Nanoindentation Measurement of Mechanical Properties of Soft Solid Covered By a Thin Liquid Film

Abstract

AThe presence of a surface-covering liquid film may significantly affect property measurement by nanoindentation on an underlying solid specimen, by causing an artificial drift of the reference point for tip displacement and exerting a surface-tension traction on the tip. The first effect can be corrected for by identifying the hard contact point between the tip and the solid in the load-displacement curve. The second effect can be corrected for by a formula derived in this work, which can also correct for the intrinsic viscoelasticity effects of the solid sample. The correction procedure proposed is validated by experimentation on wet polypropylene.

AFM nanoindentation detection of the elastic modulus of tongue squamous carcinoma cells with different metastatic potentials

“…(2) will be the instantaneous value at the moment when the rate jump is applied [36]. The validity of this rate-jump 11 method in general has been verified in a wide range of soft materials on different mechanical testing platforms, including depth-sensing indentation on bone tissues, polymers and soft metals [18,37,38]， micro-plate compression on stem-cell inserted collagen micro-masses for tissue engineering purposes [39], AFM nanoindentation of cells and soft polymers [19,20,39], as well as macroscopic uniaxial tensile testing on polymers [40]. In the results below, the values of the Young modulus E are reported and these were calculated from the measured reduced moduli…”

Response of power-law-viscoelastic and time-dependent materials to rate jumps

“…5,6,20 Surface adhesion between the specimen and the probe, and other effects pertinent to wet or moist samples, such as hydrodynamic forces resulting from infiltrated liquid in porous samples or for samples immersed in liquid, are ignored. These are challenging test conditions to model from a mechanics viewpoint, and more work needs to be done in this area, 21 although simple analytical models are not expected to exist generally.…”

Use of focused ion beam milling for investigating the mechanical properties of biological tissues: A study of human primary molars

“…At least 30 min were given to stabilize the system and rehydrate the samples before the loading was applied on the micro-cantilevers. Effects on the measurement due to the viscoelasticity of the sample and meniscus forces from the fluid were corrected using a protocol described by Ngan et al (2005) and Tang and Ngan (2007).…”