Mechanical Engineering Commons^™

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 …

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 …

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 …

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 …

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 …