Biomechanical Engineering Commons^™

Development And Evaluation Of A Smart Vacuum-Assisted Suspension System For Transtibial Prostheses, Zahraa Kathem Ali, Wajdi Sadik Aboud

Al-Bahir

A prosthetic socket is essential for achieving comfort, gait symmetry, and overall satisfaction for amputees. Effective suspension systems are crucial for securely attaching prostheses, thereby optimizing comfort, functional performance, and long-term limb health. This study aimed to develop and evaluate an intelligent vacuum-assisted suspension system for transtibial prostheses to improve socket fit, gait stability, and reduce residual limb movement. The system integrates force-sensitive resistors (FSRs) and an inertial measurement unit (MPU6050) with accelerometer and gyroscope sensors, continuously monitoring interface pressure and limb motion. Real-time data from these sensors dynamically adjusts vacuum pressure based on the user's gait pattern .Quantitative gait …

Expansion Limits Of Meshed Split-Thickness Skin Grafts, Haomin Yu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Split-thickness skin grafts are widely used to treat chronic wounds. Procedure design requires surgeons to predict how much a patch of the patient's own skin expands when it is meshed with rows of slits and stretched over a larger wound area. Accurate prediction of graft expansion remains a challenge, with current models overestimating the actual expansion, leading to suboptimal outcomes. Inspired by the principles of mechanical metamaterials, we developed a model that distinguishes between the kinematic rearrangement of structural elements and their stretching, providing a more accurate prediction of skin graft expansion. Our model was validated against extensive data …

Three-Dimensional Printing Of Calcium Phosphate-Mesoporous Bioactive Glass Scaffolds For Bone Tissue Engineering, Ana Beatriz Gomes De Carvalho, Lais Medeiros Cardoso, Igor Paulino Mendes Soares, Joyce Rodrigues De Souza, Arpita Roy, Prabaha Sikder, Et. Al.

Mechanical Engineering Faculty Publications

Calcium phosphate cements (CPCs) and biomaterials, such as mesoporous bioactive glass (MBG), are critical for bone tissue engineering. This study aimed to 3D-print CPC scaffolds modified with MBG to enhance their osteogenic potential and regenerative ability. MBG powder was synthesized and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption techniques. A commercial CPC ink (hydroxyapatite/alpha-tricalcium phosphate) was mixed with 5% MBG (w/w; CPC/MBG), and, after rheological assessment, the mixture was used to obtain scaffolds via 3D printing. These scaffolds were then tested for chemical, morphological, and mechanical properties, as well as ion release analysis. Unmodified CPC …

Design And Development Of Biomimetic Hydrogel Interfaces For Enhanced Bioelectrical Signal Acquisition, Daniela Nikoloska

UNLV Theses, Dissertations, Professional Papers, and Capstones

Every second, human skin processes over one million sensory signals while maintaining properties such as electrical conductivity, mechanical adaptability, and regenerative capability that surpass all synthetic materials. Contemporary bioelectronic devices prove inadequate when contacting skin surfaces due to poor adhesion and electrical contact issues that prevent effective sensing. Despite advancements in wearable and bioelectronic technologies, current devices face major drawbacks when interfacing with human skin, particularly in maintaining firm adhesion, conformability, and low-noise electrical signal acquisition.

This research focuses on the development of a biomimetic hydrogel-based interface for bioelectronic sensing. Specifically, a hybrid hydrogel system composed of polydopamine (PDA)- doped …

Recreating Fiber Recruitment With Fiber Recruitment Using Additive Manufacturing, Natalia D. Mciver

Biomedical Engineering ETDs

Injured ligaments are often repaired with tendon grafts which may over or under constrain the joint; there is a need for an artificial graft option with the mechanical properties of a native ligament. Crimped fibers within ligaments allow for recruitment which means the viscoelastic properties of stress relaxation and creep are not inversely related. A feasibility study using ACLs and large-scale crimp models to study viscoelasticity, led to an in-depth analysis of the scapholunate interosseous ligament. Using the Modified Kelvin spring-dashpot model, for describing viscoelasticity with a variable stiffness property (time dependent fiber recruitment), we defined the relationship between creep …

Reproducibility In Modeling Of Knee Joint Mechanics, Maryam Nazem

Electronic Theses and Dissertations

Computational modeling of knee joint biomechanics can provide valuable insights into joint function, injury mechanisms, and patient outcomes, and can support surgical planning and informed clinical decision-making. However, achieving consistent and repeatable results, or reproducibility, is a significant challenge that affects the credibility of these models. This thesis addresses reproducibility through two studies related to the KneeHub Project, which is a multi-institutional collaboration designed to investigate reproducibility in finite-element modeling of the knee.

