Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.


Numerical study of submicroparticle acoustophoresis using higher-order modes in a rectangular microchannel

Jorick van 't Oever, Jennifer Herek, Frieder Mugele, Dirk van den Ende, Herman L. Offerhaus
Journal of Sound and Vibration
dec 1, 2017
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Manipulation of submicrometer particles in Lab-on-a-Chip systems using acoustophoresis is challenging due to the effect of acoustic stream ing. We numerically study the transition from radiation force dominated to streaming-induced drag force dominated acoustophoresis using the fundamental and higher-order resonances of a water-filled rectangular microchannel. We consider the cases of single mode excitation and simultaneous double mode excitation. The acoustic fields at resonance are calculated usi ng a second-order perturbation expansion of the thermoviscous acoustic problem. We show that the acoustophoretic forces using simul- taneous mode excitation can be obtained from a linear combination of the single mode forces. We find that the critical size of suspended particles at the transition scales inversely with the square root of the resonance frequency. Particle tracing shows radiation-dominated concen- tration of 800 nm diameter polystyrene particles using the fifth-order resonance at 9.8 MHz. For smaller particles we find a streaming-assisted concentration regime where particles are concentrated into the streaming regions close to the walls. In case of double mode excitation, the particle concentrations increase a factor 4 to 18 times for 200 nm to 800 nm particles respectively. We include the numerical model, consisting of a COMSOL implementation and MATLAB control script, as supplemental material. © 2017 Elsevier Ltd. All rights reserved.
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