Research Experiences for Undergraduates (REU)
2018 Mechanical Engineering Opportunities
Name: Paul Funkenbusch
Department: Mechanical Engineering
Research area: Dental Biomechanics
Processing and performance of materials for medical/dental applications
Man-made materials such as metal alloys and cements are routinely used for repair and improvement in medicine and dentistry (e.g. dental fillings). These materials often need to be prepared quickly, on site, and in relatively poorly controlled conditions. How does this affect their performance? Given the process variability, can fabrication protocols be robustized” to improve performance and consistency?
The student(s) will design and run an in vitro material fabrication process incorporating realistic variability, test the resultant material properties, and analyze the results to determine an optimum material fabrication protocol.
Name: Sheryl Gracewski
Department: Mechanical Engineering
Research area: Ultrasound
The cochlea is a spiral-shaped, liquid-filled organ in the inner ear that converts sound with high frequency selectivity over a wide pressure range to neurological signals that are eventually interpreted by the brain.
External sound stimuli are encoded at different locations along the cochlear coil (35 mm in human cochlea) according to their frequency. The cochlear partition, consisting of the organ of Corti supported below by the basilar membrane and attached above to the tectorial membrane, plays a major role in the frequency selectivity. The stiffness gradient of the cochlear partition along the length of the cochlea is in part responsible for the tonotopy—the relation between excitation frequency and location of maximum response.
This project involves modeling and improving a device designed for experimentally measuring the stiffness of a cochlear partition section and its response to acoustic stimulation.
Different types of hearing loss/difficulty are ascribed to the failure/disturbance of subtle balance between two types of lymphatic fluids in the cochlea. The cochlea operates like an electrochemical battery. The cochlea is partitioned into three compartments filled with the lymphatic fluids. The separation of the two fluids provides an electric potential of approximately 80 mV that is crucial for hearing. To transduce sounds into neural impulses, there exists constant leaking (depolarizing) currents between the two fluid spaces though the sensory epithelium called the organ of Corti. Supporting cells in the organ of Corti must transport ions to maintain the electric potential. According to current theory, cochlear fluid homeostasis is responsible for the loss of auditory receptor cells (hair cells). The PIs propose to examine the converse of the current theory: they hypothesize that the mechanical feedback of auditory receptor cells facilitates the maintenance of cochlear fluid homeostasis.
This proposed project challenges the assumption of diffusion-limited ionic transport in the cochlear fluid. Recent observations show unique deformation patterns of the organ of Corti due to active mechanical feedback of the hair cells. This project aims to connect the active organ of Corti mechanics with the cochlear fluid homeostasis by demonstrating a different mode of ion transport—peristaltic fluid mixing. Specifically, it will be shown that: 1) the electromotility of outer hair cells generates peristaltic fluid motions in the organ of Corti, and 2) the peristaltic fluid motions help to homogenize cochlear fluids. This proposed project will transform hearing science by integrating two research domains that have not been considered together: mechanics and ion homeostasis of the cochlea. The unique expertise of Drs. Nam and Kelley is crucial for the success of this ambitious project. Nam has a solid research record in hair cell physiology, cochlear micro-mechanics, and finite element analysis. Kelley has expertise in experimental fluid dynamics, especially in the mixing and reaction of solutes within viscous fluids.