Contactless transport of matter in the first five resonance modes of a line-focused acoustic manipulator

Foresti, Daniele; Nabavi, Majid; Poulikakos, Dimos

doi:10.1121/1.3672700

Cited by 11 publications

(11 citation statements)

References 36 publications

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“…Owing to its material independency, acoustic levitation has found a wide spectrum of applications in contactless processing and analysis of liquid samples (Trinh, Thiessen & Holt 1998;Yarin, Pfaffenlehner & Tropea 1998). The contactless manipulation and transportation of particles and droplets is one of the most interesting challenges in the acoustic levitation field (Koyama & Nakamura 2010;Foresti et al 2011;Foresti, Nabavi & Poulikakos 2012) with applications ranging from the handling of living cells in lab-on-a-chip devices (Bruus et al 2011) to millimetre-size sample manipulations in air (Bjelobrk et al 2010).…”

Section: Introductionmentioning

confidence: 99%

On the acoustic levitation stability behaviour of spherical and ellipsoidal particles

2012

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We present here an in-depth analysis of particle levitation stability and the role of the radial and axial forces exerted on fixed spherical and ellipsoidal particles levitated in an axisymmetric acoustic levitator, over a wide range of particle sizes and surrounding medium viscosities. We show that the stability behaviour of a levitated particle in an axisymmetric levitator is unequivocally connected to the radial forces: the loss of levitation stability is always due to the change of the radial force sign from positive to negative. It is found that the axial force exerted on a sphere of radius R s increases with increasing viscosity for R s /λ < 0.0125 (λ is the acoustic wavelength), with the viscous contribution of this force scaling with the inverse of the sphere radius. The axial force decreases with increasing viscosity for spheres with R s /λ > 0.0125. The radial force, on the other hand, decreases monotonically with increasing viscosity. The radial and axial forces exerted on an ellipsoidal particle are larger than those exerted on a volume-equivalent sphere, up to the point where the ellipsoid starts to act as an obstacle to the formation of the standing wave in the levitator chamber.

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Section: Introductionmentioning

confidence: 99%

On the acoustic levitation stability behaviour of spherical and ellipsoidal particles

2012

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“…After the results presented above, we can explain quantitatively the significant improvement that the herein presented technique brings to the contactless droplet transportation compared to the state of the art. The numerical results reported by Foresti et al 34 showed that for the line-focussed levitator used in this study, the maximum volume of the water droplet that could be safely levitated, and transported by H regulation through the two acoustic resonances in the H 1 mode is 0.9 nl. With the presented control technique, by adjusting V d based on the aspect ratio of the droplet, we are able to levitate and transport water droplets of 1.9 ll in volume, which means a volume increase by three orders of magnitude.…”

Section: Resultsmentioning

confidence: 53%

Acoustic levitator for contactless motion and merging of large droplets in air

Bjelobrk

Nabavi

Poulikakos

2012

Journal of Applied Physics

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Flow and noise predictions for the tandem cylinder aeroacoustic benchmark Phys. Fluids 24, 036101 (2012) Acoustic cloak for airborne sound by inverse design Appl. Phys. Lett. 99, 074102 (2011) Influence of gases on Lamb waves propagations in resonator Appl. Phys. Lett. 95, 223505 (2009) Sound control by temperature gradients Appl. Phys. Lett. 95, 204102 (2009) Quenching of acoustic bandgaps by flow noise Appl. Phys. Lett. 94, 134104 (2009) Additional information on J. Appl. Phys.Large droplet transport in a line-focussed acoustic manipulator in terms of maximum droplet size is achieved by employing a driving voltage control mechanism. The maximum volume of the transported droplets in the order of few microliters is thereby increased by three orders of magnitude compared to the constant voltage case, widening the application field of this method significantly. A drop-on-demand droplet generator is used to supply the liquid droplets into the system. The ejected sequence of picoliter-size droplets is guided along trajectories by the acoustic field and accumulates at the selected pressure node, merging into a single large droplet. Droplet movement is achieved by varying the reflector height. This also changes the intensity of the radiation pressure during droplet movement, which in turn could atomise the droplet. The acoustic force is adjusted by regulating the driving voltage of the actuator to keep the liquid droplet suspended in air and to prevent atomisation. In the herein presented levitation concept, liquids with a wide range of surface tension (water and tetradecane were tested) can be transported over distances of several mm. The aspect ratio of the droplet in the acoustic field is shown to be a good indicator for radiation pressure intensity and is kept between 1.1 and 1.4 during droplet transport. Despite certain limitations with volatile liquids, the presented acoustic levitator concept has the potential to expand the range of analytical characterisation and manipulation methods in applications ranging from chemistry and biology. V C 2012 American Institute of Physics. [http://dx.

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“…3C). We note that a linear improvement is expected with increasing driving frequency, because the absolute dimensions of the system scale with the acoustic wavelength ( 31 ). In addition, for the same acoustic pressure amplitude and droplet diameter, the acoustophoretic force increases linearly with the frequency.…”

Section: Resultsmentioning

confidence: 94%