Compression of a capsule: Mechanical laws of membranes with negligible bending stiffness

Abstract

The compression of a capsule between two plates is considered. The problem is solved numerically for a capsule made of an incompressible liquid drop surrounded by a thin elastic membrane which has a negligible bending stiffness. Numerical results are provided for three different mechanical laws of the membrane. By considering elastic moduli independent of the deformation, we show that the isotropic dilation plays the major role. In particular, an asymptotic behavior independent of the shear modulus is found for large deformations. For more complex models, the deformation limits beyond which the variation of elastic moduli starts to play a role are examined. The results indicate that the distinction between the different models requires a careful inspection of both small and large deformations. The theoretical predictions are compared with experimental results. For millimetric capsules with membranes made of covalently linked human serum albumin and alginate, the best agreement is obtained by considering that the elastic moduli are independent of the deformation and range from 0.1 to 4 N/m.

Determination of the elastic properties of single microcapsules using micromanipulation and finite element modeling

“…9(a)). This similarity is not surprising because they are from the same batch and rupture occurs at strains far beyond the elastic regime, and even if it did not, rupture is likely to be independent of elasticity (Smith et al, 2000).…”

“…(2) (Lulevich et al, 2004;Risso and Carin, 2004). The profile of the dimensionless force would not depend on the shell thickness (h).…”

Motion of a spherical capsule in branched tube flow with finite inertia

“…For biological membranes, the factor C is usually much larger than unity, because of their quasi area incompressibility. In the case of artificial capsules, the SK law has been found to fit experimental data when values of order 1 are used for the factor C (Carin et al 2003;Risso & Carin 2004;Rachik et al 2006). In the present study, the simulations are conducted for capsules enclosed by an SK membrane with C = 1, unless otherwise stated.…”

Identification of the elastic properties of an artificial capsule membrane with the compression test: Effect of thickness

“…This powerful technique is often used to evaluate a bursting force only [12][13][14][15]. However, by means of an inverse analysis, it is also possible to extract information on the membrane material mechanical behavior [16][17][18][19][20]. The procedure consists in assuming a constitutive law for the capsule wall material and then in performing a complete mechanical analysis of the compression process.…”