Graduate Studies


First Advisor

Carl Nelson

Date of this Version



Tze Yeen, Y., 2019, “Design of a Portable Venomanometer System for Episcleral Venous Pressure Measurement,” M.S thesis, Department of Mechanical and Materials Engineering. University of Nebraska - Lincoln, Lincoln, NE.


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 & Applied Mechanics, Under the Supervision of Professor Carl Nelson. Lincoln, Nebraska: December, 2019

Copyright 2019 Tze Yeen Yap


Traumatic brain injury (TBI) has been considered a precarious public health problem, especially within the military population. Unlike some of the life-threatening TBI cases, relatively mild TBI often goes overlooked and undetected since most of the cases have no noticeable signs of trauma. When the injury is left untreated, service members are left exposed to neurocognitive injury. To be able to treat TBI early, early detection of TBI is crucial. Yet, the measuring apparatus of TBI are not accessible in the military triage where the injured person has to be sent to well-equipped hospitals. Therefore, there is a need for a TBI detection device that is portable and does not require a clinical setting or trained operators without compromising the measurement reliability.

Intracranial pressure (ICP) is an important marker of outcomes in traumatic brain injury (TBI). However, current techniques for ICP measurement are invasive, expensive, and require specialized surgical and procedural skills. Meanwhile, episcleral venous pressure (EVP) is a promising biomarker using a vein in the eye that could be done noninvasively using a venomanometer. Previous research shows that EVP is an excellent biomarker for acute changes in intracranial pressure. Despite having a non-invasive device, current technology for measuring EVP is not portable. A slit-lamp or operating microscope is needed along with a skilled operator during testing. Furthermore, the testing is subjective from operator to operator, which negatively affects the reliability of each reading.

In order to resolve the stated limitations, the main goal of this project is to design a portable venomanometer system for episcleral venous pressure measurement that is portable, rugged, and easy to use. Several iterations of the prototype were developed based on feedback obtained through animal testing. Rapid prototyping techniques such as 3D printing and laser cutting were implemented, and commercially available tools and devices were retrofitted to fabricate the prototype proposed in this thesis. Although the final design of the prototype is not perfect, it has proved to have great potential in reliably measuring EVP.

Advisor: Carl A. Nelson