Performance of a quarter-wavelength particle concentrator

Townsend, R.J., Hill, M., Harris, N.R. and McDonnell, M.B (2008) Performance of a quarter-wavelength particle concentrator Ultrasonics, 48, (6-7), pp. 515-520. (doi:10.1016/j.ultras.2008.06.005).


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A series of devices have been investigated which use acoustic radiation forces to concentrate micron sized particles. These multi-layered resonators use a quarter wavelength resonance in order to position an acoustic pressure node close to the top surface of a fluid layer such that particles migrate towards this surface. As flow through devices, it is then possible to collect a concentrate of particulates by drawing off the particle stream and separating it from the clarified fluid and so can operate continuously as opposed to batch processes such as centrifugation. The methods of construction are described which include a micro-fabricated, wet-etched device and a modular device fabricated using a micro-mill. These use silicon and macor, a machinable glass ceramic, as a carrier layer between the transducer and fluid channel, respectively. Simulations using an acoustic impedance transfer model are used to determine the influence of various design parameters on the acoustic energy density within the fluid layer and the nodal position. Concentration tests have shown up to 4.4-, 6.0- and 3.2 fold increases in concentration for 9, 3 and 1 ?m diameter polystyrene particles, respectively. The effect of voltage and fluid flow rates on concentration performance is investigated and helps demonstrate the various factors which determine the increase in concentration possible.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1016/j.ultras.2008.06.005
ISSNs: 0041-624X (print)
Keywords: acoustic radiation force, concentration, particle separation, suspension, bio-sensing.
ePrint ID: 52031
Date :
Date Event
8 June 2007Submitted
November 2008Published
Date Deposited: 05 Jun 2008
Last Modified: 16 Apr 2017 18:04
Further Information:Google Scholar

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