Numerical Modelling of a Microfluidic Ultrasonic Particle Separator
R.J. Townsend, M. Hill, N.R. Harris, N.M. White and S.P. Beeby
University of Southampton, UK
acoustic separation, microfluidics, CFD, FEA, modelling
Particles held in a fluid suspension and within an acoustic standing wave experience an acoustic radiation force. The force causes particles to move to the pressure nodes of the acoustic field creating a concentrate, contributing to the sensing of particles or cells. To predict the performance of devices relying on acoustic radiation forces and to assist with design, a simulation approach is used which combines several modelling techniques. Particle trajectories through the acoustic field and the resulting concentration profile are determined by resolving the forces experienced by particles numerically. This particle simulation model is further supported by more detailed analysis of the acoustic and fluid flow fields using finite element analysis and computational fluid dynamics, applicable to the microfluidic flow. These modelling techniques are applied to the simulation of a microfluidic ultrasonic particle separator, driven using a printed PZT transducer and relying on silicon and Pyrex etch fabrication. The device issues particle concentrated and clarified flow through two outlets, respectively. Test data taken from a fabricated device is used to evaluate the simulation approach which correlate well with eachother. The simulation approach is used successfully to redesign the acoustic and fluid geometry and to predict the influence of operating conditions.
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Nanotech 2005 Conference Program Abstract