Estimation of the quasi-static Young's modulus of the eardrum using a pressurization technique

• Published in: Computer methods and programs in biomedicine Vol. 110; no. 3; pp. 231 - 239
• Main Authors: Ghadarghadar, Nastaran, Agrawal, Sumit K., Samani, Abbas, Ladak, Hanif M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ireland Ltd 01.06.2013; Elsevier
• Subjects: Algorithms; Animals; Biological and medical sciences; Computer Simulation; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Eardrum; Elastic Modulus; Exact sciences and technology; Finite element; Finite Element Analysis; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); Humans; Internal Medicine; Measurement and testing methods; Mechanical contact (friction...); Middle Ear Ventilation; Models, Biological; Optimization; Other; Pars tensa; Physics; Pressure; Rats; Rats, Sprague-Dawley; Solid mechanics; Static elasticity (thermoelasticity...); Structural and continuum mechanics; Tympanic Membrane - anatomy & histology; Tympanic Membrane - physiology; Tympanic Membrane - surgery; User-Computer Interface; Vertebrates: nervous system and sense organs; Young's modulus; Young's modulus; Pars tensa; Eardrum; Optimization; Finite element; Elastic constant; Tympanum; Hardness test; Point contact; Deformation modulus; Thin shell; In situ; Quasi static theory; Mechanical contact; Experimental study; Indentation; Modeling; Pressurizing; Inverse problem; Young modulus; Finite element method; Tympanic organ; Middle ear; Curved shape
• ISSN: 0169-2607; 1872-7565; 1872-7565
• DOI: 10.1016/j.cmpb.2012.11.006

The quasi-static Young's modulus of the eardrum's pars tensa is an important modeling parameter in computer simulations. Recent developments in indentation testing and inverse modeling allow estimation of this parameter with the eardrum in situ. These approaches are challenging because of the curved shape of the pars tensa which requires special care during experimentation to keep the indenter perpendicular to the local surface at the point of contact. Moreover, they involve complicated contact modeling. An alternative computer-based method is presented here in which pressurization is used instead of indentation. The Young's modulus of a thin-shell model of the eardrum with subject-specific geometry is numerically optimized such that simulated pressurized shapes match measured counterparts. The technique was evaluated on six healthy rat eardrums, resulting in a Young's modulus estimate of 22.8±1.5MPa. This is comparable to values estimated using indentation testing. The new pressurization-based approach is simpler to use than the indentation-based method for the two reasons noted above.