Fig. 4

Effects of thickness on spherical wall tension. According to the modified LaPlace equation (T = PR/2z), the thicker of two spheres with the same volume will experience less wall tension from the same internal pressure (center). In a sphere whose wall has a thickness comprised of a fixed quantity of expandable biomaterial, expansion decreases (thins) relative thickness, helping augment wall tension (right). Conversely, lower volumes increase relative wall thickness, diminishing wall tension (left)