Simulation of Dynamic Rigidity Modulus of Brain Matter by that of Agar Gel

Abstract

Agar gel is a linear viscoelastic material with low deformations ( < 0.01%). Here, characterization technique used is the rheometer-type Carri-Med “CSL 100”. This rheometer offers us the opportunity to study the gel in static and dynamic shear. The study is done at low frequencies (0.1–40Hz). Mechanical characterization of the agar gel in terms of dynamic modulus is performed for different concentrations. The dynamic rigidity of the gel decreases with increasing concentration. The 8% agar gel simulates very well the dynamic rigidity of brain tissue at low frequency. The range of low frequencies is rarely studied for this material (brain) in the literature. Most tests done on brain tissue are in a frequency range between 50Hz and 600Hz. Yet, the Maxwell–Kelvin–Voigt model simulates very well the 8% agar gel. The instant elasticity derived from mathematical modeling of agar gel is similar to that measured in the literature for the brain tissue. Hence agar gel can be used in the construction of physical models of the human head used to analyze the dynamic response of the head to shock or to an inertial load.