Mechanical Engineering Commons^™

Lamina Cribrosa Insertions Into The Sclera Are Sparser, Narrower, And More Slanted In The Anterior Lamina, Fengting Ji, Mohammad R. Islam, Bingrui Wang, Yi Hua, Ian A. Sigal

Mechanical Engineering Faculty Publications and Presentations

Purpose: The lamina cribrosa (LC) depends on the sclera for support. The support must be provided through the LC insertions. Although a continuous insertion over the whole LC periphery is often assumed, LC insertions are actually discrete locations where LC collagenous beams meet the sclera. We hypothesized that LC insertions vary in number, size, and shape by quadrant and depth.

Methods: Coronal cryosections through the full LCs from six healthy monkey eyes were imaged using instant polarized light microscopy. The images were registered into a stack, on which we manually marked LC insertion outlines, nothing their position in-depth and quadrant …

Sharprazor: Automatic Removal Of Hair And Ruler Marks From Dermoscopy Images, Reda Kasmi, Jason Hagerty, Reagan Harris Young, Norsang Lama, Januka Nepal, Jessica Miinch, William V. Stoecker, R. Joe Stanley

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Background: The removal of hair and ruler marks is critical in handcrafted image analysis of dermoscopic skin lesions. No other dermoscopic artifacts cause more problems in segmentation and structure detection. Purpose: The aim of the work is to detect both white and black hair, artifacts and finally inpaint correctly the image. Method: We introduce a new algorithm: SharpRazor, to detect hair and ruler marks and remove them from the image. Our multiple-filter approach detects hairs of varying widths within varying backgrounds, while avoiding detection of vessels and bubbles. The proposed algorithm utilizes grayscale plane modification, hair enhancement, segmentation using tri-directional …

Dynamic Body-Weight Support To Boost Rehabilitation Outcomes In Patients With Non-Traumatic Spinal Cord Injury: An Observational Study, Justin P. Huber, Lumy Sawaki

Neurology Faculty Publications

BACKGROUND: Dynamic body-weight support (DBWS) may play an important role in rehabilitation outcomes, but the potential benefit among disease-specific populations is unclear. In this study, we hypothesize that overground therapy with DBWS during inpatient rehabilitation yields greater functional improvement than standard-of-care in adults with non-traumatic spinal cord injury (NT-SCI).

METHODS: This retrospective cohort study included individuals diagnosed with NT-SCI and undergoing inpatient rehabilitation. All participants were recruited at a freestanding inpatient rehabilitation hospital. Individuals who trained with DBWS for at least three sessions were allocated to the experimental group. Participants in the historical control group received standard-of-care (i.e., no DBWS). …

Computational Approach To Correcting Joint Instability In Patients With Recurrent Patellar Dislocation, Oliver Alvarez, Robert N. Steensen, Paul J. Rullkoetter, Clare K. Fitzpatrick

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Patellar dislocation is a debilitating injury common in active adolescents and young adults. Conservative treatment after initial dislocation is often recommended, but almost half of these patients continue to suffer from recurrent dislocation. The objective of this study was to compare preoperative patellofemoral joint stability with stability after a series of simulated procedures, including restorative surgery to correct to pre-injury state, generic tibial tubercle osteotomy, patient-specific reconstructive surgery to correct anatomic abnormality, less invasive patient-specific surgery, and equivalent healthy controls. Three-dimensional, subject-specific finite element models of the patellofemoral joint were developed for 28 patients with recurrent patellar dislocation. A …

Development Of A Sonically Powered Biodegradable Nanogenerator For Bone Regeneration, Avi Patel

Honors Scholar Theses

Background: Reconstruction of bone fractures and defects remains a big challenge in orthopedic surgery. While regenerative engineering has advanced the field greatly using a combination of biomaterial scaffolds and stem cells, one matter of difficulty is inducing osteogenesis in these cells. Recent works have shown electricity’s ability to promote osteogenesis in stem cell lines when seeded in bone scaffolds; however, typical electrical stimulators are either (a) externally housed and require overcomplex percutaneous wires be connected to the implanted scaffold or (b) implanted non-degradable devices which contain toxic batteries and require invasive removal surgeries.