The first study involved model benchmarking, where predicted results of the calibrated models were compared with the experimental data to evaluate model reproducibility. While all models replicated …

Characterization Of The Fatigue Threshold Behavior Of Uhmwpe, Bethany B. Smith, Anurag Roy, Robert O. Ritchie, Lisa A. Pruitt

Faculty Journal Articles

Ultra-high-molecular-weight-polyethylene (UHMWPE) has been the material of choice for bearings in total joint replacements (TJRs) for decades as a result of its excellent wear resistance, chemical inertness, energetic toughness, low friction, and biocompatibility. Utilization of this polymer in orthopedic devices requires oxidation, wear, and fatigue resistance. Balancing these important properties by tailoring processing techniques and modulating microstructural features has been an ongoing endeavor in the field. Research into the clinical applications of UHMWPE has primarily focused on the challenges of wear and oxidation while studies into the realm of fatigue have been more limited. Literature gaps exist in fully understanding …

Optimizing Hip And Knee Assistance For Walking And Sit-To-Stand Transitions: An Intrinsic Muscle Mechanics Based Predictive Approach, Neethan Ratnakumar

Dissertations

As the global population ages, the demand for wearable assistive technologies continues to rise, driven by their potential to enhance mobility and independence in older adults. Effectively designed controllers for lower-limb exoskeletons to assist sit-to-stand (STS) and walking are crucial for delivering efficient, safe, and comfortable assistance during daily activities. Traditionally, controller optimization involves biomechanical modeling and user-specific customization. Musculoskeletal simulations play a central role in this process by providing insights into human-exoskeleton interaction dynamics, thereby informing and refining control strategies.

This work presents a simulation-driven approach for developing exoskeleton controllers for walking and STS using two distinct methods: optimal …

Influence Of Obesity On Knee Joint Mechanics: A Subject-Specific Musculoskeletal Modeling Approach, Ryan C. Knowles

Electronic Theses and Dissertations

Obesity has been consistently linked to knee osteoarthritis (KOA), a debilitating joint disease. While prior work has shown that obese individuals often walk with altered biomechanics compared to normal-weight (NW) individuals, which may accelerate KOA progression, less is known about how these mechanics affect load distribution between the medial and lateral tibiofemoral (TF) compartments, particularly during higher-demand activities. This study developed subject-specific musculoskeletal models of five obese and five NW individuals, incorporating CT-based bone measurements and individualized joint contact points. Simulations were driven by six degree-of-freedom (6DOF) kinematics obtained from high-speed stereo radiography (HSSR) to predict TF loading and associated …

Functional Biopolymers Applied To Sustainable Technologies In The Environment And Healthcare, Fengjie He

UNLV Theses, Dissertations, Professional Papers, and Capstones

Biodegradable polymeric materials (biopolymers) are naturally derived materials known for their excellent biocompatibility, biodegradability, sustainability, and versatile chemical functionality. They have attracted increasing attention in various applications as alternative to synthetic materials ranging from food packaging to tissue engineering. Meanwhile, with intrinsic advantages, biopolymers have also emerged as promising materials in addressing contemporary challenges in both biomedical and environmental fields. Motivated by the significant potential of biopolymers and the growing need for sustainable materials, my research focuses on the design and engineering of biodegradable polymers with novel modification methods and application directions. In this work, two representative biopolymers are selected: …

Joint Kinematics And Kinetics During Vertical Jump Landings With Progressively Increasing External Loads, Darcie L. Yount

Dissertations

This study examined sagittal and frontal plane kinematics and kinetics during countermovement jump (CMJ) landings performed with either a traditional barbell (BB) or a hexagonal bar (HEX) across increasing submaximal loads in recreationally active males. Generally, hip and knee flexion angles and joint mean angular velocities decreased as loads increased. Hip extension and knee flexion moments increased as load increased up to 20 kg, at which point these values decreased. Performing the CMJ with the HEX exhibited increased frontal plane stability compared with the BB group. Additionally, the BB group exhibited stiffer landing strategies, with decreased sagittal plane joint angles …

The Development And Application Of A Method To Simulate Commotio Cordis Inducing Impacts For The Evaluation Of Football Chest Protective Equipment, Bianca J. Henline

