Indentation Analysis of Microcapsule with Initial Stretch

Abstract

A deformation analysis of a liquid-filled spherical microcapsule indented by a sharp truncated-cone indenter was conducted, in which a circumferential wrinkling model was introduced in the dimpled region near the indenter tip. The initial stretch of the membrane of an alginate-poly(L)lysine-alginate microcapsule was determined by fitting the calculated and measured force-displacement curves. In the fitting procedure, the effect of the membrane permeability in the experiment on the force-displacement curve was taken into account. The calculated deformed shape of the indented microcapsule was almost identical to the experimentally observed one. The influences of the initial stretch on the force-displacement relationship, transmural pressure-displacement relationship, and deformation shape before membrane rupture due to the indenter-tip piercing were demonstrated. The importance of taking the initial stretch into account in the mechanical characterization of microcapsules or cells was shown.

Keywords

• indentation
• microcapsule
• mechanical modeling
• initial stretch
• mechanical characterization