Invariant elastic modulus of viscoelastic materials measured by rate-jump tests

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…”

Mechanical properties of biological specimens explored by atomic force microscopy

“…The data set is almost equivalent to a classical force-volume file with a considerable gain in terms of recording speed and resolution (512 2 pixels images). A relatively recent approach, called the rate-jump method [14,15], has been developed to measure with high precision the stiffness of soft biological samples. The approach is inspired from the indentometry techniques that are in use in material sciences and that have been developed to dissociate the viscous from the elastic components that both influence the classical indentation measurements.…”

Accurate measurement of stiffness of leukemia cells and leukocytes using an optical trap by a rate-jump method

“…This provides a means to measure the intrinsic elastic modulus of a viscoelastic material in any test platform. For example, in a tensile test, if the loading rate undergoes a step jump at time tc, then the intrinsic Young's modulus at tc is given as the ratio of the difference in stress rates to the difference in strain rates across the jump 14 . If the material behavior is time-or structure-dependent, then the modulus measured this way will be specific to the moment at which the rate jump is imposed, but will be independent of magnitude of the rate jump at that time point, i.e.…”

“…If the material behavior is time-or structure-dependent, then the modulus measured this way will be specific to the moment at which the rate jump is imposed, but will be independent of magnitude of the rate jump at that time point, i.e. it will be an intrinsic material property [12][13][14] . This method is better than the traditional viscoelasticity analysis of the overall force-displacement response which would require the assumption of linear viscous behavior and an a priori known spring-dashpot network as the constitutive law [15][16][17][18][19] .…”