Developing a Physical Model of the Human Cochlea Using Microfabrication Methods

Steele, Charles R.; Puria, Sunil

doi:10.1159/000090683

Cited by 58 publications

(34 citation statements)

References 34 publications

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“…Recently, researchers have developed fluid-filled microscale models that respond to sound in a manner similar to the mammalian cochlea. The work by Zhou et al (25) (27) developed a device containing a polyimide membrane with an aluminum frame, which shared some similarities with the biological cochlea in terms of traveling waves. The work by White and Grosh (28) used silicon micromachining technology to create their cochlea model.…”

Section: Generation Of Voltage Output By the Implanted Device In Respmentioning

confidence: 99%

Piezoelectric materials mimic the function of the cochlear sensory epithelium

Inaoka

Shintaku²,

Nakagawa³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

121

127

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Cochlear hair cells convert sound vibration into electrical potential, and loss of these cells diminishes auditory function. In response to mechanical stimuli, piezoelectric materials generate electricity, suggesting that they could be used in place of hair cells to create an artificial cochlear epithelium. Here, we report that a piezoelectric membrane generated electrical potentials in response to sound stimuli that were able to induce auditory brainstem responses in deafened guinea pigs, indicating its capacity to mimic basilar membrane function. In addition, sound stimuli were transmitted through the external auditory canal to a piezoelectric membrane implanted in the cochlea, inducing it to vibrate. The application of sound to the middle ear ossicle induced voltage output from the implanted piezoelectric membrane. These findings establish the fundamental principles for the development of hearing devices using piezoelectric materials, although there are many problems to be overcome before practical application.cochlear implant | hearing loss | mechanoelectrical transduction | traveling wave | regeneration T he cochlea is responsible for auditory signal transduction in the auditory system. It responds to sound-induced vibrations and converts these mechanical signals into electrical impulses, which stimulate the auditory primary neurons. The human cochlea operates over a three-decade frequency band from 20 Hz to 20 kHz, covers a 120-dB dynamic range, and can distinguish tones that differ by <0.5% in frequency (1). It is relatively small, occupying a volume of <1 cm 3 , and it requires ∼14 μW power to function (2). The mammalian ear is composed of three parts: the outer, middle, and inner ears (Fig. 1A) (3). The outer ear collects sound and funnels it through the external auditory canal to the tympanic membrane. The cochlea consists of three compartments: scala vestibuli and scala tympani, which are filled with perilymph fluid, and scala media, which is filled with endolymph fluid (Fig. 1C). The scala vestibuli and scala tympani form a continuous duct that opens onto the middle ear through the oval and round windows. The stapes, an ossicle in the middle ear, is directly coupled to the oval window. Sound vibration is transmitted from the ossicles to the cochlear fluids through the oval window as a pressure wave that travels from the base to the apex of the scala vestibuli through the scala tympani and finally to the round window (Fig. 1B). The scala media are membranous ducts that are separated from the scala vestibuli by Reissner's membrane and separated from the scala tympani by the basilar membrane. The pressure wave propagated by the vibration of the stapes footplate causes oscillatory motion of the basilar membrane, where the organ of Corti is located. The organ of Corti contains the sensory cells of the auditory system; they are known as hair cells, because tufts of stereocilia protrude from their apical surfaces (Fig. 1D). The oscillatory motion of the basilar membrane results in the shear motion of the st...

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Section: Generation Of Voltage Output By the Implanted Device In Respmentioning

confidence: 99%

Piezoelectric materials mimic the function of the cochlear sensory epithelium

Inaoka

Shintaku²,

Nakagawa³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

121

127

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“…This assumption was accepted in general for the study of cochlear mechanics using mathematical, FE and physical models. 2,14,16,21,28,[34][35][36][37] The geometry of cochlear model was based on dimensions and structure published in the literature similar to the real curved geometry of the cochlea, including the oval window, round window, scala vestibuli, scala tympani, and BM. 3,30,36 Figure 2 shows the structure of the cochlear model with detailed dimensions and boundary conditions.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…The published data on BM motion were mainly obtained from mathematical and physical models of human cochlea. [2][3][4]14,28,34,36,37 Every mathematical or physical model has its own features, numerical analysis methods, and limitations. For The magnitude of the BM displacement vs. the stapes displacement of 11-25 dB obtained from our model (Fig.…”

Section: Preliminary Studies On Cochlear Mechanicsmentioning

confidence: 99%

“…Several cochlear models isolated from the middle ear have been reported in the literature such as the numerical model, FE model, and physical model of the human or animal cochlea. The mathematical models, 21,28,34 FE models, [2][3][4]14 and physical models 16,[35][36][37] of the cochlea were assuming that the vibrations were applied on the oval window or one side of the scala vestibule. All the cochlear models were isolated from the middle ear.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of Sound Transmission from Ear Canal to Cochlea

2007

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A 3-D finite element (FE) model of the human ear consisting of the external ear canal, middle ear, and cochlea is reported in this paper. The acoustic-structure-fluid coupled FE analysis was conducted on the model which included the air in the ear canal and middle ear cavity, the fluid in the cochlea, and the middle ear and cochlea structures (i.e., bones and soft tissues). The middle ear transfer function such as the movements of tympanic membrane, stapes footplate, and round window, the sound pressure gain across the middle ear, and the cochlear input impedance in response to sound stimulus applied in the ear canal were derived and compared with the published experimental measurements in human temporal bones. The frequency sensitivity of the basilar membrane motion and intracochlear pressure induced by sound pressure in the ear canal was predicted along the length of the basilar membrane from the basal turn to the apex. The satisfactory agreements between the model and experimental data in the literature indicate that the middle ear function was well simulated by the model and the simplified cochlea was able to correlate sound stimulus in the ear canal with vibration of the basilar membrane and pressure variation of the cochlear fluid. This study is the first step toward the development of a comprehensive FE model of the entire human ear for acoustic-mechanical analysis.

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“…Wittbrodt, et al [6] developed a membrane made of polymide using aluminum beams. Their paper states that this membrane had traveling waves similar to those of the biological basilar membrane.…”

Section: Methodsmentioning

confidence: 99%