Transport and harvesting of suspended particles using modulated ultrasound

Whitworth, Glenn; Grundy, Martin; Coakley, W. Terence

doi:10.1016/0041-624x(91)90073-h

Cited by 110 publications

(55 citation statements)

References 16 publications

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“…Several different approaches have been employed for the manipulation of particles using ultrasonic fields. For example, focussed ultrasound [2,3] or near-field effects [4] can be used to trap particles prior to analysis, particles can be moved by using two or more opposing transducers to modulate the standing wave field [5,6], or particles can be held and moved within USWs excited by plate waves coupled into the containing fluid [7,8]. However, the use of a simple planar layered resonator with a single transducer [9][10][11] offers the simplest approach to establishing a USW suitable for particle movement.…”

Section: Introductionmentioning

confidence: 99%

Modelling for the robust design of layered resonators for ultrasonic particle manipulation

2008

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a b s t r a c t Several approaches have been described for the manipulation of particles within an ultrasonic field. Of those based on standing waves, devices in which the critical dimension of the resonant chamber is less than a wavelength are particularly well suited to microfluidic, or ''lab on a chip" applications. These might include pre-processing or fractionation of samples prior to analysis, formation of monolayers for cell interaction studies, or the enhancement of biosensor detection capability. The small size of microfluidic resonators typically places tight tolerances on the positioning of the acoustic node, and such systems are required to have high transduction efficiencies, for reasons of power availability and temperature stability. Further, the expense of many microfabrication methods precludes an iterative experimental approach to their development. Hence, the ability to design sub-wavelength resonators that are efficient, robust and have the appropriate acoustic energy distribution is extremely important. This paper discusses one-dimensional modelling used in the design of ultrasonic resonators for particle manipulation and gives example of their uses to predict and explain resonator behaviour. Particular difficulties in designing quarter wave systems are highlighted, and modelling is used to explain observed trends and predict performance of such resonators, including their performance with different coupling layer materials.

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Section: Introductionmentioning

confidence: 99%

Modelling for the robust design of layered resonators for ultrasonic particle manipulation

2008

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“…Many implementations have been proposed for continuous ultrasonic separation where enriched and clarified streams are generated by concentrating the suspended particles on one side of the flow path (Benes et al, 1991;Whitworth et al, 1991;Frank et al, 1993). Trampler et al (1994) successfully developed a cell retention device for perfusion culture by an alternate approach in which the cells were aggregated and retained in the standing wave field of an ultrasonic resonator, then returned to the bioreactor by sedimentation and dispersed by the impeller (Figure 4).…”

Section: Ultrasonic Cell Retentionmentioning

confidence: 99%

Mammalian cell retention devices for stirred perfusion bioreactors

Woodside¹,

Bowen²,

Piret³

1998

Current Applications of Cell Culture Engineering

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Within the spectrum of current applications for cell culture technologies, efficient large-scale mammalian cell production processes are typically carried out in stirred fed-batch or perfusion bioreactors. The specific aspects of each individual process that can be considered when determining the method of choice are presented. A major challenge for perfusion reactor design and operation is the reliability of the cell retention device. Current retention systems include cross-flow membrane filters, spin-filters, inclined settlers, continuous centrifuges and ultrasonic separators. The relative merits and limitations of these technologies for cell retention and their suitability for large-scale perfusion are discussed.

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“…When particles of the appropriate size, density and compressibility are suspended in a MHz frequency ultrasonic standing wave (at a frequency that does not allow disruptive cavitation), several acoustically induced phenomena occur that act to localise the particles at multiple discrete positions throughout the suspending phase [18,21,23]. Suspended particles such as antibody-coated microspheres experience an acoustic radiation force [18,24] that causes accumulation of micro-particles at the pressure nodes occurring at half wavelength intervals.…”

Section: Ultrasonic Standing Wavesmentioning

confidence: 99%