ABSTRACT
Spherical cellular aggregates are in vitro systems to study the physical and biophysical properties of tissues. We present a novel approach to characterize the mechanical properties of cellular aggregates using a micropipette aspiration technique. We observe an aspiration in two distinct regimes: a fast elastic deformation followed by a viscous flow. We develop a model based on this viscoelastic behavior to deduce the surface tension, viscosity, and elastic modulus. A major result is the increase of the surface tension with the applied force, interpreted as an effect of cellular mechanosensing.
Subject(s)
Biopsy, Needle/methods , Elasticity , Animals , Biomechanical Phenomena , Cell Aggregation , Cell Line, Tumor , Mice , Surface Tension , ViscosityABSTRACT
To investigate the link between discrete small-scale and continuous large scale mechanical properties of a foam, we observe its two-dimensional flow in a channel, around an elliptical obstacle. We measure the drag, lift, and torque acting on the ellipse versus the angle between its major axis and the flow direction. The drag increases with the spanwise dimension, in marked contrast with a square obstacle. The lift passes through a smooth extremum at an angle close to, but smaller than 45 degrees. The torque peaks at a significantly smaller angle 26 degrees. No existing model can reproduce the observed viscous, elastic, plastic behavior. We propose a microscopic visco-elasto-plastic model which agrees qualitatively with the data.