Objective: Here, we establish a biodegradable, piezoelectric …

Ring And Peg Simulation For Minimally Invasive Surgical Robot, Evan Brown

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Surgical procedures utilizing minimally invasive laparoscopic techniques have shown less complications, better cosmetic results, and less time in the hospital than conventional surgery. These advantages are partially offset by inherent difficulties of the procedures which include an inverted control scheme, instrument clashing, and loss of triangulation. Surgical robots have been designed to overcome the limitations, the Da Vinci being the most widely used. A dexterous in vivo, two-armed robot, designed to enter an insufflated abdomen with a limited insertion profile and expand to perform a variety of operations, has been created as a less expensive, versatile alternative to the Da …

Ureteral Tunnel Length Versus Ureteral Orifice Configuration In The Determination Of Ureterovesical Junction Competence: A Computer Simulation Model, Carlos A. Villanueva, J. Tong, Carl A. Nelson, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Introduction The long-held belief that a ureteral re-implant tunnel should be five times the diameter of the ureter, as proposed by Paquin in 1959, ignores the effect of the orifice on the occurrence of reflux. In 1969, Lyon proposed that the shape of the ureteral orifice (UO) is more important than the intravesical tunnel. However, both theories missed quantitative evidence from principles of physics. The goal of the current study was to test Lyon’s theory through numerical models (i.e. to quantify the sensitivity of ureterovesical junction (UVJ) competence to intravesical tunnel length and to the UO).

Materials and methods The …

Analytical Cpg Model Driven By Limb Velocity Input Generates Accurate Temporal Locomotor Dynamics, Sergiy Yakovenko, Anton Sobinov, Valeriya Gritsenko

Faculty & Staff Scholarship

The ability of vertebrates to generate rhythm within their spinal neural networks is essential for walking, running, and other rhythmic behaviors. The central pattern generator (CPG) network responsible for these behaviors is well-characterized with experimental and theoretical studies, and it can be formulated as a nonlinear dynam- ical system. The underlying mechanism responsible for locomotor behavior can be expressed as the process of leaky integration with resetting states generating appropriate phases for changing body velocity. The low-dimensional input to the CPG model generates the bilateral pattern of swing and stance modulation for each limb and is consistent with the desired …

Tissue Stresses In Stented Coronary Arteries With Different Geometries: Effect Of The Relation Between Stent Length And Lesion Length, Xiang Shen, Song Ji, Yong-Quan Deng, Hong-Fei Zhu, Jia-Bao Jiang, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

In-stent restenosis after stent deployment remains an obstruction in the long-term benefits of stenting. This study sought to investigate the influence of the relation between stent length and lesion length on the mechanics of the arterial wall with different geometries, including straight and tapered vessels. Results showed that when the length of the stent was longer than the lesion length, the maximum stress in plaque and vessel increased as the length of stent increased. When the length of the stent was shorter than the lesion length, the vessel stress induced by stent inflation was lower; both ends of the stenosis …

Computational Sensitivity Investigation Of Hydrogel Injection Characteristics For Myocardial Support, Hua Wang, Christopher B. Rodell, Madonna E. Lee, Neville N. Dusaj, Joseph H. Gorman Iii, Jason A. Burdick, Robert C. Gorman, Jonathan F. Wenk

Mechanical Engineering Faculty Publications

Biomaterial injection is a potential new therapy for augmenting ventricular mechanics after myocardial infarction (MI). Recent in vivo studies have demonstrated that hydrogel injections can mitigate the adverse remodeling due to MI. More importantly, the material properties of these injections influence the efficacy of the therapy. The goal of the current study is to explore the interrelated effects of injection stiffness and injection volume on diastolic ventricular wall stress and thickness. To achieve this, finite element models were constructed with different hydrogel injection volumes (150 µL and 300 µL), where the modulus was assessed over a range of 0.1 kPa …

Finite Element Simulation And Additive Manufacturing Of Stiffness-Matched Niti Fixation Hardware For Mandibular Reconstruction Surgery, Ahmadreza Jahadakbar, Narges Shayesteh Moghaddam, Amirhesam Amerinatanzi, David Dean, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Process parameters and post-processing heat treatment techniques have been developed to produce both shape memory and superelastic NiTi using Additive Manufacturing. By introducing engineered porosity, the stiffness of NiTi can be tuned to the level closely matching cortical bone. Using additively manufactured porous superelastic NiTi, we have proposed the use of patient-specific, stiffness-matched fixation hardware, for mandible skeletal reconstructive surgery. Currently, Ti-6Al-4V is the most commonly used material for skeletal fixation devices. Although this material offers more than sufficient strength for immobilization during the bone healing process, the high stiffness of Ti-6Al-4V implants can cause stress shielding. In this paper, …

