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Publication Citation: Kilohertz Rotation of Nanomotors Propelled by Ultrasound Traced by Microvortex Advection of Nanoparticles

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Author(s): Andrew L. Balk; Lamar O. Mair; Pramod P. Mathai; Paul N. Patrone; Wei Wang; Suzanne Ahmed; Thomas Mallouk; James A. Liddle; Samuel M. Stavis;
Title: Kilohertz Rotation of Nanomotors Propelled by Ultrasound Traced by Microvortex Advection of Nanoparticles
Published: Date Unknown
Abstract: We use polystyrene nanoparticles as tracers of the microvortical flows around gold nanorods propelled by ultrasound in water, and we infer the rotational frequencies of these nanomotors by a hydrodynamic model of this interaction. In a half-wavelength layered acoustic resonator driven at ≈ 3 MHz with an energy density of < 10 J/m3, we estimate that nanomotors rotate at frequencies of up to ≈ 2.5 kHz, corresponding to tangential velocities at the nanomotor surfaces of ≈ 2.5 mm/s. The nanomotors also translate at velocities of up to ≈ 20 μm/s, with large variations in both modes of motion but without evident correlation between rotation and translation. Our study is an important step towards understanding the interesting behavior and fulfilling the significant potential of this active nanotechnology for hydrodynamically interacting with biological media, while also establishing the fastest measured rotation of an autonomous nanoscale object at low Reynolds number.
Citation: ACS Nano
Research Areas: Optical microscopy, Nanofluidics, Nanomagnetics