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By Julia Ferrante
LEWISBURG, Pa. — Megan Long sits perfectly still in the rolling office chair with her chin turned up slightly. Three gold electrodes are affixed firmly to the center of her forehead and the back of her head, and two green and red plastic monitors are positioned on her neck.
"OK, close your eyes, Megan," her classmate Kelsey Wiggin says. Several seconds later, a toy car-sized motor on wheels borrowed from a Lego set begins to crawl across a set of strings suspended above the table.
"Now open your eyes," Wiggin says. The motor crawls to a stop.
"Flex your neck" she says. The motor switches directions.
Long and Wiggin are testing a brainwave- and muscle-activated mechanism they developed with fellow rising senior and biomedical engineering major Ben Geib for a Fundamentals of Biomedical Signals and Systems class at Bucknell University. Their hope is that the technology, if further developed, could be used in prosthetic devices or with stroke patients, for example, to help them better control their movements and motion.
Signals and systems
Assistant Professor of Biomedical and Electrical Engineering Joseph Tranquillo asked the students in the class to develop devices that incorporated the theory and practical uses of biomedical signals and systems. The students were to define a problem on their own and come up with a solution.
Other class projects included a prototype for an automatic insulin pump that turns on when needed rather than manually; a device to simulate the effects of varying red blood cell counts and measure how the body reacts to those variations; and a mechanism to monitor how the body over time learns to react to nicotine from cigarettes, snuff and chewing tobacco.
Long, Wiggin and Geib wanted to pursue a project that explored brain power, Wiggin said. Geib had conducted research in the summer of 2009 on neuroprosthetics and was familiar with such devices. Similar mechanisms in development by others include brain-powered wheelchairs and computer word processors.
Tranquillo conceded he was skeptical when the students proposed the project, noting that isolating a particular brainwave is similar to picking out an individual alto voice in the Halleluiah Chorus.
"When you record a signal from the body, especially from the brain, it is tiny and needs to be hugely amplified," he said. "On top of that, there are thousands of little processes occurring all at once, and we may only want to pick out one of them. The question for the students was: How do you isolate the signal you want?"
Before developing the device, Wiggin, Long and Geib researched how to identify specific signals based on their range of frequency. They consulted Psychology Professor David Evans about EEG and EMG technology and asked Professor of Mechanical Engineering Steve Shooter for advice about robotic motors.
The students chose to isolate signals from the occipital lobe or vision center for the EEG readings, Long said, because it produces a pronounced signal.
The results, Tranquillo said, came through following "an excellent engineering design process combined with a good dose of hard work."
"The device is pretty primitive, but this is what it looks like when someone builds a first prototype to show proof of the concept," he said. "What is impressive about this is that the students did this entirely on their own."
How it works
The device is in principle very simple, but because it involves isolating brain signals, it includes several electrical devices.
Electrode sensors are attached to a human subject and an amplifier, which magnifies the brain and muscle signals up to 10,000 times. The magnified signals are then filtered to remove non-biological noise such as lights and radio waves. The signal is then sent to a laptop computer where it is further filtered to isolate the specific brainwave and muscle twitches of interest. The presence of these particular signals is what triggers the motion of the motor through another series of electronic amplifiers.
Each person has different peaks and valleys in their brainwaves, and those patterns vary depending on the day, Wiggin noted.
"Every time we come in, there are variables depending on hours of sleep and how much caffeine they have had," Wiggin said.
"Today, my earrings were interfering," Long said, holding up a pair of silver hoops. "If someone is doing an experiment upstairs, it also can affect the readings."
Once they discern a pattern in the brainwaves, the students instruct the computer to send signals to the motor to switch it on or off or change its direction from left to right, Wiggin explained. The group has had about a 75 percent success rate.
The students hope someday to have the chance to further develop their device.
"In the future, we would hope to add four or five dimensions to the movement of the motor," Wiggin said. "With time and money, we could adapt this. It is just the very beginning of something that could be used for a prosthetic limb."
"I think we created a really good base," Long agreed.
Shooter, the professor who offered the group advice about robotics, commended the students for their ingenuity.
"We tend to think of engineering and our fields as acting in a silo, but they're all integrated," he said. "The students start thinking about it and they realize, 'Hey, they are doing the same kinds of things in psychology, too, just from a different perspective.'"
Dan Cavanagh, chairman of the biomedical engineering department, said the project demonstrated to the students how taking risks can pay off in engineering.
"What makes this most exciting is that here are three students who chose to go outside the boundaries of what we thought the project was and to answer something we did not know the answer to," he said. "Instead of following a recipe step by step, it was a real discovery process."
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