AYREU Project 7 Functional Model of a Cadaveric Human Middle Ear William Holden Senior Chemical Engineering Margaret Welch PreJunior Biomedical Engineering College of Engineering and Applied Science ID: 770079
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AY-REU Project 7: Functional Model of a Cadaveric Human Middle Ear William Holden, Senior Chemical EngineeringMargaret Welch, Pre-Junior Biomedical EngineeringCollege of Engineering and Applied Science, University of Cincinnati; Cincinnati, OhioMentor: Dr. Vasile Nistor, CEAS-Biomedical Engineering Sponsored by the National Science Foundation Grant ID No.: DUE-0756921
Presentation OutlineBackgroundExperimental Objectives Measurement and Analysis MethodsResultsConclusions2
BackgroundMany ailments lead to middle ear damageA functional model is needed to better test prostheses and prepare surgeonsUsing MicroCT and rapid 3-D printing, models could be customized to patients33-D Model of Incus bone created in previous senior design project
Experimental ObjectivesLong Term Goal: Create an accurate functional model of the human middle ear Our Project’s Goals: Develop measurement setup and techniques to evaluate model performanceDetermine repeatability of measurementsDevelop analysis methods from LDV measurements4
Measurement Setup Tripod for mounting laserMiddle Ear Model Driving piston Beam tracking Laser Doppler Vibrometer 5
Laser Doppler VibrometryLaser sample beam directed at surface to be measuredVibrating surface reflects and Doppler shifts beam Doppler shift is measured to determine surface velocity6
Measurement MethodsMeasure:Velocity of different parts of model: Malleus, Short Process, StapesAt different angles For different driving amplitudesFor different driving frequenciesColeman, J. “Organs of Hearing." Biological Foundations of Language: Speaking and Hearing. (Apr. 4, 2013) <http://www.phon.ox.ac.uk/jcoleman/speaking_hearing.htm>7
Analysis MethodsAxis of motionFrequency spectrum of velocitiesResponse linearityMeasurement repeatability 8
Axis of MotionFor stapes, motion was determined to be piston-like, in and out of the oval windowDetermining axis of motion of stapes can be point of comparison Axis of motion can be determined for different pointsMethod could be extrapolated to three dimensionsFrom: Chien, W., Rosowski, J. J., Ravicz, M. E., Rauch, S. D., Smullen, J., and Merchant, S. N. (2009). "Measurements of stapes velocity in live human ears." Hearing Research, 249(1-2), 54-61.9
Axis of MotionMeasured velocity VM is only fraction of total velocity VT:For certain quantities of interest (Energy, Maximum Displacement), total velocity is important V θ 10 Sample Beam
Axis of MotionMeasurements taken at different anglesBeam path traced onto paper Angles between paths estimated11
Axis of Motion Angle Average Peak Frequency (Hz) Stdev (Hz) Average Peak Velocity (um/sec) Stdev (um/sec) Estimated θ ( deg ) V T *Cos( β-θ) Difference divided by Standard Deviation 0degree 499.47 0.06 1242 79 0.0 1251 0.12 Angle1 499.69 0.36 2702 105 20.1 2630 0.68 Angle2 499.64 0.10 3724 141 42.1 3767 0.30 Angle3 499.86 0.52 593 56 -8.4 619 0.48 1 2 3 True Axis 12 Model Equation:
Axis of Motion13 Defined 0°Determined Axis Usual Assumed Measured
Frequency Spectrum of VelocitiesSeveral publications use this form of measurementVelocities are measured for interval of frequenciesVelocity versus frequency plot is made 14
Frequency Spectrum of VelocitiesStapes Head Malleus15Driving Piston:Frequency Range: 10-90 Hz Amplitude: 3 Volts Measurement Points: Stapes & Malleus
Frequency Spectrum of Velocities16
Frequency Spectrum of Velocities17
Frequency Spectrum of Velocities18
Response LinearityPrevious work has shown a linear response of measured velocities for changing pressuresWe tested linearity of measured velocity for changing driving voltages 19
Response Linearity 20 These measurements were made on the Malleus of the model.
Response Linearity 21 These measurements were made on the Malleus of the model.
Measurement RepeatabilityMeasurement repeatability was tested by taking multiple measurementsBetween measurements, the setup was reconstructed 22
Measurement Repeatability These measurements were made on the Malleus of the model.23
ConclusionsLDV measurement setup and techniques have been successfully demonstratedLDV measurement repeatability has been verified Analysis methods have been created that allow for model performance to be evaluatedAnalysis methods will allow for improvement of future models with increasing accuracy24
Project #7 - Functional Model of a Cadaveric Human Middle Ear Long Term Goal: Create an accurate functional model of the human middle earOur Project’s Goals: Develop measurement setup and techniques to evaluate model performanceDetermine repeatability of measurementsDevelop analysis methods from LDV measurements25