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Trapping of microparticles in the near field of an ultrasonic transducer

Lilliehorn, Tobias; Simu, Urban; Evander, Mikael LU ; Almqvist, Monica LU ; Stepinski, Tadeusz; Laurell, Thomas LU ; Nilsson, Johan LU and Johansson, Stefan (2005) In Ultrasonics 43(5). p.293-303
Abstract
We are investigating means of handling microparticles in microfluidic systems, in particular localized acoustic trapping of microparticles in a flow-through device. Standing ultrasonic waves were generated across a microfluidic channel by ultrasonic microtransducers integrated in one of the channel walls. Particles in a fluid passing a transducer were drawn to pressure minima in the acoustic field, thereby being trapped and confined at the lateral position of the transducer. The spatial distribution of trapped particles was evaluated and compared with calculated acoustic intensity distributions. The particle trapping was found to be strongly affected by near field pressure variations due to diffraction effects associated with the finite... (More)
We are investigating means of handling microparticles in microfluidic systems, in particular localized acoustic trapping of microparticles in a flow-through device. Standing ultrasonic waves were generated across a microfluidic channel by ultrasonic microtransducers integrated in one of the channel walls. Particles in a fluid passing a transducer were drawn to pressure minima in the acoustic field, thereby being trapped and confined at the lateral position of the transducer. The spatial distribution of trapped particles was evaluated and compared with calculated acoustic intensity distributions. The particle trapping was found to be strongly affected by near field pressure variations due to diffraction effects associated with the finite sized transducer element. Since laterally confining radiation forces are proportional to gradients in the acoustic energy density, these near field pressure variations may be used to get strong trapping forces, thus increasing the lateral trapping efficiency of the device. In the experiments, particles were successfully trapped in linear fluid flow rates up to 1 mm/s. It is anticipated that acoustic trapping using integrated transducers can be exploited in miniaturised total chemical analysis systems (μTAS), where e.g. microbeads with immobilised antibodies can be trapped in arrays and subjected to minute amounts of sample followed by a reaction, detected using fluorescence. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Microfluidic, PZT, Particles, Ultrasound, Piezoelectric, Near field, Trap
in
Ultrasonics
volume
43
issue
5
pages
293 - 303
publisher
Elsevier
external identifiers
  • pmid:15737379
  • wos:000227927600001
  • scopus:13944262235
ISSN
0041-624X
DOI
10.1016/j.ultras.2004.11.001
language
English
LU publication?
yes
id
90a042eb-6489-447d-8019-81d01131ba79 (old id 745362)
date added to LUP
2007-12-12 15:28:09
date last changed
2017-08-27 05:08:41
@article{90a042eb-6489-447d-8019-81d01131ba79,
  abstract     = {We are investigating means of handling microparticles in microfluidic systems, in particular localized acoustic trapping of microparticles in a flow-through device. Standing ultrasonic waves were generated across a microfluidic channel by ultrasonic microtransducers integrated in one of the channel walls. Particles in a fluid passing a transducer were drawn to pressure minima in the acoustic field, thereby being trapped and confined at the lateral position of the transducer. The spatial distribution of trapped particles was evaluated and compared with calculated acoustic intensity distributions. The particle trapping was found to be strongly affected by near field pressure variations due to diffraction effects associated with the finite sized transducer element. Since laterally confining radiation forces are proportional to gradients in the acoustic energy density, these near field pressure variations may be used to get strong trapping forces, thus increasing the lateral trapping efficiency of the device. In the experiments, particles were successfully trapped in linear fluid flow rates up to 1 mm/s. It is anticipated that acoustic trapping using integrated transducers can be exploited in miniaturised total chemical analysis systems (μTAS), where e.g. microbeads with immobilised antibodies can be trapped in arrays and subjected to minute amounts of sample followed by a reaction, detected using fluorescence.},
  author       = {Lilliehorn, Tobias and Simu, Urban and Evander, Mikael and Almqvist, Monica and Stepinski, Tadeusz and Laurell, Thomas and Nilsson, Johan and Johansson, Stefan},
  issn         = {0041-624X},
  keyword      = {Microfluidic,PZT,Particles,Ultrasound,Piezoelectric,Near field,Trap},
  language     = {eng},
  number       = {5},
  pages        = {293--303},
  publisher    = {Elsevier},
  series       = {Ultrasonics},
  title        = {Trapping of microparticles in the near field of an ultrasonic transducer},
  url          = {http://dx.doi.org/10.1016/j.ultras.2004.11.001},
  volume       = {43},
  year         = {2005},
}