Experimental and numerical study on the mechanical behavior of rat brain tissue.

Brain tissue is a very soft tissue in which the mechanical properties depend on the loading direction. While few studies have characterized these biomechanical properties, it is worth knowing that accurate characterization of the mechanical properties of brain tissue at different loading directions is a key asset for neuronavigation and surgery simulation through haptic devices. In this study, the hyperelastic mechanical properties of rat brain tissue were measured experimentally and computationally. Prepared cylindrical samples were excised from the parietal lobes of rats' brains and experimentally tested by a tensile testing machine. The effects of loading direction on the mechanical properties of brain tissue were measured by applying load on both longitudinal and circumferential directions. The general prediction ability of the proposed hyperelastic model was verified using finite element (FE) simulations of brain tissue tension experiments. The uniaxial experimental results compared well with those predicted by the FE models. The results revealed the influence of loading direction on the mechanical properties of brain tissue. The Ogden hyperelastic material model was suitably represented by the non-linear behavior of the brain tissue, which can be used in future biomechanical simulations. The hyperelastic properties of brain tissue provided here have interest to the medical research community as there are several applications where accurate characterization of these properties are crucial for an accurate outcome, such as neurosurgery, robotic surgery, haptic device design or car manufacturing to evaluate possible trauma due to an impact.