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Optical micro-elastography with magnetic excitation for high frequency rheological characterization of soft media

Torres, Jorge; Callejas, Antonio; Gomez, Antonio; Rus, Guillermo; (2023) Optical micro-elastography with magnetic excitation for high frequency rheological characterization of soft media. Ultrasonics , 132 , Article 107021. 10.1016/j.ultras.2023.107021. Green open access

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Abstract

The propagation of shear waves in elastography at high frequency (>3 kHz) in viscoelastic media has not been extensively studied due to the high attenuation and technical limitations of current techniques. An optical micro-elastography (OME) technique using magnetic excitation for generating and tracking high frequency shear waves with enough spatial and temporal resolution was proposed. Ultrasonics shear waves (above 20 kHz) were generated and observed in polyacrylamide samples. A cutoff frequency, from where the waves no longer propagate, was observed to vary depending on the mechanical properties of the samples. The ability of the Kelvin–Voigt (KV) model to explain the high cutoff frequency was investigated. Two alternative measurement techniques, Dynamic Mechanical Analysis (DMA) and Shear Wave Elastography (SWE), were used to complete the whole frequency range of the velocity dispersion curve while avoid capturing guided waves in the low frequency range (<3 kHz). The combination of the three measurement techniques provided rheology information from quasi-static to ultrasonic frequency range. A key observation was that the full frequency range of the dispersion curve was necessary if one wanted to infer accurate physical parameters from the rheological model. By comparing the low frequency range with the high frequency range, the relative errors for the viscosity parameter could reach 60 % and they could be higher with higher dispersive behavior. The high cutoff frequency may be predicted in materials that follow a KV model over their entire measurable frequency range. The mechanical characterization of cell culture media could benefit from the proposed OME technique.

Type: Article
Title: Optical micro-elastography with magnetic excitation for high frequency rheological characterization of soft media
Location: Netherlands
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.ultras.2023.107021
Publisher version: https://doi.org/10.1016/j.ultras.2023.107021
Language: English
Additional information: © 2023 The Author(s). Published by Elsevier B.V. under a Creative Commons license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Optical elastography, Magnetism, High frequency, Rheological modeling, Kelvin-Voigt model
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10215599
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