Estimation of the quasi-static Young’s modulus of the rat eardrum using a pressurization method
Date of Award
Master of Engineering Science
Electrical and Computer Engineering
Dr. Abbas Samani
Dr. Hanif Ladak
Accurate estimates of the quasi-static Young's modulus of the eardrum are important for finite-element (FE) modeling of clinical procedures such as tympanometry or myringotomy. Tympanometry is a medical examination used to test the middle ear condition by creating variations of air pressure in the ear canal. Myringotomy is a surgical procedure in which a tiny incision is created in the eardrum, so as to relieve pressure caused by the excessive buildup of fluid. Although a few authors have reported estimates of the quasi-static Young's modulus, simplifying assumptions in the analytical approaches may raise questions as to the accuracy of the various methodologies. The objective of this project is to develop a method for estimating the quasi-static Young's modulus of the rat eardrum from pressurized shape measurements made using Fourier transform profilometry and optimization of a FE model. First the technique was validated on a synthetic membrane with properties similar to the eardrum. As a synthetic
membrane we used five soft contact lenses. A pressurization system was used to apply quasi static pressures up to 4 kPa to each contact lens. The resting and deformed shapes of each lens were measured using a Fourier transform profilometer, a non-contacting optical device for shape measurements. A FE model was constructed for each contact lens from the resting shape data, and the Golden-Section optimization technique was used to automatically find the Young's modulus of the contact lens model. The average value estimated for the contact lenses was 1.33 ± 0.02 MPa which is within the range of values reported for this type of contact lens (1.2 to 1.4 MPa). Finally after technique validation, measurements were made on six rat eardrums with immobilized ossicular chains. The same procedure as for the contact lens was
used to measure the eardrum Young's modulus. For the six eardrum samples, an average value of 22.8 ± 1.5 MPa was obtained for the Young's modulus, which is comparable to values found in the literature. Moreover, the results are repeatable as indicated by the low standard deviation.
Ghadarghadar Jahromi, Seyedeh Nastaran, "Estimation of the quasi-static Young’s modulus of the rat eardrum using a pressurization method" (2009). Digitized Theses. 3966.