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Acoustomicrofluidic application of quasi-shear surface waves.
A N Darinskii1, M Weihnacht2, H Schmidt3
1Institute of Crystallography FSRC "Crystallography and Photonics", Russian Academy of Sciences, Leninskii pr. 59, Moscow 119333, Russia; National University of Science and Technology "MISIS", Leninsky pr. 4, Moscow 119049, Russia.
Ultrasonics
|March 11, 2017
Summary
This study explores using boundary polarized surface acoustic waves for microfluidic actuation in PDMS devices. These waves offer improved efficiency over vertically polarized waves, especially in thicker-walled containers.
Area of Science:
- Microfluidics
- Acoustic wave devices
- Materials science
Background:
- Conventional microfluidic actuation using vertically polarized surface acoustic waves suffers from signal attenuation in Polydimethylsiloxane (PDMS) containers due to leakage.
- PDMS's low shear elastic modulus presents a challenge for efficient acoustic wave propagation and energy transfer.
Purpose of the Study:
- To investigate the use of predominantly boundary polarized surface acoustic waves for actuating fluidic effects in PDMS microchannels.
- To overcome the limitations of vertically polarized waves, particularly signal loss in container side walls.
Main Methods:
- Computational analysis comparing predominantly vertically polarized surface waves (on 128YX LiNbO3) with quasi-shear leaky waves (on 64YX LiNbO3).
- Modeling acoustic field scattering within microchannels to enhance vertical displacement amplitudes.
- Simulating fluid actuation efficiency based on container wall thickness and presence of scatterers.
Main Results:
- Quasi-shear leaky waves are predicted to drive fluid more efficiently than surface waves on 128YX LiNbO3 in PDMS microchannels when wall thickness exceeds 25-30 wavelengths.
- The efficiency advantage of quasi-shear waves increases in the presence of internal scatterers (e.g., gold strips), becoming more effective at wall thicknesses over 10-15 wavelengths.
- Boundary polarized modes are expected to experience significantly lower losses in PDMS compared to vertically polarized modes.
Conclusions:
- Predominantly boundary polarized surface acoustic waves, specifically quasi-shear leaky waves, show promise for more efficient microfluidic actuation in PDMS.
- The findings suggest that optimizing wave mode and considering channel geometry (wall thickness, scatterers) are crucial for effective acoustic-driven microfluidics in PDMS.
