Matching Items (2)
Description
The football helmet is a device used to help mitigate the occurrence of impact-related traumatic (TBI) and minor traumatic brain injuries (mTBI) in the game of American football. The current design methodology of using a hard shell with an energy absorbing liner may be adequate for minimizing TBI, however it has had less effect in minimizing mTBI. The latest research in brain injury mechanisms has established that the current design methodology has produced a helmet to reduce linear acceleration of the head. However, angular accelerations also have an adverse effect on the brain response, and must be investigated as a contributor of brain injury.
To help better understand how the football helmet design features effect the brain response during impact, this research develops a validated football helmet model and couples it with a full LS-DYNA human body model developed by the Global Human Body Modeling Consortium (v4.1.1). The human body model is a conglomeration of several validated models of different sections of the body. Of particular interest for this research is the Wayne State University Head Injury Model for modeling the brain. These human body models were validated using a combination of cadaveric and animal studies. In this study, the football helmet was validated by laboratory testing using drop tests on the crown of the helmet. By coupling the two models into one finite element model, the brain response to impact loads caused by helmet design features can be investigated. In the present research, LS-DYNA is used to study a helmet crown impact with a rigid steel plate so as to obtain the strain-rate, strain, and stress experienced in the corpus callosum, midbrain, and brain stem as these anatomical regions are areas of concern with respect to mTBI.
To help better understand how the football helmet design features effect the brain response during impact, this research develops a validated football helmet model and couples it with a full LS-DYNA human body model developed by the Global Human Body Modeling Consortium (v4.1.1). The human body model is a conglomeration of several validated models of different sections of the body. Of particular interest for this research is the Wayne State University Head Injury Model for modeling the brain. These human body models were validated using a combination of cadaveric and animal studies. In this study, the football helmet was validated by laboratory testing using drop tests on the crown of the helmet. By coupling the two models into one finite element model, the brain response to impact loads caused by helmet design features can be investigated. In the present research, LS-DYNA is used to study a helmet crown impact with a rigid steel plate so as to obtain the strain-rate, strain, and stress experienced in the corpus callosum, midbrain, and brain stem as these anatomical regions are areas of concern with respect to mTBI.
ContributorsDarling, Timothy (Author) / Rajan, Subramaniam D. (Thesis advisor) / Muthuswamy, Jitendran (Thesis advisor) / Oswald, Jay (Committee member) / Mignolet, Marc (Committee member) / Arizona State University (Publisher)
Created2014
Biomechanical Micromotion at the Neural Interface Modulates Intercellular Membrane Potential In-Vivo
Description
Brain micromotion is a phenomenon that arises from basic physiological functions such as respiration (breathing) and vascular pulsation (pumping blood or heart rate). These physiological processes cause small micro displacements of 2-4µm for vascular pulsation and 10-30µm for respiration, in rat models. One problem related to micromotion is the instability of the probe and its ability to acquire stable neural recordings in chronic studies. It has long been thought the membrane potential (MP) changes due to micromotion in the presence of brain implants were an artefact caused by the implant. Here is shown that intracellular membrane potential changes are a consequence of the activation of mechanosensitive ion channels at the neural interface. A combination of aplysia and rat animal models were used to show activation of mechanosensitive ion channels is occurring during a neural recording. During simulated micromotion of displacements of 50μm and 100μm at a frequency of 1 Hz, showed a change of 8 and 10mV respectively and that the addition of Ethylenediaminetetraacetic acid (EDTA) inhibited the membrane potential changes. The application of EDTA showed a 71% decrease in changes in membrane potential changes due to micromotion. Simulation of breathing using periodic motion of a probe in an Aplysia model showed that there were no membrane potential changes for <1.5kPa and action potentials were observed at >3.1kPa. Drug studies utilizing 5-HT showed an 80% reduction in membrane potentials. To validate the electrophysiological changes due to micromotion in a rat model, a double barrel pipette for simultaneous recording and drug delivery was designed, the drug delivery tip was recessed from the recording tip no greater than 50μm on average. The double barrel pipette using iontophoresis was used to deliver 30 μM of Gadolinium Chloride (Gd3+) into the microenvironment of the cell. Here is shown a significant reduction in membrane potential for n = 13 cells across 4 different rats tested using Gd3+. Membrane potential changes related to breathing and vascular pulsation were reduced between approximately 0.25-2.5 mV for both breathing and heart rate after the addition of Gd3+, a known mechanosensitive ion channel blocker.
ContributorsDuncan, Jonathan Leroy (Author) / Muthuswamy, Jitendran (Thesis advisor) / Greger, Bradley (Committee member) / Sridharan, Arati (Committee member) / Arizona State University (Publisher)
Created2020