Mechanical & Materials Engineering, Department of


Date of this Version

Spring 4-21-2016


Welch, C.R. Design of Medical Devices for Diagnostics in the Gastrointestinal System (2016).


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering and Applied Mechanics, Under the Supervision of Professor Carl A. Nelson. Lincoln, Nebraska: May, 2016

Copyright © 2016 Charles Ross Welch


This thesis presents the design, controls, and testing of two systems: a novel colonoscope locomotion design for diagnostics, and a biosensor capsule that implants a sensor in the small intestine. Each system requires special design considerations for use in the gastrointestinal system.

Colonoscopy procedures are recommended as a screening for colon cancer and related conditions after the age of 50. The need for an improved colonoscope that reduces the colonoscopy time and patient discomfort is apparent. The semi-autonomous device presented here could likely reduce the colonoscopy procedure time by allowing the physician to focus more on the diagnosis and less on the procedure itself. It greatly reduces shear forces experienced on the colon wall, reducing pain and discomfort experienced by the patient.

The biosensor capsule presented in this thesis is also used for diagnostics. The device implants a sensor into the intestine wall, a sensor that could be used to track pH levels, temperature, or possibly even caloric intake. This thesis explores the transport capsule design and some of the electrical hardware used.

The thesis is divided into two parts, exploring both devices. Part one focuses on the design and testing of the colonoscope device, while part two focuses on the biosensor capsule device. In each part, the motivation behind each of the devices and the related works being accomplished at other research institutions are described. Each part then explores the design of the respective device and the reasons behind some of the design choices presented. For both projects, a significant amount of bench-top testing was performed; an in-depth look at the test methods and setup used, followed by the results of each is given. Results for the colonoscopy robot show full capability of traversing a 5-foot porcine colon with four 90-degree turns and potential for full automation. Results for the biosensor capsule device demonstrate the capability of sensor plate implantation and attachment lasting more than 40 hours. Finally, the conclusion section describes the future work associated with the device as well as the possibilities and accomplishments achieved through the design of each device, respectively.

Advisor: Carl A. Nelson