14 Oct PhD student takes Torgersen Graduate Research prize
For the second time in three years, a mechanical engineering doctoral student has earned the Paul Torgersen Graduate Student Research Excellence Award. The award recognizes the top research done by a graduate student.
The first place award, presented in the spring, was given to Sheyda Davaria, a student working in the Vibration, Adaptive Structures and Testing Lab with advisor Pablo Tarazaga, associate professor of mechanical engineering and John R. Jones III Faculty Fellow.
Born in Maryland but raised in Iran, Davaria graduated from the University of Tehran with bachelors and master’s degrees in mechanical engineering, and arrived at Virginia Tech in 2015.
“During my first year here, I was a teaching assistant and I took a vibrations class with Dr. Tarazaga and at the same time I was looking at different faculty’s research to choose my project and advisor,” Davaria said.
Davaria’s father and uncles, all engineers, have degrees from different universities, and they encouraged her to come to Virginia Tech. “I was looking at top 30 graduate programs, especially those with faculty researching in areas such as biomedical applications, vibrations, controls, and mechatronics,” she said. “Virginia Tech was the perfect university for me.”
Though struck originally by the small town and green surroundings of Blacksburg, what Davaria found in Tarazaga’s lab, both in terms of research and community, made choosing her project easy.
Her mother was part of the reason Davaria chose to develop active artificial hair cells.
“A few years ago, my mom lost partial hearing in one of her ears, and it was a sudden loss,” Davaria explained. “She woke up and couldn’t hear anything. From that time I wanted to work on the ear and for people with hearing loss. After I joined the lab I told my mom about the project and it is really interesting that I can give her information that is very different than what she gets from her ENT doctor.”
The project Davaria is working on, and that won the Torgersen award, is an NSF-sponsored $300,000 project called Developing Active Artificial Hair Cells Inspired by the Cochlear Amplifier.
When sound enters the ear it travels from the outer ear to the inner ear and reaches the cochlea, where it decomposes into its frequency contents. These frequencies are captured by two types of sensory hair cells. One is responsible for amplification or compression of the sound, and the other for converting the mechanical motion caused by sound waves into electrical signals that can be processed by the brain.
“Our ears compress large sounds, such as at a concert, to protect the ear, which is why we can hear over a large range of sound pressure levels,” Davaria said. “The same system amplifies sound so we can hear faint noises or catch bits of a conversation amid other sounds. This important process is called the cochlear amplifier and it is what we are trying to mimic with our research.”
Currently, the research is using large scale structures to mimic the hair cells’ function in the ear. These cantilever beams use piezoelectric materials which convert the mechanical motion of the beam into electrical signals.
“We shake the base of the beams and measure the velocity at the tip of the beam with a laser vibrometer,” Davaria explained. “Then we pass the signal through a nonlinear controller, feed it back to the beam’s piezoelectric layers and try to mimic the cochlear amplifier. The system amplifies or compresses the output based on the level of input and because of this it works very similarly to biological cochlea.”
The current work, in scales of 1-inch beams, needs to be reduced to micro scales more comparable to the biological system, but Davaria is confident the algorithms that she has developed are working.
“We’re trying to provide algorithms that work – and it works perfectly for large scale artificial hair cells,” Davaria said, “but we need to miniaturize the system and then use bio-compatible materials. We still have a long way to go, but the results so far are promising.”