Mechanical & Materials Engineering, Department of


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A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Engineering (Biomedical Engineering), Under the Supervision of Professor Carl A. Nelson. Lincoln, Nebraska: August, 2014

Copyright (c) 2014 Abolfazl Pourghodrat


Minimizing the invasiveness of surgery is believed to improve patient outcomes. Bleeding, infection, and pain are major concerns in surgery afflicting patients for decades. Minimally invasive techniques have come into play to reduce these concerns and smooth the evolution of abdominal surgery to a scarless process where nearly all surgeries can be performed without a skin incision. Technology continually advances the frontier of development of novel surgical devices to implement less invasive surgical techniques.

Fusion of robotics and Minimally Invasive Surgery (MIS) has created new opportunities to develop diagnostic and therapeutic tools. Surgical robotics is advancing from externally actuated systems such as the da Vinci® Surgical System [Intuitive, 2013] to miniature in-vivo robotics where the entire robot is inserted into the patient’s body. However, with miniaturization of surgical robots there comes a trade-off between the size of the robot and its capability. Miniature electric motors have been mostly used in many in-vivo robots as the main means of actuation. Slow actuation, low load capacity, sterilization difficulty, leaking electricity and transferring produced heat to tissues, and high cost are the key limitations of use of electric motors in in-vivo applications.

The research described here presents an alternative actuation scheme to overcome these limitations by taking advantage of the inherent high power density of fluidic actuators to develop two different types of in-vivo robotic systems: a robot arm with a multifunctional manipulator for Natural Orifice Transluminal Endoscopic Surgery (NOTES), and a fluidic disposable self-propelling self-steering robot for colonoscopy.

To create a fully hydraulically-driven surgical robot, it was first necessary to build new fluidic actuators according to design requirements. Novel miniature linear and rotary actuators were designed and built. These actuators are seal-less, disposable, light, and inexpensive. Additionally, an electro-hydraulic tool-changing manipulator was built in response to the need for frequent tool exchange in NOTES.

Bench-top testing was performed for both robotic systems and the results are presented. Future work and conclusions are discussed.

Adviser: Carl A. Nelson