Enhanced synchronized ultrasonic and flow-field fractionation of suspensions

Mandralis, Zenon I.; Feke, Donald L.; Bolek, W.; Bürger, Wolfgang; Benes, E.

doi:10.1016/0041-624x(94)90019-1

Cited by 38 publications

(20 citation statements)

References 9 publications

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“…This was demonstrated by Mandralis et al 47 in combination with a synchronised field-flow fractionation system, whereby particles were cycled away and towards a surface, with 35 larger particles moving further and experiencing regions of higher flow. Another fractionation method achieved by frequency switching and relying on response time of the particle has been proposed b y Harris et al 48 which used a half-wavelength mode to position particles to a known location in the flow field, then by switching between the second and third modes particles are fractionated across the depth of the channel.…”

Section: Position Control In Resonatorsmentioning

confidence: 89%

Acoustofluidics 9: Modelling and applications of planar resonant devices for acoustic particle manipulation

2012

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5This article introduces the design, construction and applications of planar resonant devices for particle and cell manipulation. These systems rely on the pistonic action of a piezoelectric layer to generate a one dimensional axial variation in acoustic pressure through a system of acoustically tuned layers. The resulting acoustic standing wave is dominated by planar variations in pressure causing particles to migrate to planar pressure nodes (or antinodes depending on particle and fluid properties). The consequences of 10 lateral variations in the fields are discussed, and rules for designing resonators with high energy density within the appropriate layer for a given drive voltage presented.  IntroductionThere is a need to manipulate micron-scale particles and cells in many areas of physics, analytical chemistry and the biosciences. Techniques such as filtration, centrifugation and sedimentation are well-established in macro-scale applications, but in microfluidic 15 systems the use of other approaches including optical, magnetic, dielectrophoretic and acoustic forces are of interest. Acoustic radiation forces, typically at ultrasonic frequencies in the hundreds of kHz to tens of MHz region, have wavelengths that are well matched to microfluidic channel scales, yet are capable of generating potential wells with significantly larger length scales. The technology is also relatively straightforward to integrate within microfluidic systems. Acoustic radiation forces 20Acoustic radiation forces can be generated on particles by both travelling and standing acoustic fields. Those in standing wave fields (of primary interest in the applications considered here) are generated by the nonlinear interaction between the acoustic field scattered by the particle and the standing wave field itself. The time averaged radiation force () F r on a small (in comparison with a wavelength) spherical particle of volume V located at r within a stationary acoustic field was shown by Gor'kov 1 to relate to the gradients of the time averaged kinetic and potential energy densities ( kin E and pot E respectively) within the field:The kinetic energy density gradient (a function of the acoustic velocity field within the standing wave) is weighted by a function of the densities ( on them that tends to move them to the acoustic pressure node, and the acoustic velocity antinode. In a planar resonator these are colocated. Generating the required acoustic fieldMany approaches to generating the required acoustic wave field have been reported in the literature. These include the use of near-field effects 2 or focussed ultrasound 3, 4 to trap particles and cells, the excitation of lateral standing waves in which the predominant energy 35 gradients run parallel to the face of the excitation transducer 5,6 , and the generation of cylindrical resonances to focus 7 or arrange

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Section: Position Control In Resonatorsmentioning

confidence: 89%

Acoustofluidics 9: Modelling and applications of planar resonant devices for acoustic particle manipulation

2012

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“…(Doblhoff-Dier et al, 1994; Trampler et al, 19941, yeast (Hawkes and Coakley, 1996), and bacteria (Hawkes et al, 1997). Fractionation according to particle size (Mandralis et al, 1994), continuous fractionation of mixed-particulate suspensions based on the compressibility of the solid phase (Gupta et al, 19951, and the selective retention of generally larger viable mammalian cells over nonviable cells and cell debris (Gaida et al, 1996) have been reported.Particle separation by ultrasonic forces exhibits innate advantages relative to conventional methods, particularly in the area of biotechnology. Cross-flow membrane filtration and spin-filter separators suffer from fouling; continuous centrifuges are susceptible to mechanical failure; conventional sedimentation systems require long holdup times.…”

