T-ray test
Clough, an R.P.I. doctoral student in electrical, computer and systems engineering who hopes to complete his PhD within a year, has demonstrated a cost-effective technique for using sound waves to boost the effective distance of terahertz spectroscopy from less than a meter to several meters.

Passing terahertz waves through an object renders a spectral fingerprint of its chemical composition. Because this frequency (which exists in the electromagnetic spectrum between the infrared and microwave bands) is able to penetrate many optically opaque barriers, terahertz waves effective at longer range hold potential for detecting hidden explosives, chemicals and other dangerous materials while allowing security personnel to keep their distance. Terahertz radiation is also low energy, so if they are used to scan people, the waves are less dangerous than x-rays or microwaves.

Unfortunately, terahertz waves do not propagate very well through the air, limiting their practical applications. "Even after a few feet you have quite a bit of your energy lost due to absorption by the water vapor in the air," says Clough, a 26-year-old native of Albuquerque, N.M. As a result, even though several airports already rely on a type of terahertz security scanners, they typically use low-frequency, continuous-wave energy at a single terahertz frequency, which enables them to create images of items carried in suitcases and pockets but not a spectral signature of those items that would indicate their composition.

Clough sees his sound-wave work having commercial and military applications. He is interested in postgraduate work at Sandia National Laboratories, where his father worked for years as a chemist and where Clough has had several internships. "I really enjoyed the environment there, and I know they are really security oriented, so I can envision possibly taking this tech there and hoping to further develop it," he says.

In gear
Daigle is a second-year graduate student in mechanical science and engineering at U.I.U.C. who plans to graduate in August. His mission over the past few years has been to make life easier for people who rely on manual wheelchairs for mobility. To that end, he co-founded IntelliWheels, Inc., in May 2010 with Marissa Siebel, a PhD candidate in community health and disability studies at U.I.U.C. and the athletic trainer for the Illinois wheelchair athletics team. The company's mission is to develop and commercialize an automatic gear shifter that can be installed on manual wheelchairs to reduce the amount of exertion required to operate them. "Gear shifting is in cars, it's in bikes, but for some reason it's not in wheelchairs right now," Daigle says.

The IntelliWheels device senses how fast the wheelchair is moving, whether it is on an incline or a decline, and how hard the chair's user is pushing. It uses that information to select the best gear and shift into that gear between pushes. Daigle says he was careful to not add too much weight to the wheelchair when designing the IntelliWheels device. "An ultralight wheelchair weighs about 10 pounds [4.5 kilograms]," he says. "Our system would add about 10 pounds of weight to the wheelchair, but you also end up with 95 percent mechanical efficiency when the gears are added." The device features a user interface that displays what gear the chair is in and offers a manual override button if the user would like to shift to a different gear.

Daigle has a working prototype of the device and has gotten approval to let wheelchair users begin testing it. "We're basically going to take about a month and run through about 20 wheelchair users to get them to test the chair in an everyday environment and get their feedback on the design," he says. "After that we are planning on life-cycle testing, where we put it through a simulated three years of life using a computer-controlled system. This should flush out all of the mechanical bugs."

The 24-year-old Westmont, Ill., native's plans after graduation are to devote as much time as possible to building IntelliWheels as a company. In order to support the flagship gear-shifting device, Daigle is also developing caster skis that clip onto a manual wheelchair's wheels to help them move more easily through snow. Another idea is to create snap-on snow chains for the winter months. "We're working to develop these and hope to get them for sale on our Web site in the next few months," he says.

View a slide show of the Lemelson-M.I.T. award-winning technology.

1 Comments

1. 1. JDahiya 04:01 AM 3/16/11

   Intriguing! More power to these dynamic inventors!

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