All Theses

As one of the most widely played and watched contact sports in the United States, football presents a significant risk of blunt chest trauma. Thus, effective chest protection is essential to prevent rare but fatal injuries like commotio cordis. Despite this, current test methods for certifying chest protective equipment fail to account for injury metrics relevant to commotio cordis events. Recent literature identifies rib deformation and viscous criterion as critical predictors of commotio cordis, yet these metrics are not adequately addressed in the existing testing standard. Furthermore, this standard exclusively assesses chest gear specific to baseball and lacrosse through projectile …

Experimental Evaluation And Comparison Of Football-Related Head Impacts Among Ovine, Human, And Hybrid Iii Headforms, Madysn D. Cardinal

All Dissertations

Concussions and traumatic brain injury (TBI) remains a significant public health concern, especially in American football, where repeated head impacts pose long-term risks to athlete health. While current helmet testing standards rely heavily on the Hybrid III surrogate headform to evaluate protective performance, these surrogate models lack anatomical accuracy and exclude the presence of a brain component, limiting their ability to capture the true mechanics of concussion. To address this limitation, this research developed and validated a novel inverted impact testing method that allows the impact testing of a Hybrid III headform and a cadaveric specimen. Additionally, this fixture preserves …

Towards Improving Computational Modeling Of The Lumbar Spine - Impact Of Material Properties And Laminotomy On Spinal Biomechanics, Isaac K. Kumi

Mechanical & Aerospace Engineering Theses & Dissertations

Spinal ligaments play a crucial role in maintaining the mechanical stability of the lumbar spine. These dense, collagenous tissues not only resist excessive motion but also distribute loads between spinal components to protect neural structures. Traditionally, the mechanical response of ligaments has been modeled using linear elastic assumptions, which treat the tissue as having a constant stiffness regardless of loading history. While this simplifies analysis, it fails to capture the time-dependent behaviors, such as creep, stress relaxation, and hysteresis, that are characteristic of biological tissues.

Viscoelastic modeling may provide a more physiologically accurate representation by incorporating both elastic and viscous …

Inter-Cellular Forces Modulate Cell-Ecm Traction Forces, Zaria Booth

Mechanical & Aerospace Engineering Theses & Dissertations

Epithelial cells are among the most abundant cell types in the human body, making up sheets of epithelial tissues that cover the linings of organs and body cavities. Cellular adhesion and force transmission across epithelial tissues are crucial in maintaining tissue integrity and ensuring proper tissue regeneration. Defects in cellular force transmission have been found in various diseases, including cancer. Force transmission at cell-cell and cell-ECM junctions drive cell survival and development. It has been previously shown that changes in cell-ECM traction directly modulates forces at cell-cell contacts. In this study, we aim to determine the effects of perturbations in …

Van Accessibility, Ann Larson, Camelia Anne Noureddine, Stephanie Rose Ruzicka, Kayla Joanne Gowey

Mechanical Engineering

The SLO Achievement House provides resources and activities for their clients, including daily trips to different parts of the community, to keep their clients connected to society. These trips require the clients, many of whom struggle with general mobility and strength, to step up to the high entrance of a van or company car. This daily activity poses a challenge both physically and emotionally for the clients. The current solution utilizes commercially available step stools, which lack handrails, overall stability, and adequate step depth. The Achievement House needs a stool or ramp tailored to their client’s needs and their specific …

7lr-C Upper Limb Dancing Prosthetic, Victor Ochoa, Zoe Kelemen, Ged Mulingtapang, Marley Paltiel

Mechanical Engineering

Ella Wallis, a student at Cal Poly and performer in the Cal Poly Drag Club with a trans humeral upper limb difference, wants a prosthetic device that allows for a large range of motion and high degree of articulation to help them better dance in the style of voguing, allowing them to express themselves further while performing. The prosthetic arm is body-driven and relies on momentum to reposition. It attaches to the user through a harness, which is clipped to a socket with elastic straps to not impede the shoulder’s range of motion. The design contains urethane resin, aluminum, stainless …

One-Handed Wheelchair, Brian Azevedo, Cade Veljovich, Carlos Perez, Jakob Zuckermandel, Alexander Harper

Mechanical Engineering

A person who uses a wheelchair for mobility needs a way to operate it with only one hand. This may be necessary if they lack functionality in one hand or prefer to use only one hand while operating the wheelchair. Even for users with two available hands, it is difficult to operate As of now, such wheelchairs are not widely available or easily accessible, yet these devices are crucial for improving the quality of life and mobility of many people. The goal of this project is to design a more viable and ergonomic solution for people who operate a wheelchair …

Gamified Gait Rehabilitation Via Real-Time Biofeedback And Adaptive Hip-Exoskeleton Control, Mariya Huzaifa Tohfafarosh

