Sound velocity determination in gel-based emulsions.
Sound velocity is a main parameter in non destructive characterization, closely related to the elastic properties and to the microstructure of heterogeneous materials. The accurate determination of the sound velocity using pulse-echo technique relies on the ability to reduce pulse distortion and to measure specimen dimensions with a high precision. In the field of bio-mimetic materials and biological tissues, the nature of the specimen makes this last requirement highly difficult or inappropriate. The present work, using a through-transmission configuration, allows, in a stress free environment, to access the sound velocity in soft, low acoustic contrast materials without requiring the specimen dimensions. The specimen sound velocity is obtained from the echo time-of-flights through a Z-scan process providing the absolute medium sound velocity as reference. The technique uses an excitation burst at a frequency below the transducer resonance to ensure a significantly reduction in pulse distortions and improve signal-to-noise ratio. The accurate determination of the echo time-of-flight relies on a highly efficient cross-correlation/Hilbert transform signal processing. The method has been applied to gel-based emulsions of different microstructures considered as biomimetic phantoms, as well as to their constituents: pure gelatin and vegetable oil.
Ammann
Jean-Jacques
JJ
Department of Physics, Universidad de Santiago de Chile (USACH), Ecuador 3493, Santiago, Chile. jammann@lauca.usasch.cl
Galaz
Belfor
B
D040761:Biomimetic Materials; D004655:Emulsions; D005782:Gels; D013016:Sound; D014159:Transducers
D004655:Emulsions; D005782:Gels