Session: 06-01-02: Injury and Damage Biomechanics II - Organ and Tissue Injury Biomechanics 2

Paper Number: 150543

150543 - On the Cavitation Dynamics of 2 Phase Fluids Using Drop Tower Based Integrated System 

The increasing utilization of cavitation in medical treatments and the recognition of cavitation-induced brain injuries underscore the necessity for precise characterization and understanding of dynamic cavitation in heterogeneous soft materials. Despite its significance, the current understanding of cavitation dynamics in such materials is limited, primarily due to the lack of reliable experimental methodologies. Loading delicate samples like gelatin, a popular tissue simulant for studying potential human body and brain injuries, poses significant challenges. This study employs a recently developed drop tower integrated system featuring a unique sample holder and an array of effective springs and dampers to investigate soft materials under high-rate loading conditions. This system uniquely allows for the adjustment of the input acceleration profile, a critical feature for accurately replicating the acceleration patterns of blunt force injuries and examining the biological responses of living cells or tissues. This methodology facilitates the observation of the temporal progression of cavitation and enables quantitative measurements of the critical acceleration required for cavitation nucleation. The integrated drop tests incorporate a conventional drop tower impact system, high-speed cameras, accelerometers, a cuvette with a specialized holder, and a comprehensive data acquisition system. Typically, bio-simulants such as extracellular matrix (ECM) materials (gelatin and agar) are tested individually to develop risk assessment curves that predict the critical cavitation threshold. However, the brain's interior comprises both white and grey matter with varying concentrations. This research investigates the onset, evolution, and collapse of cavitation bubbles within a two-phase sample consisting of a gelatin layer at the bottom and a water layer on top, with different interface orientations such as vertical, horizontal, and inclined interfaces. Our findings indicate that the onset of cavitation nucleation in the gelatin region is consistently delayed and tends to occur when a secondary cavitation wave is initiated in the water region. Also, the cavitation duration in the gelatin region is much shorter than in water. These observations suggest that tissues might exhibit similar cavitation behavior, which has important implications for medical treatment protocols, such as ultrasound therapy. Understanding the differential response of materials to cavitation can inform the establishment of safety margins for protective equipment, such as advanced helmets designed to mitigate cavitation-induced traumatic brain injury. The implications of this study extend to several critical applications. In the medical field, precise replication of acceleration patterns associated with blunt injuries and the subsequent biological reactions can elucidate the mechanisms underlying these injuries. This is particularly relevant for improving the safety and efficacy of medical treatments that utilize cavitation phenomena. Furthermore, the ability to quantitatively measure critical accelerations corresponding to cavitation nucleation provides valuable data for developing predictive models and risk assessment tools. 

Presenting Author: Sachan Johny The University of Texas at Arlington

Presenting Author Biography: Mr. Sachan Johny is a graduate student at Multi-scale Mechanics and Physics Lab (MMPL). He is doing PhD in Mechanical Engineering at The University of Texas at Arlington. His research efforts focusses on addressing cavitation related traumatic brain injury mechanisms.

Authors:

Sachan Johny The University of Texas at Arlington
Ashfaq Adnan The University of Texas at Arlington