Theses

Gait impairments arise from systemic diseases, age-related degeneration, musculoskeletal dysfunctions, or neurological conditions. While traditional rehabilitation can be effective, they often face challenges such as high costs, inaccessibility, and low patient engagement. To address these challenges, my work introduces a virtual reality-based rehabilitation (VRBR) system, integrating real-time motion and electromyographic (EMG) muscle activation feedback with a gamified virtual environment for enhanced adaptability and engagement. The system includes a custom-designed hip-exoskeleton that provides adaptive spring-like assistance or resistance, supporting both mobility-impaired users and strength training. Assistance levels can be tuned to match the user's progress. Additionally, a custom pressure insole was …

Preliminary Study: Minimizing The Gap Between Pre-And Post-Spaceflight, Caleb E. Scheideger, Louis A. Diberardino

Aurora

Long-duration space missions pose significant challenges to astronaut health, primarily due to the detrimental effects of microgravity on musculoskeletal and cardiovascular systems. This research proposal aims to address the critical gap between pre- and post-spaceflight physiological conditions, focusing on the marked decline in muscle mass, bone density, and cardiovascular function. Existing countermeasures, such as resistive exercise, are insufficient to prevent muscle atrophy and bone demineralization, highlighting the need for novel solutions. Neuromuscular Electrical Stimulation (NMES) emerges as a promising intervention, capable of eliciting muscle contractions to maintain function and mitigate atrophy. By integrating NMES into existing exercise regimens, we hypothesize …

Deciphering And Translating Bioinspired Structures For Engineering Materials Design Via Computational Modeling And Machine Learning, Zhangke Yang

All Dissertations

Nature has evolved extraordinary structural materials—such as nacre, bone, and the mantis shrimp’s dactyl club—that achieve remarkable combinations of strength, toughness, and impact resistance. These properties arise from sophisticated synergies between structure and composition. Inspired by these biological systems, this dissertation presents a comprehensive investigation into bioinspired materials, uncovering fundamental mechanisms and providing guidance on designing materials with superior mechanical properties.

This dissertation begins by examining the "brick-and-mortar" structure of nacre, which informs the design of layered polymer-graphene nanocomposite films. Using coarse-grained molecular dynamics simulations, I elucidate mechanisms of dynamic wave propagation and energy dissipation in these systems, providing critical …

Manipulating Martensitic Transformation And Residual Stress Development In Stress Superposed Incremental Forming Of Ss304, Elizabeth M. Mamros, Fabian Maaß, Thomas Gnaupel-Herold, A. Erman Tekkaya, Brad L. Kinsey, Jinjin Ha

Faculty Journal Articles

Stress superposition is one of the strategies used in metal deformation processes to increase the material formability, decrease the required forming forces, and create highly customized components. To investigate the effects of tensile and compressive stresses superposed to the single point incremental forming (SPIF) process, experiments and numerical simulations were conducted for a stainless steel 304 (SS304) truncated square pyramid geometry. Tensile stresses were superposed in-plane on the specimen blank by a custom hydraulic frame, and compressive stresses were incorporated via a polyurethane die. Identified parameters for a martensitic transformation kinetics model for SS304 were used in a two-step finite …

Cruising On The Beach (Cob), Juan Diego Molina Ii, Ashley Kianna Burga

Biomedical Engineering

This report details the design and development process of Cruising on the Beach (COB), a modular motorized wheelchair intended to improve beach accessibility for high school students with mobility impairments. The project aimed to create an affordable, portable, and sand-capable device using balloon wheels, an adjustable control panel, and a customizable base. Extensive background research, market analysis, design modeling, and test plans were completed. However, final fabrication was not achieved due to financial constraints and limited access to industrial machining tools needed for custom metal components. Despite these setbacks, the project delivered a robust conceptual design and a fully …

Design And Optimization Of Lattice-Integrated Plif Cages Using Additive Manufacturing And Finite Element Modeling, Olivia Draughn

Honors Theses

The customization, characterization, and development of biomedical implants through additive manufacturing (AM) and finite element methods (FEM) becomes imperative to the success of surgical operations and long-term patient satisfaction. To combat stiffness mismatches and prevent stress shielding between implant and bone tissue, lattice structures can be implemented within bone implant design to reduce the effective Young’s modulus (EYM) of the implant and to promote osteointegration within bone tissue. Lattice structures are highly customizable, three dimensionally repeated patterned unit cells that can be manipulated to mimic the porous nature of bone tissues to increase implant-bone interface longevity. The study presents the …

