Biomechanics/Neuroscience/Impact Engineering

Yuzhe Liu, Ph.D.

Contacts: yuzheliu@stanford.edu

I am currently a Post-doc Scholar at David Camarillo Lab in the Department of Bioengineering, Stanford University. In CamLab, I work on the studies about the concussion, which is also known as mild Traumatic Brain Injury (mTBI), including the development of instrumented mouthguard, the biomechanics of the brain deformation in mTBI-level impact and the biomechanics mechanism underlying of the cerebral vascular injury in mTBI.

 

I finished my Ph.D. in Mechanics at Tsinghua University, Beijing. During my Ph.D., I worked on two projects: One was to explain how the woodpecker protect its brain from a concussion during pecking, and another was to propose a framework to analyze the expansion, inversion, shrinking and splitting of the tube-type energy absorbers.

 

I completed my Bachelor of Engineering Mechanics at Tsinghua University, Beijing. I participated in the Student Research Training program to perform mechanical analyses of the "Y" type tube under high pressure.

 

Besides research, I also enjoy mentoring talented students, and I worked as an advisor of undergraduates at Tsinghua University. During my spare time, I play basketball, work out in the gym, swim, and bike.

Blood-Brain Barrier Disruption in mTBI

Postdoc Scholar, Bioengineering, Stanford University 
Ph.D., Engineering Mechanics, Tsinghua University

Bachelor, Engineering Mechanics, Tsinghua University

Yuzhe Liu

Yuzhe Liu

3.8 million people in the United States each year sustaining mild traumatic brain injuries (mTBI), which can only be subjectively diagnosed without imaging or biomechanical supports. We study a set of the traumatic cerebral vascular injury following the Blood-Brain Barriers (BBB) disruption. Our aim is to use the BBB disruption as a "neuro-sensor" to bridge the brain biomechanics and neuropathological funding, i.e. p-tau.

Accurate measurement of head kinematics is the key to reconstruct the brain tissue deformation during impact. The instrument mouthguard moves rigidly with the teeth, and record the linear acceleration and angular velocity above a threshold. Based on the head kinematics, the biomechanical basis of pathology can be explored. We work to develop and improve the current instrumented mouthguard to make them more accurate, more robust but less expensive.  We also work to widen the applicability of the mouthguard to different sports besides football. 

 

Instrumented Mouthguard

Biomechanics of Brain Deformation

In the field of concussion, the biomechanics of the brain deformation was extensively studied. Several famous FEA head models have been developed and validated, which essentially provides tools to calculate the brain strain. Although considerable simulations of the brain deformation were performed and reported, the actual mechanism that drives the brain deformation is still unclear. We applied the FEA head model to the on-field football data and analyzed how the brain is deformed theoretically and statistically.

Resistance of Woodpecker to Concussion

Woodpecker is famous for its extraordinary resistance to the concussion. The deceleration of the woodpecker head is high than 1000 g, but not a concussion case was reported before. We performed the experiment to record the woodpecker pecking process, and develop a material point method (MPM) model to simulate the brain deformation. Based on the simulation results, we found that the woodpecker's hyoid bone enhances the constraint between the skull the neck, which reduces the deformation in the brainstem.

Theoretical Models of Tube Expansion/Inversion/Shrinking

The expansion/inversion/shrinking of the metal tube is a preferrable deformation for energy-absorbing since it can provide steady and constant compressional force, which is the ideal force-time trace to dissipate kinetic energy. We provide a series of analytical deformation model to calculate the deformation of the tube and the compressional force. Based on these models, we also provided designing methods to determine the geometry parameters according to the material property adopted to achieve the best energy absorption.