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Issue 10, 2014
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Design of a fluorinated magneto-responsive material with tuneable ultrasound scattering properties

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Abstract

In this work, we describe the preparation of emulsions of fluorinated ferrofluid droplets suspended in a yield-stress hydrogel (Bingham fluid) with potential applications for ultrasound (US) spectroscopy and imaging. Fluorinated ferrofluids were obtained using an original multi-step process leading to an appropriate suspension of magnetic nanoparticles (MNPs) coated by a layer of fluoroalkylsilane in fluorinated oil. The efficiency of the sol–gel coating reaction was assessed by several methods including infrared and X-ray photoelectron spectroscopy, small angle neutron scattering and magnetometry. The resulting suspension of silanized-MNPs behaves as a true fluorinated ferrofluid, remaining stable (i.e. a monophasic suspension of well dispersed MNPs) in magnetic inductions as high as 7 T. These ferrofluids were employed to prepare monodisperse emulsions in a Bingham gel using a robotic injection device. Using ultrasound spectroscopy, we show that the emulsion droplets behave as Mie-type acoustic wave resonators due to the high sound–speed contrast between the droplets and the matrix. When subjected to a magnetic field, the ferrofluid droplets elongate in the field direction, which in return modifies the acoustic response of the material. The resonance frequency peaks scale as the inverse of the emulsion droplet size encountered by the wave propagation vector. These results might open a new road towards the realisation of ultrasound contrast agents guided by magnetic fields and with a tuneable attenuation spectrum.

Graphical abstract: Design of a fluorinated magneto-responsive material with tuneable ultrasound scattering properties

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Publication details

The article was received on 09 Nov 2013, accepted on 24 Dec 2013 and first published on 03 Jan 2014


Article type: Paper
DOI: 10.1039/C3TB21585G
Citation: J. Mater. Chem. B, 2014,2, 1285-1297
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    Design of a fluorinated magneto-responsive material with tuneable ultrasound scattering properties

    K. Zimny, B. Mascaro, T. Brunet, O. Poncelet, C. Aristégui, J. Leng, O. Sandre and O. Mondain-Monval, J. Mater. Chem. B, 2014, 2, 1285
    DOI: 10.1039/C3TB21585G

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