A Novel Air Bubble Method to Compare the Pressure of the Brain Tissue in Head Decelerating Impact

A new physical head model with air bubble to simulate the brain injury in head decelerating impact is presented in this paper. This new method has its advantage on investigating the brain injury using a direct and visual technique. A hollow transparent glass model was used to simulate the skull, and a transparent gel was used to substitute the brain tissue. Three air bubbles were created in the gel at the respective position of coup site (impacting site), middle site and contrecoup site (opposite to impacting site). After this, the head model was made to free fall from a position and impact on a fixed platform. The decelerating impacting process was recorded by a high-speed video camera and an accelerometer system. Through analysing the video, the volume change, namely, the mean pressure change of the air bubbles were calculated and compared. The results showed explicitly and effectively that during the decelerating impact the contrecoup site air bubble was exposed mainly to a negative pressure which could lead to a tensile stress; and the coup site air bubble was exposed mainly to a positive pressure which could form a compressive force.