The Search For High-Impact Diagnostic And Management Tools For Low-And Middle-Income Countries: A Self-Powered Low-Cost Blood Pressure Measurement Device Powered By A Solid-State Vibration Energy Harvester, Onur Bilgen, John G. Kenerson, Muge Akpinar-Elci, Rebecca Hattery, Lisbet M. Hanson

Mechanical & Aerospace Engineering Faculty Publications

The World Health Organization has established recommendations for blood pressure measurement devices for use in low-resource venues, setting the triple A expectations of Accuracy, Affordability, and Availability. Because of issues related to training and assessment of proficiency, the pendulum has swung away from manual blood pressure devices and auscultatory techniques towards automatic oscillometric devices. As a result of power challenges in the developing world, there has also been a push towards semiautomatic devices that are not dependent on external power sources or batteries. Beyond solar solutions, disruptive technology related to solid-state vibrational energy harvesting may be the next iterative solution …

A Sensorless Haptic Interface For Robotic Minimally Invasive Surgery, Baoliang Zhao

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Robotic minimally invasive surgery (R-MIS) has gained in popularity due to its advantages of improving the accuracy and dexterity of surgical interventions while minimizing trauma to the patient. However, because of the loss of direct contact with the surgical site, the surgeon cannot perceive tactile information, which may adversely affect surgical efficiency and/or efficacy. The lack of haptic feedback is regarded as a limiting factor in existing R-MIS technology.

To solve this problem, researchers have incorporated force sensors on the surgical tools to measure the tool-tissue interaction forces, and reproduce these forces at the surgeon console. However, the employment of …

The Microstructure And The Electrochemical Behavior Of Cobalt Chromium Molybdenum Alloys From Retrieved Hip Implants, Christopher P. Emerson

FIU Electronic Theses and Dissertations

Because of their excellent mechanical, tribological, and electrochemical properties, Cobalt Chromium Molybdenum alloys have been used as the material for both the stem and head of modular hip implants. Corrosion is one mechanism by which metal debris, from these implants, is generated, which can lead to adverse events that requires revision surgery. Manufacturing process such as wrought, as-cast, and powder metallurgy influences the microstructure, material properties, and performance of these implants

The current research focuses on analyzing the microstructure of CoCrMo alloys from retrieved hip implants with optical and scanning electron microscopy. Additionally, energy disperse spectroscopy was utilized to determine …

A Collagen‐Glycosaminoglycan‐Fibrin Scaffold For Heart Valve Tissue Engineering Applications, Claire Brougham, Stefan Jockenhoevel, Thomas Flanagan, Fergal O'Brien

Conference Papers

The field of heart valve biology and tissue engineering a heart valve continue to expand. The presentatio ns at this meeting reflect the advances made in both areas due to the multi-disciplinary approach taken by many laboratories.

Implementation And Validation Of Aortic Remodeling In Hypertensive Rats, Shijia Zhao, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

A computational framework was implemented and validated to better understand the hypertensive artery remodeling in both geometric dimensions and material properties. Integrating the stress-modulated remodeling equations into commercial finite element codes allows a better control and visualization of local mechanical parameters. Both arterial thickening and stiffening effects were captured and visualized. An adaptive material remodeling strategy combined with the element birth and death techniques for the geometrical growth were implemented. The numerically predicted remodeling results in terms of the wall thickness, inner diameter, and the ratio of elastin to collagen content of the artery were compared with and fine-tuned by …

Stress And Strain Adaptation In Load-Dependent Remodeling Of The Embryonic Left Ventricle, Christine Buffinton

Faculty Journal Articles

Altered pressure in the developing left ventricle (LV) results in altered morphology and tissue material properties. Mechanical stress and strain may play a role in the regulating process. This study showed that confocal microscopy, three-dimensional reconstruction, and finite element analysis can provide a detailed model of stress and strain in the trabeculated embryonic heart. The method was used to test the hypothesis that end-diastolic strains are normalized after altered loading of the LV during the stages of trabecular compaction and chamber formation. Stage-29 chick LVs subjected to pressure overload and underload at stage 21 were reconstructed with full trabecular morphology …

