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Piezo-driven acoustic streaming in an electrowetting-on-dielectric digital microfluidics device

Abstract

We report the integration of a lead zirconate titanate, \(\hbox {Pb[Zr}_{x}\hbox {Ti}_{1-x}\hbox {O}_{3}\)] (PZT), piezoelectric transducer disk into the top plate of an otherwise conventional electrowetting-on-dielectric (EWD) digital microfluidics device to demonstrate on-demand induction of circulating fluid flow within single 200 nL droplets. Microparticle image velocimetry was used to measure in-plane velocity distributions for PZT excitation voltages that ranged from 0 to 50 \(\hbox {V}_{\text {RMS}}\). Intra-droplet streaming velocities in excess of 2.0 \(\hbox {mm}\cdot \hbox {s}^{-1}\) were observed without droplet breakup or damage to the EWD device layer. Additionally, we found median intra-droplet streaming velocity to depend quadratically on PZT excitation voltage up to the stress limit of the interfacial boundary. Our approach offers an alternative device architecture for active micromixing strategies in EWD digital microfluidics laboratory-on-chip systems.

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Notes

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    The EWD control GUI software is available upon request.

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Acknowledgements

The authors thank the staff of Duke University’s Shared Materials Instrumentation Facility (SMiF) for fabrication support, Dr. Yasheng Gao of the Light Microscopy Core Facility (LCMF) of Duke University for microscopy assistance, and Dr. Laura B. Lewandowski for editorial support.

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Correspondence to Andrew C. Madison.

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The authors declare no conflicts of interest.

Additional information

DARPA Grant HR0011-12-C-0057.

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Madison, A.C., Royal, M.W. & Fair, R.B. Piezo-driven acoustic streaming in an electrowetting-on-dielectric digital microfluidics device. Microfluid Nanofluid 21, 176 (2017). https://doi.org/10.1007/s10404-017-2012-6

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Keywords

  • Electrowetting on dielectric
  • Digital microfluidics
  • Acoustofluidics
  • Acoustic streaming
  • Piezoelectric transducer
  • Particle image velocimetry