Katie Otim PhD Candidate B.S. MSE with French minor, Stanford University 2003 Cook 2017, 1-7706 k-otim at northwestern dot edu

Adhesive and Mechanical Properties of Vocal Fold Tissue

The vocal folds play a vital role in communication, vibrating to produce sound as air flows through the glottis. The folds have a limited range of vibrations and adhesive levels within which they can operate properly; anything outside of this range has direct, negative consequences on a person’s ability to communicate and breathe properly. It is well known that vocal fold disorders are triggered by a wide variety of factors, from infection to environmental irritants to cancer[1], but relatively little is understood about the underlying causes and treatments of these disorders. An improved understanding of the mechanical and adhesive properties of these tissues will provide greater insight into potential therapeutic treatments for speech disorders.

My project will explore the mechanical and adhesive properties of the vocal folds through the use of a membrane expansion chamber. The image below depicts a schematic of the system developed by our research group [2]. In this system, a piece of tissue or other soft material is positioned in the holder. After submersion in liquid, the sample is inflated into contact with a substrate surface through the application of pressure on the backside of the sample. Upon contact the system comes to equilibrium as the tissue interacts with the surface. The pressure is then released, causing the sample to detach from the substrate and return to its original position. The elastic modulus is determined from differences between applied pressure and tissue displacement. This membrane expansion technique will be used in conjunction with a variety of substrates, including a quartz crystal resonator, a glass prism, and a second piece of tissue. Images of the contact area during the inflation experiments will provide direct visualization of the tissue's adhesiveness in response to varying surface types and hydration levels. Optical imaging of surface contact is essential to understanding the adhesive process, since the vocal fold tissue is an active material that transports ions and other molecular species from one side of the tissue to the other. Changes in the transport process could affect adhesion. Any variations in the tissue’s response can be used to better understand how the vocal fold tissue acts in its native environment.

This is a joint project with Dr. Kim Fisher in the Department of Communication Sciences and Disorders at Northwestern. This work is supported by the NIH.

[1] Titze, Ingo R. Principles of Voice Production. Iowa: National Center for Voice and Speech, 2000. [2] Brass, D. and Shull, K. Langmuir 2006, 22 (22), 9225-9233.