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Focusing of Micrometer-Sized Metal Particles Enabled by Reduced Acoustic Streaming via Acoustic Forces in a Round Glass Capillary

Gerlt, M. S. LU orcid ; Paeckel, A. ; Pavlic, A. ; Rohner, P. ; Poulikakos, D. and Dual, J. (2021) In Physical Review Applied 17(1).
Abstract
Two-dimensional (2D) metal-particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two-dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labor-intensive cleanroom production. Here, we present 2D metal microparticle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles toward the capillary center. We experimentally investigate the particle line width for different particle materials and concentrations. We... (More)
Two-dimensional (2D) metal-particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two-dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labor-intensive cleanroom production. Here, we present 2D metal microparticle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles toward the capillary center. We experimentally investigate the particle line width for different particle materials and concentrations. We demonstrate the focus of copper particles approximately 1μm in diameter down to a line of width 60.8±7.0μm and height 45.2±9.3μm, corresponding to a local concentration of 4.5% v/v, which is 90 times higher than the concentration of the initial solution. Further, we achieve the focusing of 1-μm polystyrene particles, which is usually prevented due to acoustic streaming. Through numerical analysis, we reveal the mechanism enabling the manipulation of particles in the low-micrometer range. Due to a transition of the acoustic streaming patterns from two dominant vortices in the lower half to two dominant vortices in the upper half, the streaming velocity exhibits a local minimum while the overall acoustic energy density stays at a sufficiently high level for particle focusing, leading to a lower critical particle radius than in conventional rectangular microchannels. Finally, we use our method to eject copper particles through a tapered round capillary with an opening of 25μm in diameter, which would not be possible without particle focusing. Our setup can be utilized for various applications that otherwise might suffer from abrasion, clogging, and limited resolution. (Less)
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author
; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review Applied
volume
17
issue
1
publisher
American Physical Society
external identifiers
  • scopus:85124243694
ISSN
2331-7019
DOI
10.1103/PhysRevApplied.17.014043
language
English
LU publication?
no
id
cf5feca5-ca53-4456-94dc-ca7e27b74017
date added to LUP
2023-04-12 09:31:58
date last changed
2024-04-09 04:00:39
@article{cf5feca5-ca53-4456-94dc-ca7e27b74017,
  abstract     = {{Two-dimensional (2D) metal-particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two-dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labor-intensive cleanroom production. Here, we present 2D metal microparticle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles toward the capillary center. We experimentally investigate the particle line width for different particle materials and concentrations. We demonstrate the focus of copper particles approximately 1μm in diameter down to a line of width 60.8±7.0μm and height 45.2±9.3μm, corresponding to a local concentration of 4.5% v/v, which is 90 times higher than the concentration of the initial solution. Further, we achieve the focusing of 1-μm polystyrene particles, which is usually prevented due to acoustic streaming. Through numerical analysis, we reveal the mechanism enabling the manipulation of particles in the low-micrometer range. Due to a transition of the acoustic streaming patterns from two dominant vortices in the lower half to two dominant vortices in the upper half, the streaming velocity exhibits a local minimum while the overall acoustic energy density stays at a sufficiently high level for particle focusing, leading to a lower critical particle radius than in conventional rectangular microchannels. Finally, we use our method to eject copper particles through a tapered round capillary with an opening of 25μm in diameter, which would not be possible without particle focusing. Our setup can be utilized for various applications that otherwise might suffer from abrasion, clogging, and limited resolution.}},
  author       = {{Gerlt, M. S. and Paeckel, A. and Pavlic, A. and Rohner, P. and Poulikakos, D. and Dual, J.}},
  issn         = {{2331-7019}},
  language     = {{eng}},
  month        = {{12}},
  number       = {{1}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review Applied}},
  title        = {{Focusing of Micrometer-Sized Metal Particles Enabled by Reduced Acoustic Streaming via Acoustic Forces in a Round Glass Capillary}},
  url          = {{http://dx.doi.org/10.1103/PhysRevApplied.17.014043}},
  doi          = {{10.1103/PhysRevApplied.17.014043}},
  volume       = {{17}},
  year         = {{2021}},
}