Improving Health Care Quality And Safety: The Development And Assessment Of Laparoscopic Surgery Instrumentation, Practices And Procedures, Bernadette Mccrory

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Adverse events due to medical errors are a leading cause of death in the United States exceeding the mortality rates of motor vehicle accidents, breast cancer and AIDS. Improvements can and should be made to reduce the rates of preventable surgical errors since they account for nearly half of all adverse events within hospitals. Although minimally invasive surgery has proven patient benefits such as reduced postoperative pain and hospital stay, its operative environment imposes substantial physical and cognitive strain on the surgeon increasing the risk of error. In order to mitigate errors and protect patients, a multidisciplinary approach was taken …

A Comparison Of Two Headless Compression Screws For Operative Treatment Of Scaphoid Fractures, Ruby Grewal, Joseph Assini, David Sauder, Louis Ferreira, Jim Johnson, Kenneth Faber

Surgery Publications

PURPOSE: The purpose of this study was to compare the interfragmentary compression force across a simulated scaphoid fracture by two commonly used compression screw systems; the Acutrak 2 Standard and the 3.0 mm Synthes headless compression screw.

METHODS: Sixteen (8 pairs; 6 female, 2 male) cadaver scaphoids were randomly assigned to receive either the Acutrak 2 or Synthes screw with the contralateral scaphoid designated to receive the opposite. Guide wires were inserted under fluoroscopic control. Following transverse osteotomy, the distal and proximal fragments were placed on either side of a custom load cell, to measure interfragmentary compression. Screws were placed …

Intelligibility Of Electrolarynx Speech Using A Novel Hands-Free Actuator, Brian Madden, Mark Nolan, Ted Burke, James Condron, Eugene Coyle

Conference Papers

During voiced speech, the larynx provides quasi-periodic acoustic excitation of the vocal tract. In most electrolarynxes, mechanical vibrations are produced by a linear electromechanical actuator, the armature of which percusses against a metal or plastic plate at a frequency within the range of glottal excitation. In this paper, the intelligibility of speech produced using a novel hands-free actuator is compared to speech produced using a conventional electrolarynx. Two able-bodied speakers (one male, one female) performed a closed response test containing 28 monosyllabic words, once using a conventional electrolarynx and a second time using the novel design. The resulting audio recordings …

Intelligibility Of Electrolarynx Speech Using A Novel Actuator, Brian Madden, Mark Nolan, Ted Burke, James Condron, Eugene Coyle

Conference Papers

During voiced speech, the larynx provides quasi-periodic acoustic excitation of the vocal tract. Following a laryngectomy, some people speak using an electrolarynx which replaces the excitatory function of the absent larynx. Drawbacks of conventional electrolarynx designs include the buzzing monotonic sound emitted, the need for a free hand to operate the device, and difficulty experienced by many laryngectomees in adapting to its use. Despite these shortcomings, it remains the preferred method of speech rehabilitation for a substantial minority of laryngectomees. In most electrolarynxes, mechanical vibrations are produced by a linear electromechanical actuator, the armature of which percusses against a metal …

Indentation Fracture Of Bovine Cortical Bone: Acoustic Emission Technique, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

Indentation cutting may result in microcracking and main crack growth which was previously reported. In this study, we recorded the AE signals produced by cracking processes during cutting on cortical bone, measuring the cutting force and correlating between load-displacement curves and AE activities.

Analysis Of Indentation Loading Of Cortical Bone Using Acoustic Emission Techniques, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

In this study, we recorded the number of Acoustic emission (AE) hits and related AE energy during indentation fracture of cortical bone using a PAC PCI-2 card and pico sensor. A threshold value of 43dB was used to filter premature trigger due to background noise. Registered AE hits had more than one count (threshold crossing). Amplifier gain was set at 40dB with a (0.1-1) MHz band pass filter. 8mm cubes of cortical bones were indented in the longitudinal direction at constant crosshead speed of 1 mm min-1 using a large 2D, 50˚ wedge indenter. We hypothesised that signals occurring as …