Automated Plant Morphological Assessment And Microbial Community Monitoring In Simulated Lunar Regolith, Collin R. Topolski

Doctoral Dissertations and Master's Theses

Upcoming lunar bases will need to leverage in-situ resources to ensure long-term sustainability and reduce mission costs. One key challenge is food production, which could be addressed by growing crops in lunar regolith-based substrates. However, lunar regolith lacks essential nutrients, requiring organic amendments to support continuous plant cultivation. This study examined the impact of manure-amended lunar regolith simulant on Mizuna mustard growth while assessing microbial community diversity and functionality. To support this effort, a custom software pipeline utilizing an open-source library, PlantCV, was developed to automatically track plant leaf area and height via image analysis. Results indicated that amended rhizosphere …

Determinants Of Knee Motion In Health, Disease, And Repair, Sean Edward Higinbotham

Electronic Theses and Dissertations

The human knee joint is a complex and intricate structure, enabling a wide range of motions and facilitating various dynamic activities throughout a person's lifetime. The combination of the knee's complexity and its role as a primary load-bearing joint has made it susceptible to regular wear and tear, leading to pain and the development of Osteoarthritis (OA), to which, the only treatment currently is total knee arthroplasty (TKA). Despite TKA being a mature procedure, 20% of patients receiving a TKA are dissatisfied with their “new” knee. To reduce that 20% dissatisfaction and improve surgical outcomes, orthopedic companies are developing advanced …

Advancing Tka Biomechanics: From Joint Simulator To Boundary Condition Development, Yashar Ali Behnam

Electronic Theses and Dissertations

This dissertation addresses four specific aims that collectively attempted to advance the experimental and computational analysis of total knee arthroplasty (TKA) components. The first study focused on the development of a novel whole knee joint simulator capable of simultaneous tibiofemoral and patellofemoral knee loading. This simulator employs custom fixturing to facilitate dynamic, unconstrained, muscle-driven PF articulation alongside controlled TF contact mechanics. Validation against experimental measurements showed strong agreement, demonstrating the simulator's potential as a valuable tool for future TKA design and surgical technique investigations.

The second study verified implant-specific physiological boundary conditions which accurately simulate activities of daily living using …

Emg-Based Intraoperative Neuromonitoring Using Advanced Machine Learning Approaches, Abdalla Nabil Elsharkawy, Nourhan Zayed

Mechanical Engineering

Intraoperative neuromonitoring (IONM) plays a critical role in minimizing nerve damage during surgeries by providing real-time feedback on neural integrity. This study evaluated models associated with deep learning and machine learning models for electromyography classification of signal during intraoperative neuromonitoring (IONM). The CNNLSTM model achieved the highest accuracy (85.2%), outperforming traditional models like KNN (53%), RF (62%), and CNN (76%). This demonstrates the degree to which the CNN-LSTM model can gain insight into temporal and spatial dependencies throughout the EMG signals, which makes it optimal for real-time classification in IONM applications. This implies that deep learning techniques can improve surgical …

Advancing Prosthetic Technology: 3d-Printed Robotic Arm With Micro Linear Actuators, Vu Tran, Nathan Reed, Mahdi Yazdanpour

Posters-at-the-Capitol

The increasing demand for affordable and accessible prosthetic solutions has driven innovation in the field of robotics. In this project, we present the design and development of a 3D-printed robotic prosthetic arm aimed at addressing the challenges faced by individuals with upper limb amputations. Our prosthetic arm utilizes five micro linear actuators to achieve precise and naturalistic movement. The design of the prosthetic arm prioritizes affordability and accessibility, with a focus on leveraging 3D printing technology to reduce manufacturing costs and enable customization. The use of micro linear actuators offers advantages in terms of compactness, lightweight construction, and efficient power …

Feasibility Study Of A Smart Insole With Triboelectric Energy Harvesters For Early Flatfoot Detection, Mohammad Alghamaz

Mechanical Engineering Theses

This study introduces a self-powered smart insole system designed for real-time monitoring of foot health, with a specific focus on detecting flatfoot conditions. The insole integrates multiple triboelectric energy harvesters strategically positioned to capture electrical signals generated from ground reaction forces during daily activities such as walking, jogging, and running. Proof-of-concept testing was conducted on a single participant under two conditions: a healthy foot and a simulated flatfoot created by reducing the medial arch height by approximately 70\. In the healthy foot trials, the system demonstrated consistent and reliable performance, with negligible electrical output from the medial arch sensor, as …