The selection of layer thicknesses to control acoustic radiation force profiles in layered resonators
The selection of layer thicknesses to control acoustic radiation force profiles in layered resonators
Ultrasonic standing waves can be used to generate radiation forces on particles within a fluid. A number of authors have derived detailed representations of these forces but these are most commonly applied using an approximation to the energy distribution based upon an idealized standing wave within a mode based upon rigid boundaries. An electro-acoustic model of the acoustic energy distribution within a standing wave with arbitrary thickness boundaries has been expanded to model the radiation force on an example particle within the acoustic field. This is used to examine the force profile on a particle at resonances other than those predicted with rigid boundaries, and with pressure nodes at different positions. A simple analytical method for predicting modal conditions for combinations of frequencies and layer thickness characteristics is presented, which predicts that resonances can exist that will produce a pressure node at arbitrary positions in the fluid layer of such a system. This can be used to design resonators that will drive particles to positions other than the center of the fluid layer, including the fluid/solid boundary of the layer, with significant potential applications in sensing systems. Further, the model also predicts conditions for multiple subwavelength resonances within the fluid layer of a single resonator, each resonance having different nodal planes for particle concentration
2654-2661
Hill, Martyn
0cda65c8-a70f-476f-b126-d2c4460a253e
2003
Hill, Martyn
0cda65c8-a70f-476f-b126-d2c4460a253e
Hill, Martyn
(2003)
The selection of layer thicknesses to control acoustic radiation force profiles in layered resonators.
Journal of the Acoustical Society of America, 114 (5), .
(doi:10.1121/1.1616581).
Abstract
Ultrasonic standing waves can be used to generate radiation forces on particles within a fluid. A number of authors have derived detailed representations of these forces but these are most commonly applied using an approximation to the energy distribution based upon an idealized standing wave within a mode based upon rigid boundaries. An electro-acoustic model of the acoustic energy distribution within a standing wave with arbitrary thickness boundaries has been expanded to model the radiation force on an example particle within the acoustic field. This is used to examine the force profile on a particle at resonances other than those predicted with rigid boundaries, and with pressure nodes at different positions. A simple analytical method for predicting modal conditions for combinations of frequencies and layer thickness characteristics is presented, which predicts that resonances can exist that will produce a pressure node at arbitrary positions in the fluid layer of such a system. This can be used to design resonators that will drive particles to positions other than the center of the fluid layer, including the fluid/solid boundary of the layer, with significant potential applications in sensing systems. Further, the model also predicts conditions for multiple subwavelength resonances within the fluid layer of a single resonator, each resonance having different nodal planes for particle concentration
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Published date: 2003
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Local EPrints ID: 22574
URI: http://eprints.soton.ac.uk/id/eprint/22574
ISSN: 0001-4966
PURE UUID: 5bcfce8e-f955-4f19-b513-aa2a6f0d91e2
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Date deposited: 23 Mar 2006
Last modified: 16 Mar 2024 02:41
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