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Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations
Published on: August 21, 2018
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Viscous torque on spherical micro particles in two orthogonal acoustic standing wave fields.
Andreas Lamprecht1, Thomas Schwarz1, Jingtao Wang1
1Department of Mechanical and Process Engineering, Institute for Mechanical Systems, ETH Zurich, Zurich, Switzerland.
The Journal of the Acoustical Society of America
|August 3, 2015
Summary
This study demonstrates acoustic rotation of microparticles using orthogonal standing waves. Acoustic streaming generates viscous torque, causing particle rotation and enabling prediction of steady-state velocity.
Area of Science:
- Acoustics
- Fluid Dynamics
- Microparticle Manipulation
Background:
- Acoustic streaming around particles arises from time-averaged acoustic fields.
- This streaming generates a viscous torque, inducing particle rotation.
- Previous theories on viscous torque for non-rotating spheres are expanded.
Purpose of the Study:
- To experimentally investigate the acoustic rotation of spherical microparticles.
- To analyze the viscous torque generated by acoustic streaming.
- To predict the steady-state rotational velocity of microparticles.
Main Methods:
- Utilizing two orthogonal standing waves with a phase shift.
- Developing analytical calculations to expand upon existing viscous torque theories.
- Designing a macroscopic experimental device to create necessary boundary conditions.
Main Results:
- Experimental results show good agreement with analytical predictions.
- Demonstrated that viscous torque from acoustic streaming can dominate particle dynamics.
- Successfully predicted the steady-state rotational velocity of microparticles.
Conclusions:
- Acoustic streaming is a viable mechanism for inducing microparticle rotation.
- The developed analytical model accurately explains experimental observations.
- Viscous torque plays a significant role in the dynamics of near-spherical particles.
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