Compressive Deformation Analysis of Alginate-Poly(L)lysine-Alginate (APA) Microcapsule

Abstract

An analysis of the compressive deformation of alginate-poly(L)lysine-alginate (APA) microcapsules by two rigid parallel plates was performed under the assumptions that the bending stiffness and permeability of the membrane were negligible. The static equilibrium equations of force for axisymmetric elastic deformation were solved using the Runge-Kutta method with the constraint of constant microcapsule volume during deformation. The constitutive laws of a neo-Hookean material and that proposed by Evans and Skalak(1) were used. The Young's modulus of the membrane was determined by an atomic force microscopy (AFM)-based technique, and a comparison with a semianalytical solution neglecting the shear stiffness of the membrane validated the present analysis method. The force-displacement curve for the compressive deformation of an APA microcapsule is calculated and compared with the experimentally measured result. A nonlinear increase in the transmural pressure with increasing displacement and the meridional and circumferential stress resultant distributions near rupture of the membrane are also shown.

Keywords

• microcapsule
• mechanical properties
• compression
• modeling
• membrane
• constitutive law