mentioning

confidence: 98%

Acoustic force distribution in resonators for ultrasonic particle separation

et al. 1998

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The effectiveness of particle -liquid separation by ultrasonic radiation forces depends on the acoustic energy density distribution in the standing-wavefield. The energy distribution in an ultrasonic particle-separation device was analyzed to assist continued optimization and design efforts. Measurements of the energy-density distribution in the liquid using a microscope-based imaging system were compared to laser inteferometer measurements of the velocity-amplitude distribution on the transducer and rejlector sur- introductionThe capabilities of ultrasonic radiation forces for manipulating suspended particles have engendered a broad spectrum of experimental investigations. Ultrasonic aggregation has been exploited to improve the sensitivity of medical latex agglutination tests for detecting immunogenic agents (Grundy et al., 1994; Gualano et al., 19951, to fuse different cell types in combination with electric-field pulses (Vienken et al., 19851, and to enhance the recovery of two cell populations by phase partitioning (Allman and Coakley, 1994). The potential for continuous separation of particles from fluid suspensions was demonstrated by Tolt and Feke (1993). Continuous cell separation has been achieved for mammalian cells Correspondence concerning this article should be addressrd to S. M. Woodside. (Doblhoff-Dier et al., 1994; Trampler et al., 19941, yeast (Hawkes and Coakley, 1996), and bacteria (Hawkes et al., 1997). Fractionation according to particle size (Mandralis et al., 1994), continuous fractionation of mixed-particulate suspensions based on the compressibility of the solid phase (Gupta et al., 19951, and the selective retention of generally larger viable mammalian cells over nonviable cells and cell debris (Gaida et al., 1996) have been reported.Particle separation by ultrasonic forces exhibits innate advantages relative to conventional methods, particularly in the area of biotechnology. Cross-flow membrane filtration and spin-filter separators suffer from fouling; continuous centrifuges are susceptible to mechanical failure; conventional sedimentation systems require long holdup times. For ultrasonic separation, no physical barrier is required, there are no 1976September 1998 Vol. 44, No. 9 AIChE Journal moving mechanical parts, holdup times are low, and chemical flocculants are not necessary. Trampler et al. (1994) demonstrated the advantages of ultrasonic separation, running a continuous mammalian-cell perfusion culture for more than one month at cell concentrations up to 6X107/mL, with no decline in separation performance. In continuous separation systems, particles collect at the nodal planes of the standing-wave field due to the axial primary radiation force (PRF). Fluid flow is generally parallel to the nodal planes. The transverse PFR aggregates the particles within the nodal planes and retains them in the field against the flow-induced drag. The retention performance of these devices is therefore particularly dependent on the magnitude of the transverse PRF. The axial and transverse pri...

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“…This complicates the deposition of highly uniform coatings by continuously reducing the number of particles transported to the drying front over the deposition period. Sonication was evaluated as means to suppress particle sedimentation during deposition, since sonic standing waves have been used successfully in noncontact manipulation of suspended particles [31][32][33][34][35]. Coatings were deposited using a glass substrate and either a stationary or sonicated continuous delivery system.…”

Section: Coating Structure Dependence On Suspension Sonication Duringmentioning

confidence: 99%

Continuous Convective-Sedimentation Assembly of Colloidal Microsphere Coatings for Biotechnology Applications

2013

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Continuous convective-sedimentation assembly (CCSA) is a deposition method that constantly supplies the coating suspension to the meniscus behind the coating knife by inline injection, allowing for steady-state deposition of ordered colloids (which may include particles or cells or live cell-particle blends) by water evaporation. The constant inflow of suspended particles available for transport to the drying front yields colloidal arrays with significantly larger surface areas than previously described and thus expands the ability of convective assembly to deposit monolayers or very thin films of multiple sizes of particles on large surfaces. Using sulfated polystyrene microspheres as a model system, this study shows how tunable process parameters, namely particle concentration, fluid sonication, and fluid density, influence coating homogeneity when the meniscus is continuously supplied. Fluid density and fluid flow-path sonication affect particle sedimentation and distribution. Coating microstructure, analyzed in terms of void space, does not vary significantly with relative humidity or suspended particle concentration. This study evaluated two configurations of the continuous convective assembly method in terms of ability to control coating microstructure by varying the number of suspended polymer particles available for transport to the coating drying front through variations in the meniscus volume.

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Enhanced synchronized ultrasonic and flow-field fractionation of suspensions

Cited by 38 publications

References 9 publications

Acoustofluidics 9: Modelling and applications of planar resonant devices for acoustic particle manipulation

Acoustofluidics 9: Modelling and applications of planar resonant devices for acoustic particle manipulation

Acoustic force distribution in resonators for ultrasonic particle separation

Continuous Convective-Sedimentation Assembly of Colloidal Microsphere Coatings for Biotechnology Applications

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