Water jet indentation for local elasticity measurements of soft materials

• Published in: The European physical journal. E, Soft matter and biological physics Vol. 39; no. 1; p. 10
• Main Authors: Chevalier, N. R., Dantan, Ph, Gazquez, E., Cornelissen, A. J. M., Fleury, V.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2016
• Subjects: Biological and Medical Physics; Biophysics; Complex Fluids and Microfluidics; Complex Systems; Dimethylpolysiloxanes - chemistry; Dimethylpolysiloxanes - standards; Elasticity; Gels - chemistry; Gels - standards; Microfluidics - methods; Nanotechnology; Nylons - chemistry; Nylons - standards; Physics; Physics and Astronomy; Polymer Sciences; Soft and Granular Matter; Surfaces and Interfaces; Thin Films; Tips and Tricks; Tips and Tricks
• ISSN: 1292-8941; 1292-895X
• DOI: 10.1140/epje/i2016-16010-1

.
We present a novel elastography method for soft materials (100Pa-100kPa) based on indentation by a μm-sized water jet. We show that the jet creates a localized deformation (“cavity”) of the material that can be easily visualized. We study experimentally how cavity width and depth depend on jet speed, height, incidence angle and sample elasticity. We describe how to calibrate the indenter using gels of known stiffness. We then demonstrate that the indenter yields quantitative elasticity values within 10% of those measured by shear rheometry. We corroborate our experimental findings with fluid-solid finite-element simulations that quantitatively predict the cavity profile and fluid flow lines. The water jet indenter permits
in situ
local stiffness measurements of 2D or 3D gels used for cell culture in physiological buffer, is able to assess stiffness heterogeneities with a lateral resolution in the range 50-500μm (at the tissue scale) and can be assembled at low cost with standard material from a biology laboratory. We therefore believe it will become a valuable method to measure the stiffness of a wide range of soft, synthetic or biological materials.
Graphical abstract