels. The distance of the focus from the channel center was 0.2-0.8 of the channel half-width, depending on the flow velocity and (particle size)/(channel width) ratio. The focuLsing became more pronounced with the increase of erythrocyte concentration.

show abstract

Non-equilibrium analytical focusing field-flow fractionation using intrinsic hydrodynamic force and integral Doppler anemometry

Cited by 20 publications

References 14 publications

Cell Separation on Microfabricated Electrodes Using Dielectrophoretic/Gravitational Field-Flow Fractionation

Cell Separation on Microfabricated Electrodes Using Dielectrophoretic/Gravitational Field-Flow Fractionation

Anomalous Dynamic Light Scattering from Solutions of Light Absorbing Polymers

Integral Doppler anemometry: an effective technique for rapid measurements of concentrational and velocity profiles in the flow exploiting biomedical instrumentation

Contact Info

Product

Resources

About